Image quality and dose evaluation of MVCT TomoTherapy acquisitions: A phantom study.
Phys Med
; 57: 200-206, 2019 Jan.
Article
em En
| MEDLINE
| ID: mdl-30738526
ABSTRACT
BACKGROUND:
The aim of this study is to evaluate the dose delivered and the image quality of pre-treatment MVCT images with Hi-Art TomoTherapy system, varying acquisition and reconstruction parameters. MATERIALS ANDMETHODS:
Catphan 500 MVCT images were acquired with all acquisition pitch and reconstruction intervals; image quality was evaluated in terms of noise, uniformity, contrast linearity, contrast-to-noise ratio (CNR) and spatial resolution with the Modulation Transfer Function (MTF). Dose was evaluated as Multi Slice Average Dose (MSADw) and measurements were performed with the Standard TomoTherapy® Quality Assurance Kit composed by the TomoTherapy Phantom, the Exradin A1SL ion chamber and TomoElectrometer. For each pitch-reconstruction interval, acquisitions were repeated 5 times.RESULTS:
Differences in noise and uniformity, though statistically significant in some cases, were very small noise ranged from 2.3% for Coarse - 3â¯mm to 2.4% for Coarse - 6â¯mm, while uniformity passed from 99.5% for Coarse - 6â¯mm to 99.8% for Normal - 4â¯mm. No differences at all were found for CNR for high and low density inserts, while MTF was higher for pitch Coarse, even if no differences in spatial resolution were observed visually (spatial resolution was up to 4â¯lp/cm for all combinations of pitch and reconstruction interval). Dose was dependent on pitch, being 1.0â¯cGy for Coarse, 1.5â¯cGy for Normal and 2.85â¯cGy for Fine.CONCLUSIONS:
We observed negligible differences in image quality among different pitch and reconstruction interval, thus, considerations regarding pre-treatment imaging modalities should be based only on dose delivered and on the desired resolution along the cranio-caudal axis for image-guided radiotherapy and adaptive radiotherapy purposes.Palavras-chave
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Doses de Radiação
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Tomografia Computadorizada por Raios X
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Imagens de Fantasmas
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Radioterapia Guiada por Imagem
Idioma:
En
Revista:
Phys Med
Assunto da revista:
BIOFISICA
/
BIOLOGIA
/
MEDICINA
Ano de publicação:
2019
Tipo de documento:
Article