ABSTRACT
Objective To examine the dosimetric advantages of three-dimensional (3D) computed tomography (CT)-guided interstitial brachytherapy (BT) for target volume and surrounding normal tissue in patients with locally advanced cervical cancer,and to provide a simple and effective clinical treatment approach.Methods A total of 52 patients who had poor tumor response to external beam radiotherapy (EBRT) with a residual tumor greater than 5 cm at the time of BT were included.The patients were treated by 3D CT-guided interstitial BT using a hybrid applicator comprised of uterine tandem and free metal needles.The high-risk clinical target volume (HR-CTV),intermediate-risk clinical target volume (IR-CTV),and organs at risk (OAR) were contoured.The total dose,including external beam radiotherapy and high dose-rate BT,was biologically normalized to conventional 2 Gy fractions (EQD2).D90and D100for both HR-CTV and IR-CTV,and D2 ccfor the bladder,rectum,and sigmoid were analyzed.Results The mean D90value for HR-CTV was 88.4±3.5 Gy.The D2 ccfor the bladder,rectum,and sigmoid were 81.1±5.6,65.7±5.1,and 63.1±5.4 Gy,respectively.D2 cc≤90 Gy for the bladder and D2 cc≤70 Gy for the sigmoid were observed in all the patients.D2 cc≤70 Gy for the rectum was observed in 89% of patients.Conclusions 3DCT-guided interstitial BT has a significant dosimetric advantage for target volume accompanied by few minor complications,and thereby may be clinically feasible for treating locally advanced cervical cancer.However,its long-term efficacy and possible toxicities will require further clinical observation.
ABSTRACT
Objective To investigate the dosimetric difference between inverse planning simulated annealing(IPSA)and manual optimized plan for isodose line in interstitial brachytherapy for locally advanced cervical cancer and to provide a better optimization method for clinical application. Methods A total of 104 patients with cervical cancer were enrolled in this study. They received pelvic external beam radiotherapy and interstitial brachytherapy in five fractions. Both IPSA and manual optimized plan for isodose line were used to optimize the dose in each fraction. Dose volume parameters of the two plans were compared to analyze the dosimetric outcome by paired t-test. Results There were no significant differences in mean D 90and D 100for high-risk clinical target volume(HR-CTV)and D 90for intermediate-risk clinical target volume(IR-CTV)between the two groups(P>0.05). The IPSA group had a significantly higher D 100for IR-CTV than the manual optimized group(58.36±2.06 Gy vs. 53.99±2.17 Gy, P=0.025). For organs at risk,the IPSA group had a significantly lower mean rectum D 2ccand a significantly higher bladder D 2ccthan the manual optimized group(68.53± 2.85 Gy vs. 71.77± 1.79 Gy, P=0.002;80.49± 3.36 Gy vs. 78.71± 2.64 Gy,P=0.034). There was no significant difference in sigmoid D 2ccbetween the two groups(P>0.05). The IPSA group had significantly higher relative dose homogeneity index(HI)and conformity index (CI)of radiation dose for target volume than the manual optimized group(P<0.05), and there was no significant difference in overdose volume index(OI)between the two groups(P= 0. 1 0 7).Conclusions Compared with manual optimized plan for isodose line, IPSA can improve the dose distribution of tumor tissue,reduce mean rectum D 2cc,and increase CI and HI,so it is a preferable optimized treatment planning method in clinical application.
ABSTRACT
Objective To compare the performances of Monaco and Pinnacle treatment planning systems (TPS) for volumetric modulated arc therapy (VMAT) optimization regarding lung cancer.The TPS was compared in terms of dose distributions,treatment delivery parameters and quality control results.Methods For 20 patients,including 10 cases of left lung cancer and l0 cases of right lung cancer,two VMAT plans were generated for each case:one with Monaco 3.0 TPS and the other with Pinnacle 9.2 TPS.Two plans were compared among plan dosimetrie distribution.conformity index and homogeneity index of the targets,the average dose,maximum dose,minimum dose and interested dose volume histograms of organs at risk(OAR,and delivery time and MUs of the therapy plans,the accuracy of treatment plans dose verification.Results Monaco provided better PTV coverage than Pinnacle (t =5.927-12.034,P ＜ 0.05) except Dminof PTV.Monaco had a worse sparing effect on lung than Pinnacle (t =3.545-7.485,P ＜0.05) except V10of diseased side lung and V5of total lung.In addition,Monaco had a better sparing effect on heart(t =2.836-4.011,P ＜0.05).Monaco had fewer delivery time(t =9.780,P ＜0.05)and MUs(t =5.304,P ＜0.05)of the therapy plans,and the pass rate of QA was better than Pinnacle(t =4.937,P ＜ 0.05).Conclusions For lung cancer patients,VMAT treatment plans obtained with Monaco and Pinnacle could offer clinically acceptable dose distributions.Pinnacle might have a better sparing effect on lung and fewer delivery time and MUs of the therapy plans.Monaco had a better PTV coverage and heart sparing.Moreover,Monaco had better accuracy of treatment plans dose verification.