Abstract
ObjectiveTo assess the radiation dose and image quality of ultra‐low dose (ULD)‐CT colonography (CTC) obtained with the combined use of automatic tube current (mAs) modulation with a quality reference mAs of 25 and sinogram‐affirmed iterative reconstruction (SAFIRE), compared to low‐dose (LD) CTC acquired with a quality reference mAs of 55 and reconstructed with filtered back projection (FBP).MethodsEighty‐two patients underwent ULD‐CTC acquisition in prone position and LD‐CTC acquisition in supine position. Both ULD‐CTC and LD‐CTC protocols were compared in terms of radiation dose [weighted volume computed tomography dose index (CTDI vol) and effective dose], image noise, image quality, and polyp detection.ResultsThe mean effective dose of ULD‐CTC was significantly lower than that of LD‐CTC (0.98 and 2.69 mSv respectively, P < 0.0001) with an overall dose reduction of 63.2%. Image noise was comparable between ULD‐CTC and LD‐CTC (28.6 and 29.8 respectively, P = 0.09). There was no relevant difference when comparing image quality scores and polyp detection for both 2D and 3D images.Conclusion ULD‐CTC allows to significantly reduce the radiation dose without meaningful image quality degradation compared to LD‐CTC.
Highlights
Since its introduction in 1994,1 CT colonography (CTC) has progressively evolved to a validated examination for colorectal diseases
Conventional colonoscopy is associated to increased anxiety, fear, and discomfort compared to CTC and, especially in elderly patients, it is burdened with the risk to have incomplete examination necessitating an alternative diagnostic method.[3]
LD‐ CTC and ultra‐low dose (ULD)‐CTC were compared in terms of radiation dose (CTDIvol and effective dose), image noise, image quality, polyp detection, and size measurement by using Wilcoxon signed ranked test
Summary
Since its introduction in 1994,1 CT colonography (CTC) has progressively evolved to a validated examination for colorectal diseases. Evidence from the literature shows that the diagnostic performance for the detection of colorectal cancer and large polyps in symptomatic and asymptomatic individuals are similar to conventional colonoscopy and are largely superior to barium enema.[2]. Conventional colonoscopy is associated to increased anxiety, fear, and discomfort compared to CTC and, especially in elderly patients, it is burdened with the risk to have incomplete examination necessitating an alternative diagnostic method.[3]. The main disadvantage of CTC remains the use of ionizing radiation. This topic becomes of particular interest when CTC is proposed as a screening tool. New strategies to keep the dose as low as reasonably achievable, without significantly sacrificing image quality, are strongly advisable.[4,5]
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