Vernon Matthew Chapman MD, Presenter: Nothing to Disclose

Mannudeep K. Kalra MD, Abstract Co-Author: Nothing to Disclose

Chris Constantinou PhD, Abstract Co-Author: Nothing to Disclose

Brian Grottkau MD, Abstract Co-Author: Nothing to Disclose

Maurice Albright MD, Abstract Co-Author: Nothing to Disclose

Diego Jaramillo MD, MPH, Abstract Co-Author: Nothing to Disclose

To determine the optimum scanning parameters and associated radiation exposure for 16-slice multidetector CT (MDCT) of the elbow in pediatric patients being evaluated for acute trauma.

16-slice MDCT of the elbow was performed on the forelimb of a 10-week-old Yorkshire pig cadaver with a supracondylar fracture. Scanning was performed using various kVp, fixed tube current and noise index settings using z-axis automatic tube current modulation (ATCM). Remaining parameters were held constant and included 2.5 mm slice thickness, 2.5 mm spacing and pitch 1.375. Two blinded radiologists graded the scans based on degree of confidence for fracture conspicuity from 0 (not identified) to 3 (definitely identified). The scanning parameters that allowed definite identification of the fracture by both readers and resulted in the lowest CT dose index-volume (CTDIvol) and dose-length product (DLP) were used to develop a scanning protocol for the pediatric elbow. This protocol was then applied to 4 pediatric patients (age range 4-11 years, average 5.8) referred for elbow MDCT following acute trauma. All patients were scanned in the prone position, with the affected elbow held above the head; CTDIvol and DLP data were recorded.

With fixed tube current technique, the fracture of the porcine cadaver forelimb was definitely identified at 100 kVp and 50 mA (CTDIvol= 1.14 mGy, DLP= 11.35 mGy·cm). Using ATCM, the fracture was definitely identified at 100 kVp with a minimum mA of 25 and a noise index of 20 (CTDIvol= 1.45 mGy DLP= 14.49 mGy·cm). As there was minimal difference in radiation exposure using fixed and automated tube current settings, ATCM was chosen to allow for variations in patient size and elbow position. Four pediatric patients were subsequently scanned using ATCM with the following technique: 100 kVp, noise index 20, minimum mA 25, maximum mA 200. Resulting CTDIvol values were between 1.95 and 7.38 mGy (average 4.38) and DLP values were between 20.48 and 55.0 mGy·cm (average 34.63).

16-slice multidetector CT of the post-traumatic pediatric elbow is optimally performed at 100 kVp using automatic tube current modulation with a noise index of 20 and mA range of 25 to 200.

Chapman, V, Kalra, M, Constantinou, C, Grottkau, B, Albright, M, Jaramillo, D, 16-slice Multidetector CT of the Post-traumatic Pediatric Elbow: Optimum Parameters and Associated Radiation Exposure.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4408612.html