Dosimetric evaluation of stereotaxic body radiotherapy (SBRT) in the bone oligometastasis planning in Radixact

Dosimetric Evaluation of Stereotactic Body Radiotherapy (SBRT) for Bone Oligometastasis Planning on Radixact Bone oligometastasis is one of the primary metastatic conditions resulting from the spread of a primary cancer, and its treatment is largely palliative, with Stereotactic Body Radiotherapy (SBRT) commonly employed. At the Arturo Lopez Perez Foundation, this treatment is currently performed exclusively using Volumetric Modulated Arc Therapy (VMAT) equipment. Although the institution also possesses a Radixact Helical Tomotherapy (HT) unit, no dosimetric studies have been conducted to explore its use as an alternative in case of equipment failure. This study aims to dosimetrically compare SBRT treatment plans for bone oligometastasis previously conducted with VMAT to recalculated plans using HT. The Mann-Whitney U test was performed on analyzed variables, revealing no statistically significant differences between VMAT and HT in coverage of the prescribed isodose surface on the PTV (p = 0.55), doses to the spinal cord and cauda equina (p = 0.75), skin (p = 0.57), and organs-at-risk by anatomical location, including the esophagus (p = 0.54), trachea (p = 0.38), bladder (p = 0.6), and rectum (p = 0.75). A significant difference was found only in high-dose spill (p = 0.01), attributed to mechanical and beam modulation differences between the two modalities. The results suggest that VMAT and HT are dosimetrically comparable for SBRT treatments in bone oligometastasis. This finding supports the potential future validation of the Radixact system at the Arturo Lopez Perez Foundation as an alternative or backup to VMAT equipment for such treatments