P De Marco1, I Abdi Osman2, F Castellini3, R Ricotti3, M C Leonardi3, E Miglietta3, R Cambria4, D Origgi4, B A Jereczek-Fossa5, C Garibaldi6, F Cattani4. 1. IEO, European Institute of Oncology IRCCS, Unit of Medical Physics, Milan, Italy. Electronic address: paolo.demarco@ieo.it. 2. University of Milan, Milan, Italy. 3. IEO, European Institute of Oncology IRCCS, Department of Radiation Oncology, Milan, Italy. 4. IEO, European Institute of Oncology IRCCS, Unit of Medical Physics, Milan, Italy. 5. IEO, European Institute of Oncology IRCCS, Department of Radiation Oncology, Milan, Italy; University of Milan, Department of Oncology and Hemato-Oncology, Milan, Italy. 6. IEO, European Institute of Oncology IRCCS, Radiation Research Unit, Milan, Italy.
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 AND METHODS: 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 - 3 mm to 2.4% for Coarse - 6 mm, while uniformity passed from 99.5% for Coarse - 6 mm to 99.8% for Normal - 4 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 4 lp/cm for all combinations of pitch and reconstruction interval). Dose was dependent on pitch, being 1.0 cGy for Coarse, 1.5 cGy for Normal and 2.85 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.
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 AND METHODS: 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 - 3 mm to 2.4% for Coarse - 6 mm, while uniformity passed from 99.5% for Coarse - 6 mm to 99.8% for Normal - 4 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 4 lp/cm for all combinations of pitch and reconstruction interval). Dose was dependent on pitch, being 1.0 cGy for Coarse, 1.5 cGy for Normal and 2.85 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.
Authors: Bin Yang; Hui Geng; Tien Yee Amy Chang; Mei Yan Tse; Wai Wang Lam; Chen-Yu Huang; Tungho Wu; Ka Ki Lau; Kin Yin Cheung; George Chiu; Siu Ki Yu Journal: Phys Eng Sci Med Date: 2022-08-04