Dosimetric Verification of Dose Distribution as Three Dimensional Intensity Modulated Radiation Therapy based MRI Using Polymer Gel

Document Type : Original Article


1 Radiation Protection Dosimetery, National Center for Radiation Research and Technology, Atomic Energy Authority.

2 Physics Dept., Faculty of Girls, Ain Shams University.


Polymer gel dosimeter have been developed as means of detecting and verifying an absorbed
doses given to cancer patients for radiotherapy in the range (0-10Gy) as measured and verification
dose distributions of three-dimensional (3D) treatments. This article reports on the dosimeter of a
new N-isopropanol acrylamide NIPAM, high weight percent T%, %C the mass percent of all comonomer
polymer gel formulation (6T%, 20C%), optimized for magnetic resonance imaging
(MRI). The aim to investigated MR-based polymer gel dosimeter as a three-dimensional 3D
dosimeter in IMRT. Magnetic resonance spin-spin relaxation rate images were acquired and, after
calibration, converted to absorbed dose distribution. The dose maps were compared with the dose
distribution calculated using ion chamber in one plan and radiographic film for two plans. The
dosimeters were irradiated by 4, and 10MV photons for doses in the range (4–10) Gy. The multiecho
sequence was used for the evaluation of T2 (spin-spin relaxation times) in the irradiated gel
dosimeters. (%dd) percentage depth dose for (IMRT) intensity modulated radiation therapy /
polymer gel & Magnetic resonance imaging = 5.7% at 5cm, other the average dose are 10.45 for
dose profile, where %dd percentage depth dose for (IMRT) intensity modulated radiation therapy
/ionization chamber and radiographic film(IC&RF) = 4.6% at 5cm other the average dose are 10.45
for dose profile. DVH dose volume histogram for polymer gel & magnetic resonance imaging = 94%, but DVH dose volume histogram for point by point ionization chamber and radiographic film = 86%.which lessince timing for protocol of integral part of verification radiation therapy.