Prog Med Phys.  2019 Dec;30(4):160-166. 10.14316/pmp.2019.30.4.160.

Acceptance Test and Clinical Commissioning of CT Simulator

• An HJ
• Son J
• Jin H
• Sung J
• Chun M

• KMID: 2468178
• DOI: http://doi.org/10.14316/pmp.2019.30.4.160

Abstract

This study examined the clinical use of two newly installed computed tomography (CT) simulators in the Department of Radiation Oncology. The accreditation procedure was performed by the Korean Institute for Accreditation of Medical Imaging. An Xi R/F dosimeter was used to measure the CT dose index for each plug of the CT dose index phantom. Image qualities such as the Hounsfield unit (HU) value of water, noise level, homogeneity, existence of artifacts, spatial resolution, contrast, and slice thickness were evaluated by scanning a CT performance phantom. All test items were evaluated as to whether they were within the required tolerance level. CT calibration curves"”the relationship between CT number and relative electron density"”were obtained for dose calculations in the treatment planning system. The positional accuracy of the lasers was also evaluated. The volume CT dose indices for the head phantom were 22.26 mGy and 23.70 mGy, and those for body phantom were 12.30 mGy and 12.99 mGy for the first and second CT simulators, respectively. HU accuracy, noise, and homogeneity for the first CT simulator were −0.2 HU, 4.9 HU, and 0.69 HU, respectively, while those for second CT simulator were 1.9 HU, 4.9 HU, and 0.70 HU, respectively. Five air-filled holes with a diameter of 1.00 mm were used for assessment of spatial resolution and a low contrast object with a diameter of 6.4 mm was clearly discernible by both CT scanners. Both CT simulators exhibited comparable performance and are acceptable for clinical use.

Keyword

CT simulator; Acceptance test; CT dose index; Image quality

MeSH Terms

Accreditation
Artifacts
Calibration
Cone-Beam Computed Tomography
Diagnostic Imaging
Head
Noise
Radiation Oncology
Water
Water

Figure

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  Fig. 1 (a) A modular 76-410 AAPM computed tomography (CT) Performance Phantom (Fluke Corporation, Everett, WA, USA); CT slices of (b) water Hounsfield unit (HU), noise level, homogeneity evaluation, (c) spatial resolution, (d) low contrast resolution insert, and (e) slice thickness. Ave, average; SD, standard deviation.

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  Fig. 2 (a) Wilke phantom, (b) an axial slice, and (c) a coronal slice. The deviations between laser position and groove position in the images are marked.

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