ABSTRACT
Objective To evaluate the dosimetric difference between fixed-field static intensity-modulated radiotherapy (IMRT), fixed-field dynamic multileaf collimator (DMLC), and volumetric modulated arc therapy (VMAT), all of which involve supraclavicular and infraclavicular regions, in breast cancer patients after breast-conserving surgery.Methods This study included 14 female patients with breast cancer who received radiotherapy after breast-conserving surgery in our hospital from October 2012 to April 2016.The radiation field included the chest wall and supraclavicular and infraclavicular regions.IMRT, DMLC, and VMAT plans were generated for each patient while using identical optimization conditions.The doses to planning target volume (PTV) and organs at risk (OARs) were compared based on dose-volume histogram (DVH);one-way analysis of variance or nonparametric Wilcoxon rank test was used for comparison.Results For the dose distribution of PTV, VMAT achieved the best V95, V98, CI, and HI (P<0.009).Concerning the doses to OARs, VMAT achieved the best V5, V20, and Dmean of the ipsilateral lung and the best V5 and Dmean of the contralateral lung (P<0.022).Dmean of the spinal cord was significantly lower in VMAT than in IMRT and DMLC (P=0.004).Conclusions VMAT is preferred for the patients with breast cancer to be treated with radiotherapy involving supraclavicular and infraclavicular regions after breast-conserving surgery.It can improve the dose distribution of target and reduce the doses to organs at risk and radiotherapy toxicities.
ABSTRACT
Objective To examine the effects of gross tumor volume (GTV) and radiation dose on the prognosis of hepatocellular carcinoma (HCC) patients treated with whole body gamma knife.Methods The clinical data of 69 HCC patients who underwent body gamma knife treatment from January 2012 to June 2015 in the Radiotherapy Center of the PLA General Hospital were retrospectively reviewed.Based on a 50% or 60% isodose coverage of the planning target volume (PTV), patients were treated with a radiation dose of 4-5 Gy per fraction, and a total marginal dose of 36-50 Gy (median dose 45 Gy).Short-term efficacy, overall survival (OS), and the adverse effect of the treatment were evaluated.The optimal cut-off tumor volume was identified using the receiver operating characteristic curve, and survival was determined by the Kaplan-Meier method.Univariate and multivariate analyses were performed using the log-rank test and Cox proportional hazards regression model, respectively.Results The overall short-term response rate of the 69 patients was 67%.The 1-and 2-year OS rates were 62% and 40%, respectively, with a median survival of 18.6 months.The multivariate analysis showed that gross tumor volume (GTV)93 cm3(P=0.665).Conclusions GTV is an independent prognostic factor for overall survival of HCC patients.Although high-dose radiotherapy provides survival benefits to patients with small GTV, it is not necessarily suitable for patients with large GTV.