Abstract
PurposeEvaluation of a new software tool for generation of simulated low-dose computed tomography (CT) images from an original higher dose scan.Materials and MethodsOriginal CT scan data (100 mAs, 80 mAs, 60 mAs, 40 mAs, 20 mAs, 10 mAs; 100 kV) of a swine were acquired (approved by the regional governmental commission for animal protection). Simulations of CT acquisition with a lower dose (simulated 10–80 mAs) were calculated using a low-dose simulation algorithm. The simulations were compared to the originals of the same dose level with regard to density values and image noise. Four radiologists assessed the realistic visual appearance of the simulated images.ResultsImage characteristics of simulated low dose scans were similar to the originals. Mean overall discrepancy of image noise and CT values was −1.2% (range −9% to 3.2%) and −0.2% (range −8.2% to 3.2%), respectively, p>0.05. Confidence intervals of discrepancies ranged between 0.9–10.2 HU (noise) and 1.9–13.4 HU (CT values), without significant differences (p>0.05). Subjective observer evaluation of image appearance showed no visually detectable difference.ConclusionSimulated low dose images showed excellent agreement with the originals concerning image noise, CT density values, and subjective assessment of the visual appearance of the simulated images. An authentic low-dose simulation opens up opportunity with regard to staff education, protocol optimization and introduction of new techniques.
Highlights
Computed tomography (CT) examination plays a fundamental role in an all-day radiological work-up of patients in hospitals with modern healthcare equipment all around the world
Confidence intervals of discrepancies ranged between 0.9–10.2 Hounsfield units (HU) and 1.9–13.4 HU (CT values), without significant differences (p.0.05)
An authentic low-dose simulation opens up opportunity with regard to staff education, protocol optimization and introduction of new techniques
Summary
Computed tomography (CT) examination plays a fundamental role in an all-day radiological work-up of patients in hospitals with modern healthcare equipment all around the world. A clinically justified CT examination and its benefit of an accurate diagnostic work-up always outweigh its associated individual risks like e.g. stochastically induced risk of cancer [4,5] These considerations encourage the demand for establishment of CT examination protocols according to the ‘‘as low as reasonably achievable’’ (ALARA) principle. This means an image acquisition at a radiation dose as low as possible while still maintaining a diagnostic image quality. A valid determination of the optimized dose levels for all specific CT examination protocols would demand a comparison of images of patients obtained at different dose levels This would require repeated scans of the patients resulting in a significant increase of radiation exposure to these patients or probands. It is desirable to have a computer simulation tool for reconstructing images from one original data set simulating images were acquired at lower dose levels
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