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The influence of scatter on the design of optimized intensity modulations
Author(s) -
Chen Zhe,
Wang Xiaohong,
Bortfeld T.,
Mohan Radhe,
Reinstein Lawrence
Publication year - 1995
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.597536
Subject(s) - intensity modulation , imaging phantom , intensity (physics) , homogeneity (statistics) , optics , mathematics , computer science , physics , statistics , phase modulation , phase noise
In contrast to the traditional treatment planning process where beam parameters are adjusted in order to produce a desired dose distribution, the inverse treatment planning technique starts from the desired dose distribution and employs mathematical inversion to derive a set of optimal intensity profiles for beams with predefined directions. Crucial to the success of the inverse technique is the mathematical inversion process that yields the optimized intensity modulation. This paper systematically investigates the influence of phantom scatter in the process of designing the optimized intensity modulation and assesses its clinical consequences through the resultant treatment plans. Optimized intensity modulations and the resultant dose distributions were calculated for four prostate patients and for a simple cubic phantom under two conditions: one includes scatter and the other ignores scatter in designing the optimized intensity modulation. The effects of scatter were assessed by comparing the isodose distributions, the dose–volume histograms of the target and of the critical organs, and the tumor control probabilities and the normal tissue complication probabilities of two set prostate treatment plans. The comparison reveals that the dose homogeneity to the target is significantly improved when scatter is included in the optimization process. For prostate patients, the dose to the volume enclosed by the outer rectal contour is concomitantly reduced. Our results suggest that it is important to include the scatter in the iterative design of the optimized intensity modulations.