Dosimetry in radiotherapy using a-Si EPIDs: Systems, methods, and applications focusing on 3D patient dose estimation

7th International Conference on 3D Radiation Dosimetry

McCurdy, B.M.C.^1,2,3

Medical Physics Department, CancerCare Manitoba, Winnipeg, MB R3E 0V9, Canada^1

Department of Physics and Astronomy, University of Manitoba, Winnipeg, MB R3T 2N2, Canada^2

Department of Radiology, University of Manitoba, Winnipeg, MB R3T 2N2, Canada^3

关键词: Amorphous silicon (a-Si);    High spatial resolution;    Radiological imaging;    Silicon electronics;    Stereotactic radiosurgery;    Treatment techniques;    Treatment verification;    Volumetric modulated arc therapy;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/444/1/012002/pdf
DOI  :  10.1088/1742-6596/444/1/012002

来源: IOP

【 摘 要 】

An overview is provided of the use of amorphous silicon electronic portal imaging devices (EPIDs) for dosimetric purposes in radiation therapy, focusing on 3D patient dose estimation. EPIDs were originally developed to provide on-treatment radiological imaging to assist with patient setup, but there has also been a natural interest in using them as dosimeters since they use the megavoltage therapy beam to form images. The current generation of clinically available EPID technology, amorphous-silicon (a-Si) flat panel imagers, possess many characteristics that make them much better suited to dosimetric applications than earlier EPID technologies. Features such as linearity with dose/dose rate, high spatial resolution, realtime capability, minimal optical glare, and digital operation combine with the convenience of a compact, retractable detector system directly mounted on the linear accelerator to provide a system that is well-suited to dosimetric applications. This review will discuss clinically available a-Si EPID systems, highlighting dosimetric characteristics and remaining limitations. Methods for using EPIDs in dosimetry applications will be discussed. Dosimetric applications using a-Si EPIDs to estimate three-dimensional dose in the patient during treatment will be overviewed. Clinics throughout the world are implementing increasingly complex treatments such as dynamic intensity modulated radiation therapy and volumetric modulated arc therapy, as well as specialized treatment techniques using large doses per fraction and short treatment courses (ie. hypofractionation and stereotactic radiosurgery). These factors drive the continued strong interest in using EPIDs as dosimeters for patient treatment verification.