A quantitative analysis of intensity-modulated radiation therapy plans and comparison of homogeneity indices for the treatment of gynecological cancers

Abstract

The aim of present study was to evaluate the intensity-modulated radiation therapy (IMRT) plans using different homogeneity and conformity indices in gynecological cancers, as well as to compare and find out the most reliable and accurate measure of the dose homogeneity among the available indices. In this study, a cohort of 12 patients were registered for evaluation, those receiving dynamic IMRT treatment on Clinac-2300C/D linear accelerator with 15-Mega Voltage (MV) photon beam. Dynamic IMRT plans were created on Eclipse treatment planning system with Helios dose volume optimization software. Homogeneity indices (HI) such as H index, modified H index, HI index, modified HI index, and S-index (sigma-index) proposed by M Yoon et al. (2007) were calculated and compared. The values of S-index vary from 1.63 to 2.99. The results indicate that the H and HI indices and their modified versions may not provide the correct dose homogeneity information, but the S-index provides accurate information about the dose homogeneity in the Planning Target Volume (PTV). Each plan was compared with 6-MV photon energy on the basis of S-index and conformity index (CI). Organs at risk (OAR) doses with 6-MV and 15-MV beams were also reported.

Influence of increment of gantry angle and number of arcs on esophageal volumetric modulated arc therapy planning in Monaco planning system: A planning study

“…[ 9 ] HI of zero indicates the dose distribution is homogeneous. Conformity Index (CI) : V pres /TV p , a ratio evaluating the coverage of the prescription dose in treatment plan, where V pres was the volume of body receiving the prescribed dose and TV p was the volume of GTV receiving the prescription dose[ 10 ] CI of one indicates the good dose conformity. Target volumes: D 98% , D 95% , D 50% and D max for GTV were analyzed, where D 98% , D 95% , D 50% is minimum dose delivered to 98%, 95% and 50% Volume of GTV respectively and D max is the maximum dose.…”

Dosimetric study of volumetric arc modulation with RapidArc and intensity-modulated radiotherapy in patients with cervical cancer and comparison with 3-dimensional conformal technique for definitive radiotherapy in patients with cervical cancer

“…7 Planning studies comparing VMAT with IMRT for the primary treatment of prostate and bladder cancer have also demonstrated some improvements in plan quality. 8,9 Nevertheless, studies comparing conventional techniques to intensitymodulated techniques in cervical cancer are scarce 10,11 and report data for a small number of patients. 7 In this study, we compared dosimetric parameters for 3D-CRT, "step-and-shoot" IMRT, and VMAT in a series of patients with cervical cancer receiving definitive RT.…”

Comparison between the Effect of using Similar Wedges and Opposed Wedges in Brain Tumor Cases

“…For this purpose, another or additional parameters are introduced for this purpose. Of these addition parameters, the homogeneity index (HI) [14] and the conformity index (CI) are two such tools for treatment plan analysis have been introduced in conformal radiotherapy.…”

“…In all definitions, HI basically indicates the ratio between the maximum and minimum dose in the target volume and the lower value indicates a more homogenous dose distribution within this volume. The HI in the present work was calculated using the following formula: HI= [(D2-D98)/D50] [21], Where D2 is the minimum dose in 2% of the Planning Target Volume (PTV), indicating the "maximum dose", D98 = minimum dose to the 98% of the target volume, indicating the "minimum dose" and D50 = minimum dose to the 50% of the target volume. As described by the Radiation Therapy Oncology Group RTOG, the value approaching zero is the better indication of the dose distribution in the target volume.…”