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ABSTRACT
Year : 2015  |  Volume : 11  |  Issue : 7  |  Page : 93-100

Medical Physics


Date of Web Publication24-Nov-2015

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How to cite this article:
. Medical Physics. J Can Res Ther 2015;11, Suppl S3:93-100

How to cite this URL:
. Medical Physics. J Can Res Ther [serial online] 2015 [cited 2019 Nov 22];11:93-100. Available from: http://www.cancerjournal.net/text.asp?2015/11/7/93/170053

Abstract: 004

Clinical implementation and application of Monte Carlo methods in photon and electron dose calculation

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L. Aggarwal , S. Pradhan, N. Sharma, S. Sharma, A. Kajaria

Institute of Medical Sciences (BHU), 1 School of Biomedical Engineering Indian Institute of Technology (BHU) Varanasi,

Uttar Pradesh, India, E-mail: lmaggarwal@yahoo.com


In radiotherapy, the dose delivered to patients needs to be determined before the treatment. Therefore, it is necessary to have an accurate method for predicting the dose distribution. In the past, planning computers calculate radiation dose using data obtained by measurement in a water phantom. This will lead to about 5% to 10% error in the situations where in homogeneity and lateral electron disequilibrium occur, especially in small field sizes. For these situations, Monte Carlo Simulation (MCS) has been proposed to give the most accurate solution. The first available MCS code for treatment planning was developed as part of the OMEGA project, which started in the early 90s by the National Research Council of Canada and the University of Wisconsin in Madison. The MCS code used was called EGS4 and it modeled the transport of photons and electrons. For radiotherapy, the BEAM system (which was based on EGS4) was used for modeling of radiotherapy sources. These days, EGS4 and BEAM have been replaced by their new versions EGSnrc and BEAMnrc. MCS models the transport of photon and electron by recording the interactions of each particle until it reaches the preset threshold energy. Therefore, MCS requires an extensive use of computer power. In the early 90s when the processing speed of computers was slow, one simulation would require several days before a result was available. The time required was impractical for clinical purposes. As an alternative deterministic dose calculation algorithms where developed for treatment planning. The Monte Carlo method has been shown through many research studies to calculate accurate dose distributions for clinical radiotherapy, particularly in heterogeneous patient tissues where the effects of electron transport cannot be accurately handled with deterministic dose calculation algorithms.

Abstract: 005

Monte Carlo study of a flattening filter-free 6 MV varian linac using the BEAMnrc code

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A. Kajaria , N. Sharma, S. Sharma, S. Pradhan, L. Aggarwal

School of Biomedical Engineering Indian Institute of Technology (BHU), 1 Institute of Medical Sciences (BHU), Varanasi,

Uttar Pradesh, India, E-mail: akajaria.rs.bme12@itbhu.ac.in


In conventional linear accelerators, the flattening filter scatters and absorbs a large fraction of primary photons. Increasing the beam-on time, which also increases the out-of-field exposure to patients, compensates for the reduction in photon fluency. In recent years, intensity modulated radiation therapy has been introduced, yielding better dose distributions than conventional three dimensional conformal therapy. The drawback of this method is the further increase in beam-on time. An accelerator with the flattening filter removed, which would increase photon fluence greatly, could deliver considerably higher dose rates. The objective of the present study is to investigate the dosimeter properties of 6 MV photon beams from a Varian linear accelerator without a flattening filter. The dosimetry data were generated using the Monte Carlo programs BEAMnrc and DOSXYZnrc. We compared depth doses, dose rates, lateral profiles, and doses outside collimation for an accelerator with and without flattening filter. The study showed that unflattened beams have the following characteristics: a higher dose rate by factors of 2 on the central axis; lower out-of-field dose due to reduced head scatter and softer spectra and less variation of the shape of lateral dose profiles with depth. The findings suggest that with a flattening filter free accelerator better radiation treatments can be developed, with shorter delivery times and lower doses to normal tissues and organs.

Abstract: 064

Postoperative strontium-90 beta irradiation in bulbar conjunctival carcinoma: A case series

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B. Dutta , R. Tudu, A. Halder, N. Biswas, D. Barman, P. Deb

Medical College Hospital, Kolkata, West Bengal, India, E-mail: bodhiyumyum@gmail.com

Background: Conjunctival squamous cell carcinoma, a rare, slow growing malignancy, is associated with an unacceptably high rate of local recurrence after simple excision, prompting the use of various adjuvant treatments, including localised beta irradiation. Aim: Our case series aims to demonstrate the safety and efficacy of postoperative beta irradiation for bulbar conjunctival squamous cell carcinoma. Materials and Methods: From September 2013 to June 2015, a total of 11 patients (corresponding to 11 eyes with disease) were referred to us after primary surgical removal of a suspicious growth of the bulbar conjunctiva, followed by histopathological diagnosis of invasive or in-situ squamous cell carcinoma. Beta irradiation was given in a dose of 80 Gy in 10 fractions, 3 fractions per week. The machine used was a Strontium 90 β-ray applicator that has been in our centre since the 1950s. It consists of a circular strontium source mounted on a long handle, with an intervening Perspex disc meant to protect the treating doctor from the harmful effects of β-rays. The radioactive Strontium 90 and its decay product, Yttrium 90 are pure β emitters of low penetrating power, ideal for treatment of surface lesions, including conjunctival carcinoma. Regular follow up was done at our OPD for assessment of response, recurrence and adverse events. Results: After a relatively brief median follow up of 13 months, none of the patients showed locoregional recurrence, and none of them developed a cataract. Two of the patients reported local eye irritation and foreign body sensation during and after treatment, which were controlled with steroid-antibiotics and lubricant eye drops. No other adverse events were seen. Conclusion: Beta irradiation with a Strontium90 Applicator is a simple, yet remarkably safe and efficient method for local control of postoperative conjunctival carcinoma. However, a longer follow up with a larger number of patients would be a better assessment of the efficacy and safety of this method.

Abstract: 068

Role of paperless clinic in modern radiotherapy practices

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A. Nachankar , M. Bhosale, V. Mhatre, P. Patwe, R. Patil, P. Dandekar

Sir H. N. Reliance Foundation Hospital, Mumbai, Maharashtra, India, E-mail: ankita.nachankar@rfhospital.org

Background: Electronic medical records are safe & efficient data recording & verification system available in today's era. Aim: We conducted an audit of paperless radiotherapy processes in our institution to assess safety & efficiency of the systems. Materials and Methods: We use ARIA paperless system (VMS version 13.0) as the Oncology Information System right from the inception of the department of Radiation Oncology at our institution. The data entered in ARIA included diagnosis, simulation documents, scanned copy of consent and clinical assessment. We developed customized care path for workflow, prescription templates and dose constrains for organs at risk (OAR) for common sites. To ensure complete compliance and safety, we have developed customized checklists and questionnaires for every task in the care path. All the patients undergo clinical review, audit of processes and offline review of the images acquired during IGRT at regular intervals to ensure compliance. In addition to several checks we devolved clinical alert system to convey messages, deviation related patient treatment parameter like offline image review. We conducted audit our services from Feb 2015 to July 2015 for all the cancer patients (N = 71). Results: Compliance to digital data entry was 100%, care path was followed for 80% and checklist compliance was 100%. Electronic prescription were used in 100%, templates were used in 65% while the rest were prescribed with customized prescription. Regular evaluation of toxicity, treatment tolerance was nutritional status was recorded in 100% with mean number of reviews documented in system 2.44 per patient (range 2.0 to 2.85). Mean number of audits per patients were 1.65 (range 1.38 to 1.92), which resulted in mean 3.46 clinical alerts (range 2.61 to 4.32) per patient. Mean number of onboard imaging (IGRT) performed was 20.3 and off line reviews by radiation Oncologists was done in 89%. The discrepancies between online and off line matching was 10% and appropriate actions were taken. Conclusion: Electronic records and verification system provides better data documentation & verifications. Also it helps to streamline radiotherapy treatment planning processes to ensure compliance, consistency and safety for radiotherapy patients.

Abstract: 092

A dosimetric comparison of inverse planned tangential beam IMRT and field-in-field 3D-CRT in whole breast irradiation following breast conservation surgery

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D. Divya , D. Kumar, D. Sarma, M. Janardhan, M. Jagadeesan,

M. Ibrahim

Omega Hospitals, Hyderabad, Telangana, India, E-mail: divyasmrithi@yahoo.co.in

Background: WBI +/- RNI is an integral component of breast conservation treatment protocols in breast cancer. Though 3D-CRT is traditionally employed, with the advancement in technology, the role of IMRT in WBI has been evolving in the past decade. Aim: To compare the dose-volume statistics of the target volume (whole breast) and OAR's between FiF-3D-CRT and Tangential beam IMRT and to assess how the breast volumes affect the target dosimetry. Materials and Methods: A total of 35 early stage, node negative breast cancer patients (15 right sided and 20 left sided) were randomly selected and two plans were generated for each patient (total of 70 plans) using CMS Elekta TPS for a dose of 4256 cGy in 16 fractions at 266 cGy per fraction. Plans were evaluated and comparison of dose volume statistics was done using student 't' test. Dosimetric variations with respect to breast volumes i.e., small (<800 cc), medium (800-1100cc) and large (>1100 cc) were also analysed. Results: TB-IMRT had significantly better HI, CI, D95, D2, Dmean and Dmin values of the PTV over 3D-CRT. On subset analysis, HI and D2 values were significantly superior only in medium and large breast volumes while CI and Dmin were significant in all breast volumes. Superiority of D95 in TB-IMRT was lost on subset analysis while Dmean remained significant only in medium breast volumes. 3D-CRT had significantly lower Dmax for PTV, Dmax of C/L breast and significantly reduced low dose volumes i.e., V5 of C/L breast, V10, V5 of I/L lung and V5 of C/L lung while TB-IMRT significantly reduced only V30 of I/L lung. No significant difference was noted between the two plans in terms of V20, Dmean of I/L lung and V10 of C/L lung. In right breast irradiation, the V33 & V25 of heart were similar in both plans, but low dose volumes (V10, V5), Dmax and Dmean were significantly less with 3D-CRT. In left breast irradiation, TB-IMRT significantly reduced the V33 and Dmax of heart while 3D-CRT reduced the low dose volumes and Dmean values of heart. No difference was noted in V25 between both the plans. Conclusion: TB-IMRT had superior PTV dose volume statistics in all breast volumes. 3D-CRT, though had inferior target dosimetry, it was acceptable and the OAR parameters were superior or equivalent to TB-IMRT in right breast irradiation making it the modality of choice in them. But, in left breast irradiation, TB-IMRT can be considered a better modality, as it achieved better heart dose volume parameters over 3D-CRT.

Abstract: 100

Comparison of VMAT and IMRT in different subsites-single institutional experience

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D. Kumaran , D. Sharma, P. Agarwal, K. Hareesh, S. Gupta,

M. Laviraj, G. K. Rath

All India Institute of Medical Sciences, New Delhi, India, E-mail: damodaronc@gmail.com

Background: IMRT has proved its role in many sites like head and neck malignancies, prostate in better sparing of OAR's. There are many anecdotal reports of the new technique VMAT, which is actually a modification of IMRT, showing better and in some reports same as IMRT. This study taken up to know the exact role of VMAT technique. Aim: To evaluate the plan quality in terms of physical and radiobiological model assessment of IMRT and VMAT for various sites based on the same CT scan and contouring data. Materials and Methods: Retrospective analysis of 30 plans of IMRT and VMAT using Monoco planning system, to be delivered on Elekta linear accelerators were taken for evaluation. For plan evaluation statistics, PTV95, PTV2, homogeneity index, conformity index, mean doses, low dose regions and max doses to organs at risk (OAR) were analyzed. Treatment time and number of monitor units were assessed. EUD, NTCP and TCP were compared in both the plans. Follow up data of the patient were checked to see for toxicities. Results: Comparison of VMAT and IMRT plans within the same patient showed significantly better sparing for almost all OARs with VMAT. The dose conformity at 95% of the prescribed dose for PTV total was 1.23 for IMRT and 1.12 for VMAT, respectively. The average effective delivery time was reduced for VMAT compared to IMRT. Organ sparing was better with VMAT. Low dose region was significantly high compared to IMRT plan. An advantage of VMAT plans was that the average number of MUs (348 MU) was less than for IMRT plans (554 MU). Conclusion: VMAT plan was better in organ sparing but not achieved statistical significance. It reduced treatment time and MU with same quality of plan compared to IMRT.

Abstract: 157

IMRT plan evaluation in complex situations

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J. Elagandula

M.S. Ramaiah Medical College, Bengaluru, Karnataka, India, E-mail: jyosthna.elagandula@gmail.com

Background: Use of Intensity Modulated Radiotherapy has increased over the time. Since IMRT is characterized by steep dose fall off, ideal cases are those which have small volumes and relatively away from critical structures like spinal cord, brainstem as in non-nasopharyngeal head and neck cancers. However in most cases tumor and normal structures are closely related to each other and evaluation of the plan is challenging as there are no standard guidelines. In this study we compared various IMRT plan evaluations and tried to identify factors affecting the evaluation. Aim: To compare target coverage in different IMRT plans. To compare OAR doses in different IMRT plans. To identify various factors that influenced plan evaluation Materials and Methods: Twenty eight patients treated with Intensity Modulated Radiotherapy technique in our department from April 2015 to July 2015 were included. Treatment plans of these patients were evaluated qualitatively as well as quantitatively. PTV coverage, 107% volume, D max location, cold spot volume, homogeneity index, conformity index and OAR doses were compared. Results: Total of 28 patients out of which 17 male and 11 female were evaluated. Disease sites were 9 Pelvis, 12 Head & Neck, 3 Brain and 4 Abdomen. In 21 pts plan inputs in terms of target as well as OARs were achieved. In 7 pts IMRT plan resulted in compromise of coverage or little excess dose to OAR. Conclusion: IMRT plan evaluation is quite challenging in sites where target and OARs are closely located. A compromise has to be made either with respect to the tumor or critical structure. How far these dosimetric factors translate to clinical end points needs to be studied further.

Abstract: 158

Dosimetric comparison study between point based and volume based treatment planning for intracavitory brachytherapy in carcinoma cervix

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K. Vivekanand , M. G. Janaki, K. S. Mohan, S. Arvind, R. Sami

M.S. Ramaiah Medical College, Bengaluru, Karnataka, India, E-mail: drvivekanandnambiar@gmail.com

Background: To compare intracavitory brachytherapy (ICBT) planning methods for cervical cancer based on either orthogonal radiograph (conventional planning) or CT based (CT planning). The comparison is based on target volume coverage and dose volume analysis of organs at risk (OAR) s, by representing point doses defined by ICRU (International Commission on Radiation Units and Measurements) and dose volume histograms (DVH) from 3D planning. Aim: To compare the HRCTV coverage in both the plans and to compare the dose received by bladder and rectum in both the plans. Materials and Methods: We analyzed the dosimetric data for 22 patients conventional and CT based ICBT plans. The HRCTV (HIgh risk clinical target volume) and organs at risk (OAR) were contoured on CT plan. Point A, Point B and ICRU 38 rectal and bladder reference points were defined on reconstructed CT images. We calculated V100 V150 V200 for both CT based and conventional based plans. Also find out D 2cc of bladder and rectum in CT based plan. Results: Coverage in volume based planning 82.3% (v100=49.605) is significantly lower compared to conventional planning 92.07% (V100= 54.48). However better coverage with conventional planning, it is at the cost of higher dose to organs at risk. The mean bladder dose is 1.33 times and mean rectal dose is 1.51 times higher in conventional planning compared to CT based planning. Conclusion: The conventional planning is superior to the CT planning in terms of target volume coverage, however it is at the cost of higher dose to bladder and rectum.

Abstract: 164

Intensity modulated radiotherapy versus three dimensional conformal radiotherapy for chestwall irradiation in breast cancer patients: A dosimetric study

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M. Kausar , O. Gurjar, K. Gupta, V. Bhandari, P. Bagdare

Sri Aurobindo Medical College and P.G. Institute, Indore, Madhya Pradesh, India, E-mail: mehlamkausar52@gmail.com

Background: For Chest wall irradiation in breast cancer patients, three dimensional conformal radiotherapy (3DCRT) and intensity modulated radiotherapy (IMRT) have made tremendous changes in treatment delivery. However, the dose to organs at risk (OAR) is the matter of concern in both the techniques. Aim: This study evaluates dose distribution between IMRT and 3DCRT. Materials and Methods: For twenty five randomly postmastectomy breast cancer patients IMRT and 3DCRT plans were generated for radiotherapy treatment. The prescribed dose (PD) was 50 Gy/25# (with 2 Gy/#) planned to deliver in five weeks. Dose Volume Histograms (DVH) was evaluated for planning target volume (PTV) coverage and dose to OAR. Parameters of dose distribution were compared using unpaired student t-test. Results: Dose to 90% volume of PTV was greater than 90% both the techniques i.e., 90% of PTV receiving 94.8΁2.5% and 92΁1.4% of PD in IMRT and 3DCRT respectively. Confirmity Index (CI) was 1.40 and 1.83 in IMRT and 3DCRT respectively and homogeneity index (HI) was 1.08 and 1.1 in IMRT and 3DCRT respectively. V20 Gy of ipsilateral lung (33.67΁11.6 vs 36.6΁9.5), V5 Gy of contralateral lung (33.67΁23.5 vs 1.7΁6.50), V5 Gy of contralateral breast (38.7΁29.37 vs 7.7΁4.5), V5 Gy of heart in right sided patients (77.8΁28.3 vs 5.68΁5.04), V25 Gy of heart for left sided patients (28.23΁8.43 vs 21.9΁9.7) was observed in IMRT vs 3DCRT respectively. Conclusion: Adequate target coverage was achieved by both the techniques, however dose to OAR were lesser in 3DCRT plans as compared to that in IMRT plans. Thus, it can be concluded that 3DCRT is an efficient as well as cost effective technique for the chest wall irradiation as compared to IMRT.

Abstract: 167

Cone beam computed tomography an accurate imaging technique in comparison to orthogonal portal imaging in case of intensity modulated radiotherapy of prostate cancer

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A. Mutneja

Sri Aurobindo Medical College and P.G. Institute, Indore,

Madhya Pradesh, India, Email: mutnejaabhinav@hotmail.com

Background: Various factors cause geometric uncertainties during prostate radiotherapy including inter and intra fractional patient motion, organ motion and daily setup errors. This may lead to increased normal tissue complications when a high dose to the prostate is prescribed. More accurate treatment delivery is possible with daily imaging and localization of the prostate. Aim: To measure the shift of prostate by kilo voltage (kV) cone beam computed tomography (CBCT) after position verification by kV orthogonal portal imaging OPI. Materials and Methods: Position verification of ten patients of prostate cancer was done by OPI followed by CBCT before treatment delivery in 25 sessions for each patient. In each session OPI was done using On Board Imaging (OBI) system and pelvic bones to pelvic bones were matched. After applying the noted shift by OPI, CBCT was performed using OBI system and prostate to prostate was matched. Isocentre shifts along all three translational directions in both the techniques were combined in to a three dimensional iso-displacement vector (IDV). Results: The mean IDV (in cm) calculated from 250 imaging sessions is 0.931 (Standard deviation (SD): 0.598) with median 0.825 and 0.515 (SD: 336) with median 0.43 for OPI and CBCT respectively. Even after perfect bone to bone matching by OPI, significant shift in prostate was noted by CBCT. Conclusion: This study concludes that imaging with CBCT gives more accurate prostate localization compared to the OPI technique, hence CBCT should be chosen as the preferred imaging technique.

Key words: Cone beam computed tomography, organ motion, orthogonal portal imaging, prostate cancer

Abstract: 168

Intensity modulated radiotherapy versus three dimensional conformal radiotherapy in locally advanced carcinoma cervix patients: A comparative dosimetric study

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A. Naik , O. Gurjar, P. Bagdare, K. L. Gupta, V. Bhandari, M. Kausar

Sri Aurobindo Medical College and P.G. Institute, Indore,

Madhya Pradesh, India, E-mail: ayushnaik@gmail.com

Background: External beam radiotherapy (EBRT) is mainstay of treatment in locally advanced carcinoma cervix (LACC) patients. Treatment fields and target volumes for LACC have remained largely unchanged despite of various technological advances in radiotherapy delivery. In order to deliver adequate doses to these target volumes very large portion of rectum, bladder and bowel are also included in the high dose region exceeding critical normal tissue tolerance which highlights a persistent problem in the treatment of LACC. Three dimensional conformal radiotherapy (3DCRT) and intensity modulated radiotherapy (IMRT) are most commonly used techniques for EBRT however which one is superior is controversial. Aim: To compare dosimetric aspects of 3DCRTand IMRT planning in pelvic irradiation in LACC patients. Materials and Methods: Forty patients of LACC referred for definitive radiotherapy treated with IMRT which were treated in last one year were selected. For all these patients 3DCRT plans were also created for study purpose following Radiation Therapy Oncology Group (RTOG) guidelines. Both kind of plans were compared on the basis of planning target volume (PTV) coverage, dose conformity (CI95%), homogeneity index (HI) and doses to organs at risk (OAR). Results: Adequate PTV coverage was achieved with both the techniques. 95% and 99% PTV was covered by 98% and 96% respectively for IMRT and 3DCRT. Dose conformity was found much better in IMRT than seen with 3DCRT (1.462 ΁ 0.207 vs. 2.183 ΁ 0.317). HI was found similar in both the techniques. For bowel, V45 (volume receiving 45 Gy) was significantly reduced in IMRT compared with 3DCRT (132.01cc ΁ 91.08 cc. vs.227.7 ΁ 113.6 cc). In regard to rectum and bladder, D15, D35 and D50 (Dose to 15%, 35% and 50% volume respectively) were reduced by 7.46%, 23.82% and 43.68% for rectum and 2.09%, 14.623% and 32.57% for bladder in IMRT compared to 3DCRT respectively. No significant difference was seen in doses received by femoral heads of both sides. Conclusion: Using IMRT with proper immobilization devices and minimal setup errors results in reduction in doses received by OAR with better dose conformity compared to that in 3DCRT. Hence IMRT should be preferred technique for EBRT in LACC patients.

Abstract: 207

Dosimetric comparison of 3DCRT and IMRT in radiotherapy for carcinoma esophagus

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P. Roselil , J. Sachdeva, R. Chandran, P. A. Kingsley, P. Negi,

D. A. Phansopkar

Christian Medical College, Ludhiana, Punjab, India, E-mail: prarthanasamuel@yahoo.com

Background: Carcinoma esophagus is a tumor with rising incidence in India with most patients presenting with locally advanced tumors. With the improvement in survival with the availability of multimodality treatment, the need to prevent long term complications of radiation therapy which is an important part of treatment, becomes important. So in this study we proposed to analyze dosimetrically, 3 dimentional conformal radiotherapy (3DCRT) and intensity modulated radiotherapy (IMRT) plans of 19 patients treated in our department, between January 2014 and May 2015. Materials and Methods: IMRT plans were generated for these patients and were compared with the 3DCRT plans by which the patients were treated, extrapolated for a dose of 5040 cGy. All these patients had been simulated with 3mm slice computed tomography scans with oral and intravenous contrast, in supine position with hands above the head, immobilized with thermoplastic cast. The clinical target volume (CTV) included gross tumor volume (GTV) plus 5 cm cranial and caudal margin and 2 cm circumferential margin. The organs at risk considered for analysis were the heart, lungs and spinal cord. The dose volume histograms of both plans were analyzed for the dose to organs at risk (OAR), volume of OAR irradiated and target volume coverage for 6 megavoltage photons. Results: The mean lung dose and the volumes of lung receiving low doses were more with IMRT whereas, the volumes of lung receiving high doses were less with IMRT. Heart doses were less with IMRT. IMRT was useful in reducing spinal cord dose, more so in reducing volume of spinal cord receiving high doses. Target conformity was better with IMRT. Conclusion: With the large target volumes that we encounter as is the case in our setting the use of multiple beams in IMRT to achieve better target conformity, leads to larger volume of lung receiving small doses. In general IMRT is beneficial in reducing the volume of organs at risk receiving higher doses but not lower doses and should be used with caution in patients with large target volumes.

Abstract: 260

Study on comparison of setup errors and comfort levels of two commercially available immobilization systems for the treatment of head and neck cancer

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D. Kumaran , S. John 1 , R. Isiah 1 , S. Das 1

All India Institute of Medical Sciences, New Delhi, 1 Christian Medical College, Vellore, Tamil Nadu, India, E-mail: damodar.dr@gmail.com

Background: Intensity modulated radiotherapy [IMRT] is en effective tool in the treatment of head and neck tumors as the critical organs are in continuity with the target organ. Sparing of the critical organs with adequate tumor coverage is the highlight of IMRT. Immobilisation is an integral part of high precision radiotherapy like intensity modulated radiotherapy [IMRT] for accurate reproducibility of the patient setup and to decrease the patient movement during the radiation therapy so decreasing the set up errors. Aim: Comparison of setup errors and margins between five point ray cast and BrainLAB immobilization system in head and neck IG-IMRT. To assess the impact of weight loss on setup errors and to analyse the comfort levels between the two immobilization devices. Materials and Methods: Patient diagnosed to have head and neck malignancy were assigned to either of the group and prospectively analysed the displacement errors. In both the groups, systematic and random errors were analysed. The CTV-PTV margin was calculated using Van Herks formula and compared. The upper neck and lower neck points were also analysed in terms of systematic error, random error and CTV-PTV margin. All the patients were serially monitored with weekly weight and its impact was analysed on the setup errors and margins. Patients' comfort level was analysed at the completion of treatment in both the immobilization devices. Results: The five point ray cast and BrainLAB immobilization was found to be similar in terms of systematic errors and random errors, except in the anterior-posterior [AP] and medial-lateral axis [ML]. BrainLAB showed significant less margin in ML axis [3.61 Vs 3.14 mm, p = 0.0005] and in AP axis [3.33 Vs 2.66 mm, p = 0.0001]. The total margin required was similar in both the groups. The margin requirement in the upper neck fields was marginally better in the BrianLAB system than the five point ray cast. Weight loss of more than 3 kg required more margins, but was not statistically significant. Comfort levels were same in both the groups. Conclusion: The total CTV-PTV margin requirement for five point ray cast and BrainLAB immobilization is less than 5mm in all three directions. In patients requiring only upper neck irradiation BrainLAB system is recommended. Overall Five point ray cast and BrainLAB immobilization was comparable in terms of setup errors, margins and comfort levels.

Abstract: 276

High dose rate intra cavitary radiotherapy for cervical cancer, the physicist's experiences

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P. P. Chaurasia , S. B. Chand, M. P. Adhikary, R. N. Yadav, A. K. Jha, S. Pandit

B.P. Koirala Memorial Cancer Hospital, Chiwan, Nepal, E-mail: pradumnachaurasia@gmail.com

Objective: To demonstrate the medical physics activities in treatment of carcinoma cervix in B.P. Koirala Memorial Cancer Hospital (BPKMCH), Bharatpur, Nepal. Materials and Methods: Mega voltage external beam radiation therapy (EBRT) combined with (ICR) is the standard radio therapeutic management for the patients with carcinoma cervix. Patients have advantage of 6MV and 20 MV photons from linear accelerators compared with Tele cobalt beam. Vari source HDR machine with single Iridium -192 source wire of 5 mm length diameter 0.38 mm with half- life of 74 days requires source change in every 4 months. BPKMCH has its own protocol to prescribe total dose, time and fractionation will be discussed with its biologically effective dose. The physical aspects of the machine, ICR application, orthogonal simulation images import, and ICRU -38 point A, B, rectum and bladder point definition followed for dosimetry. Source activity measurement, quality assurance test, position verification, radiation protection and physics specific concerns and final check list followed. Clinicians must communicate about tumor volume to planning physicist so that he can optimized plan with pear shaped covering the diseased volume. Results: On site source strength measurements is within standard deviation of 0.6. The dose to rectum and bladder points is accepted between 60 to 70% of dose of point A and dose to Point B is about 25% of A. QA results and different pear shapes shown. Benefits are shorter treatment time, treatment on outpatient basis, less discomfort reduced risk of applicator displacement and safe practice. Conclusions: It is a vital clinical tool and 6/7 patients are treated daily. To tailor the dose according to shape of tumor volume is still a challenge in 2D.

Abstract: 278

Large single institutional report on the investigation of action level for site specific pre-treatment IMRT QA

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S. Rasal , P. Shaju, S. Mayur, K. Talapatra, P. Chada, S. Dayananda

Kokilaben Dhirubai Ambani Hospita and Medical Research Institute, Mumbai, Maharashtra, India, E-mail: srasal0@gmail.com

Background: There is no general consensus on the evaluation parameters of patient specific pretreatment quality assurance (QA) of IMRT plans. Aim: The aim of this study is to investigate the influence of lower threshold dose and dose difference at distance on 2D fluence verification of IMRT plans and derive site specific acceptance criteria. Materials and Methods: QA data of 1001 clinicaly treated IMRT plan (503 H&N, 131 Brain, 196 pelvis, 23 thorax, 19 breast & 129 others) were retrospectively analyzed with "low dose threshold" set at 0%, 5%, 10% & 20% respectively. For every chosen threshold value, agreement between Eclips TPS calculated & 2D ion-chamber array (MatriXX) measured planar dose distribution were analyzed using gamma (γ) index set at 3% dose difference at 3 mm distance to point agreement (DTA) and 2% dose difference at 2 mm DTA. Three γ scaling parameters, maximum γ (γmax), average γ (γavg) and percentage of points with γ≤1 γ%) were estimated for each IMRT plan. Single gantry angle composite exposure approach was adopted throughout the QA. Results: Increasing threshold dose from 0% up to 20% showed decrease in overall mean values of γavg (0.39to 0.13) & increase in γ% (96.02% to 99.16%) at 3%/3mm excepting γmax which remains comparable (1.42 to1.45) both at 3%/3mm & (1.89 to 1.90) at 2%/2mm. The number (%) of plan which fails the general acceptance criteria of γ%≥95% reduces from 160 (15.9%) at 0% threshold dose to 11 (1.1%) at 20% threshold dose respectively. When the reference condition is tighten to 2% at 2 mm, significant improvement in γavg and γ%≤1 was observed with increase in threshold dose. However majority of the plan 59.34%, 41.56%, 33.17% & 22.88% at 0%, 5%, 10% & 20% lower threshold dose fail to fulfill general acceptance criteria of γ% ≥95%. Analysis of treatment site specific plan QA with 10% lower threshold dose and 3%/3mm DTA, overall mean value of γ% was better than 97% for all clinical sites. However, when 2%/2mm is selected, the site specific mean value of γ% was better than 95% except pelvis and H&N region. Conclusion: Patient specific IMRT QA results are influence by the user chosen evaluation parameters. Based on the ranges of IMRT plan of varied sites, evaluation using 3%, 3 mm & 10% threshold dose is chosen for all clinical sites. γ acceptance criteria are set at γmax ≤2, γavg≤ 0.5 and γ% ≥97%. Except H&N and pelvis other relatively regular shape tumours, selection of a limit of 2% 2mm10% threshold & γ% ≥95% seems to be appropriate.

Abstract: 308

Dosimetric impact of set up errors in head and neck cancer patients treated by image guided radiotherapy

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I. Kaur , S. Rawat, P. Ahlawat, A. Kakria, G. Gupta, U. Saxena

Rajiv Gandhi Cancer Institute and Research Center, New Delhi, India, E-mail: drijkwahi@gmail.com

Aim: To assess and analyse the impact of set up uncertainties on target volume coverage and doses to organs at risk (OARs) in head and neck cancer patients treated by Image guided radiotherapy (IGRT). Materials and Methods: Translational set up errors in 25 head and neck cancer patients were observed by kilovoltage cone beam computed tomography (kV CBCT). Two plans were generated. Plan One - the original plan which was the initial optimised and approved plan of the patient. All patients were treated according to their respective approved plans at a defined isocenter. Plan two, the plan sum which was the sum of all plans recalculated at a different isocenter according to set up errors in x, y and z directions. Plan sum was created to evaluate doses that would have been received by target volumes and OARs if set up errors were not corrected. These 2 plans were analysed and compared for target volume coverage and doses to OARs. Results: A total 503 kV CBCT images were acquired for evaluation of set up errors in 25 HNC patients. The systematic (mean) and random (standard deviation) error in x, y and z directions were 0.08 cm, 0.11 cm and 0.10 cm and 0.05 cm, 0.07 cm, and 0.05 cm respectively. The study showed that there was a significant difference, although small, in target volume coverage between 2 plans. The doses to various OARs showed a non significant increase in plan sum. Conclusion : The correction of translational set up errors is essential for IGRT treatment in terms of delivery of planned optimal doses to target volume.

Abstract: 326

Evaluation of inter-fractional setup error and fiducial marker migration during IMRT treatment of prostate

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D. Udayakumar , S. A. Yoganathan, K. J. M. Das, N. Rastogi,

P. K. Gupta, S. Kumar

Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India, E-mail: udayamphy@gmail.com

Background: Image guided radiotherapy is increasingly used in clinics for precise daily localization of the target. There may be a residual error even after online couch correction. Further, the marker based image guidance assumes that the implanted markers positions are constant over the course of the treatment. This study investigates (1) the planning target volume (PTV) margin required for the residual setup error after image guidance and (2) whether the implanted gold seed position in prostate is constant over the course of the treatment. Aim: The purpose of this study was to evaluate the inter-fractional setup error and stability of gold seed position during the IMRT treatment of prostate. Materials and Methods: Eleven patients of prostate cancer who had 3 intra-prostatic gold seeds implanted and treated with IMRT were retrospectively included in this study. They underwent 2D kV based online image guidance (only translational) based on marker matching. A total of 282 image pairs were analyzed for recording online corrected and offline residual setup errors. PTV margins were calculated (excluding rotational error) for online corrected and offline residual setup error based on the Van-Herk recipe. In addition, the inter-marker distance variations of the implanted markers between the planning CT and the daily kV image pairs were also analyzed to quantify the marker migration. Results: The PTV margins for online corrected setup positions in medio-lateral, cranio-caudal and anterior-posterior direction were 11.1mm, 16.5mm and 11.7mm respectively; whereas the same for the residual error were 2.5mm, 3.4mm and 4.9mm respectively. The residual rotational error for pitch, yaw and roll (deg) were -0.7 ΁ 5.2, 1.5 ΁ 1.9 and 0.9 ΁ 2.0 respectively. The overall seed migration was negligible and the maximum standard deviation of marker migration was less than 1.9 mm. Conclusions: Though significant reductions in both systematic and random errors in localizing the prostate can be achieved with online maker matching; there exist a substantial residual error. This has to be accounted for as a residual margin during planning.

Abstract: 328

Does a complex beam arrangement improve conformal treatment plans for post-operative carcinoma stomach?

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Rahul Rai , S. Misra, S. K. Senthil Kumar, K. J. Maria Das, S. Kumar

Sanjay Gandhi Postgraduate Institute of Medical Sciences, India, E-mail: happyrahulrai@gmail.com

Background: Postoperative radiotherapy in carcinoma stomach has significant toxicity owing to the concurrent chemotherapy administered along with large fields based on 2D bony anatomy. There is need to improve standard treatment, and theoretically three dimensional treatment planning allows for a better identification along with coverage of target coupled with Organs at risk (OAR) sparing. Aim: The purpose of this study was to dosimetrically compare different conformal treatment plans for post-operative carcinoma stomach. Materials and Methods: Ten treated cases of carcinoma stomach were retrospectively included. For each case, three 3DCRT treatment plans (2-Field, 3-Field and 5-Field) were generated with photon beams (6 MV and/or15 MV) for the total dose of 45 Gy in 25 fractions. All the plans were normalized to a reference point, and to reduce the hotspots (>107%), field in field technique was used when necessary. The ICRU 50 was followed for target coverage and QUANTEC guidelines for OAR constraints. These techniques were compared and analyzed (mean΁SD) in terms of target coverage, conformity index (CI) and OAR sparing (kidneys, liver & spinal-cord). Results: Mean ΁SD for CTV and PTV were 368΁106 and 927΁199 cc. Target coverage was similar in all these 3 techniques; whereas CI was 3.10΁0.41, 1.90΁0.29 and 1.67΁0.10 for 2F, 3F and 5F respectively. Mean dose (Gy) of left kidney was similar in all these 3 techniques; whereas right kidney was lower with 3F (13.4΁3) as compared to 2F (19.5΁11) and 5F (17΁5). Dose to volume matrices i.e., V 12 , V 20 , V 23 and V 28 (%) for bilateral kidney were observed to be 45.5΁12, 40.6΁12, 38.9΁12 and 36.7΁12 for 2F; 49.8΁12, 30.0΁12, 27.1΁12 and 22.3΁10 for 3F and 55.0΁8, 43.1΁14, 36.9΁12 and 23.2΁ 8 for 5F. Mean dose (Gy) to liver was 18.7΁2, 30.8΁2 and 29.4΁2 for 2F, 3F and 5F respectively. Maximum spinal cord dose (Gy) was 47.3΁1, 24.5΁11 and 35.4΁7 for 2F, 3F and 5F respectively. Conclusion: Five field beam arrangement did not offer advantage over 3F. This demonstrates multiple complex beam arrangement might not be necessary for carcinoma stomach treatment planning.

Abstract: 338

Quantifying the target relocation accuracy using two matching techniques in prostate image guided radiotherapy

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S. K. Senthil Kumar , K. J. Maria Das, S. A. Yoganathan,

D. Udayakumar, N. Rastogi, S. Kumar

Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India, E-mail: sen_kum5@yahoo.co.in

Background : Image guided radiotherapy uses different matching protocols for quantifying the relocation accuracy. A thorough investigation should be carried out to understand the pros and cons of each matching methods. Aim: The aim of this study was to determine the target relocation accuracy using bony anatomy match and marker match in offline review during prostate conformal radiotherapy. Materials and Methods: Five patients of prostate cancer treated with IMRT using 2D kV marker based image guided radiotherapy were included retrospectively. Three dimensional co-ordinates (lateral, longitudinal and vertical direction) of a marker were recorded for each patient in planning CT. The same coordinates were recorded in the daily kV verification images for bony anatomy match and marker match in offline review. Mean and standard deviation of the translational coordinates were analyzed using SPSS software between these two techniques. Results: The mean and standard deviation of lateral coordinates (mm) for planning CT, bony anatomy match and marker match were 11.3΁0.0, -1.7΁2.6 and -7.64΁2.74 for P1, 8.9΁0.0, -0.1΁4.7 and 8.5΁4.6 for P2, -9.7΁0.0, -0.4΁2.5 and -7.5΁4.0 for P3, -7.5΁0.0, -2.5΁3.4 and -9.5΁3.36 for P4 and -19.3΁0.0, 2.9΁2.8 and -13.2΁2.7 for P5. The same for longitudinal were -35.0΁0.0, -1.86΁3.3 and -39.9΁3.3 for P1, -24.5΁0.0, -10.3΁9.3 and m-31.6΁15.4 for P2, -25.0΁0.0, -1.5΁3.8 and 2.3΁4.6 for P3, -19.6΁0.0, -1.6΁1.7 and -7.4΁10.8 for P4 and -27.4΁0.0, -0.10΁2.6 and -31.9΁3.5 for P5. Similarly, the vertical displacement values for planning CT, bony anatomy match and marker match were -11.3΁.0, 1.7΁2.6 and -7.6΁2.7 for P1, -0.2΁0.0, -3.8΁4.4 and -4.5΁4.7 for P2, -4.10΁0.0, 1.5΁3.8 and 2.3΁4.6 for P3, -13.1΁0.0, -1.3΁1.2 and -7.4΁10.8 for P4 and 0.3΁0.0, 2.9΁2.2 and 2.9΁4.3 for P5. Conclusions: The marker based image guidance demonstrated better prostate relocation accuracy compared to bony anatomy match.

Abstract: 349

Dosimetric analysis and correlation between point doses and volumetric doses in HDR intracavitary brachytherapy: A mathematical analysis

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J. Bisht , R. Kant, R. Tyagi 1 , V. Nautiyal, M. Gupta, H. P. Raj,

M. Ahmad, S. Bansal

SRHU, Dehradun, 1 HNBPG College, Khatima, Uttarakhand, India, E-mail: jyoti797bisht@gmail.com

Aim: The classical method of defined point doses is now revolutionized by the GEC-ESTRO guidelines for evaluating the doses to OARs. The purpose of this study is to find the correlation between the ICRU defined point dosimetry and GEC-ESTRO guided volumetric dosimetry for OARs and its significance. Materials and Methods: Sixty intracavitary brachytherapy applications had performed between Jan-Dec 2014 in institute. Patients had been given the EBRT dose of 46 Gy/23# and 9 Gy/2 session of brachytherapy. Each patient had undergone for CT scan for brachytherapy session and brachytherapy treatment planning had done on 3D-Oncentra treatment planning system. Bladder and rectum were delineated in CT slices and doses to the bladder and rectum had been measured with ICRU-38 and GEC-ESTRO guidlines. The data analyzed in SPSS 16.0 software. Statistical and descriptive tests had been applied to find correlation between the point and volumetric dosimetry. Q-Q test done for normal distribution ofdata. Pearson Correlation test had been performed for finding the correlation in point and volumetric data. Non-parametric test Kruskal-Wallis had done for the significance of the analyzed data. The regression linear curve fit test had run for finding the relation between point dosimetry and volume dosimetry. Results: Q-Q plot showed that data is normally distributed and unweighted for bladder and rectum. For bladder and rectum the ratio test is 1.009 and 1.056 resp. for point dose to 2cc volume dose. The Pearson correlation coefficient is found 0.685, 0.639 and covariance is 67.51, 26.65 for bladder and rectum resp. Mean studentised residual came 0.004, 0.000 for bladder and rectum resp. The Kruskal Wallis test showed p value for bladder 2cc volumetric and point dosimetry is 0.018* and for rectum 0.004*. *significant the regression analysis equation (intercept model) is- For Bladder-E2cc = 0.9578 Epoint + 0.968 or Rectum-E2cc = 1.346 Epoint - 4.21. Conclusion: This statistical analysis study describes that the point dose data show strong correlation with 2cc volumetric dose data for OARs and statistically significant but point dosimetry might not be the alternative for defining the doses to the OARs. The regression equations show that it is under estimating the dose to the bladder as well as it is over estimating the rectum doses. Thus for precise and accurate dosimetry of OARs (bladder and rectum) three dimensional imaging and volumetric dosimetry is necessary.

Abstract: 355

Challenges in development and implementation of pneumatic abdominal devices in reducing cranio-caudal (cc) motion of abdominal tumors for patients undergoing external beam radiation treatment/stereotactic body radiation therapy

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D. Arora , V. Goel, T. Singh, A. Anand, R. Munjal, K. Patro

Max Healthcare, New Delhi, India, E-mail: deepak.arora3@maxhealthcare.com

Background: Cranio-cordal Movement always has been a challenge in treatment of abdominal cancers like liver, pancreas, GE junction, Stomach etc. Large motion leads to inceased ITV thus increase in normal tissue toxicity. Aim: Abdominal Compression is used to reduce cranio-caudal motion in abdominal cancers which helps in reduced ITVs and improved normal tissue tolerance. This advantage can help facility in introducing SBRT technique at very nominal costs. We already had been using mechanical compression devices at both locations effectively. Pneumatic devices were introduced to overcome technical limitations like assembly, ease of use, compression measurement, reproducibility etc. associated with mechanical devices. Materials and Methods: Pneumatic abdominal compression was made using an air bladder from Blood Pressure Measurement Instrument (Heine, German make). Position of the air bladder on abdomen was determined for its maximum efficacy. Its shape was determined by number of folds given to air bladder with or without compression plate (125 x 100mm) if used. Daily reproducibility is assured by taking an impression of deflated air bladder on thermoplastic held in All In One (AIO, Orfit make) immobilization board. Pneumatic pressure is monitored through dial gauge and set in such a way that patient can feel its pressure and shallowing of breathing during simulation as well as during treatment. Under Fluoroscopy reduction in CC motion is seen by observing difference in two sets of video images of diaphragm, ribs, mass or markers, one with air bladder deflated and second with air bladder inflated to known pressure. Results: 7 number of patients have been treated using this device at our institutes since its introduction. Mean CC motion of 18mm (Range 15-25mm) was observed without compression and reduced mean CC motion of 10mm (Range 6-12mm) when pneumatic compression was used. An effective reduction was observed in 90% of cases. Conclusion: Pneumatic abdominal compression device can be used effectively for reduction of CC motion in abdominal cancers radiation treatment. It can help in dose escalation due to reduced ITVs and reduced normal tissue toxicity.

Abstract: 366

Dosimetric study to compare static conformal field, static conformal arc and dynamic conformal arc techniques in delivering stereotactic radiation therapy for pituitary adenoma and craniopharyngioma

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M. Giriyappagoudar , B. Selvamani, S. Vargese, R. R. Singh, T. Peace, S. K. Abraham, K. Rekha

Christian Medical College, Vellore, Tamil Nadu, India, E-mail: mgggoudar@gmail.com

Aim: To compare the dosimetric outcomes of the three linear accelerator based stereotactic radiotherapy techniques, Static Conformal Field (SCF), Static conformal Arc and Dynamic conformal arc (DCA), for the treatment of Pituitary adenoma and Craniopharyngioma. Materials and Methods: Computer image sets of 20 patients who have been diagnosed either as Pituitary adenoma or Craniopharyngioma and treated with Stereotactic radiotherapy (SRT) were selected for the study. For each data set, three SRT plans, one each with SCF, SCA and DCA techniques were generated using Brain LAB, iplan RT V.4.5.3, TPS software. The Conformity index (CI), Homogeniety index (HI), Quality of coverage of the target, Dose volume histograms for the target and organs at risk were compared across these three sets of plan. Results: There were 12 patients with Pituitary adenoma and eight patients with Craniopharyngioma. All patients had undergone surgical excision of the tumour prior to radiotherapy. The conformity and Homogeneity indices were comparable across three techniques. The quality of coverage was comparable in static conformal field and DCA techniques, where as it is slightly inferior in static conformal arc technique. The organs at risk are better spared in SCF and DCA techniques compared to SCA technique. Conclusions : This dosimetric study shows that SCF and DCA techniques deliver stereotactic radiotherapy to pituitary adenoma and craniopharyngioma with better quality of coverage and better sparing of OAR compared to SCA technique.

Abstract: 430

Analysis of Intrafraction Motion in Cyberknife based Stereotaxy using 6D skull tracking

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Deepak Gupta , Tejinder Kataria, Kushal Narang, Shyam Singh Bisht, Shikha Goyal, Trinanjan Basu, Ashu Abhishek, Susovan Banerjee,

K. P. Karrthick

Medanta Cancer Institute, Medanta - The Medicity, Gurgaon, Haryana, India.

Introduction: Analysis of intrafraction translational and rotational variations in patients treated for various cranial/head-neck lesions with frameless, mask based stereotactic radiosurgery (SRS) or stereotactic radiotherapy (SRT) using 6-D skull tracking on CyberKnife. Materials and Methods: Twenty-three patients were planned for treatment with CyberKnife using customized, non-invasive frameless thermoplastic cast based immobilization. Standard CyberKnife couch was used for correction of positional offsets and 6-D Skull tracking was used for calculating and correcting the intrafraction shifts. Datasets of twenty-six fractions of the twenty-three patients depicting intrafraction positional offsets were used to calculate intrafraction translational and rotational shifts. Mean shifts and standard deviations were subsequently calculated and analyzed. Results: The mean and 1 standard deviation (SD) intrafraction translational shifts were 0.18 ΁ 0.37 mm in the left-right (L-R) direction, 0.19 ΁ 0.38 mm in the antero-posterior (AP) direction and 0.13 ΁ 0.19 mm in the supero-inferior (SI) direction, with a mean 3D-vector of 0.35 mm. On an average, 2.5%, 0.8%, and 0.2% of the translational shifts exceeded 1, 2, and 3 mm, respectively. The mean and 1 SD intrafraction rotational shifts were 0.11 ΁ 0.26 degrees roll, 0.16 ΁ 0.26 degrees pitch and 0.18 ΁ 0.26 degrees yaw. On an average, 1.7%, 0.4%, and 0.1% of the rotational shifts exceeded 1, 2, and 3 degrees. Conclusion: In our experience, CyberKnife SRS/SRT carried out with frameless thermoplastic mask based immobilization coupled with 6D skull tracking, effectively detects and compensates for intrafraction variability.

Abstract: 434

Development and implementation of in-house wireless and wired last man out switch in radiotherapy machines

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S. Senthilkumar

Madurai Medical College and Government Rajaji Hospital, Madurai, Tamil Nadu, India, E-mail: drsenthilgh@gmail.com

Introduction: The aim of this work was to develop indigenously both the wireless and wired Last Man Out Switch to fulfills and satisfies the AERB regulatory requirements for the radiotherapy machines. Radiotherapy machines are used to deliver the ionizing radiations, while treating the cancer patients. Such machines are provided with safety interlocks, which plays a vital role in radiation protection. The recent incidences reported to AERB regarding inadvertent exposure of radiation workers during setting up patient inside treatment room as beam was switched on from control panel assuming that nobody is inside treatment room. Considering the potential exposure, AERB decided to make a mandatory provision for installation of "last man out switch" in all the radiotherapy installations to prevent inadvertent exposures. So, we have developed indigenously both the wireless and wired Last Man Out Switch and implemented all types radiotherapy machines like Varian, Electa, Siemens LINAC machine, HDR Brachytherapy, Telecobalt machine, Cyber Knife and Gamma Knife machines. Materials and Methods: Both the wireless and wired last man out switch has been developed successfully and installed in many Radiotherapy machines. To install the last man out switch (LMOS) in the radiotherapy rooms, wire has to be brought from the door interlock to treatment room area and the switch has to be fixed in the front of the RT machine room. To avoid the wiring in the existing radiotherapy room, we have used the latest RF technology to develop the wireless LMOS. So, there is no need of any wire connection between machine and Wireless Last Man Out Switch (WILLMOS). Radio waves act as a intermediate link between radiotherapy machine and interlock door systems integrated with switching device. And also developed the wired LMOS, which was connected with the interlock switch by connecting wires. The working principle of wireless and wired last man out switch: Both the wireless and wired last man out switch connected with the door interlock. The machine cannot be operated without pressing the last man out switch and closing the door thereafter. After completion of patient set-up, the operator needs to press the last man out switch after ensuring that nobody is present in the treatment room, inadvertently. Once the Last Man Out Switch is pressed, it activates an Audio Alarm & red light flashing for 20 sec. Inside the treatment room that will alert anyone who inadvertently stays back in the room. Subsequently operator needs to close the door within 20Sec. (or) Operator needs to close the door and also switch ON the beam within 20Sec. However, if the door is opened, either before switching ON the beam or during treatment, Once again the operator needs to press the last man out switch in order to switch ON the beam. Conclusion: The developed both the wireless and wired last man out switchs fulfills and satisfies the regulatory requirements of the AERB. The device was successfully installed many HDR brachytherapy machines and also different Radiotherapy machines like Varian, Electa, Siemens LINAC machine, Telecobalt machine, Cyber Knife and Gamma Knife machines. In all clinical situations, treatment interruption, machine failure, computerized errors etc., were found during radiation treatment. Accidental exposure to the radiation workers, without our knowledge can be rectified by this device. We stressed accidental exposure could not occur with our mistakes, this device enables us to protect from unwanted irradiation from radiotherapy machines. As a beneficial point of view, this device has high sensitivity, no time delay and function instantly.

Miscellaneous

Abstract: 088

Exploring the role of phycocyanin in modern oncology

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A. Soni , M. Verma, A. Kumar Dhull, R. Dhankhar, V. Kaushal, R. Atri, M. Dubey

Post Graduate Institute of Medical Sciences, Rohtak, Haryana, India, E-mail: abhisheksoni246@gmail.com

Background: Phycocyanin is extracted from Spirulina and is used as a dietary supplement for individuals who are undergoing chemotherapy and radiation for cancer and is used to ease negative symptoms during treatment as well as rejuvenate post treatment. Its nutritional values and therapeutic values are well documented. Phycocyanin is a non-toxic molecule with anticancer, antioxidant, antiviral and anti-inflammatory activities and it provides protection from a number of diseases including cancer. Aim: Most of the studies are based on the laboratory experimental results and, very less literature is available for Phycocyanin use in oncological practice. This article reviews the role of phycocyanin in today's oncological practice. Materials and Methods: This literature review was performed by conducting a systematic search of PUBMED, MEDLINE and PMC, including all articles up to November 2014. All articles were reviewed and were included if they were relevant to the topic, and deemed to be of good quality. Results: Studies have shown that phycocyanin can induce apoptosis in cancer cells such as a mouse macrophage cell line (RAW 264.7), prostate cell line (LNCaP), breast cell line (MCF-7), and erythromyeloid leukemia cell line (K562). Phycocyanin is used in treatment of hepatocellular carcinoma, rectal cancer, colon cancer, leukemia (CML, CLL), myeloproliferative neoplasm, melanoma, cervix cancer and prostate cancer (with topotecan). Phycocyanin mediated photodynamic therapy is approved as a potential therapy for cancer. Phycocyanin acts via interference of DNA synthesis, activation of caspase-dependent programmed cell death pathways (apoptosis), inhibition of tumor cell growth and by membrane destruction. Phycocyanin is usually non-toxic, but may cause liver damage, stomach pain, nausea, vomiting, weakness, thirst, rapid heartbeat, shock, and death. Phycocyanin may cause systemic anaphylaxis, diarrhea and diffuse erythema. Conclusion: The antioxidant properties of phycocyanin have been investigated for their anti-inflammatory, anti-proliferative and anti-cancer effects. The results revealed for the first time that the C-phycocyanin activities and its antitumor actions such as in leukemia, colon cancer, pancreatic cancer etc. could be a promising natural antitumor agent with a potential for future pharmacological and medical applications. Phycocyanin being a natural product, should be more acceptable as an anticancer compound.

Abstract: 133

Knowledge, attitude and awareness of cancer and its prevention among resident doctors in North India: A prospective survey

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M. Annamalai , D. Chouhan 1 , H. Kunhiparambath, S. Krishnan,

S. Mallick, P. Ventrapati, S. Gupta, D. Sharma

All India Institute of Medical Sciences, 1 Ram Manohar Lohia Hospital, New Delhi, India, E-mail: drmanikandan88@gmail.com

Background: Cancer is among the top three killers in both rural and urban India and potentially the most preventable disease. Resident doctors significantly contribute to cancer prevention & to create awareness among the people. Aim: This survey was designed to benchmark current levels of knowledge, attitude and awareness of cancer among resident doctors in north India and to provide a basis for health education on cancer prevention. Materials and Methods: The survey was carried out in April-July 2015. A questionnaire was designed to assess the awareness, understanding of resident doctors towards cancer prevention. Resident doctors include both junior & senior residents. Questionnaire was simple to understand and had 25 points addressing the above issues. The multiple choice questions format was used. It was handed over personally or sent by E-mail to resident Doctors of Medical Colleges in North India. Total of 570 questionnaires were distributed. Results: Total of 316 respondents (55%) sent their responses of which 76.04% responses were by junior residents. Only 9.26% received oncology training in their curriculum. Regarding the most common cancer in India, among males 74.6% & 19.8% opined as lung and head & neck cancers and for females, 62.8% & 33.9% opined as cervix and breast cancer respectively. Diet and lifestyle (65.6%) was cited as major reason for increasing incidence followed by environmental factors (23.2%). 3% of residents opined as cancer is not preventable and 44.1% answered only 20% of cancers as preventable. 89.1% answered tobacco as single most important preventable cause. 96.3% of residents were aware of HPV vaccination but only 57.7% are referring patients for vaccination and 68.2% opined that lack of awareness as the major obstacle. More than one-third (35.2%) were not referring their patients for screening of breast & cervical cancer. More than two thirds (70%) suggested lack of awareness as the most important barrier to screening and health education is the best way to increase awareness. For tobacco control, complete ban (47.7%) was opined as best strategy. Over 95% suggested preventive oncology need to be more refined and Oncology training essential for under graduates. Conclusion: Among residents of various departments, there is lack of training & cancer awareness. Majority of residents are interested to have oncology training and MCI should consider this in undergraduate curriculum to promote the cancer awareness.

Abstract: 177

Desmoplastic small round cell tumor: A rare case report

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S. Dikkala , S. Surana, G. Nethula, P. R. Thammineni

Krishna Institute of Medical Sciences, Secunderabad, Telangana, India, E-mail: drsrikanthd@gmail.com

Background: Desmoplastic small round cell tumor (DSRCT) is a rare aggressive malignant tumor that occurs in young adults. First described in 1989 by Gerald and Rosai, less than 200 cases have been reported till date and hence no prospective data is available. Multi modality treatment with chemotherapy and maximal surgical debulking followed by Whole Abdominopelvic radiation is the current line of management. The 3-year and 5-year overall survival (OS) rates after multimodality treatment are in the order of 55% and 15%, respectively. The 3 year survival rate in those patients who did not receive all three therapies is 27%. DSRCT has high propensity to spread intra peritoneally and hence consolidative WAP-RT to a dose of 30 Gy with a further boost of 12 to 24 Gy to the residual tumor is being used. We present a recurrent case of DSRCT treated with WAP-RT using Rapidarc technique. Case Report: A 23 yr old female presented with pain abdomen of 1 month duration. On evaluation she was found to have a 17 x 12 x 8 cms pelvic mass, which was excised. Characteristic histopathologic features and poly phenotypic immunohistochemical expression of antibody markers were consistent with a diagnosis of DSRCT. She received chemotherapy with Ewing sarcoma/PNET protocol. Post chemotherapy PET CT did not show any residual disease. She developed recurrence 4 months after completion of chemotherapy and re surgery was done. Planning PET-CT scan did not show any gross residual disease. WAP-RT was planned. Entire peritoneal cavity with pelvic lymph nodal regions, pouch of Douglas, vaginal vault including surface of liver and kidneys was contoured as Target. Organs at risk were delineated and VMAT Rapidarc planning was done respecting normal tissue tolerances especially Liver and Kidneys. Setup was verified with KV imager and CBCT. A dose of 30 Gy was delivered in 20 fractions @ 150 cGy per fraction. She developed grade 2 GI toxicity and was managed symptomatically. She also received G-CSF for grade 2 neutropenia. Conclusion: DSRCT is a rare and fatal disease that mainly affects young adults. WAP-RT after multi agent chemotherapy and surgical resection has improved overall survival. WAP RT with VMAT is associated with better tolerance.

Abstract: 205

Primary nonmetastatic angiosarcoma of the spleen

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K. L. Jayakumar , V. George Kuriakose, D. V. Somasekharan Nair

Government Medical College, Trivandrum, Kerala, India, E-mail: anayit@gmail.com

Background: Primary splenic angiosarcoma is an extremely rare, highly aggressive malignancy hypothesized to be originating from the splenic vascular endothelium. Splenectomy is the mainstay of treatment but majority of the cases will have already metastasized at the time of presentation and hence they carry a very dismal prognosis. We wish to report a non metastatic primary splenic angiosarcoma. Case Report: A 69-year-old post-menopausal female with a past history of hypothyroidism on oral thyroxine presented with complaints of fatigue and vague left upper abdominal pain and fullness. Splenomegaly on palpation was confirmed by imageology. Laboratory investigations revealed anemia. She underwent splenectomy through an open laparotomy. Histopathological examination confirmed angiosarcoma with gross, microscopy and immunohistochemistry. A whole-body positron emission tomography scan, done three weeks after operation, ruled out metastasis. She underwent six cycles of chemotherapy with ifosfamide and adriamycin. She has completed four months of post-chemotherapy follow up and remains non-metastatic till date. Conclusion: Early detection and splenectomy prior to a splenic rupture is the best chance for maximizing survival, as spontaneous or traumatic splenic rupture carries the worst prognosis, with a high likelihood of immediate mortality due to hypovolemia. Pathogenesis is yet to be established. Benefit of adjuvant chemotherapy and radiotherapy is doubtful. There is no phase 2 or 3 data regarding the management protocol due to its rare incidence. Prognosis is dismal with survival of two to fourteen months.

Abstract: 227

Injectable liposome-in-in situ gels as a platform for regional delivery of paclitaxel as a radiosensitizer for synergistic chemoradiotherapy: A preclinical study

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J. S. Goda , V. Gota, S. Guha Sarkar 1 , N. Sudhalkar, R. Banerjee 1

Tata Memorial Centre, 1 Indian Institute of Technology, Mumbai, Maharashtra, India, E-mail: godajayantsastri@gmail.com

Background: In clinical radiotherapy, effects of radiation can be enhanced by the use of radiosensitizers, but current chemoradiation approaches are limited by their systemic toxicity. The objective of the present study was to develop a novel liposome-in-in situ gel (LG-PTX) as an injectable system for regional delivery of radiosensitizers and evaluating its efficacy when used concurrently with radiation therapy. Materials and Methods: Paclitaxel (PTX) was chosen as the model radiosensitizer. The formulation LG-PTX was developed to contain PTX-loaded liposomes, with sizes around 120nm, incorporated into a porous hydrogel matrix. In vitro radiosensitization of LG-PTX in conjunction with radiation was evaluated by apoptotic assays in B10F16 murine melanoma cells. In vivo radiosensitization was studied with tumor growth delay in C57BL/6 mice xenografts, and was carried out with a two hour interval between drug administration and irradiation. The mice were treated with 40 mg/kg of LG-PTX followed by incremental doses of focal external radiation to a total dose of 15 Gy in five daily fractions (5 x 3 Gy). Results: The LG-PTX formulation was found to have an IC50 of 325 ΁ 117nM on B16F10 murine melanoma cells, as a model radio-resistant tumor, and in vitro studies with concurrent fractionated doses of radiation showed a significant increase in the percentage of apoptotic cells (75%) compared to cells treated with radiation (39%) or paclitaxel (43%) alone. In vivo intra-tumoral injection in mice showed accumulation of PTX in the tumor two hours after administration, while no drug was detected in the plasma or other organs, indicating localization of the drug at the site of the tumor. In vivo efficacy studies with concomitant doses of fractionated radiation showed significant reduction in tumour volume (p < 0.05) on application of the LG-PTX formulation along with radiation, compared to both the control (6.6 fold lower) and radiation alone (1.4 fold lower) groups. The use of the formulation along with radiation also significantly increased tumor inhibition and improved animal survival compared to control and radiation alone groups. Conclusion: The novel LG-PTX formulation has potential use as a local injectable regional drug delivery system for enhancing efficacy of radiotherapy without any systemic toxicity.

Abstract: 237

Retroperitoneal follicular lymphoma: A case report

th
J. Sebastian , M. G. Janaki 1 , R. Charith 1

MS Ramiah Medical College, 1 Alva, Bengaluru, Karnataka, India, E-mail: johnsebastianmg@gmail.com

Background: Follicular lymphoma (FL) is the second most common subtype of non-Hodgkin lymphoma. The disease has been seen as incurable, apart from the relatively infrequent patients with early stage disease. They are very rarely reported in Asian countries like India and presents a diagnostic challenge. Aim: Here we are reporting a case of early stage retroperitoneal follicular lymphoma treated with radical radiotherapy and demonstrate the gross reduction in size of the lymphoma as shown by the verification Cone Beam CT. Materials and Methods: A 60 yr male was incidentally detected with a retroperitoneal mass in an ultrasonography abdomen done as part of routine check-up. This mass was diagnosed as Follicular Lymphoma following further imaging studies and histopathological and immunohistochemical studies. Patient was treated with external beam radiation therapy to a dose of 45 Gy in 25 fractions on 6MV LINAC using VMAT technique with daily CBCT verification. Results: Patient was treated with external beam radiation therapy to a dose of 45 Gy in 25 fractions on 6MV LINAC using VMAT technique with daily CBCT verification. Verification CBCT showed near total response by the last week of radiotherapy. Conclusion: Radiotherapy is a very effective treatment modality in the management of early stage Follicular Lymphomas. Cone Beam CT which is routinely used for setup verification was helpful in response evalution to radiotherapy and demonstrated near total response.

Abstract: 253

Bowen's disease: A rare case presentation

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M. Aal , G. Krishnamurty, R. Ravind, S. C. Reddy, V. Priyadarshini,

V. L. Bhaskr, R. S. Bilimagga, G. Aparna

Health Care Global Enterprises Ltd., Bengaluru, Karnataka, India, E-mail: mahalakshmi.aall@gmail.com

Introduction: In India, skin cancers constitute about 1-2% of all diagnosed cancers. The exact incidence of Bowen's disease is unknown, approximate incidence being 142 per 1,00,000 persons. It was first described by John T. Bowen in 1912. Bowen's disease is a squamous cell carcinoma in situ, affecting both skin and mucous membranes. Extra genital Bowen's disease is a rare entity. Case Report: A 68 year old gentleman, presented to the hospital with multiple brownish skin lesions on the abdominal wall of 1 ΍ years duration. The lesion appeared initially as an asymptomatic small plaque, which gradually progressed in size, not associated with itching or pain. On examination, the patient had multiple well defined erythematous plaques, largest of size 4 * 5 cms size on the right anterior abdominal wall. There was no regional lymphadenopathy. Discussion: Bowen's disease, a pre-malignant skin lesion usually affects fair skinned individuals. The etiology includes sun/arsenic exposure, ionizing radiation & HPV16. Typically presents as a discrete, slowly enlarging, erythematous plaque with well-demarcated borders. The risk of Bowen's disease progressing to invasive squamous cell carcinoma has been estimated to be approximately 5%. Taking into consideration, the presence of multiple skin lesions, patient was started on 5% topical 5-FU and is kept on close follow up. Conclusion: We are highlighting this case because of its rarity in photo-protected areas, especially abdomen. The potential of transformation into malignancy should always be taken into consideration during follow up.

Abstract: 285

A case report on disseminated cutaneous malignancy

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N. Sharma , S. Gupta, D. Sachan, L. Pandey, P. Singh

Sarojini Naidu Medical College, Agra, Uttar Pradesh, India, E-mail: 2007neh@gmail.com

Background: Squamous cell carcinoma is the second most common skin cancer, after basal cell carcinoma and its incidence is increasing throughout the world. It is well accepted that cutaneous squamous cell carcinoma arising in previously injured skin (e.g., a burn site, scar, chronic wound, or ulcer) have an increased risk of metastasis, with a recurrence rate of 58% and an overall five-year survival of 52%. The most common sites are the lung (21%), bone (18%), central nervous system (6%) and liver (4%). Multiple squamous cell carcinoma of the skin is an exceedingly rare entity. The diagnosis of metastasized cutaneous SCC hinges on histopathologic evaluation of involved skin. Most patients with primary cutaneous SCC have an excellent prognosis but SCC developing as cutaneous metastasis; the long-term prognosis is poor. Aim: The aim of reporting this case lies in its extremely rare presentation of multiple cutaneous metastasis. We present a case of disseminated marjolin's ulcer in a 46yr old male who presented with a painless non-healing warty growth on abdomen persisting for the last 2 years. According to the patient, he developed non healing ulcer in his left ankle following thermal burn 2 yr back for which he underwent amputation of left lower limb. The histopathology report showed well differentiated squamous cell carcinoma. Physical examination revealed multiple non tender lumps on multiple sites of the body, i.e., epigastrium, left hypochondrium, right scapular, right cubital and left clavicular region. FNAC from left hypochondrial lump and left clavicular lump showed smears suggestive of metastatic poorly differentiated carcinoma. On USG Abdomen sub diaphragmatic hypoechoic deposits were seen likely metastatic deposits and on chest x ray multiple cannon ball secondaries were seen on bilateral lung fields. Conclusion: Although in-transit metastasis in cutaneous squamous cell carcinoma is unique presentation of metastatic SCC and is associated with poor prognosis but disseminated cutaneous metastasis is an unusual presentation and its management is still undefined.




 

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