A dosimetric evaluation of knowledge‐based VMAT planning with simultaneous integrated boosting for rectal cancer patients

RapidPlan, a commercial knowledge‐based optimizer, has been tested on head and neck, lung, esophageal, breast, liver, and prostate cancer patients. To appraise its performance on VMAT planning with simultaneous integrated boosting (SIB) for rectal cancer, this study configured a DVH (dose‐volume histogram) estimation model consisting 80 best‐effort manual cases of this type. Using the model‐ generated objectives, the MLC (multileaf collimator) sequences of other 70 clinically approved plans were reoptimized, while the remaining parameters, such as field geometry and photon energy, were maintained. Dosimetric outcomes were assessed by comparing homogeneity index (HI), conformal index (CI), hot spots (volumes receiving over 107% of the prescribed dose, [Formula: see text]), mean dose and dose to the 50% volume of femoral head ([Formula: see text] and [Formula: see text]), and urinary bladder ([Formula: see text] and [Formula: see text]), and the mean DVH plotting. Paired samples t‐test or Wilcoxon signed‐rank test suggested that comparable CI were achieved by RapidPlan ([Formula: see text] for [Formula: see text] , and [Formula: see text] for PTV) and original plans ([Formula: see text] for [Formula: see text] and [Formula: see text] for PTV), respectively [Formula: see text]. Slightly improved HI of planning target volume [Formula: see text] and PTV were observed in the RapidPlan cases ([Formula: see text] for [Formula: see text] , and [Formula: see text] for PTV) than the original plans ([Formula: see text] for [Formula: see text] and [Formula: see text] for PTV), [Formula: see text]. More cases with positive [Formula: see text] were found in the original (18 plans) than the RapidPlan group (none). RapidPlan significantly reduced the [Formula: see text] (by [Formula: see text] from [Formula: see text] to [Formula: see text]), [Formula: see text] (by [Formula: see text] from [Formula: see text] to [Formula: see text] G), [Formula: see text] (by [Formula: see text] from [Formula: see text] to [Formula: see text]), and [Formula: see text] (by [Formula: see text] from [Formula: see text] to [Formula: see text]), respectively. The more concentrated distribution of RapidPlan data points indicated an enhanced consistency of plan quality. PACS number(s): 87.55.de; 87.55.dk