Sharad P. Menon MD, Presenter: Nothing to Disclose

Donald Paul Frush MD, Abstract Co-Author: Nothing to Disclose

Terry T. Yoshizumi PhD, Abstract Co-Author: Nothing to Disclose

John F. Rhodes MD, Abstract Co-Author: Nothing to Disclose

J. Rene Herlong MD, Abstract Co-Author: Nothing to Disclose

Giao Nguyen MS, Abstract Co-Author: Nothing to Disclose

Greta Toncheva MS, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

To compare conventional cardiac angio and CT angio (CTA) for radiation doses in the 1 and 5 yr-age group.

For dose rate measurements, 20 organs were monitored with MOSFET detectors (Thomson-Nielson), calibrated using an Integris Allura biplane cardiac cath unit (Philips), in anthropomorphic 1 and 5 year-old phantoms (CIRS). Mean fluoro and cine dose rates at various routine projection angles were determined, and a calculator was developed that determines effective dose (ED) based on entered projection, and cine vs angio. This allows a calculation for virtually any conventional angio. Subsequently, radiation doses were calculated for a representative routine pulmonary artery (PA) and aortic (Ao) evaluation in a 1 and 5 yr-old. Using the same MOSFET technique and phantoms, organ and EDs were also measured on a 16-slice scanner (GE Healthcare), 16 x 0.625; 0.5 sec; 100kVp, 120 mA, small FOV from apex through lung base. EDs were compared for CT and conventional angio.

For conventional angio, organ dose rates were highest for Ao evaluation in marrow (AP; 0.28 cGy/min) for the 5 yr-old, and kidney/adrenals (AP; 0.016 cGy/min) for the 1 yr-old; and for PA evaluation, in adrenal/kidneys (LAO 30 deg; 0.513 cGy/min) 5 yr-old and adrenals (LAO 30 deg; 0.25 cGy/min) in the 1 yr-old. From organ doses, calculation of ED for a virtual angio procedure was possible. For example, Ao diagnostic angio was an estimated ED (combined cine plus fluoro) of 7.27mSv (1 yr-old) and 7.57mSv (5 yr-old); PA diagnostic angio was an estimated 18.21mSv (1 yr-old) and 18.7mSv (5 yr-old); when the examinations for the 1 yr-old included interventional procedure, the ED could be 21.63mSv for Ao and 22.88mSv for the PA. The EDs for the CTA were 2.36mSv (1 yr-old), highest organ dose was 0.75cGy lungs, and 1.6mSv (5 yr-old), highest organ dose 1.19cGy thyroid.

An angiographic dose calculator provides for prospective dose estimates, and retrospective dose calculations for pediatric cardiac angio, and the calculator model can be developed for any angiography. For pediatric PA and Ao evaluation, CTA provides a lower effective dose for diagnostic evaluation.

D.P.F.: GE Healthcare research support and medical advisor

Menon, S, Frush, D, Yoshizumi, T, Rhodes, J, Herlong, J, Nguyen, G, Toncheva, G, et al, , CT and Conventional Pediatric Cardiac Angiography: Dose Comparisons Using a Unique Dose Calculator.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4417762.html