Evaluation of scatter dose received by the thyroid region in patients with breast cancer receiving adjuvant chest wall irradiation using 2-d radiotherapy

Abstract

According to the Global Cancer Observatory 2020 report, breast cancer is the top most cancer among females in Sri Lanka. It has been reported that thyroid can receive a significant amount of radiation dose in breast cancer patients who received adjuvant two dimensional (2D) conventional therapy. The aim of this study was to evaluate the scatter dose received by thyroid region during chest wall radiation in conventional 2d-radiotherapy. 41 breast cancer patients who had adjuvant 2D-conventional radiotherapy were included in this study. All selected patients were treated by TheratronTM 780e cobalt teletherapy at Apeksha Hospital, Maharagama, Sri Lanka. Polimaster PM1610 dosimeter was used to measure the scatter dose. A statistical analysis was performed using IBM SPSS. The mean values for the total scatter dose from the glancing fields and the SCF (supraclavicular fossa) field were 112.33 5.50 mSv and 421.79 32.49 mSv respectively. The mean value of the total scatter dose was 534.10 34.11 mSv. Moreover, 78.97% of the scatter dose was received by the SCF field while 11.36% and 9.66% were received by medial and lateral glancing fields. A considerable amount of radiation has been received by the thyroid region among breast cancer patients who received chest wall irradiation with SCF irradiation. In order to reinforce the conclusion, further studies need to be performed with accurate dose measurement especially with Thermoluminescent dosimeter (TLD).