Dosimetric Comparison of Volumetric Modulated Arc Therapy and Intensity Modulated Radiation Therapy for Soft Tissue Sarcoma of the Extremities.

PURPOSE: Radiation therapy is a standard part of limb conserving therapy for extremity soft tissue sarcoma (STS) at high risk of recurrence. Toxic effects increase with radiation dose and volume of normal tissue irradiated. This study sought to compare dosimetry of volumetric modulated arc therapy (VMAT) with intensity modulated radiation therapy (IMRT) and to investigate the optimal planning technique. METHODS AND MATERIALS: Twenty patients with extremity STS who underwent preoperative radiation therapy (50 Gy in 25 fractions) between 2016 and 2020 at a specialised sarcoma center were included. The original treatment techniques were sliding window IMRT or 3-dimensional conformal. VMAT plans were retrospectively generated according to the original tumor and organ-at-risk constraints. Quality assurance was performed as per departmental protocol. Wilcoxon signed-rank test was used to compare dosimetric parameters (for planning target volume [PTV], in-field bone, and soft tissue structures), monitor units (MUs), and treatment time. RESULTS: Median patient age was 65 years and the majority were male (n = 14, 70%). The most common subtype was undifferentiated pleomorphic sarcoma (n = 14, 70%), and most tumors were located on the thigh (n = 12, 60%). Median PTV was 1110 cm3 and median volume of in-field bone 236 cm3. VMAT plans had significantly lower average MU (480 vs 862 MU, P < .001) and overall treatment time (300 vs 153 seconds, P < .001). PTV coverage favored VMAT, with marginally higher mean, minimum, and maximum doses and higher conformity index. However, differences were not statistically significant. Dose to infield bone and soft tissue structures were similar or slightly lower with VMAT. CONCLUSIONS: In extremity STS, VMAT plans demonstrated a favorable trend toward tumor coverage and dose conformity compared with IMRT along with significantly lower MUs and half the overall treatment time.

Patient-reported outcomes of prostate high-dose-rate brachytherapy boost comparing an outpatient and inpatient protocol: a two-center chronologic cohort study.

PURPOSE: To determine patients' self-reported experiences of outpatient high-dose-rate prostate brachytherapy boost, and compare with previous cohort treated as inpatients. METHODS AND MATERIALS: Using the Prostate Brachytherapy Questionnaire, we previously examined patients' subjective experience of the brachytherapy procedure when it involved one implant and hospitalization with the template in situ for 2 days (Group 1). The protocol was subsequently changed to two implants, 2 weeks apart as outpatients. Fifty-eight patients treated with the new protocol (Group 2) completed the same questionnaire. We compared the self-reported experiences between Groups 1 and 2 and also between the first and second implant for those in Group 2. Our hypothesis was that the worst rated issues in Group 1 might be reduced with the new approach. RESULTS: Group 2 patients were less troubled overall by the procedure (mean scores 2.3 vs. 3.2, p=0.0293). Specifically, they were less troubled by "discomfort" (2.8 vs. 3.8, p=0.0254); "being stuck in bed" (1.7 vs. 4.2 p<0.0001); "feeling helpless" (1.3 vs. 2.8, p=0.0009); "fear of opening my bowels" (2.1 vs. 3.3, p=0.0055); and "fear of coping with the implant" (1.3 vs. 2.5, p=0.0004). There was no significant increase in "thought of implant" or "fear of implant" before the second implant. However, more patients rated worse than expected "fear of passing urine" during the second implant. CONCLUSIONS: Patients rated high-dose-rate brachytherapy less troublesome when delivered as outpatient with two implants, 2 weeks apart than as inpatient over 3 days, despite the additional invasive procedure and anesthesia.