A comparative study between MC simulation and TLD measurements of radiation doses to other parts of the body during gynaecological brachytherapy

The study of long-term radiation effects has become important due to the growing survival rates among cancer patients. Brachytherapy treatment planning systems do not account for radiation doses remote from the irradiated regions. The use of Monte Carlo (MC) simulation for the evaluation of scattered radiation doses received by other parts of the body of patients undergoing gynaecological brachytherapy has therefore become crucial to avert the causation of secondary cancers. This study compares two methods (MC simulation and TLD measurements) used to estimate scattered radiation doses received by other parts of the body (breast and thyroid) of patients undergoing gynaecological brachytherapy.

100 patients undergoing HDR intracavitary brachytherapy were randomly selected and TLDs placed on their breast and thyroid region during treatment delivery. The patient treatment was modelled with SimpleGeo for the considered cancer types and simulated with MCNP using a predefined patient model based on the mean BMI of patients involved in this study.

Average MC simulation doses were 2.65 ± 0.07 mSv and 8.62 ± 0.03mSv to thyroid and breast, respectively. The TLD measurements were 2.76 ± 0.14 mSv and 8.73 ± 0.09 mSv to the thyroid and breast, respectively. P-values of 0.64 for thyroid and 0.43 for breast (p > 0.05) were recorded.

P-values reveal an insignificant difference between measured and simulated doses. It is recommended that the verified MC models be used to develop an algorithm for organ dose estimation of other parts of the body (i.e. organs not considered by the treatment planning system).