Search

The purpose of this study is to evaluate the clinical usefulness of modulated arc (mARC) treatment techniques. The mARC treatment plans of the non-small cell lung cancer (NSCLC) patients were performed in order to verify the clinical usefulness of mARC. A pre study was conducted to find the most competent plan condition of mARC treatment and the usefulness of mARC treatment plan was evaluated by comparing it with the other Arc treatment plans such as Tomotherapy and RapidArc. In the case of mARC, the optimal condition for the mARC plan was determined by comparing the dosimetric performance of the mARC plans with the use of various parameters. The various parameters includes the photon energies (6 MV, 10 MV), optimization point angle (6{\deg}-10{\deg} intervals), and total segment number (36-59 segment). The best dosimetric performance of mARC was observed at 10 MV photon energy and the point angle 6 degree, and 59 segments. The each treatment plans of three different techniques were compared with the following parameters: conformity index (CI), homogeneity index (HI), target coverage, dose in the OARs, monitor units (MU), beam on time and the normal tissue complication probability (NTCP). As a result, all three different treatment techniques show the similar target coverage. The mARC results the lowest V20 and MU per fraction compared with both RapidArc and Tomotherapy plan. The mARC plan reduces the beam on time as well. Therefore, the results of this study provided a satisfactory result which mARC technique is considered as a useful clinical technique for radiation treatment., Comment: 11 pages, 4 figures

This study evaluated the performance of tissue equivalent polymer gel dosimetry as a tool for 3-dimensional dose quality assurance to using Magnetic Resonance Imaging (MRI) measure the dose characteristics of therapeutic radiation using and applying it to intensity modulated radiation therapy (IMRT). The polymer gel under normoxic conditions was synthesized using Gelatin, methyacrylic acid (MAA), hydroquinone (HQ) and tetrakis hydroxymethyl phosphonium chloride (THPC), and a polymer gel dosimeter was fabricated by placing the gel into each phantom appropriate for experimental use. The dose reaction experiment employed Co gamma-rays and a 6-MV photon beam with a dose range of 0 ∼ 14 Gy. The dose characteristics of the polymer gel were compared with those of an ion chamber, Gafchromic EBT2 film, by using MRI. The linear correlations coefficient for the polymer gel, the ion chamber and the film were r = 0.970, r = 0.999, and r = 0.972, respectively. The percentage depth doses at a depth of 50 mm were 85.8% and 84.6% for the polymer gel and the ion chamber, respectively, giving a difference of 1.2%. On the other hand, the percentage depth dose at the depth of 100 mm was 66.2% and 63.7% for the polymer gel and the ion chamber, respectively, indicating a 2.5% gap. The flatness and the symmetry of the gel dosimeter on the cross plane were 3.80% and 3.58%, respectively. The gel dosimeter was applied to an IMRT. The doses measured in the 100% dose domain of the therapeutic plan was 96.2%, 103.0%, and 100% for the axial, sagittal and coronal planes, respectively, highlighting the applicability of the gel dosimeter as a 3-dimensional dosimeter.