Purpose:Evaluate and compare retrospective prostate treatment plan using Volumetric Modulated Arc Therapy (RapidArc™ – Varian) technique with single or double arcs at COI Group.Methods:Ten patients with present prostate and seminal vesicle neoplasia were replanned as a target treatment volume and a prescribed dose of 78 Gy. A baseline planning, using single arc, was developed for each case reaching for the best result on PTV, in order to minimize the dose on organs at risk (OAR). Maintaining the same optimization objectives used on baseline plan, two copies for optimizing single and double arcs, have been developed. The plans were performed with 10 MV photon beam energy on Eclipse software, version 11.0, making use of Trilogy linear accelerator with Millenium HD120 multileaf collimator. Comparisons on PTV have been performed, such as: maximum, minimum and mean dose, gradient dose, as well as the quantity of monitor units, treatment time and homogeneity and conformity index. OARs constrains dose have been evaluated, comparing both optimizations.Results:Regarding PTV coverage, the difference of the minimum, maximum and mean dose were 1.28%, 0.7% and 0.2% respectively higher for single arc. When analyzed the index of homogeneity found a difference of 0.99% higher when compared with double arcs. However homogeneity index was 0.97% lower on average by using single arc. The doses on the OARs, in both cases, were in compliance to the recommended limits RTOG 0415. With the use of single arc, the quantity of monitor units was 10,1% lower, as well as the Beam‐On time, 41,78%, when comparing double arcs, respectively.Conclusion:Concerning the optimization of patients with present prostate and seminal vesicle neoplasia, the use of single arc reaches similar objectives, when compared to double arcs, in order to decrease the treatment time and the quantity of monitor units.

Radiotherapy is a medical modality that has been constantly revolutionizing with the offer of three-dimensional computational for treatment planning systems (TPS), providing greater security in the release of the radiation dose in the target volume, improving the therapeutic response and minimizing the radiobiological effects unwanted. The incorporation of modern radiotherapy techniques, along with studies that contribute to the development of radiotherapy protocols in veterinary medicine, may contribute to improve the quality of treatments and survival of animals affected by cancer. A TPS applied in a human radiotherapy clinic was used and the radiometric, clinical and anatomical parameters were adequate for the feasibility of use in veterinary radiotherapy. Tomographic images of the pelvic region of wild animals assisted by the School of Veterinary Medicine and Animal Science (FMVZ/UNESP) were used to perform them. Protocols for the implementation of computational planning in veterinary medicine were verified by analyzing the homogeneity of the radiation dose distribution in the planned treatment volume (PTV) and ensuring the protection of the organs surrounding the PTV. The methodology applied for the use of TPS Eclipse in veterinary radiotherapy planning proved to be feasible, and can present itself as an important tool to improve veterinary oncological therapeutic approaches.