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Titolo:
LINEAR-ACCELERATOR OUTPUT VARIATIONS AND THEIR CONSEQUENCES FOR MEGAVOLTAGE IMAGING
Autore:
PARTRIDGE M; EVANS PM; MOSLEHSHIRAZI MA;
Indirizzi:
ROYAL MARSDEN HOSP,NHS TRUST,CANC RES INST,JOINT DEPT PHYS,DOWNS RD SUTTON SM2 5PT SURREY ENGLAND
Titolo Testata:
Medical physics
fascicolo: 8, volume: 25, anno: 1998,
pagine: 1443 - 1452
SICI:
0094-2405(1998)25:8<1443:LOVATC>2.0.ZU;2-7
Fonte:
ISI
Lingua:
ENG
Soggetto:
COMPENSATOR DESIGN; PORTAL IMAGES; RADIOTHERAPY; DEVICE; NOISE; VERIFICATION; TOMOGRAPHY; DOSIMETRY; SYSTEMS;
Keywords:
PORTAL IMAGING; MEGAVOLTAGE COMPUTED TOMOGRAPHY; IMAGE QUALITY; ACCELERATOR OUTPUT FLUCTUATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
39
Recensione:
Indirizzi per estratti:
Citazione:
M. Partridge et al., "LINEAR-ACCELERATOR OUTPUT VARIATIONS AND THEIR CONSEQUENCES FOR MEGAVOLTAGE IMAGING", Medical physics, 25(8), 1998, pp. 1443-1452

Abstract

An experimental study of radiation output intensity fluctuations of aPhilips SL25 Linear accelerator is presented. Measurements are obtained using an electronic portal imaging device, and the consequences of the measured fluctuations for various different applications of megavoltage imaging including portal imaging, transit dosimetry and megavoltage computed tomography (MVCT) are discussed with examples. Fluctuations in output of +/- 0.7% (1 SD) are seen on every radiation pulse after photon noise and uncertainties caused by the detection system have been accounted for. Large fluctuations are also seen during the initialbeam stabilization period (15%), during normal accelerator operation after the beam has been on for more than 1 min (4.5%) and during are therapy as a repeatable function of gantry angle (9%). Such output intensity fluctuations are shown to produce image artifacts in portal imaging devices with scanned detector readout and can also produce systematic errors in detector calibration that would lead to uncertainty in transit dose calculations. The propagation of these intensity fluctuations through MVCT image reconstruction is shown to produce ring artifacts in the reconstructed image. Sample portal and MVCT images are presented. All observed fluctuations in accelerator output are well within the manufacturer's specifications and do not affect the total dose delivered during normal treatment. Finally, megavoltage imaging is shown to be a powerful tool for accelerator quality assurance and treatment verification. (C) 1998 American Association of Physicists in Medicine.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 06/07/20 alle ore 05:25:47