Arc Delivered Intensity-Modulated Radiotherapy Achieves Highly Conformal Radiotherapy for Brain Tumor Patients With Minimal Hair Loss.

INTRODUCTION Intensity-modulated radiotherapy (IMRT) improves planning target volume (PTV) coverage and organ at risk (OAR) avoidance in the brain compared to three-dimensional conformal radiotherapy (3-D CRT). However, IMRT is time consuming with considerable resource implications. Volumetric modulated arc therapy (VMAT) offers a quicker method of delivering an IMRT plan and requires less monitor units. Planning studies have shown VMAT compares well to IMRT in the brain but there is little data regarding clinical experience, particularly in fractionated schedules. METHODS Prospectively collected data (treatment details, delivery parameters, dosimetry, time, toxicity, and quality assurance) from the first 10 patients treated with RapidArc (a VMAT product) for brain tumors at our institution was analyzed in an observational study to establish whether the theoretical advantages of VMAT in the treatment of brain tumors translate into clinical practice. RESULTS Patients were selected for RapidArc due to the proximity of PTV to OAR and complex geometric tumor volumes. These included a range of tumor sites, histology, treatment volumes, and dose schedules. In all cases the PTV received >95% prescribed dose and dose to OAR was within tolerance. One patient required a second noncoplanar arc. Quality assurance parameters were easily met. Treatment time and monitor units were approximately half that taken to deliver IMRT. Patients tolerated treatment well and experienced minimal alopecia. CONCLUSION In practice RapidArc provides excellent radiotherapy plan conformity for a wide range of brain tumors with reduced treatment times and monitor units compared to IMRT. Our experience suggests patients treated with RapidArc may suffer minimal alopecia. [ABSTRACT FROM AUTHOR]