Evaluation of image quality and dose in renal colic: comparison of different spiral-CT protocols.
The aim of this study was to test different technical spiral-CT parameters to obtain optimal image quality with reduced X-ray dose. Images were acquired with a spiral-CT system Philips Tomoscan AVE1, using 250 mA, 120 kV, and 1-s rotational time. Three protocols were tested: protocol A with 5-mm thickness, pitch 1.6, slice reconstruction every 2.5 mm; protocol B with 3-mm thickness, pitch 1.6, slice reconstruction every 1.5 mm; and protocol C with 3-mm thickness, pitch 2, slice reconstruction every 1.5 mm. Two phantoms were employed to evaluate the image quality. Axial images were acquired, then sagittal and coronal images were reconstructed. Finally, the absorbed X-ray dose for each protocol was measured. Regarding image quality, 5-mm-thick images (protocol A) showed greater spatial resolution and lower noise compared with 3-mm-thick images (protocols B and C) on the axial plane; 3-mm reconstructed sagittal and coronal images (protocols B and C) showed an improved image quality compared with 5-mm reformatted images (protocol A). Concerning X-ray dose, the mean dose was: protocol A 19.6 +/- 0.8 mGy; protocol B 14.4 +/- 0.6 mGy; protocol C 12.5 +/- 1.0 mGy. Our study supports the use of thin slices (3 mm) combined with pitch of 1.6 or 2 in renal colic for X-ray dose reduction to the patient and good image quality.
Rimondini
A
A
Department of Radiology, University of Trieste, Ospedale di Cattinara, Italy.
Pozzi Mucelli
R
R
De Denaro
M
M
Bregant
P
P
Dalla Palma
L
L
D002985:Clinical Protocols; D003085:Colic / Q000000981:diagnostic imaging*; D007089:Image Enhancement / Q000295:instrumentation / Q000379:methods*; D007674:Kidney Diseases / Q000000981:diagnostic imaging*; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D014057:Tomography, X-Ray Computed / Q000379:methods*