Radiation dose evaluation in 64-slice CT examinations with adult and paediatric anthropomorphic phantoms

• Published in: British journal of radiology Vol. 82; no. 984; pp. 1010 - 1018
• Main Authors: FUJII, K, AOYAMA, T, YAMAUCHI-KAWAURA, C, KOYAMA, S, YAMAUCHI, M, KO, S, AKAHANE, K, NISHIZAWA, K
• Format: Journal Article
• Language: English
• Published: London British Institute of Radiology 01.12.2009; The British Institute of Radiology
• Subjects: Adult; Anthropometry - methods; Biological and medical sciences; Child; Female; Humans; Investigative techniques, diagnostic techniques (general aspects); Male; Medical sciences; Miscellaneous. Technology; Pelvis - diagnostic imaging; Phantoms, Imaging; Radiation Dosage; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Radiography, Abdominal - methods; Radiography, Thoracic - methods; Radiometry - methods; Tomography Scanners, X-Ray Computed; Tomography, X-Ray Computed - methods; Human; Radiodiagnosis; Thorax; Abdomen; Radiation dose; Radiobiology; Pelvic cavity; Medical imagery; Adult; Computerized axial tomography; Dosimetry; Effective dose; Child; Comparative study; Test object
• ISSN: 0007-1285; 1748-880X
• DOI: 10.1259/bjr/13320880

The objective of this study was to evaluate the organ dose and effective dose to patients undergoing routine adult and paediatric CT examinations with 64-slice CT scanners and to compare the doses with those from 4-, 8- and 16-multislice CT scanners. Patient doses were measured with small (<7 mm wide) silicon photodiode dosemeters (34 in total), which were implanted at various tissue and organ positions within adult and 6-year-old child anthropomorphic phantoms. Output signals from photodiode dosemeters were read on a personal computer, from which organ and effective doses were computed. For the adult phantom, organ doses (for organs within the scan range) and effective doses were 8-35 mGy and 7-18 mSv, respectively, for chest CT, and 12-33 mGy and 10-21 mSv, respectively, for abdominopelvic CT. For the paediatric phantom, organ and effective doses were 4-17 mGy and 3-7 mSv, respectively, for chest CT, and 5-14 mGy and 3-9 mSv, respectively, for abdominopelvic CT. Doses to organs at the boundaries of the scan length were higher for 64-slice CT scanners using large beam widths and/or a large pitch because of the larger extent of over-ranging. The CT dose index (CTDI(vol)), dose-length product (DLP) and the effective dose values using 64-slice CT for the adult and paediatric phantoms were the same as those obtained using 4-, 8- and 16-slice CT. Conversion factors of DLP to the effective dose by International Commission on Radiological Protection 103 were 0.024 mSvmGy(-1)cm(-1) and 0.019 mSvmGy(-1)cm(-1) for adult chest and abdominopelvic CT scans, respectively.