A simple scoring ratio to index the conformity of radiosurgical treatment plans

Abstract

✓ A conformity index is a measure of how well the volume of a radiosurgical dose distribution conforms to the size and shape of a target volume. Because the success of radiosurgery is related to the extremely conformal irradiation of the target, an accurate method for describing this parameter is important. Existing conformity ratios and indices used in radiosurgery are reviewed and criticized. It will be demonstrated that previously proposed measurements of conformity can, under certain conditions, give false perfect scores. A new conformity index is derived that gives an objective score of conformity for a treatment plan and gives no false scores. An analysis of five different treatment plans is made using both the existing scoring methods and the new conformity index.

Effect of Photon-Beam Energy on VMAT and IMRT Treatment Plan Quality and Dosimetric Accuracy for Advanced Prostate Cancer

“…Hence, the HI will decrease with increasing homogeneity. The conformity index was calculated as CI Paddick = TV² PI /(PI*TV), where TV PI is the target volume, TV, within the prescribed isodose volume PI [21].…”

Dosimetrischer Vergleich eines erweiterten Collapsed-Cone-Algorithmus mit einem neuen kommerziell verfügbaren Monte-Carlo-Algorithmus anhand klinisch relevanter Fälle

“…In addition, we reported tumor coverage as percentage of the respective PTV volume covered with 95% of the prescribed dose for IMRT cases or 65% for SBRT cases. The target conformity index (CI), as proposed by Paddick [27], (1) describes the ratio of the PTV volume covered with prescribed dose (V(PTV) Dprescribed ) to the product overall PTV volume (V PTV ) and volume covered by the prescribed dose(V Dprescribed ). In addition to the CI, target homogeneity index (HI) [15], defined as (2) was calculated.…”

Reirradiation of Spinal Column Metastases

“…The conformity index (CI) and homogeneity index (HI40) were used to compare conformity and homogeneity between treatment plans [20]. Due to the fact that we prescribe dose to the median dose level in the PTV, we had to modify the CI as follows:…”