Topological detector: measuring continuous dosimetric quantities with few-element detector array

Abstract

A prototype topological detector was fabricated and investigated for quality assurance of radiation producing medical devices. Unlike a typical array or flat panel detector, a topological detector, while capable of achieving a very high spatial resolution, consists of only a few elements and therefore is much simpler in construction and more cost effective. The key feature allowing this advancement is a geometry-driven design that is customized for a specific dosimetric application. In the current work, a topological detector of two elements was examined for the positioning verification of the radiation collimating devices (jaws, MLCs, and blades etc). The detector was diagonally segmented from a rectangular thin film strip (2.5 cm × 15 cm), giving two contiguous but independent detector elements. The segmented area was the central portion of the strip measuring 5 cm in length. Under irradiation, signals from each detector element were separately digitized using a commercial multichannel data acquisition system. The center and size of an x-ray field, which were uniquely determined by the collimator positions, were shown mathematically to relate to the difference and sum of the two signals. As a proof of concept, experiments were carried out using slit x-ray fields ranging from 2 mm to 20 mm in size. It was demonstrated that, the collimator positions can be accurately measured with sub-millimeter precisions.

Effective Contact Potential of Thin Film Metal-Insulator Nanostructures and Its Role in Self-Powered Nanofilm X-ray Sensors

“…The high-energy current (HEC) X-ray detection scheme was recently proposed and demonstrated by our group. − Several prototype HEC detectors have been developed and tested, possessing various shapes (square, rectangular, strip, triangular, or pixelated) and areas (from about a few mm 2 to 1800 cm 2 ) on rigid and flexible substrates (glass, polymer) and material combinations (Cu, Al, Pb, Ta, ITO electrodes and polymers, oxide or air as dielectrics) using either micro- or nanofilm fabrication approaches (printing or electron beam physical vapor deposition).…”

“…The main advantage of HEC structures is their suitability for medical dosimetry, radiation protection, or monitoring X-ray devices and their subsequent integration with existing equipment. They are further apt to adapt to difficult geometry and rugged conditions. ,− …”

Self‐powered nano‐porous aerogel x‐ray sensor employing fast electron current

“…We envision several possible medical applications, for instance, in beam monitoring and transmission dosimetry in radiotherapy and interventional radiology. Other possible application is in mechanical QA of linac or CT (topological detectors).…”

Resistive electrode array (REA) for radiotherapy beam monitoring and quality assurance

“…However, in REA the discrimination of radiation fields is achieved not via segmentation or angling (differential sensitivity to x-rays) but rather via the finite resistance of the collecting electrode. Localization of the readouts at the edges of REA outside of the irradiation beam is more like localization of readouts in ion chamber strip arrays (Brivio et al 2019a, Albert et al 2020 and in a segmented ion chamber detector (Han et al 2016).…”