Ultra‐low dose CT colonography with automatic tube current modulation and sinogram‐affirmed iterative reconstruction: Effects on radiation exposure and image quality

Objective To assess the radiation dose and image quality of ultra‐low dose ( ULD )‐C T colonography ( CTC ) obtained with the combined use of automatic tube current ( mA s) modulation with a quality reference mA s of 25 and sinogram‐affirmed iterative reconstruction ( SAFIRE ), compared to low‐dose ( LD ) C TC acquired with a quality reference mA s of 55 and reconstructed with filtered back projection (FBP). Methods Eighty‐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. Results The mean effective dose of ULD ‐ CTC was significantly lower than that of LD ‐ CTC (0.98 and 2.69  mS v 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 .