Abstract
PurposeEvaluation of 15,000 computed tomography (CT) examinations to investigate if iterative reconstruction (IR) reduces sustainably radiation exposure. Method and MaterialsInformation from 15,000 CT examinations was collected, including all aspects of the exams such as scan parameter, patient information, and reconstruction instructions. The examinations were acquired between January 2010 and December 2012, while after 15 months a first generation IR algorithm was installed. To collect the necessary information from PACS, RIS, MPPS and structured reports a Dose Monitoring System was developed. To harvest all possible information an optical character recognition system was integrated, for example to collect information from the screenshot CT-dose report. The tool transfers all data to a database for further processing such as the calculation of effective dose and organ doses. To evaluate if IR provides a sustainable dose reduction, the effective dose values were statistically analyzed with respect to protocol type, diagnostic indication, and patient population. ResultsIR has the potential to reduce radiation dose significantly. Before clinical introduction of IR the average effective dose was 10.1±7.8mSv and with IR 8.9±7.1mSv (p*=0.01). Especially in CTA, with the possibility to use kV reduction protocols, such as in aortic CTAs (before IR: average14.2±7.8mSv; median11.4mSv /with IR:average9.9±7.4mSv; median7.4mSv), or pulmonary CTAs (before IR: average9.7±6.2mSV; median7.7mSv /with IR: average6.4±4.7mSv; median4.8mSv) the dose reduction effect is significant(p*=0.01). On the contrary for unenhanced low-dose scans of the cranial (for example sinuses) the reduction is not significant (before IR:average6.6±5.8mSv; median3.9mSv/with IR:average6.0±3.1mSV; median3.2mSv). ConclusionThe dose aspect remains a priority in CT research. Iterative reconstruction algorithms reduce sustainably and significantly radiation dose in the clinical routine. Our results illustrate that not only in studies with a limited number of patients but also in the clinical routine, IRs provide long-term dose saving.
Highlights
During the last years, Iterative Reconstruction (IR) algorithms for diagnostic Computed Tomography (CT) have found great popularity in the clinical community due to their dose reduction potentials
Each protocol was adjusted over a period of time with respect to image parameters to achieve the minimal dose while maintaining diagnostic quality
This has been reported previously that IR allows a higher reduction in radiation exposure when it comes to high-contrast acquisitions
Summary
Iterative Reconstruction (IR) algorithms for diagnostic Computed Tomography (CT) have found great popularity in the clinical community due to their dose reduction potentials. Each of the CT vendors has introduced their own flavor of such reconstruction methods [1,2,3,4,5,6]. For each of these methods it is claimed that the image noise can be significantly reduced, which, in turn, allows for reduction of radiation exposure. Several investigators have presented phantom as well as clinical studies for evaluation of different IR algorithms with respect of dose reduction, image quality, and diagnostic confidence [8,9,10,11,12,13,14,15,16]. Even with the illustrated possible dose reductions, this poses the risk that over time, during the clinical routine, the protocols are transformed back to the previous image impression and to higher dose levels
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