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Titolo:
A two-step algorithm for predicting portal dose images in arbitrary detectors
Autore:
McCurdy, BMC; Pistorius, S;
Indirizzi:
Canc Care Manitoba, Dept Phys Med, Winnipeg, MB R3E 0V9, Canada Canc Care Manitoba Winnipeg MB Canada R3E 0V9 innipeg, MB R3E 0V9, Canada Univ Manitoba, Dept Phys, Winnipeg, MB R3T 2N2, Canada Univ Manitoba Winnipeg MB Canada R3T 2N2 ys, Winnipeg, MB R3T 2N2, Canada Univ Manitoba, Dept Radiol, Winnipeg, MB, Canada Univ Manitoba Winnipeg MB Canada toba, Dept Radiol, Winnipeg, MB, Canada
Titolo Testata:
MEDICAL PHYSICS
fascicolo: 9, volume: 27, anno: 2000,
pagine: 2109 - 2116
SICI:
0094-2405(200009)27:9<2109:ATAFPP>2.0.ZU;2-3
Fonte:
ISI
Lingua:
ENG
Soggetto:
IMAGING DEVICE; CONVOLUTION/SUPERPOSITION METHOD; RADIOTHERAPY; VERIFICATION; DOSIMETRY; BEAMS; DISTRIBUTIONS; QUALITY; RADIOGRAPHY; ENERGY;
Keywords:
portal dose images; predicting portal images; pencil beam algorithm; treatment verification;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Clinical Medicine
Life Sciences
Citazioni:
37
Recensione:
Indirizzi per estratti:
Indirizzo: McCurdy, BMC Canc Care Manitoba, Dept Phys Med, 100 Olivia St, Winnipeg, MB R3E 0V9, Canada Canc Care Manitoba 100 Olivia St Winnipeg MB Canada R3E 0V9 a
Citazione:
B.M.C. McCurdy e S. Pistorius, "A two-step algorithm for predicting portal dose images in arbitrary detectors", MED PHYS, 27(9), 2000, pp. 2109-2116

Abstract

Recently, portal imaging systems have been successfully demonstrated in dosimetric treatment verification applications, where measured and predicted images are quantitatively compared. To advance this approach to dosimetric verification, a two-step model which predicts dose deposition in arbitrary portal image detectors is presented. The algorithm requires patient CT data, source-detector distance, and knowledge of the incident beam fluence. Thefirst step predicts the fluence entering a portal imaging detector locatedbehind the patient. Primary fluence is obtained through ray-tracing techniques, while scatter fluence prediction requires a library of Monte Carlo-generated scatter fluence kernels. These kernels allow prediction of basic radiation transport parameters characterizing the scattered photons, including fluence and mean energy. The second step of the algorithm involves a superposition of Monte Carlo-generated pencil beam kernels, describing dose deposition in a specific detector, with the predicted incident fluence. This process is performed separately for primary and scatter fluence, and yields a predicted dose image. A small but noticeable improvement in prediction isobtained by explicitly modeling the off-axis energy spectrum softening dueto the flattening filter. The algorithm is tested on a slab phantom and a simple lung phantom (6 MV). Furthermore, an anthropomorphic phantom is utilized for a simulated lung treatment (6 MV), and simulated pelvis treatment (23 MV). Data were collected over a range of air gaps (10-80 cm). Detectorsincorporating both low and high atomic number buildup are used to measure portal image profiles. Agreement between predicted and measured portal doseis better than 3% in areas of low dose gradient (<30%/cm) for all phantoms, air gaps, beam energies, and detector configurations tested here. It is concluded that this portal dose prediction algorithm is fast, accurate, allows separation of primary and scatter dose, and can model arbitrary detectors. (C) 2000 American Association of Physicists in Medicine. [S0094-2405(00)02209-4].

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 11/07/20 alle ore 04:39:42