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Enhanced CT Dose Reduction for a Pediatric Population Using Peak Tube Potential (kVp) Reduction Combined with ASiR™ Reconstruction

S Brady

S Brady*, R Kaufman, St. Jude Children's Research Hospital, Memphis, TN

TU-G-217BCD-5 Tuesday 4:30:00 PM - 6:00:00 PM Room: 217BCD

Purpose: To demonstrate enhanced CT dose reduction for a pediatric phantom population by implementing an iterative reconstruction (ASiR™) technique to compensate for added noise in reconstructed CT images from kVp reduction.

Methods: (1) This study compared contrast to noise (CNR) for three contrast targets inserted into the abdomen of a 1, 5, and 10 yr anthropomorphic phantoms (CIRS). The contrast targets were the respective bone, brain tissue and spinal cord plugs manufactured for each phantom age. The phantoms were imaged using an abdomen protocol with 40% ASiR™ at 120 kVp. The CNR and noise (standard deviation of ROI) for each phantom at 120 kVp were measured as a baseline from which subsequent scans at 80 and 100 kVp were compared. (2) MOSFET detectors were placed inside the major abdominal organs of the phantoms. Absorbed dose was measured and converted to effective dose.

Results: Increased CNR and noise were found when the phantoms were imaged with 80 and 100 kVp compared to 120 kVp. Soft tissue and bone CNR increased by ~0% and 7-10%, respectively, at 100 kVp and 10-22% and 7-25%, respectively, at 80 kVp. Increase in noise magnitude was held below 6% for both 80 and 100 kVp. Dose reduction on the order of 35-45% was demonstrated at 120 kVp when 40% ASiR™ was introduced. Total dose reduction of 55-62% was demonstrated for the 1, 5, and 10 yr phantom when imaged at 100 kVp and 50% ASiR™, but only 49-54% for the 1 and 5 yr phantoms at 80 kVp and 50% ASiR™.

Conclusions: CT dose reduction on the order of 55-62% was achieved for a pediatric phantom population when modifications of kVp were combined with ASiR™. Increases in bone and soft tissue contrast were demonstrated. Noise level increase was kept to = 6%.

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