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Medical Physics |
1 From the Departments of Radiology (H.G., T.A.) and Medical Physics (K.W.B., B.J., J.P.), Örebro Medical Centre Hospital, 701 85 Örebro, Sweden. From the 1999 RSNA scientific assembly. Received February 8, 2000; revision requested April 7; revision received May 25; accepted July 31. Supported by the research committee of Örebro County Council and the Swedish Radiation Protection Institute, project SSI P1141.99. Address correspondence to H.G. (e-mail:hakan.geijer@orebroll.se).
PURPOSE: To evaluate the radiation dose, image quality, and Cobb angle measurements obtained with a digital scanning method of scoliosis radiography.
MATERIALS AND METHODS: Multiple images were reconstructed into one image at a workstation. A low-dose alternative was to use digital pulsed fluoroscopy. Dose measurements were performed with thermoluminescent dosimeters in an Alderson phantom. At the same time, kerma area-product values were recorded. A Monte Carlo dose calculation also was performed. Image quality was evaluated with a contrast-detail phantom and visual grading system. Angle measurements were evaluated with an angle phantom and measurements obtained on patient images.
RESULTS: The effective radiation dose was 0.087 mSv for screen-film imaging, 0.16 mSv for digital exposure imaging, and 0.017 mSv for digital fluoroscopy; the corresponding kerma area-product values were 0.43, 0.87, and 0.097 Gy · cm2, respectively. The image quality of the digital exposure and screen-film images was about equal at visual grading, whereas fluoroscopy had lower image quality. The angle phantom had lower angle values with digital fluoroscopy, although the difference in measured angles was less than 0.5°. The patient images showed no difference in angles.
CONCLUSION: The described digital scanning method has acceptable image quality and adequate accuracy in angle measurements. The radiation dose required for digital exposure imaging is higher than that required for screen-film imaging, but that required for digital fluoroscopy is much lower.
Index terms: Dosimetry Images, quality, 30.11, 30.1215 Radiations, exposure to patients and personnel Radiography, digital, 30.1215 Spine, curvature, 30.861 Spine, radiography, 30.11, 30.1215
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