Volumetric‐modulated arc therapy versus intensity‐modulated radiotherapy for large volume retroperitoneal sarcomas: A comparative analysis of dosimetric and treatment delivery parameters

Abstract

PurposeTo compare dosimetric and treatment delivery parameter differences between volumetric‐modulated arc radiotherapy (VMAT) and intensity‐modulated radiotherapy (IMRT) for large volume retroperitoneal sarcomas (RPS).Materials and MethodsBoth VMAT and IMRT planning were performed on CT datasets of 10 patients with RPS who had been previously treated with preoperative radiotherapy. Plans were optimized to deliver ≥95% dose to the PTV and were evaluated for conformity and homogeneity. Dose to the organs at risk (OARs) (kidney, liver, spinal cord, and bowel space), unspecified tissue, and dose evaluation volumes (DEVs) at 1, 2, and 5 cm from PTV were calculated and compared. Monitor units (MUs) and treatment delivery times were recorded and compared between the two techniques. The deliverability of the large volume RPS VMAT plans was verified by portal dosimetry on a Truebeam™ linac.Results VMAT and IMRT plans were equivalent for PTV coverage and homogeneity (P > 0.05); however, VMAT plans had slightly better conformity index, CI (P < 0.001). Doses to the OARs were not significantly different between VMAT and IMRT plans (P > 0.05). Mean doses to the unspecified tissue as well as at 1, 2, and 5 cm DEVs were lower with VMAT compared with IMRT, P = 0.04 and P < 0.01, respectively. MUs and average beam‐on times were both significantly lower in the VMAT vs IMRT plans, P < 0.001 and P = 0.001, respectively. All VMAT plans passed portal dosimetry delivery verification with an average gamma passing rate of 99.6 ± 0.4%.Conclusions VMAT planning for large volume RPS improved CI, and achieved comparable OAR sparing, as compared with IMRT. As treatment delivery time was lower, the use of VMAT for RPS may translate into improved treatment delivery efficiency.

Radiation pneumonitis in lung cancer treated with volumetric modulated arc therapy

“…Among other factors included in the multivariate analyses, increasing values of heart V 5 and heart V 30 in the high dose group might best explain why patients administered a high dosage of radiation did worse than the patients who were administered a standard dosage of radiation. Several studies demonstrated that VMAT could reduce delivery time and MUs compared with IMRT (21)(22)(23). Reduction in delivery time has the potential of decreasing the uncertainty occurred during treatment.…”

Effectiveness and Safety of Tissue Expander for Adjuvant Helical Tomotherapy in Curatively Resected Retroperitoneal Sarcoma

“…Unlike previous studies, this study found that the ability to deliver higher RT dose to both a TE and a non-TE group might be associated with HT advantages. A dosimetric study of RPS with large CTV confirmed the superiority of HT for dose uniformity compared to step-and-shoot IMRT (9,26). In addition, HT is optimized for image guidance using megavoltage CT (MVCT) images in an IMRT era where importance of image guidance is more emphasized (27).…”

Comparison of Volumetric Modulated Arc Therapy and Fixed Field Intensity Modulated Radiotherapy for Radical Treatment of Early Prostate Cancer using Hypofractionated Radiotherapy

“…It is now endorsed by the American Society for Radiation Oncology (ASTRO), American Society for Clinical Oncology (ASCO) and American Urology Association (AUA). 11,12 This cost-effective approach reduces hospital stays and visits and allows radiation R Ra ad di io ot th he er ra ap py y f fo or r R Ra ad di ic ca al l T Tr re ea at tm me en nt t Pak Armed Forces Med J 2023; 73(3): 911 facilities to treat more patients simultaneously. On the other hand, using a higher dose per fraction could lead to increased toxicity of neighbouring OARs, especially bladder and rectum, in the case of prostate cancer.…”