Optimization of Scan and Reconstruction Parameters for Renal Artery CT Angiography with Iterative Reconstruction at Low kVp Compared with Filtered Back Projection at 120 kVp Acquisition

Abstract

Background: As cross-sectional images expanded in clinical practice, the number of renal lesions discovered incidentally has been increasing. CT protocols for renal mass evaluation may include pre-and post-contrast phase. However, a major concern with respect to those multiphase techniques is often the involvement of radiation dose. One further critical issue is how to minimize the radiation dose for patients and provide optimizational image quality for radiologists in clinical work. Objectives: To evaluate the image quality and radiation dose of renal artery CT angiography (CTA) with optimal sinogram affirmed iterative reconstruction (SAFIRE) strength level at 80 kVp for optimizing the scan and reconstruction parameters of renal artery CTA, in comparison to 120 kVp acquisition with filtered back projection (FBP). Patients and Methods: Sixty consecutive patients were classified into three groups prospectively in this study: 1) 80 kVp group (n = 30) with FBP and 2) 80 kVp group with SAFIRE (S4) and 3) 120 kV group (n = 30) with FBP. CT values and noise were measured, contrastto-noise ratio (CNR) and signal-to-noise ratio (SNR) of the renal artery CTA were calculated for quantitative assessment. Subjective image quality was evaluated by two experienced abdominal radiologists with a five-point scale in a blinded and randomized setting for qualitative assessment. Volume CT dose index (CTDIvol) and size-specific dose estimate (SSDE) were calculated and estimated for each subject presented in this study. Results: As for quantitative assessment, CNR, SNR and CT values of renal artery in 80kVp group with SAFIRE strength levels or FBP were higher than those of 120 kVp group with FBP (all Ps < 0.05), the mean noise gradually decreased in 80kVp group when increasing the SAFIRE strength levels (S1~S5). As for qualitative assessment, the overall image quality, vessel sharpness, segmental renal artery displayed in MIP or MPR, and diagnostic confidence of the two groups were all accepted by two radiologists (inter-observer

Coronary CT angiography by modifying tube voltage and contrast medium concentration: Evaluation of image quality and radiation dose

“…However, the risk of ionization radiationinduced cancer has always been a concern which increased demands for reduced dose CTCA. 5,[7][8][9][10][11] In this regard, various strategies including tube current modulation, high pitch technique, and low X-ray tube kilovoltage (kV) have been suggested. [12][13][14][15] Since radiation dose changes with square of tube voltage, modifying kV has a dramatic effect on patient dose.…”

“…Latest generation multidetector CT (MDCT) equipment has several advantages such as high spatial and temporal resolution and postprocessing properties. However, the risk of ionization radiation‐induced cancer has always been a concern which increased demands for reduced dose CTCA . In this regard, various strategies including tube current modulation, high pitch technique, and low X‐ray tube kilovoltage (kV) have been suggested …”