Abstract
The purpose of this study is to determine whether the computed radiography system sensitivity value can be used as an image quality indicator for computed radiography excretory urography with radiation dose reduction. One hundred and twenty-four patients with gynecological malignancies were studied prospectively. Five-minute and 10-minute computed radio-graphic images of excretory urography were obtained in each patient with different radiation doses (ie, a standard dose image required with screen-film method and a reduced dose one). The images were subjectively scored by three radiologists without knowledge of the exposure factors or the system sensitivity values. The quality scores of the reduced-dose images used in the five steps were compared with those of the standard dose images (the system sensitivity value was 80 to 120). The images with reduced exposures were arbitrarily divided into five steps according to the system sensitivity value (ie, 150 to 250, 260–400, 410–600, 610–1000, and 1010–1500). There was a gradual degradation of the image quality as the system sensitivity value was increased. In terms of visualization of the bones, the images taken with the system sensitivity values of 150–250 (40%–67% of the standard dose system) showed no statistically significant difference from the standard dose images. As for visualization of the renal pelvic margins, the images taken with the system sensitivity values of 260 to 400 (25%–38% of the standard dose system) showed no statistically significant difference. We conclude that system sensitivity value can be used as a practical though approximate indicator of the image quality.
Key Words: computed radiography, system sensitivity, excretory urography, dose reduction, computers, radiology
Full Text
The Full Text of this article is available as a PDF (1.3 MB).
Footnotes
This study was partly supported by a grant for cancer research from Japan's Ministry of Health and Welfare.
References
- 1.Kogutt MS, Jones JP, Perkins DD. Low-dose digital computed radiography in pediatric chest imaging. AJR. 1988;151:775–779. doi: 10.2214/ajr.151.4.775. [DOI] [PubMed] [Google Scholar]
- 2.Nakano Y, Odagiri K. Use of computed radiography in respiratory distress syndrome in the neonatal nursery. Pediatr Radiol. 1989;19:167–168. doi: 10.1007/BF02388647. [DOI] [PubMed] [Google Scholar]
- 3.Kushner DC, Yoder IC, Cleveland RH, et al. Radiation dose reduction during hysterosalpingography. An application of scanning-beam digital radiography. Radiology. 1986;161:31–33. doi: 10.1148/radiology.161.1.3763882. [DOI] [PubMed] [Google Scholar]
- 4.Kogutt MS. Computed radiographic imaging. Use in low-dose leg length radiography. AJR. 1987;148:1205–1206. doi: 10.2214/ajr.148.6.1205. [DOI] [PubMed] [Google Scholar]
- 5.Fajardo LL, Hillman BJ, Hunter TB, et al. Excretory urography using computed radiography. Radiology. 1987;162:345–351. doi: 10.1148/radiology.162.2.3797646. [DOI] [PubMed] [Google Scholar]
- 6.McClennan BL, Ling D, Rhull KS, et al. Urography with a low-osmolality contrast agent. Comparison of Hexabrix with Conray 325. Invest Radiol. 1986;21:144–150. doi: 10.1097/00004424-198602000-00011. [DOI] [PubMed] [Google Scholar]
- 7.Strautman PR, Fajardo LL, Hillman BJ, et al. Evaluation of contrast dose reduction for excretory urography using computed radiography. Europ J Radiol. 1989;9:60–63. [PubMed] [Google Scholar]
- 8.Pettersson H, Aspelin P, Boijsen E. Digital urography using stimulable phosphor. An experimental study in the rabbit. Acta Radiol. 1988;29:273–275. doi: 10.3109/02841858809171898. [DOI] [PubMed] [Google Scholar]
- 9.Prokop M, Galanski M, Oestmann JW, et al. Storage phosphor versus screen-film radiography. Effect of varying exposure parameters and unsharp mask filtering on the detectability of cortical bone defects. Radiology. 1990;177:109–113. doi: 10.1148/radiology.177.1.2399307. [DOI] [PubMed] [Google Scholar]