Dosimetric Evaluation of Multislice CT Using AnthropomorphicHead Phantom

Purpose: The most general form to report dose in Multislice CT is the CTDI and DLP which are computed for several slices. The goal of the current study was to estimate actual doses and dose distribution during CT examinations in a head and neck anthropomorphic phantom. Methods: After construction of the head and neck phantom using natural bone and paraffin wax with NaCl as impurity, several places were considered in different sites to fill with badges of Gafchromic film. These places include brain, Parotid, Thyroid and Lens of eye. Phantom was scanned at CT Angio and Spiral protocols with 10 and 256 slice scanners. Results: Our findings showed that in 10 slice scanner, selected organ doses were in the range of 0.09-23.1 mSv while in the 256 slice scanner, it was in the range of 0.14-18.01 mSv. The CT Angio protocol has a higher organ dose at all. Conclusion: In CT Angio protocol, organ dose (except for the lens of eye) is lower in 10 slice compared to 256 slice CT; the brain dose in both protocols has no difference statistically. In the spiral protocol, the dose in 256 slice scanner is lower than the 10 slice scanner which might be due to higher number of detector arrays in 256 slice scanner.Thyroid dose is mainly due to scattered radiation and because of strict beam collimation; it has a small value in all protocols.