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Titolo:
Monte Carlo simulations of the imaging performance of metal plate/phosphorscreens used in radiotherapy
Autore:
Kausch, C; Schreiber, B; Kreuder, F; Schmidt, R; Dossel, O;
Indirizzi:
Philips Res Labs, D-22335 Hamburg, Germany Philips Res Labs Hamburg Germany D-22335 Labs, D-22335 Hamburg, Germany Univ Hamburg Hosp, Clin Radiol, Dept Radiotherapy, D-20246 Hamburg, Germany Univ Hamburg Hosp Hamburg Germany D-20246 rapy, D-20246 Hamburg, Germany Univ Karlsruhe, Inst Biomed Engn, D-76128 Karlsruhe, Germany Univ Karlsruhe Karlsruhe Germany D-76128 ngn, D-76128 Karlsruhe, Germany
Titolo Testata:
MEDICAL PHYSICS
fascicolo: 10, volume: 26, anno: 1999,
pagine: 2113 - 2124
SICI:
0094-2405(199910)26:10<2113:MCSOTI>2.0.ZU;2-S
Fonte:
ISI
Lingua:
ENG
Soggetto:
TO-NOISE ANALYSIS; PATIENT SET-UP; PORTAL IMAGES; PHOSPHOR SCREENS; MEGAVOLTAGE; REGISTRATION; ABSORPTION; VERIFICATION; LOCALIZATION; OPTIMIZATION;
Keywords:
portal images; metal plate/phosphor screens; image quality; monte carlo simulation; MTF(f); NPS(f); DQE(f);
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Clinical Medicine
Life Sciences
Citazioni:
31
Recensione:
Indirizzi per estratti:
Indirizzo: Kausch, C Philips Res Labs, Rontgenstr 24-26, D-22335 Hamburg, Germany Philips Res Labs Rontgenstr 24-26 Hamburg Germany D-22335 rmany
Citazione:
C. Kausch et al., "Monte Carlo simulations of the imaging performance of metal plate/phosphorscreens used in radiotherapy", MED PHYS, 26(10), 1999, pp. 2113-2124

Abstract

The imaging performance of metal plate/phosphor screens which are used forthe creation of portal images in radiotherapy is investigated by using Monte Carlo simulations. To this end the modulation transfer function, the noise power spectrum and the detective quantum efficiency [DQE(f)] are calculated for different metals and phosphors and different thicknesses of metal and phosphor for a range of spatial resolutions. The interaction of x-rays with the metal plate/phosphor screen is modeled with the EGS4 electron gammashower code. Optical transport in the phosphor is modeled by simulating scattering and reabsorption events of individual optical photons. It is shownthat metals with a high atomic number perform better than lighter metals in maximizing the DQE(f). It is furthermore shown that the DQE(f) for the metal plate/phosphor screen alone is nearly x-ray quantum absorption limited up to spatial frequencies of 0.4 cycles/mm. In addition, it is argued that the secondary quantum sink of optical photons imposed by the optical chain (mirror, lenses and video camera) leads to a significant degradation of thesignal-to-noise ratio at spatial frequencies which are most important for successful registration of portal images. Therefore, the conclusion is thata replacement of the optical chain by a flat array of photodiodes placed directly under the phosphor will lead to a substantial improvement in image quality of portal images. (C) 1999 American Association of Physicists in Medicine. [S0094-2405(99)01710-1].

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 07/07/20 alle ore 12:35:46