Low-dose unenhanced CT protocols according to individual body size for evaluating suspected renal colic: cumulative radiation exposures.
OBJECTIVE
The aim of this study was to assess the radiation dose of dose-reduced unenhanced abdominal multidetector computed tomography (MDCT) scan protocols for suspected renal colic in patients within normal weight range and overweight-obese patients and to record the cumulative dose of repeated examinations.


METHODS
Over a 2-year period, we performed 1,026 unenhanced CT examinations for urolithiasis; among these, 675 were performed on 636 patients referred from the emergency department. Patients were divided into two groups on the basis of body mass index (BMI): normal weight (BMI <25 kg/m(2) group 1); overweight and obese (BMI >25 kg/m(2) group 2). For patients in group 1 and group 2, the protocols of our 64-row scanner prescribe tube current settings at 70 mAs and 150 mAs, respectively. The dose-length product (DLP) estimated by using the manufacturer's software was converted into effective dose (ED).


RESULTS
Mean DLP and ED were 177 and 345 mGy/cm and 2.4 and 4.8 mSv for group 1 and group 2, respectively. A subset of 25 patients (3.7%) underwent two or more examinations, with estimated ED ranging from 4.8 to 19.2 mSv.


CONCLUSIONS
Although radiation dose is nearly double in overweight-obese patients undergoing MDCT, it remains lower than that delivered by a standard-dose protocol. Patients with flank pain, who are often young, are at increased risk for serial CT examinations. Use of a low-dose protocol is mandatory in both normal-weight and obese patients to minimise radiation exposure.
Tartari
S
S
Dipartamento di Diagnostica per Immagini e Radiologia Interventistica, Azienda USL di Ferrara, Ospedale del Delta, Lagosanto, Ferrara, Italy. s.tartari@ausl.fe.it
Rizzati
R
R
Righi
R
R
Deledda
A
A
Terrani
S
S
Benea
G
G
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D049628:Body Size / Q000528:radiation effects; D001835:Body Weight; D003287:Contrast Media; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000000981:diagnostic imaging*; D050177:Overweight / Q000000981:diagnostic imaging; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D056844:Renal Colic / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D052878:Urolithiasis / Q000000981:diagnostic imaging*
D003287:Contrast Media