Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
Dosimetric investigation and portal dose image prediction using an amorphous silicon electronic portal imaging device
Autore:
McCurdy, BMC; Luchka, K; Pistorius, S;
Indirizzi:
Canc Care Manitoba, Dept Med Phys, Winnipeg, MB R3E 0V9, Canada Canc Care Manitoba Winnipeg MB Canada R3E 0V9 innipeg, MB R3E 0V9, Canada British Columbia Canc Agcy, Dept Clin Phys, Vancouver, BC V5Z 4E6, Canada British Columbia Canc Agcy Vancouver BC Canada V5Z 4E6 BC V5Z 4E6, Canada
Titolo Testata:
MEDICAL PHYSICS
fascicolo: 6, volume: 28, anno: 2001,
pagine: 911 - 924
SICI:
0094-2405(200106)28:6<911:DIAPDI>2.0.ZU;2-D
Fonte:
ISI
Lingua:
ENG
Soggetto:
MONTE-CARLO CODE; CONVOLUTION MODEL; CONVOLUTION/SUPERPOSITION METHOD; PHYSICAL CHARACTERISTICS; EXIT DOSIMETRY; PHOTON SCATTER; RADIOTHERAPY; VERIFICATION; BEAM; DISTRIBUTIONS;
Keywords:
portal dose images; predicting portal images; treatment verification; amorphous silicon detector; electronic portal imaging device;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Clinical Medicine
Life Sciences
Citazioni:
42
Recensione:
Indirizzi per estratti:
Indirizzo: McCurdy, BMC Canc Care Manitoba, Dept Med Phys, 675 McDermot Ave, Winnipeg, MB R3E 0V9,Canada Canc Care Manitoba 675 McDermot Ave Winnipeg MB Canada R3E 0V9
Citazione:
B.M.C. McCurdy et al., "Dosimetric investigation and portal dose image prediction using an amorphous silicon electronic portal imaging device", MED PHYS, 28(6), 2001, pp. 911-924

Abstract

A two step algorithm to predict portal dose images in arbitrary detector systems has been developed recently. The current work provides a validation of this algorithm on a clinically available, amorphous silicon flat panel imager. The high-atomic number, indirect amorphous silicon detector incorporates a gadolinium oxysulfide phosphor scintillating screen to convert deposited radiation energy to optical photons which form the portal image. A water equivalent solid slab phantom and an anthropomorphic phantom were examined at beam energies of 6 and 18 MV and over a range of air gaps (similar to20-50 cm). In the many examples presented here, portal dose images in the phosphor were predicted to within 5% in low-dose gradient regions, and to within 5 mm (isodose line shift) in high-dose gradient regions. Other basic dosimetric characteristics of the amorphous silicon detector were investigated, such as linearity with dose rate (+/-0.5%), repeatability (+/-2%), andresponse with variations in gantry rotation and source to detector distance. The latter investigation revealed a significant contribution to the image from optical photon spread in the phosphor layer of the detector. This phenomenon is generally known as "glare," and has been characterized and modeled here as a radially symmetric blurring kernel. This kernel is applied tothe calculated dose images as a convolution, and is successfully demonstrated to account for the optical photon spread. This work demonstrates the flexibility and accuracy of the two step algorithm for a high-atomic number detector. The algorithm may be applied to improve performance of dosimetric treatment verification applications, such as direct image comparison, backprojected patient dose calculation, and scatter correction in megavoltage computed tomography. The algorithm allows for dosimetric applications of the new, flat panel portal imager technology in the indirect configuration, taking advantage of a greater than tenfold increase in detector sensitivity over a direct configuration. (C) 2001 American Association of Physicists in Medicine.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 11/07/20 alle ore 03:32:40