Demonstration of megavoltage and diagnostic x‐ray imaging with hydrogenated amorphous silicon arrays

Abstract

Flat-panel imagers consisting of the first large area, self-scanning, pixelated, solid-state arrays made with hydrogenated amorphous silicon (a-Si:H) are under development by the authors for applications in diagnostic x-ray and megavoltage radiotherapy imaging. The arrays, designated by the acronym MASDA for multi-element amorphous silicon detector array, consist of a two-dimensional array of a-Si:H photodiodes and thin-film transistors and are used in conjunction with scintillating materials. Imagers utilizing MASDA arrays offer a variety of advantages over existing technologies. This article presents initial megavoltage and diagnostic-quality x-ray images taken with several such arrays including the first examples of anatomical-phantom images. The external readout electronics and imaging techniques required to obtain such images are outlined, the construction, operation, and advantages of the arrays briefly reviewed, and the future potential of this new technology discussed.

Anniversary Paper: A sampling of novel technologies and the role of medical physicists in radiation oncology

“…Antonuk and Street, working with the emerging technology of hydrogenated amorphous silicon arrays, introduced active matrix flat panel imagers to radiography. Such technology has revolutionized digital radiography, 79 and has become a staple for setup verification in radiation oncology. Figure 22 shows a prototype imager and early radiograph.…”

Performance evaluation of polycrystalline photoconductors for radiation therapy imaging

“…The slit image frames and data radiation dark frames were processed through application of gain and offset corrections. 53 Subsequently, the slit image frames were corrected through subtraction of background radiation ͑using the averaged radiation dark data͒ and correction for defective pixels ͑using a 3 ϫ 3 median filter͒. The processed slit images were averaged to produce LSF data, the Fourier transforms of which yielded presampled MTF results.…”

Quality Assurance for Kilo- and Megavoltage In-Room Imaging and Localization for Off- and Online Setup Error Correction

“…The unique and essential component of an AMFPI consists of a two-dimensional grid of imaging pixels, each of which comprises an amorphous silicon photodiode coupled to a thin-film transistor (TFT). The pixels are addressed and read out by means of two orthogonal sets of control lines that extend to contacts on the periphery of the glass substrate on which the array is fabricated [5].…”