title: An Active Matrix Flat Panel Dosimeter (AMFPD) for in-phantom dosimetric measurements.
abstract: An a-Si Active Matrix Flat Panel Imager (AMFPI) prototype developed in-house has been modified to function as an in-phantom dosimetry system providing high resolution two-dimensional (2-D) data. This Active Matrix Flat Panel Dosimeter (AMFPD) system can be used as a replacement device for standard in-phantom dosimeters, such as scanning ion chambers in water, or film in solid water. The initial characterization of the device demonstrates a wide dynamic range (up to 160 cGy), a stable calibration curve (less than 1.5% variation over 1 year), dose rate independence (less than 1%), and excellent agreement of output factors with ion chamber measurements for a range of field sizes (less than 2%). The device also compares well to film for 2-D planar dose distributions. It is expected that the AMFPD system will be useful for beam commissioning, algorithm verification test data, and routine IMRT quality assurance dosimetry.
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109-0010, USA. jmmoran@med.umich.edu
authors.forename: Jean M
authors.initials: JM
authors.lastname: Moran
authors.forename: Donald A
authors.initials: DA
authors.lastname: Roberts
authors.forename: Teamour S
authors.initials: TS
authors.lastname: Nurushev
authors.forename: Larry E
authors.initials: LE
authors.lastname: Antonuk
authors.forename: Youcef
authors.initials: Y
authors.lastname: El-Mohri
authors.forename: Benedick A
authors.initials: BA
authors.lastname: Fraass
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D005240:Feasibility Studies; D019047:Phantoms, Imaging; D011856:Radiographic Image Enhancement / Q000295:instrumentation* / Q000379:methods; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D014159:Transducers