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Adaptation of Unified Dosimetry Index (UDI) and Critical Organ Scoring Index (COSI) for Target and Organ at Risk (OAR) in Prostate IMRT Technique

m kousar*, A Jhangda , S Ali , the Aga khan university and hospital, Karachi, SD


(Sunday, 7/14/2019)  

Room: ePoster Forums

The aim of the study is to formulate a dosimetry index that can be used for Quality assessment of IMRT treatment plans of prostate site.

This quality index will incorporate homogeneity index, conformity index, dose gradient and coverage index resulting in a direct comparison to an ideal plan. We developed another index in this study related to sparing of organs i.e. UDI (OAR) that incorporate the doses of OARs to compare which plan is optimum in terms of OARs sparing. In comparison to this UDI (OAR) and UDI(Target) another work was done to analyze the dosimetry of overall plan including target coverage and organ at risk sparing i.e. critical organ scoring index (COSI).
To validate UDI (Target), UDI (OAR) and COSI, 22 patients were studied which were planned on IMRT.
Dose gradient is the most influencial component for UDI because of relatively high magnitude of deviation from reference (ideal plan) values.
The dosimetry scoring method is a beneficial tool for the evaluation of quantitative and qualitative plan. It can also be used as a comparison tool for different plans of different modality. Under this scoring system, for a collection of treatment plans, the quality of plans can be classified as ‘Excellent’ ‘Average’ ‘Good’ and ‘Poor’ in term of target coverage and OARs. The proposed system can also be utilized to evaluate the plan quality of any other treatment sites by adjusting the OAR tolerance criteria following the clinical significance and standard protocols.


Treatment Planning, Dose Uniformity, Dose Volume Histograms


TH- External beam- photons: IMRT dose optimization algorithms

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