Preliminary clinical study of copper compensator in IMRT / 中华放射肿瘤学杂志

ABSTRACT

Objective To study the dosimetry for copper compensator in IMRT.Methods 10 patients (3 nasopharyngeal carcinoma,4 esophageal cancer,3 colorectal cancer) from IMRT plans made in Oncentra Planning System enrolled in this study.The fluence matrices of each plan were converted into compensator thickness matrices based on attenuation coefficient of copper under 6 MV radiation ray which was measured with ion chamber.While irradiating the homogenous phantom with the intensity modulated plans performed by copper compensator,film was used to measure the planar dose.In the end,γanalysis was carried out between the measured and calculated planar doses with the criteria of 3％ DD/3 mm DTA.Paired t test to MU differences of MLC plans and copper compensator plans.Results The γanalysis results showed the planar dose pass rates of 10 plans lie between 90.2％ and 98.2％,which means the IMRf technique based on copper compensator can meet the clinical needs.The MU for copper compensator IMRT plans is less than the MLC IMRT plans (873.9 vs.975.1,P =0.005).Conclusions Compared to conventional IMRT based on MLC,copper compensator has the advantage of lower requirement of hardware and lower scattering dose in patient.Copper compensator can meet the needs of clinical practice.