Journal of Cancer Research and Therapeutics

ORIGINAL ARTICLE
Year
: 2018  |  Volume : 14  |  Issue : 2  |  Page : 351--356

Underdosing of the maxillary sinus for small fields used in newer radiotherapy techniques: Comparison of thermoluminescent dosimeter and Monte Carlo data


Navin Singh1, Sunil Dutt Sharma2, Nirmal Kumar Painuly1, Abhijit Mandal3, Lalit Mohan Agarwal3, Ashutosh Sinha4 
1 Department of Radiotherapy, King George's Medical University, Lucknow, India
2 Radiological Physics and Advisory Division, Bhabha Atomic Research Center, CTCRS, Mumbai, Maharashtra, India
3 Department of Radiotherapy and Radiation Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
4 Department of Radiotherapy, U.P. Rural Institute of Medical Sciences and Research, Etawah, Uttar Pradesh, India

Correspondence Address:
Navin Singh
Department of Radiotherapy, King George's Medical University, Lucknow - 226 003, Uttar Pradesh
India

Aims: To evaluate the underdosing of the maxillary sinus at its distal end produced by air cavity in the path of the 6 MV photon beam. Materials and Methods: A cubic solid water slab phantom of dimensions 18 cm × 18 cm × 18 cm with 4 cm × 4 cm × 4 cm air cavity 3 cm away from its anterior surface was used in this study. The percentage depth dose (PDD) for 6 MV X-rays along the central axis of the cubical air cavity was measured using thermoluminescent dosimeter-100 chips. The EGSnrc/DOSXYZnrc Monte Carlo (MC) code was used to estimate the PDD values in both homogeneous and inhomogeneous conditions. The dose data were generated for 1 cm × 1 cm, 2 cm × 2 cm, 3 cm × 3 cm, and 5 cm × 5 cm field sizes. Results: Average percentage dose reductions at 1 mm beyond the distal surface of the maxillary sinus for the field sizes 1 × 1, 2 × 2, and 3 × 3 cm2 are 42.4%, 39.5%, and 29.4%, respectively. However, for 5 cm × 5 cm field size, there is a dose enhancement (i.e., overdosing) at 1 mm from the distal surface of the maxillary sinus and the average percentage dose enhancement is 5.9%. Also, beyond 1 cm from the air-water interface, there is dose enhancement for all the field sizes. Conclusion: This study showed that the significant dose reduction occurs near the air-water interface for the treatment techniques using small photon fields such as intensity-modulated radiotherapy or other newer techniques. MC-based treatment planning calculation predicts realistic dose distribution while using small photon fields in the treatment of maxillary sinus.


How to cite this article:
Singh N, Sharma SD, Painuly NK, Mandal A, Agarwal LM, Sinha A. Underdosing of the maxillary sinus for small fields used in newer radiotherapy techniques: Comparison of thermoluminescent dosimeter and Monte Carlo data.J Can Res Ther 2018;14:351-356


How to cite this URL:
Singh N, Sharma SD, Painuly NK, Mandal A, Agarwal LM, Sinha A. Underdosing of the maxillary sinus for small fields used in newer radiotherapy techniques: Comparison of thermoluminescent dosimeter and Monte Carlo data. J Can Res Ther [serial online] 2018 [cited 2020 Jul 11 ];14:351-356
Available from: http://www.cancerjournal.net/article.asp?issn=0973-1482;year=2018;volume=14;issue=2;spage=351;epage=356;aulast=Singh;type=0