Multidetector CT urography: experimental analysis of radiation dose reduction in an animal model

Abstract

The purpose of this study was to evaluate the possibility of reducing X-ray exposure during multidetector CT urography (MDCTU) considering image quality using a porcine model. MDCTU was performed in eight healthy pigs. Scanning was conducted using a gradual reduction of the tube current-time product at 120 kV [200-20 mAs (eff.) in ten steps]. Three blinded observers independently evaluated the image data for anatomic detail, subjective image quality, and subjective image noise. Overall image quality was compared to milliampere-second settings and radiation dose. Objective noise measurements were assessed. Noise measurements in patients were also performed to verify the comparabilty of the animal model. Adequate image quality allowing for detailed visualization of the upper urinary tract was obtained when the tube current-time product was decreased to 70 eff. mAs at 120 kV. Image noise did not impair image quality to a relevant degree using these parameters. There was high agreement among the observers (ICC = 0.95). In the animal experiments, reduced-dose MDCTU produced good image quality. A maximum current-time product reduction to 70 eff. mAs at 120 kV (CTDI(vol) = 5.3 mGy) proved to be feasible, thereby offering an advantageous dosage reduction. The study provides a basis for the development of reduced-dose MDCTU protocols in humans.

Delineation of upper urinary tract segments at MDCT urography in patients with extra-urinary mass lesions: retrospective comparison of standard and low-dose protocols for the excretory phase of imaging

“…Thus, it appears that considerable dose reduction is possible when the primary task is to delineate the course of the upper urinary tract, e.g., for surgical planning in lesions outside of the urinary tract. Our finding corroborates earlier observations in phantom studies [10] and animal studies [11] that emphasize the option of considerable dose reduction at CTU in the excretory phase. They are in keeping with observations in patients with urolithiasis that demonstrate that there is no significant diagnostic loss associated with dose reduction by a factor of about 6 in unenhanced CTs of the abdomen [12,15].…”

“…However, one major concern in CTU is additional radiation exposure due to (repetitive) CT data acquisitions in the excretory phase [3,10]. Experimental studies [10,11] and clinical experience in patients with urinary calculi [12] suggest that the high image contrast between dense matter within the urinary lumen (contrast media or urinary calculi) and surrounding tissue warrants considerable dose reduction at CTU without apparent loss of diagnostic quality.…”

64-Slice CT urography: optimisation of radiation dose

“…While awaiting the results of a study investigating the real risk of cancer resulting from CT [21], it should be recalled that this modality 6]. Alcuni studi hanno valutato la possibilità di abbassare il prodotto corrente x tempo (mAs) [6,22]. Nelle apparecchiature a 64 strati si usa una collimazione di 64×0,5-0,625 mm [1], che determina un aumento notevole di dose al paziente per mantenere gli stessi livelli di rumore ottenibili con strati più spessi (es.…”

Radiological profile of anemia on unenhanced MDCT of the thorax

“…A limitation of the present study may be related to the wide range of X-ray tube currents used for CT in our patient population who had diverse body mass indices. However, applying a weight-adapted scan protocol, as in our series, has been previously shown to yield a high and constant image quality without significant noise contribution [18,19]. Secondly, we could not extend our ROI analysis to include the left ventricular cavity owing to the known absence of contrast gradient between ventricular lumen and interventricular septum in nonanemic patients.…”