ASIR an effective dose reduction tool for pediatric CT

Clinicians can reduce radiation dose associated with pediatric CT with the implementation of 40 percent adaptive statistical iterative reconstruction (ASIR), without any change in the magnitude of the noise of the reconstructed image or the contrast-to-noise ratio in the patient, according to a study published online in Radiology.

In the study the researchers looked at chest and abdominopelvic CT images performed on 183 patients with a mean age of 8.8 years and analyzed them for contrast-to-noise ratio and image noise. These measures were used with noise models developed from anthropomorphic phantoms to establish new beam current-modulated CT parameters to implement 40 percent ASIR at 120 and 100 KVp.

The researchers found that with the 40 percent ASIR implementation the average relative dose reduction for chest CT was 39 percent, with a maximum reduction of 72 percent. The average relative dose reduction for abdominopelvic CT was 29 percent with a maximum reduction of 64 percent.

The difference in noise magnitude between 0 and 40 percent ASIR was less than 1 HU, while patient CNR increased by 8 percent at 100 kVp for chest CT and 113 for abdominopelvic CT.

"By using the ASIR algorithm to improve image noise in a reconstructed image, ASIR can be used as a dose reduction tool by allowing more noise in an image, by decreasing radiation output, and then cleaning up the noisy, dose-reduced image with the ASIR algorithm," wrote lead author, Samuel Brady, Ph.D., of the St. Jude Children's Research Hospital in Memphis, Tenn., and colleagues, according to an article in Health Imaging.

A small study published in the American Journal of Roentgenology in June of 2010 concluded that ASIR was an effective tool for lowering radiation used for CT scans of the colon. According to the study's lead author, "no significant image quality differences" could be deciphered between groups of patients who were scanned in combination with ASIR, and those who received a standard dose of radiation. 

To learn more:
- see the study in Radiology
- read the article in Health Imaging

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