Validation of the Fabricated Cast Nylon Head Phantom for Stereotactic Radiosurgery End-to-End Test using Alanine Dosimeter

BACKGROUND: Stereotactic radiosurgery (SRS) is an alternative to surgery as it precisely delivers single-large doses to small tumors. Cast nylon is used in phantom due to its computed tomography (CT) number of about 56–95 HU, which is close to that of the soft tissue. Moreover, cast nylon is also more budget-friendly than the commercial phantoms. AIMS: The aim of this study is to design and validate the fabricated cast nylon head phantom for SRS end-to-end test using an alanine dosimeter. MATERIALS AND METHODS: The phantom was designed using cast nylon. It was initially created by a computer numerical control three-axis vertical machining center. Then, the cast nylon phantom was scanned using a CT simulator. Finally, the validation of the fabricated phantom using alanine dosimeter proficiency with four Varian LINAC machines was performed. RESULTS: The fabricated phantom presented a CT number of 85–90 HU. The outcomes of VMAT SRS plans showed percentage dose differences from 0.24 to 1.55, whereas the percentage dose differences in organ at risk (OAR) were 0.09–10.80 due to the low-dose region. The distance between the target (position 2) and the brainstem (position 3) was 0.88 cm. CONCLUSIONS: Variation in dose for OAR is higher, which might be due to a high-dose gradient in the area where measurement was being conducted. The fabricated cast nylon end-to-end test head phantom had been suitably designed to image and irradiate during an end-to-end test for SRS using an alanine dosimeter.