Dosimetric evaluation of gynecological HDR brachytherapy using an in-house phantom and RPLGDs

A treatment planning system (TPS) is responsible for calculating the radiation dose for patients undergoing brachytherapy. However, to verify TPS dose accuracy of intracavitary brachytherapy, which feature particularly steep and complex dose gradients, 3D-printed phantoms made of polylactic acid (PLA) can be used. A study was designed to create an in-house phantom for verification of gynecological brachytherapy measurement using a radiophotoluminescent glass dosimeters (RPLGDs) and to evaluate the dosimetric differences between measurement and calculation by the treatment planning system under clinical conditions.An in-house phantom holder was designed to move the axis of the holder to the rectum point that differs according to the patient's anatomy. The holder of the applicator was designed for various types of applicators in intracavitary brachytherapy. This clinical study was used to quantify variations between the calculated and measured dose for 6 plans at various points in the phantom, which included point A, point B, the bladder point, and the rectum points.The RPLGDs demonstrated a linear dose response up to 10 Gy, excellent angular dependence, and an associated uncertainty of 3.3% (k  =  1). In the clinical case, the dose differences between the measured and calculated values at Point A, Point B, bladder, and rectum were +1.99  ±  1.11%, 1.01  ±  0.02 Gy, and 0.10 Gy, +4.42 ± 2.56%. and + 3.53  ± 1.44%, respectively.Dosimetry with RPLGDs using the 3D printed in-house phantom can accurately verify delivered dose in intracavitary brachytherapy for quality assurance purposes.