The study of a rectal dose in cervical carcinoma: High dose rate brachytherapy calculated based on the ICRU Report 38 Recommendation and Multiple Points Calculation in Lampang Cancer Hospital

Abstract

Objective: To compare the rectal dose of high dose rate brachytherapy treatment planning based on ICRU 38 recommendation and multiple points calculation for evaluating the rectal dose and maximum point in rectum from brachytherapy treatment planning in Lampang Cancer Hospital.

Method: The high dose rate comparison of rectal dose from two methods was performed in 30 cervical cancer patients with brachytherapy treatment. The statistic analysis was paired t-test.

Results: A rectal dose relative to point A was calculated using reference point defined by multiple points. The result showed that mean of average maximum value of rectal dose from multiple reference six points was 60.87±16.97% while average maximum value of rectal dose calculated from the ICRU 38 was 59.0±15.89%. Position of the maximum rectal dose was 1 cm upward the reference point of ICRU 38 calculation (43.3%). Comparison of doses calculated by marking the reference points from two methods showed that maximum dose of multiple point calculation was higher than that of ICRU 38 calculation significantly (p< 0.009).

Conclusion: A rectal dose calculation using the reference point according to ICRU 38 recommendation suggested only a single point. It may not be the maximum rectal dose point. Therefore, a multiple point calculation along the length of rectum should be suggested for informing radiologists to be applied to patients. Bull Chiang Mai Assoc Med Sci 2013; 46(1): 33-39