A novel QA phantom based on scintillating fiber ribbons with implementation of 2D dose tomography for small-field radiotherapy.

Purpose: To develop a novel instrument for real-time quality assurance (QA) procedures in radiotherapy. The system implements a scintillation-based phantom and associated signal acquisition and processing modules and aims to monitor two-dimensional (2D) dose distributions of small fields.

Materials And Methods: For the proposed phantom, we have designed and realized a prototype implementing six high-resolution tissue-equivalent scintillating fiber ribbons stacked with in-plane 30° rotated orientations from each other.

SciFi detector and associated method for real-time determination of profile and output factor for small fields in stereotactic radiotherapy.

Purpose: For determining small-field profile and output factor during stereotactic radiotherapy quality assurance (QA) procedures, we propose a novel system based on the scintillating fiber (SciFi) detector with output image acquisition and processing to allow real-time monitoring of profile and output factor.

Materials And Methods: The employed detector is a SciFi detector made of tissue-equivalent scintillating plastic fibers arranged in 6-layer fiber ribbons with a fiber pitch of 275 μm in each layer. The scintillating signal at the detector output is acquired by a sCMOS (scientific complementary metal-oxide-semiconductor) camera and represents the projected field profile along the fibers axis.

Design and testing of a phantom and instrumented gynecological applicator based on GaN dosimeter for use in high dose rate brachytherapy quality assurance.

Purpose: High dose rate brachytherapy (HDR-BT) is widely used to treat gynecologic, anal, prostate, head, neck, and breast cancers. These treatments are typically administered in large dose per fraction (>5 Gy) and with high-gradient-dose-distributions, with serious consequences in case of a treatment delivery error (e.g.

Implementation and validation of a fluence pencil kernels model for GaN-based dosimetry in photon beam radiotherapy.

Gallium nitride (GaN), a direct-gap semiconductor that is radioluminescent, can be used as a transducer yielding a high signal from a small detecting volume and thus potentially suitable for use in small fields and for high dose gradients. A common drawback of semiconductor dosimeters with effective atomic numbers higher than soft tissues is that their responses depend on the presence of low energy photons for which the photoelectric cross section varies strongly with atomic number, which may affect the accuracy of dosimetric measurements. To tackle this 'over-response' issue, we propose a model for GaN-based dosimetry with readout correction.

Fiber background rejection and crystal over-response compensation for GaN based in vivo dosimetry.

For dosimetric measurements using an implantable optical fiber probe with GaN (Gallium Nitride) scintillator as radioluminescence (RL) transducer, a bi-channel method is proposed to reject the background contribution of the irradiated fiber segment. It is based on spectral differences between the narrow-band light emission from GaN and the large-band background from the irradiated optical fiber. Experimental validation of this method using 6 MV photon beam has shown that the remaining background contribution after subtraction is below 1.