BM-04 * IMAGE GUIDED STEREOTACTIC RAPID ARC(R) TO SINGLE BRAIN METASTATIC ASSISTED BY INTRACRANIAL CALCIFICATION

Abstract

BACKGROUND: Image-guided radiation therapy (IGRT) cone-beam CT (CBCT) is delivering important improvements in the stereotactic radiotherapy. Volumetric Modulated Arc Therapy (VMAT), known as Rapid Arc® from Varian Medical Systems has the ability to deliver radiation in less time and treat several targets simultaneously. METHODS: We review a single case report of 82 yrs. old, female, with a contrast magnetic resonance diagnosis of enhanced single left occipital lobe brain metastases from a colorectal cancer. ECOG 1. The mental and neurologic physical examination is age-appropriate. Maximum diameter size of the single lesion was 3.8 cm (volume: 33.3 cm3). Previous immobilization with a thermoplastic head mask and brain CT scan for planning were done. Whole brain radiotherapy with simultaneous integrated boost (WBRT&SIB) for dual Rapid Arc® was planned after delineated planning tumor volume (PTV) and organs at risks (OAR). The prescribed dose to metastatic lesion (PTV 1) was 37,5Gy and normal brain (PTV 2) in 25Gy, both PTV in 10 fractions (2 weeks). A daily CBCT was applied with the auxiliary use of natural intracranial calcifications for improve the frameless position of the targets. Shift table displacements after setup using online CBCT in anterior-posterior (AP), right-left (RL), superior-inferior (SI) directions was annotated in centimeters +/- standard deviation (cm +/- SD). RESULTS: Mean dose for PTV 1 and PTV 2 was 38.9 Gy and 26.8 Gy respectively. PTV 1 Conformity Index (CI) was 1.06. Mean +/- SD residual setup shift table displacements were registered in AP: -0.01 +/- 0.06 cm; RL: -0.04 +/- 0.14 cm; SI: -0.14 +/- 0.14 cm. CONCLUSION: IN this only patient experience, frameless double arc VMAT WBRT&SIB was optimal delivered with the use of online CBCT and intracranial calcifications reposition.