A miniature "scintillator-fiberoptic-PMT" detector system for the dosimetry of small fields in stereotactic radiosurgery

Linear accelerator-based stereotactic radiosurgery is an important modality in the management of localized intracranial abnormalities and often is the only option for treatment of certain lesions. The quantification of the ab sorbed radiation doses delivered for this modality has been a challenge due to the small size of the treatment fields (typically 5-30 min collimated f ields) and the type of detectors presently available. This paper presents c omparative dose measurements performed using a miniature (1.6 x 10(-3) cm(3 )) plastic scintillator detector to the commonly used detectors for the dos imetry of small photon fields used for stereotactic radiosurgery. The spati al resolution of the plastic scintillator detector was compared to that of a p-type Si diode and a 0.1-cm(3) ionization chamber. Small field dosimetry parameters (beam profiles, percent depth doses, and dose output factors) u sing the scintillation detector, the 0.1-cm(3) ionization chamber, the p-ty pe Si diode, and radiographic film are presented. This comparative study sh ows that designing a miniature scintillator detector system is feasible and when compared to other benchmark detectors is an appropriate detector for the dosimetry of small stereotactic radiosurgery photon fields.