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 Table of Contents  
REVIEW ARTICLE
Year : 2017  |  Volume : 13  |  Issue : 4  |  Page : 607-612

Expert consensus workshop report: Guideline for three-dimensional printing template-assisted computed tomography-guided 125I seeds interstitial implantation brachytherapy


1 Department of Radiation Oncology, Peking University Third Hospital, Beijing; Chinese North Multi Center Cooperative Group of Particles Radiotherapy Specialized of Beijing Medical Association, Beijing, China
2 Department of Medical Imaging, Minimally Invasive Interventional Center, Sun Yat-Sen University Cancer Center, Guangzhou, China
3 Department of Radiology, Southeast University, Zhongda Hospital, Nanjing, China
4 Department of Thoracic Surgery, Tianjin Medical University Second Hospital, Tianjin; Chinese North Multi Center Cooperative Group of Particles Radiotherapy Specialized of Beijing Medical Association, Beijing, China
5 Department of Oncology, Tengzhou Central People's Hospital, Tengzhou; Chinese North Multi Center Cooperative Group of Particles Radiotherapy Specialized of Beijing Medical Association, Beijing, China

Date of Web Publication13-Sep-2017

Correspondence Address:
Junjie Wang
Department of Radiation Oncology, Peking University Third Hospital, 49 Huayuan North Road, Beijing 100191
China
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jcrt.JCRT_412_17

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 > Abstract 

Radioactive 125I seeds (RIS) interstitial implantation brachytherapy has been a first-line treatment for early-stage cancer of the prostate gland. However, its poor accuracy and homogeneity has limited its indication and hampered its popularization for a long time. Intriguingly, scholars based in China introduced computed tomography (CT)-guided technology to improve the accuracy and homogeneity of RIS implantation and broadened the indications. Then, they creatively designed and introduced three-dimensional printing coplanar template (3D-PCT) and 3D printing noncoplanar template (3D-PNCT) into the practice of RIS implantation. Use of such templates makes RIS implantation more precise and efficacious and aids preoperative planning, real-time dose optimization, and postoperative planning. However, studies on the standard workflow for 3D-PT-assisted CT-guided RIS implantation have not been published. Therefore, the China Northern Radioactive Seeds Brachytherapy Group organized multidisciplinary experts to formulate the guideline for this emerging treatment modality. This guideline aims at standardizing 3D-PT-assisted CT-guided RIS implantation procedures and criteria for selecting treatment candidates and assessing outcomes and for preventing and managing postoperative complications.

Keywords: Carcinoma, computed tomography guidance, implantation, interstitial brachytherapy, radioactive 125I seeds, three-dimensional printing template


How to cite this article:
Wang J, Zhang F, Guo J, Chai S, Zheng G, Zhang K, Liao A, Jiang P, Jiang Y, Ji Z. Expert consensus workshop report: Guideline for three-dimensional printing template-assisted computed tomography-guided 125I seeds interstitial implantation brachytherapy. J Can Res Ther 2017;13:607-12

How to cite this URL:
Wang J, Zhang F, Guo J, Chai S, Zheng G, Zhang K, Liao A, Jiang P, Jiang Y, Ji Z. Expert consensus workshop report: Guideline for three-dimensional printing template-assisted computed tomography-guided 125I seeds interstitial implantation brachytherapy. J Can Res Ther [serial online] 2017 [cited 2017 Sep 21];13:607-12. Available from: http://www.cancerjournal.net/text.asp?2017/13/4/607/214472


 > Introduction Top


Implantation of radioactive 125I seeds (RIS) is the first-line treatment for early-stage cancer of the prostate gland. Nearly 300,000 patients with prostate cancer receive brachytherapy using RIS implantation worldwide each year. More than 500 articles focusing on transrectal ultrasound-guided permanent prostate brachytherapy have been published in the past decade, with guidelines provided by the American Brachytherapy Society (ABS), American Urologic Association, Radiation Oncology Association, National Comprehensive Cancer Network, American Cancer Society, and American Society of Clinical Oncology.[1],[2],[3],[4]

In 2002, scholars based in China introduced computed tomography (CT)-guided technology to improve the accuracy and homogeneity of RIS implantation and broadened the indications.[5],[6],[7] Then, scholars based in China designed and invented templates such as the three-dimensional printing coplanar template (3D-PCT) and 3D printing noncoplanar template (3D-PNCT). Use of such templates makes RIS implantation more precise and efficacious and aids preoperative planning, real-time dose optimization, and postoperative planning. In this way, the quality control of RIS implantation could be realized. Moreover, scholars based in China developed a navigation system for different parts of the body and a rib-drilling gun that made 3D printing template (3D-PT)-assisted CT-guided RIS implantation more practical and precise.[8],[9],[10] However, studies on the standard workflow for 3D-PT-assisted CT-guided RIS implantation have not been published.

This consensus document represents the views of the authors regarding currently accepted workflow of 3D-PT-assisted CT-guided RIS implantation. The workflow and prescription doses are recommended based on published data and clinical experience.


 > Overview of Brachytherapy Using Radioactive 125I Seeds Implantation Top


Radiotherapy can be divided into “internal radiotherapy” and “external-beam radiotherapy.” The latter uses rays from a linear accelerator to transmit radiation into the body to kill tumor cells. Internal radiotherapy passes radionuclides through the natural cavities of the human body or implants radionuclides percutaneously into the tumor directly to kill tumor cells. Brachytherapy is a simple, outpatient procedure that avoids hospitalization so that the patient can recover and return to the normal activities of daily life.

With widespread patient education of the available treatment options, the advantages of brachytherapy have become apparent.[11] Brachytherapy can be of five types: “intraventricular,” “intracoronary,” “interstitial,” “intraoperative,” and “modal.”[12] Among them, high-dose-rate afterloading and low-dose-rate interstitial implantation are applied widely.[13] Afterloading brachytherapy is applied mainly in the treatment of cancer of the cervix, breast, and prostate gland. Afterloading brachytherapy involves a series of treatments and special protection of healthy tissue.[13] Low-dose-rate interstitial implantation is applied mainly for treatment of cancer of the head, neck, lung, pancreas, prostate gland, and soft-tissue as well as for recurrence and metastasis of solid cancers. Low-dose-rate interstitial implantation is done just once and protection from the harmful effects of radiation is simple.[13]


 > Basic Principles Top


Brachytherapy using RIS implantation under imaging guidance aims to place RIS into the target accurately according to the preoperative plan and to kill tumor cells. RIS distribution in the target volume must be highly consistent with the preoperative plan to obtain optimal dose conformity. RIS implantation must obey the principles of radiotherapy and interstitial brachytherapy including the definition of target volume, prescription dose, and dose limitation to protect organs at risks (OARs) [Figure 1].[13],[14]
Figure 1: Flowchart showing 3D-PT-assisted CT-guided implantation of radioactive 125I seeds

Click here to view



 > Definition of the Target Volume and Organs at Risks Top


Report Number 83 of the International Commission of Radiation Units and Measurement[14] defines several important parameters. The gross tumor volume (GTV) is based on various imaging and clinical examinations that show the shape of the lesion area. The clinical target volume (CTV) is the GTV and regions that may harbor microscopic diseases. The planning target volume (PTV) provides the margin around the CTV to allow for motion of the internal target, other anatomic motion during treatment, and variations in the treatment setup; a PTV is not used for RIS implantation. OARs refer to normal tissue or normal organs that are covered or adjacent to the irradiated area.


 > Evaluation Parameters for the Prescription Dose Top


The prescription dose is the value of dose that originates from evidence-based medical research or clinical practice. It can be used to control the local target tumor. However, except for prostate cancer, there has been no prospective dose-escalation trial to study the prescription dose of RIS implantation in other tumor types. The prescription dose of RIS implantation for prostate cancer patients recommended by the ABS is 140–160 Gy (at least D90 [i.e., the dose that 90% of the target volume receives from the implantation] to reach the prescription dose).[3],[4] The prescription dose for other tumor types should refer to the prescription dose used for the treatment of prostate cancer. The recommended prescription dose is 110–160 Gy.[13]


 > Evaluation Parameters for Dosimetry Top


Dosimetry parameters include those for the target and OARs, D90, D100, V100 (percentage of the target volume delineated on the postimplant CT receiving 100% of the prescribed dose), V150, and V200.

In addition, some evaluation parameters, such as the conformity index, dose homogeneity index, and external volume index, are used to evaluate the quality of the treatment plan.


 > Dose Constraints for Organs at Risks Top


The relationship between the dose covering normal tissues and side effects in RIS implantation is not clear and requires further study. Hence, it is recommended to refer to the parameters for high-dose-rate afterloading. For prostate cancer, the dose parameters of OARs include urethral D30 (i.e., the dose that covers 30% of the urethra volume), D10, D5, as well as rectal D2cc (i.e., the dose received by 2 cm3 of the rectum), D0.1cc, and V100. Values for the recommended dose for OARs during RIS implantation therapy based on single-fraction high-dose irradiation[15] are D2cc <100% of the prescription dose and D0.1cc<200 Gy for the rectum; D10 <150% of the prescription dose; and D30 <130% of the prescription dose for the urethra.


 > Physics of Radioactive 125I Seeds Top


RIS with a half-life of 59.4 days and photon energy 27 KeV is used as the radioactive source in the clinic. RIS can move in tissue readily and have been replaced in recent years by RIS chains.[16]


 > Indications and Contraindications Top


The manufacture of 3D-PTs includes several key procedures. First, by digital processing, tumor information is transmitted to a computer-based treatment planning system. Second, the treating physician and a medical physicist define the related parameters such as target volume, OARs, prescription dose, and design of the needle channel. Third, a 3D printer is used to print a 3D-PCT or 3D-PNCT.[8],[16],[17] A 3D-PT possesses information on the needle channel, coordinate system for laser positioning, and a laser-identification system.

A 3D-PCT is suitable for the treatment of tumors, in which the RIS-implantation needle channel is in parallel. A 3D-PNCT is applicable for the treatment of tumors, in which the RIS-implantation needle channel is not parallel or in a different plane. Even if the tumor has an irregular shape or moves, a 3D-PT can be used to achieve an optimal conformal dose distribution of RIS implantation for tumors in different parts of the body.


 > Indications Top


The indications are (i) recurrence after surgery or external radiotherapy, patients who refuse surgery and radiotherapy, or if the tumor diameter is ≤7 cm; (ii) definitive pathologic diagnosis; (iii) suitable puncture path; (iv) no bleeding tendency or hypercoagulable state; (v) good physical status (Karnofsky Performance Scale score >70); (vi) tolerable RIS implantation; and (vii) estimated survival time >3 months.


 > Contraindications Top


The contraindications are (i) severe hemorrhagic tendency, platelet count ≤50×109/L, and severe coagulation disorder (prothrombin time >18 s and prothrombin activity <40%). Anticoagulant therapy and/or the drug used for antiplatelet aggregation should be discontinued ≥1 week before RIS implantation; (ii) tumor ulceration; (iii) severe diabetes mellitus; (iv) no suitable puncture path; and (v) the dose of the target volume is not up to the requirement of the prescription dose.


 > Workflow Recommendations Top


3D-PT-assisted CT-guided RIS implantation is a new, minimally invasive, model of internal radiotherapy. High-quality control in each step of the procedure is crucial to its success.[8],[9] 3D-PT-assisted CT-guided RIS implantation involves eight key steps: patient immobilization, CT simulation, target delineation, and OAR limitation; preoperative planning of the prescription dose and design of the needle channel; 3D-PT production; 3D-PNCT re-setup; implantation of RIS needle and RIS; evaluation of postimplantation dosimetry; and follow-up.[8],[9],[10] It is important to form a multidisciplinary team (physicians, surgeon, medical-physicist, technician, anesthesiologist, and nurse) for detailed implementation of 3D-PT-assisted CT-guided RIS implantation. Physicians will come from the departments of radiation oncology, interventional medicine, internal medicine, ultrasound, and nuclear medicine [Table 1] and [Table 2].[17],[18]
Table 1: Workflow of 3D-PT-assisted CT-guided implantation of radioactive 125I seeds

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Table 2: Comparison of characteristics between 3D-PCT and 3D-PNCT

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 > Radiation Protection Top


The half-value layer (the thickness of the absorber is needed when the intensity of radiation attenuates to half of the primary intensity) of RIS seeds is 0.025 mmPb, and the half-life is 59.4 days. Half of the energy fall-off is observed 60 days later and reduces to 10% of its initial energy 6 months later. The amount of energy can be ignored 1 year later. Patients should avoid contact with children or pregnant women within 2 months after RIS implantation.[19],[20] If long-term contact (more than a few hours) cannot be avoided, contact must be 1.5–2 m from the patient or patients should be asked to wear a collar, lead vest, or lead apron [Table 3].[19],[21]
Table 3: Recommended applicable organs for the two types of 3D-PT-assisted CT-guided seed implantation in different organs

Click here to view


Acknowledgment

The authors thank Dr. Wenjiang Shen, Dr. Hongzhi Zhang, Dr. Xianshu Gao, and Dr. Fuquan Zhang, for their kind review of the manuscript. Moreover, the authors also thank Dr. Fujun Zhang, Dr. Jinghe Guo, Dr. Jianguo Zhang, Dr. Yuliang Li, Dr. Xuequan Huang, Dr. Xiaokun Hu, Dr. Juan Wang, Dr. Ruoyu Wang, Dr. Jie Zhang, Dr. Jing Bai, and Dr. Hongxing Liu, for their kind participation in the discussion of the manuscript.

Financial support and sponsorship

This work was supported by the Capital Characteristic Clinic Project [Grant number Z151100004015171].

Conflicts of interest

There are no conflicts of interest.

 
 > References Top

1.
Cancer.org [Internet]. Atlanta: The American Cancer Society medical and editorial content team. Radiation Therapy for Prostate Cancer. Available from:https://www.cancer.org/cancer/prostate cancer/treating/radiation-therapy.html [Last Medical Review: February 16, 2016 Last Revised: March 11, 2016].  Back to cited text no. 1
    
2.
Mohler JL. NCCN clinical practice guidelines in oncology: Prostate cancer. J Natl Compr Canc Netw 2010;8:162-200.  Back to cited text no. 2
    
3.
Nag S, Beyer D, Friedland J, Grimm P, Nath R. American Brachytherapy Society (ABS) recommendations for transperineal permanent brachytherapy of prostate cancer. Int J Radiat Oncol Biol Phys 1999;44:789-99.  Back to cited text no. 3
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4.
Davis BJ, Horwitz EM, Lee WR, Crook JM, Stock RG, Merrick GS, et al. American Brachytherapy Society consensus guidelines for transrectal ultrasound-guided permanent prostate brachytherapy. Brachytherapy 2012;11:6-19.  Back to cited text no. 4
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5.
Jun JW. The concept and practice of image guided interstitial brachytherapy for tumor. Zhonghua Fang She Yi Xue Yu Fang Hu Za Zhi 2014;34:801-2.  Back to cited text no. 5
    
6.
Lin L, Wang J, Jiang Y, Meng N, Tian S, Yang R, et al. Interstitial 125I Seed implantation for cervical lymph node recurrence after multimodal treatment of thoracic esophageal squamous cell carcinoma. Technol Cancer Res Treat 2015;14:201-7.  Back to cited text no. 6
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Wang H, Wang J, Jiang Y, Li J, Tian S, Ran W, et al. The investigation of 125I seed implantation as a salvage modality for unresectable pancreatic carcinoma. J Exp Clin Cancer Res 2013;32:106.  Back to cited text no. 7
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8.
Zhe J, Yu LJ, Fu XG. Dosimetry verification of radioactive seed implantation for malignant tumor assisted by 3D printing individual guide template. Zhonghua Fang She Yi Xue Yu Fang Hu Za Zhi 2016;36:662-6.  Back to cited text no. 8
    
9.
Yu LJ, Hao W, Zhe J. Computed tomography image-guided and personalized 3D printed template-assisted 125-iodine seed implantation for recurrent pelvic tumor: A dosimetric study. Chin J Radiat Oncol 2016;25:959-64.  Back to cited text no. 9
    
10.
Hao W, Jun JW, Hui SY. Efficacy and dosimetry of computed tomography image-guided 125I radioactive seed implantation for locally recurrent rectal cancer. Chin J Radiat Oncol 2016;25:1096-9.  Back to cited text no. 10
    
11.
Nag S, Beyer D, Friedland J, Grimm P, Nath R. American Brachytherapy Society (ABS) recommendations for transperineal permanent brachytherapy of prostate cancer. Int J Radiat Oncol Biol Phys 1999;44:789-99.  Back to cited text no. 11
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Jun JW, Dian RX, Wei QR. Interstitial Brachytherapy For Tumors By Radioactive Seeds. Version. 1. Beijing: Peking University Medical Press; 2004.  Back to cited text no. 12
    
13.
Devlin PM, Cormack RA, Holloway CL, Stewart AJ. Brachytherapy Applicantions and Techniques. 2nd ed. New York City: Demos Medical; 2015.  Back to cited text no. 13
    
14.
Hodapp N. The ICRU Report 83: Prescribing, recording and reporting photon-beam intensity-modulated radiation therapy (IMRT). Strahlenther Onkol 2012;188:97-9.  Back to cited text no. 14
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Fowler JF. 21 years of biologically effective dose. Br J Radiol 2010;83:554-68.  Back to cited text no. 15
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16.
Lee WR, deGuzman AF, Tomlinson SK, McCullough DL. Radioactive sources embedded in suture are associated with improved postimplant dosimetry in men treated with prostate brachytherapy. Radiother Oncol 2002;65:123-7.  Back to cited text no. 16
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Jun JW. 3D Printing Technology and Precise Radioactive Seeds Implantation Therapy. Beijing: Peking University Medical Press; 2016.  Back to cited text no. 17
    
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Watanabe H, Okada M, Kaji Y, Satouchi M, Sato Y, Yamabe Y, et al. [New response evaluation criteria in solid tumours-revised RECIST guideline (version 1.1)]. European J Cancer 2009;45:228-47.  Back to cited text no. 18
    
19.
Sui A, Li J, Tang F, Zhang H, Ren J, Pang L, et al. Radiation safety and protection of close contacts from radiators after implantation of radioactive 125 I seeds. Zhonghua Fang She Yi Xue Yu Fang Hu Za Zhi 2012;32:626-8.  Back to cited text no. 19
    
20.
Jun L. Radiation protection in 125I Seed implant brachytherapy. J Oncol 2004;10:363-4.  Back to cited text no. 20
    
21.
Zhuo SQ, Chen L, Zhang FJ, Zhao M, Zhang L, Liu J, et al. Environmental radiation dose monitor after 125I radioactive seed implantation. Ai Zheng 2007;26:666-8.  Back to cited text no. 21
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