A Study of Two-field, Three-field, and Four-field Techniques using Rainbow and Thermoluminescent Dosimetry for Radiotherapy Treatment of Cervix Cancer

ABSTRACT

The aim of the present study is to investigate the rectal dose during three different radiotherapy techniques of dosimeter cervicalcancer. The study was carried out using a Anderson Rando female phantom. The thermoluminescent dosimetry (TLD) capsulesand detectors of rainbow dosimeter were employed for rectal and target volume dose determination. Several techniques ofexternal beam radiation therapy such as two field (AP-PA), three field, and four field with equal applied dose were planned.During application of different radiotherapy techniques, the maximum dose received by rectum is due to the two-field technique.The results of two dosimetry types were compared with each other. The mean and standard deviation values of two field, threefield, and four field for rectum are 1.97 ± 0.01, 1.68 ± 0.026, and 1.35 ± 0.05, respectively, whereas the mean and standarddeviation values of two field, three field, and four field for cervix are 2.03 ± 0.01, 1.98 ± 0.02 and 1.92 ± 0.01, respectively. Theresults were evaluated by the paired t-test. The P values calculated from data are as follows Two field, cervix, P = 0.02; threefield, cervix, P = 0.0016; and four field, cervix, P = 0.0026, demonstrates that four field significantly reduces the rectum dose.This study showed that using TLD and rainbow dosimetry during radiotherapy could have a useful role as a predictor of choosingappropriate technique for preventing future rectal complications. Dose limitation to the rectum could possibly be achieved byusing three-field and four-field techniques with equal tumor dose while maintaining a high dose to the tumor.