A dose‐volume‐based tool for evaluating and ranking IMRT treatment plans

Abstract

External beam radiotherapy is commonly used for patients with cancer. While tumor shrinkage and palliation are frequently achieved, local control and cure remain elusive for many cancers. With regard to local control, the fundamental problem is that radiotherapy‐induced normal tissue injury limits the dose that can be delivered to the tumor. While intensity‐modulated radiation therapy (IMRT) allows for the delivery of higher tumor doses and the sparing of proximal critical structures, multiple competing plans can be generated based on dosimetric and/or biological constraints that need to be considered/compared. In this work, an IMRT treatment plan evaluation and ranking tool, based on dosimetric criteria, is presented. The treatment plan with the highest uncomplicated target conformity index (TCI+) is ranked at the top. The TCI+ is a dose‐volume‐based index that considers both a target conformity index (TCI) and a normal tissue‐sparing index (NTSI). TCI+ is designed to assist in the process of judging the merit of a clinical treatment plan. To demonstrate the utility of this tool, several competing lung and prostate IMRT treatment plans are compared. Results show that the plan with the highest TCI+ values accomplished the competing goals of tumor coverage and critical structures sparing best, among rival treatment plans for both treatment sites. The study demonstrates, first, that dose‐volume‐based indices, which summarize complex dose distributions through a single index, can be used to automatically select the optimal plan among competing plans, and second, that this dose‐volume‐based index may be appropriate for ranking IMRT dose distributions.PACS numbers: 87.53.‐j, 87.53.Tf

Influence of photon energy on the quality of prostate intensity modulated radiation therapy plans based on analysis of physical indices

“…Miften et al .,[ 8 ] have demonstrated the use of target conformity index (TCI) and normal tissue-sparing index (NTSI) to assist in the process of judging the merit of a clinical treatment plan. But, in this work, the widely accepted conformity index was used to evaluate the conformity of the treatment plans.…”

Dosimetric assessment of tumor control probability in intensity and volumetric modulated radiotherapy plans

“…It is suggested 8 that the optimization and evaluation of radiation treatment plans should be directly based on biological indices rather than physical dose parameters. Several publications [9][10][11] have discussed the application of biological tools to evaluate and rank complex treatment plans. Most commercial TPS (Elekta Monaco, Varian Eclipse and Phillips Pinnacle etc.)…”

“…7 The main difference of the Marsden Model 1 is that it explicitly incorporates inter patient variation of radio-sensitivities by assuming a normal distribution amongst patient population with a standard deviation. 14 Poisson Model 9 : Assumed cell survival from radiation dose D i in independent subvolume v i following Poisson distributions.…”

Novel approach for the evaluation of dose conformity in radiotherapy

“…To characterize degree of dose conformity, a number of indices (commonly referred to as conformity indices) have been suggested (e.g., see Refs. [1][2][3][4][5][6][7][8][9][10][11][12][13]). In general, in order to compute each of these indices, four quantities are employed: Conformity index (CI) in radiotherapy is frequently computed by using expression recommended by Shaw et al 5,6 :…”