Title: Performance of Low Dose Non Enhanced Multidetector CT in Evaluation of Urinary Calculi
Authors: Dr P. Sirisha Naidu, Dr Sonali Ullal, Dr Ajit Mahale, Dr Ashvini Kumar
DOI: https://dx.doi.org/10.18535/jmscr/v8i1.53
Abstract
Nephrolithiasis is a chronic recurrent problem and it is increasing in incidence in younger generation, patients are getting exposed repetitively to CT (Computed tomography) radiation with its attendant radiation hazards .Hence CT dose reduction technique happens to be the need of the hour to reduce the dose burden to the patient .So it is necessary to tailor a new and finer protocol with reduced dose without compromising optimum image quality.
Aims: To assess the efficiency of low dose MDCT (Multidetector Computed tomography) in detecting urinary calculus when compared to standard MDCT.
Methods and Material: This is a prospective cross sectional study of 52 adult patients, carried on Multidetector 16 slice CT scanner-G E Bright speed elite over a period of 18 months from November 2016 to May 2018. All the patients who were advised CT urogram or CT KUB in whom urinary calculus was detected by MDCT-KUB (kidney, ureter and bladder) using an average tube potential of 120 kVp and tube current of 270- 350 mAs with a slice thickness of 5mm were selected and these patients were resubjected to low dose CT at the level of urinary calculus by using 100 kVp and 100 mAs with a slice thickness of 5 mm and reconstructed at 1.25 mm.
Results: The mean stone size in standard dose is 13.395 mm and in low dose is 13.361 mm with no significant difference.
Mean CTDivol (Computed tomography dose index) in standard and low dose are respectively are 13.876 mGy and 2.796 mGy with average dose reduction by 79 .92 % in low dose.
Conclusions: Low dose CT was found to be equally sensitive with equal positive predictive value in the detection and localisation of stones when compared to standard dose CT. At the same time low dose protocol helped to reduce patient radiation dose by an average of 79.92%. Since urolithiasis is a recurring disease and patients are frequently subjected to repeat CT examinations, the present low dose CT protocol will help to reduce cumulative radiation dose to the patient without compromising the sensitivity.
Keywords: CT dose index, Low dose CT, radiation dose, renal calculus, urolithiasis
