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Lower radiation dose did not affect image quality
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Lower tube voltage and a site study volume of more than 30 scans per month were factors in reducing radiation in a recent study.
Researchers for the prospective study collected radiation-dose data on 4,862 patients suspected of CAD who underwent clinically indicated coronary CTA. Data were gathered and evaluated during a two-month control period (n=620), an eight-month intervention period (n=3,407) and a two-month follow-up period (n=835). The study’s primary endpoints included total dose-length product and effective radiation dose from all phases of the study.
According to the study results, there was a 53.3% reduction in estimated median radiation dose in the follow-up period (P<.001) and a reduction in the effective dose from 21 mSv to 10 mSv (P<.001). The researchers also reported a decrease in the most frequently received effective radiation dose range, from 25-29 mSv to 5-10 mSv, as well as an increase in the number of patients receiving the target dose below 15 mSv (P<.001 vs. control period). There was also no change in image quality assessment during the control period vs. the follow-up period (P=.13), as well as no change in frequency of diagnostic-quality scans (89% vs. 92%; P=.07). According to the researchers, the most powerful univariable factors associated with achievement of the target radiation dose were the use of lower tube voltage (P<.001) and a site study volume of more than 30 scans per month (P<.001). – by Eric Raible
Raff GL. JAMA. 2009;301:2340-2348.
This study emphasizes how much we can achieve in terms of radiation dose reduction by implementing a few relatively simple processes involved with acquiring CT. One of the problems with coronary CTA is that there has been a lot of press about the amount of radiation associated with it. This higher radiation dose is something that it had at its beginning, but implementation with the kinds of best practices that have now been learned and published, the cardiac CT scan radiation dose has come down to that of other kinds of studies that use radiation exposure in medicine.
This is a really important piece, and it is in track with everything we have learned. Many labs have implemented this on their own outside of a registry method. What Gil Raff showed was that you can take all kind of centers and using this registry approach, give feedback to centers when they’re not in line with others, and they can take corrective steps and get in line.
– Dan Berman, MD
Cardiology Today Editorial Board member