A Novel Adjustable Anthropomorphic Head Phantom for Verifying the Dose of Radiation Therapy

This study aims to make a phantom to verify dose distribution and compare two techniques of radiation therapy, including 3D conventional radiotherapy (3D-CRT) and modulated photon radiotherapy (IMRT). For treatment of brain cancer, physicians have to prescribe radiation therapy to involved patients so that organs at risk receive unwanted dose causing them to be damaged. To know precise dose delivered into them and evaluate treatment-planning system (TPs), it is necessary to do dosimetry in the phantom owing to difficulties of dosimetry in human. It is important to make a phantom with characteristics similar to humans and ability to compute dose and dose distribution in desired organs and tissue. Thus, there is possibility to compute dose in different parts, including doses delivered in ears, eyes, stem brain and optic nerve. Furthermore, this phantom has to provide this opportunity to investigate whether some techniques of radiation therapy such as 3D-CRT or IMRT depend on the size or location of tumors. To this end, a low workload, easy-to-set-up, lightweight, and transportable phantom was designed, and made from Polylactic acid (PLA) in dimensions 23×24×32 cm(3). The phantom consists of brain, tumors in different dimeters, including 2, 4, 6 cm and also parts for eyes and ears to locate TLDs. Head, brain and tumors are able to open so that they can be filled with polymer gel dosimetry making possible record dose distribution in three-dimensions (3D) and sharp dose gradients.