Korean J Radiol.  2012 Apr;13(2):165-173. 10.3348/kjr.2012.13.2.165.

Evaluation of Ultra-Low Dose CT in the Diagnosis of Pediatric-Like Fractures Using an Experimental Animal Study

• Moritz JD
• Hoffmann B
• Sehr D
• Keil K
• Eggerking
• Groth G
• Caliebe A
• Dischinger J
• Heller M
• Bolte H

• KMID: 1245380
• DOI: http://doi.org/10.3348/kjr.2012.13.2.165

Abstract

OBJECTIVE
The aim of this prospective study was to evaluate the performance of ultra-low dose CT for the diagnosis of pediatric-like fractures and ascertain the lowest dose level sufficient for diagnostics.
MATERIALS AND METHODS
Fifty-one bones of young pig cadavers were artificially fractured and subsequently examined by using a 64 multi-detector CT with 36 various dose levels down to a dose comparable with that of X-rays. Two pediatric radiologists analysed the CT scans according to the presence or absence of a fracture, determination of the fracture type and the displacement as well as the diagnostic certainty. For each dose protocol, a success rate for the correct determination of the above-mentioned CT analyses was calculated. A success rate of at least 95% was considered sufficient for diagnostics.
RESULTS
All but the lowest dose levels were sufficient to identify the fracture. Only the two lowest dose levels were insufficient to detect the fracture type. All dose levels were adequate for the identification of the displacement. The lowest dose level sufficient for diagnostics was 120 kVp, 11 mAs, and pitch 1.5, with a CTDIvol of 10% of a standard dose and an effective dose three times as large as that of X-rays.
CONCLUSION
Ultra-low dose CT provides the feasibility of a significant dose reduction, still allowing sufficient diagnostics of pediatric-like fractures.

Keyword

Ultra-low dose CT; Fractures in children; Skeletal-appendicular; Experimental study

MeSH Terms

Animals
Disease Models, Animal
Fractures, Bone/*radiography
Pediatrics/methods
Prospective Studies
*Radiation Dosage
Radiographic Image Interpretation, Computer-Assisted
Swine
Tomography, X-Ray Computed/*methods

Figure

• 

  Fig. 1 Longitudinal fracture with extension into epiphysial plate (Salter Harris II) of third metacarpal bone (black arrow). Oblique fracture with step of second metacarpal bone (white triangle). All dose levels were diagnostic. A. Reference protocol 120 kVp, 100 mAs, pitch 0.9. B. Routine standard protocol 120 kVp, 50 mAs, pitch 0.9. C. 50% of dose of standard protocol 120 kVp, 40 mAs, pitch 1.5. D. 30% of dose of standard protocol 120 kVp, 20 mAs, pitch 1.5. E. 10% of dose of standard protocol 120 kVp, 11 mAs, pitch 1.5. F. Lowest dose protocol of study 80 kVp, 11 mAs, pitch 1.5.

• 

  Fig. 2 Undislocated fissure of tibial head. Fracture is seen in high dose protocol (120 kVp, 100 mAs, pitch 0.9, A, black arrow) as well as in ultra-low dose protocol (120 kVp, 11 mAs, pitch 1.5, B, black triangles). Fracture is missed at lowest dose level (80 kVp, 11 mAs, pitch 1.5, C).

• 

  Fig. 3 Comminuted fractures of second and third metacarpals with step and impression (black arrow). All dose levels were diagnostic-A. 120 kVp, 100 mAs, pitch 0.9. B. 120 kVp, 11 mAs, pitch 1.5. C. 80 kVp, 11 mAs, pitch 1.5.

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