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Technical InnovationDecreasing the Radiation Dose for Renal Stone CT:

A Feasibility Study of Single- and Multidetector CTAudrey L. Spielmann1, Joan P. Heneghan1, Lisa J. Lee1, Terry Yoshizumi1,2, Rendon C. Nelson1he evaluation of renal colic usingunenhanced helical CT was origi-nally described by Smith et al. [1]in 1995. This technique has gained widespreadacceptance among radiologists, emergency de-partment physicians, and urologists. In theacute setting, most patients currently undergounenhanced helical CT for the initial evaluationof nephrolithiasis [2]. The frequency of this re-quest in our institution has increased substan-tially during the past 2 years because of anexpanding indication for unenhanced helicalCT in the emergency setting [3] and becausethe clinicians are increasingly familiar with thetechnique. From July 1999 through June 2000,863 unenhanced CT examinations were or-dered to evaluate for renal stones, comparedwith 650 such studies in the same time periodin 1998–1999. Of these 863 examinations, 420were ordered in the acute setting from theemergency department. In the period studied,595 (69%) of all examinations were performedon patients younger than 50 years old, 196(33%) of whom were women. Clearly, a greatnumber of these examinations are being re-quested, frequently in a young population. Aswith all pelvic CT, there is direct gonadal radia-tion exposure, particularly in female luminescent dosimeter measurements,using our institution’s standard CT protocolsfor renal stone examinations, revealed doses toTthe uterus of 18 mGy (1.8 rad) on our single-detector helical scanner (CT/i; General ElectricMedical Systems, Milwaukee, WI) and 23mGy (2.3 rad) on our multidetector scanner(QX/i LightSpeed; General Electric MedicalSystems). Most renal calculi are of high attenu-ation relative to soft tissue and are readily visu-alized because of high inherent contrast, whichraises the question: Is it possible to perform adiagnostic renal stone CT examination at alower radiation dose? The purpose of our studywas to assess detectability of human renalstones in a porcine kidney phantom at variousradiation exposures on both single-detector andmultidetector helical CT ts and Methods

Forty human calcium oxalate stones measuring 2–8 mm were implanted in the parenchyma of two por-cine kidneys (20 in each kidney) via two longitudinalincisions made in each kidney. All stones were im-planted while the kidneys were submersed in water toavoid placement of gas bubbles inside the kidneys,which could affect detectability. The incisions werethen sutured closed, also during submersion, to pre-vent movement of the calculi. The location and sizeof each stone as measured before implantation wererecorded. The kidneys were fully submersed in a wa-ter-filled elliptic phantom (Data Spectrum, Hillsbor-ough, NC). We scanned the kidneys in the transverseplane on a QX/i LightSpeed multidetector scannerand a CT/i single-detector helical CT scanner. Allscans were obtained at 140 kVp, with 5-mm collima-tion and a 0.8-sec gantry rotation speed. The tubecurrent was decreased serially as follows: 170, 120,80, 60, 40, 30 and 20 mA on the QX/i at a pitch of3:1 (15 mm per gantry rotation) and 220, 170, 110,80, 60, 40, 30, and 20 mA on the CT/i at a pitch of 1(5 mm per gantry rotation). The CT dose index wasmeasured at the center of a 32-cm diameter acrylicCT body phantom (model 20 CT14; Radcal, Mon-rovia, CA) with a pencil ion chamber (model 6000-200; Victoreen, Solon, OH) and monitor (Nero 8000;Victoreen). We used the CT dose index initially be-cause it provided a convenient method of first-orderdose comparison between two models of CT scan-ners. CT dose index data were analyzed by a linearregression method to fit the experimentally obtaineddose data from the single- and multidetector scan-ners. We found a goodness of fit of 0.9915 for theQX/i scanner and 0.9975 for the CT/i scanner.

All scans were obtained during the same dual organ doses and the effective dose equiva-lent were estimated at a different session using ther-moluminescent dosimeters (Harshaw TLD-100;Saint-Gobain Cystals & Detectors, Solon, OH) andan anthropomorphic phantom (RANDO phantom;The Phantom Laboratory, Salem, NY). Thermolu-minescent dosimeter calibration was performed us-ing a simulated CT beam with a half-value layer of8 mm of aluminum at 120 kVp. Two thermolumi-nescent dosimeter chips were placed in various or-gans of the phantom. CT scans were obtained usingthe clinical renal-stone protocols at our institution forthe CT/i scanner (peak kilovoltage, 140 kVp; variedReceived May 30, 2001; accepted after revision October 23, ted at the annual meeting of the American Roentgen Ray Society, Seattle, April–May 2001.12Department of Radiology, Duke University Medical Center, Box 3808, Durham, NC 27710. Address correspondence to J. P. ion Safety Division, Duke University Health System, Durham, NC 2002;178:1058–1062 0361–803X/02/1785–1058 © American Roentgen Ray Society1058AJR:178, May 2002

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AFig. 1.—CT images of simulated torso phantom with water-submersed porcine kid-neys, obtained on single-detector helical scanner (CT/i; General Electric MedicalSystems, Milwaukee, WI).

A, Transverse scan obtained through the phantom at 140 kVp and 220 mA showsnine renal calculi.B, Transverse scan obtained through phantom at 140 kVp and 80 mA shows visual-ization of all nine renal calculi seen on higher-dose scan A, although small calculiare not as well seen.C, Transverse scan obtained through phantom at 140 kVp and 20 mA shows poor vi-sualization of only six of nine renal calculi seen on A.

BCamperage; pitch, 1; slice thickness, 5 mm) and theQX/i scanner (peak kilovoltage, 140 kVp; variedamperage; pitch, 3; slice thickness, 5 mm).

Two investigators, working by consensus, re-corded the total number of calculi identified in eachkidney at each dose. The reviewers were aware ofthe technical parameters of the scan, and one of thereviewers had participated in the stone implantationin the porcine kidneys. Three calculi in the left kid-ney shifted position during suturing of the kidney,and they became inseparable from other calculi onthe CT scans. As a result, only 17 discrete stoneswere identified in the left kidney on the initial scansobtained using the standard diagnostic finding then served as a reference for subse-quent scans obtained at lower exposures. The stonesdid not shift their position during transfer of thephantom from the QX/i to the CT/i scanner.

Six indicator calculi were identified on the ini-tial scan. The size of each indicator calculi wasevaluated at each varied exposure to assess for sizedistortion with differing techniques. A single inves-tigator measured the size of the six indicator calculiat a workstation using electronic calipers. KendallFig. 2.—Bar graph shows stone detection in right kidney (white bars) and left kidney (gray bars) as function ofdecreasing amperage in scans obtained on single-detector CT.

AJR:178, May 20021059

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ABFig. 3.—CT images of simulated torso phantom with water-submersed porcine kid-neys, obtained on multidetector scanner (QX/i LightSpeed; General Electric Medi-cal Systems, Milwaukee, WI).

A, Transverse scan obtained through phantom at 140 kVp and 170 mA shows ninerenal calculi.B, Transverse scan obtained through phantom at 140 kVp and 60 mA shows visual-ization of all nine renal calculi seen on higher-dose scan A, although calculi are notas well seen.C, Transverse scan obtained through phantom at 140 kVp and 20 mA shows poor vi-sualization of only seven of nine renal calculi seen on b correlation coefficients were computed forpairs of variables.

Results

Fig. 4.—Bar graph shows stone detection in right kidney (white bars) and left kidney (gray bars) as function ofdecreasing amperage in scans obtained on multidetector-row CT.

On the single-detector CT, all calculi werevisible in the right kidney on scans with ex-posures ranging from 220 to 60 mA and inthe left kidney on scans with exposures rang-ing from 220 to 80 mA (Figs. 1 and 2). Onthe multidetector CT scanner, all calculiwere visualized in the right kidney with ex-posures ranging from 170 to 60 mA and inthe left kidney with exposures ranging from170 to 30 mA (Figs. 3 and 4). At all levels ofamperage, no statistically significant changewas found in the measured size of the six in-dicator stones (p = 0.38 for scans obtainedon the CT/i and p = 0.07 for scans obtainedon the QX/i scanner).

The calculated dose to the phantom de-creased in a linear fashion with the decreas-1060AJR:178, May 2002

Decreasing the Radiation Dose for Renal Stone CTing amperage on both the single-detector andmultidetector scanners (Fig. 5). Specifically,on the CT/i, a decrease from 220 to 80 mAreduced the CT dose index from 11.1 to 3.8mGy. The corresponding thermolumines-cent dosimeter measurement for kidneys de-creased from 28.5 to 10.3 mGy and theestimated effective dose equivalent decreasedby 64% from 16.3 to 5.9 mSv (Fig. 6). On theQX/i, a decrease from 170 to 60 mA reducedthe CT dose index from 14.9 to 5.2 mGy. Thecorresponding thermoluminescent dosimetermeasurement for kidneys decreased from 34.6to 12.2 mGy, and the estimated effective doseequivalent decreased by 65%—from 22 to 7.8mSv (Fig. 7).

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size from 2–8 mm, when we used a much loweramperage and measured radiation dose thanthose of the standard protocols. At an exposureof 80 mA for single-detector CT and 60 mA formultidetector CT, all renal calculi were visual-ized in the porcine kidneys. These findings cor-respond to a 2.9-fold decrease in estimatedradiation dose (11.1–3.8 mGy) on the single-de-tector CT scanner and a 2.9-fold decrease(14.9–5.2 mGy) on the multidetector CT scan-ner. In addition, the findings correspond to a2.8-fold decrease in the estimated effective doseequivalent (16.3–5.9 mSv) on the single-detec-tor CT scanner and a 2.8-fold decrease (22–7.8mSv) on the multidetector CT. We measured asignificantly greater dose on the QX/i (mul-tidetector) scanner as compared with the CT/i(single-detector) scanner. We believe that thisfinding is primarily associated with the inher-ent design of multidetector CT scanners; thatis, the QX/i produces a broadened beam pro-file beyond the umbra (the main beam over theUnenhanced helical CT has been shown tohave a sensitivity of 97%, a specificity of 96%,and an accuracy of 97% for the diagnosis ofurolithiasis [4]. This examination has becomethe primary technique in many centers forthe evaluation of renal calculi in the acutesetting, and it has been well received in theclinical community, particularly in emergencydepartments [5, 6].

The main disadvantage of CT is that it ex-poses patients to a relatively high radiationdose. This high dose is of particular concern inthose young patients who are repeated stoneformers and thus may require multiple CT ex-aminations in their lifetime.

In our phantom study, we found excellent de-tectability of all renal calculi, which ranged inFig. 5.—Line graph shows measured CT dose index for varied exposures on single-detector (circles) helical scan-ner (CT/i; General Electric Medical Systems, Milwaukee, WI) and multidetector (squares) scanner (QX/i LightSpeed;General Electric Medical Systems). Linear reduction in radiation dose is function of decreasing . 6.—Line graph shows thermoluminescent detector measurements obtained atvaried exposures on single-detector helical scanner (CT/i; General Electric Medi-cal Systems, Milwaukee, WI), with circles representing doses to kidneys in milli-grays and squares representing effective dose equivalents in . 7.—Line graph shows thermoluminescent detector measurements obtained atvaried exposures on multidetector scanner (QX/i LightSpeed; General ElectricMedical Systems, Milwaukee, WI), with circles representing doses to kidneys inmilligrays and squares representing effective dose equivalents in millisieverts.

AJR:178, May 20021061

Spielmann et ors) and generates a very large penum-bra radiation et al. [7] have raised the concernof an increased radiation dose with helicalCT compared with conventional excretoryurography. Their study found that the aver-age effective dose of unenhanced helical CTwas more than three times that of three-filmexcretory urography. They commented thatthe radiation risk is somewhat offset by therisks of contrast media reaction and contrastand conspicuity; as the noise progressively in-creased with decreasing amperage, it was ob-vious to the reviewers which were the reduced-dose scans. A further limitation of our study isthat we were unable to evaluate for uretericstones in this phantom model; we were onlyable to evaluate stone size and detectability inthe kidney. Visualization of a calculus in thelumen of a dilated ureter is direct evidence ofacute urinary obstruction resulting from renalstone disease. Occasionally, the patient isAcknowledgmentsWe thank G. Allan Johnson for his contributionin the formulation of the study design and DavidDeLong for his help with statistical RC, Rosenfield AT, Choe KA, et al. Acute flankpain: comparison of non-contrast-enhanced CT andintravenous urography. Radiology 1995;194:789– MY, Zagoria RJ. Can noncontrast helicalcomputed tomography replace intravenous urog-raphy for evaluation of patients with acute urinaryall

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media–induced nephrotoxicity. They con-cluded that the increased radiation risk maybe justifiable if information that alters sub-sequent patient treatment is gained from CTthat would not have been obtained from ex-cretory urography. Liu et al. [8] described alow-dose CT protocol for evaluation of renalcolic compared with exposure on excretoryurography. The effective dose equivalent oftheir protocol was 2.8 mSv, which is doublethat of excretory urography. However, theyused parameters of 120 kVp and 280 mAson a single-detector CT, producing a greaterdose than the standard renal-stone protocolat our institution. A study by Diel et al. [9]explored increasing the pitch as a means ofreducing radiation dose in CT of patientswith suspected renal colic. The average en-trance exposures were estimated as 461 mR(1.19 × 10–4

C/kg), 553 mR (1.43 × 10–4

C/kg), and 913 mR (2.36 × 10–4

C/kg) atpitches of 3.0, 2.5, and 1.5, respectively. Al-though accuracy did not significantly changewhen they used the higher pitch of 3.0 versus2.5, the image quality did decrease.A limitation of our study is that the investi-gators were aware of the technical parametersof the scan during the evaluation of stone size1062scanned after passage of a stone, or the uretericstone remains undetected because of volumetract colic? J Emerg Med 1999;17:299–303averaging, lack of retroperitoneal fat, MY, Zagoria RJ, Saunders HS, Dyer in the use of unenhanced helical CT fortory motion, or an abundance of phlebolithsacute urinary colic. AJR 1999;173:1447–1450[10]. It is not known whether the ureter RC, Verga M, McCarthy S, Rosenfield secondary signs of ureteral obstructionDiagnosis of acute flank pain: value of unen-would be adequately evaluated with a re-hanced helical CT. AJR 1996;166:97–101duced-dose technique. Furthermore, it is ger GM, Vieweg J, Leder RA, Nelson how well this technique would visualizeUrolithiasis: detection and management with un-enhanced spiral CT: a urologic perspective.

Radi-the remainder of the abdomen and pelvis toology 1998;207:308–309evaluate for other causes of acute flank or J, Teh C, Freed K, et al. Unenhanced heli-dominal pain. A low-dose renal-stone proto-cal computerized tomography for the evaluationcol may prove most valuable in patientsof patients with acute flank pain.

J Urolrequiring follow-up scanning in the setting of1998;160:679– ER, Mackenzie A, Greenwell T, Popert R,known nephrolithiasis when other diagnosesRankin SC. Unenhanced helical CT for renalare less likely. Clearly, a low-dose techniquecolic: is the radiation dose justifiable?

Clin Radiolwould not be possible for obese patients, who1999;54:444–447routinely require a higher exposure for W, Esler SJ, Kenny BJ, Goh RH, RainbowAJ, Stevenson GW. Low-dose nonenhanced heli-nostic CT of renal colic: assessment of ureteric stoneIn conclusion, this phantom study showsdetection and measurement of effective dosethat renal stone detectability and size remainequivalent.

Radiology 2000;215:51–54constant on both the single- and multidetector9. Diel J, Perlmutter S, Venkataramanan N, Muellerhelical CT scanners at much lower radiationR, Lane MJ, Katz DS. Unenhanced helical CT us-ing increased pitch for suspected renal colic: andoses than those called for in the standardeffective technique for radiation dose reduction?renal-stone protocol. Evaluation of the clini-J Comput Assist Tomogr 2000;24:795–801cal performance of a low-dose renal-stone10. Bell TV, Fenlon HM, Davison BD, Ahari HK,technique is warranted in this frequently or-Hussain S. Unenhanced helical CT criteria to dif-dered iate distal ureteral calculi from pelvic phle-boliths. Radiology 1998;207:363–367AJR:178, May 2002Downloaded

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only; This article has been cited by: Wang, Tony Kang, Chesnal Arepalli, Sarah Barrett, Tim O’Connell, Luck Louis, Savvakis Nicolaou, Patrick McLaughlin.2014. Half-dose non-contrast CT in the investigation of urolithiasis: image quality improvement with third-generation integratedcircuit CT detectors. Abdominal Imaging . [CrossRef]Downloaded

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2.P. D. McLaughlin, K. P. Murphy, S. A. Hayes, K. Carey, J. Sammon, L. Crush, F. O’Neill, B. Normoyle, A. M. McGarrigle, J. , M. M. Maher. 2014. Non-contrast CT at comparable dose to an abdominal radiograph in patients with acute renal colic;impact of iterative reconstruction on image quality and diagnostic performance. Insights into Imaging 5, 217-230. [CrossRef] Sountoulides, Linda Metaxa, Luca Cindolo. 2013. Is Computed Tomography Mandatory for the Detection of ResidualStone Fragments After Percutaneous Nephrolithotomy?. Journal of Endourology 134. [CrossRef] Hu, Xinming Zhao, Junfeng Song, Chunwu Zhou. 2013. Reduction of the Radiation Dose by Decreasing the TubeCurrent without Degradation of Low-Contrast Detectability on Abdominal Multi-Detector Row CT: A Phantom-Based Journal of Medical Imaging 03, 110-115. [CrossRef] A. Fracchia, Georgia Panagopoulos, Richard J. Katz, Noel Armenakas, R. Ernest Sosa, Douglas R. DeCorato. 2012. Adequacyof Low Dose Computed Tomography in Patients Presenting with Acute Urinary Colic. Journal of Endourology 26, 1242-1246.[CrossRef]l C. Ost, Francis X. SchneckSurgical Management of Pediatric Stone Disease 3667-3684.e2. [CrossRef]ur Demehri, Pascal Salazar, Michael L. Steigner, Stefan Atev, Osama Masoud, Philippe Raffy, Scott A. Jacobs, FrankJ. Rybicki. 2012. Image Quality Improvement Using an Image-Based Noise Reduction Algorithm. Journal of Computer AssistedTomography 36, 610-615. [CrossRef]8.T. Niemann, M. Van Straten, C. Resinger, T. Bayer, Georg Bongartz. 2011. Detection of urolithiasis using low-dose CT—Anoise simulation study. European Journal of Radiology 80, 213-218. [CrossRef] K. Johnson, Gary J. Faerber, William W. Roberts, J. Stuart Wolf, John M. Park, David A. Bloom, Julian Wan. 2011. AreStone Protocol Computed Tomography Scans Mandatory for Children With Suspected Urinary Calculi?. Urology 78, 662-666.[CrossRef] Cornfeld, Gary Israel, Ezra Detroy, Jamal Bokhari, Hamid Mojibian. 2011. Impact of Adaptive Statistical IterativeReconstruction (ASIR) on Radiation Dose and Image Quality in Aortic Dissection Studies: A Qualitative and QuantitativeAnalysis. American Journal of Roentgenology 196:3, W336-W340. [Abstract] [Full Text] [PDF] [PDF Plus]ur Demehri, Mannudeep K. Kalra, Frank J. Rybicki, Michael L. Steigner, Matthew J. Lang, E. Andres Houseman, GaryC. Curhan, Stuart G. Silverman. 2011. Quantification of Urinary Stone Volume: Attenuation Threshold–based CT Method—A Technical Note. Radiology 258, 915-922. [CrossRef] L. Mueller-Lisse, Eva M. Coppenrath, Thomas Meindl, Christoph Degenhart, Michael K. Scherr, Christian G. Stief,Maximilian F. Reiser, Ullrich G. Mueller-Lisse. 2011. Delineation of upper urinary tract segments at MDCT urography inpatients with extra-urinary mass lesions: retrospective comparison of standard and low-dose protocols for the excretory phase ofimaging. European Radiology 21, 378-384. [CrossRef]h R. Kambadakone, Brian H. Eisner, Onofrio Antonio Catalano, Dushyant V. Sahani. 2010. New and Evolving Conceptsin the Imaging and Management of Urolithiasis: Urologists’ Perspective1. RadioGraphics 30, 603-623. [CrossRef] H. Jin, Gregory R. Lamberton, Dale R. Broome, Hans P. Saaty, Shravani Bhattacharya, Tekisha U. Lindler, D. DuaneBaldwin. 2010. Effect of Reduced Radiation CT Protocols on the Detection of Renal Calculi 1. Radiology 255, 100-107. [CrossRef]15.S. Tartari, R. Rizzati, R. Righi, A. Deledda, S. Terrani, G. Benea. 2010. Low-dose unenhanced CT protocols according toindividual body size for evaluating suspected renal colic: cumulative radiation exposures. La radiologia medica 115, 105-114.[CrossRef]16.R. Renard-Penna, A. Ayed. 2010. Diagnostic et bilan des calculs urinaires. EMC - Radiologie et imagerie médicale - Génito-urinaire- Gynéco-obstétricale - Mammaire 5, 1-18. [CrossRef]l W. Ciaschini, Erick M. Remer, Mark E. Baker, Michael Lieber, Brian R. Herts. 2009. Urinary Calculi: Radiation DoseReduction of 50% and 75% at CT—Effect on Sensitivity 1. Radiology 251, 105-111. [CrossRef] Niemann, Thilo Kollmann, Georg Bongartz. 2008. Diagnostic Performance of Low-Dose CT for the Detection ofUrolithiasis: A Meta-Analysis. American Journal of Roentgenology 191:2, 396-401. [Abstract] [Full Text] [PDF] [PDF Plus]19.F. Stacul, A. Rossi, M. A. Cova. 2008. CT urography: The end of IVU?. La radiologia medica 113, 658-669. [CrossRef] Grosjean, Benoît Sauer, Rui Matias Guerra, Michel Daudon, Alain Blum, Jacques Felblinger, Jacques Hubert. terization of Human Renal Stones with MDCT: Advantage of Dual Energy and Limitations Due to Respiratory an Journal of Roentgenology 190:3, 720-728. [Abstract] [Full Text] [PDF] [PDF Plus] K. Paulson, Carolyn Weaver, Lisa M. Ho, Lucie Martin, Jianying Li, James Darsie, Donald P. Frush. 2008. Conventional andReduced Radiation Dose of 16-MDCT for Detection of Nephrolithiasis and Ureterolithiasis. American Journal of Roentgenology190:1, 151-157. [Abstract] [Full Text] [PDF] [PDF Plus] J. Van Der Molen, Nigel C. Cowan, Ullrich G. Mueller-Lisse, Claus C. A. Nolte-Ernsting, Satoru Takahashi, RichardH. Cohan. 2008. CT urography: definition, indications and techniques. A guideline for clinical practice. European Radiology 18,4-17. [CrossRef] Meindl, Eva Coppenrath, Christoph Degenhart, Ulrike L. Müller-Lisse, Maximilian F. Reiser, Ullrich G. Müller-Lisse.2007. MDCT urography: experience with a bi-phasic excretory phase examination protocol. European Radiology 17, 2512-2518.[CrossRef]-Alexandre Poletti, Alexandra Platon, Olivier T. Rutschmann, Franz R. Schmidlin, Christophe E. Iselin, Christoph . 2007. Low-Dose Versus Standard-Dose CT Protocol in Patients with Clinically Suspected Renal Colic. American Journalof Roentgenology 188:4, 927-933. [Abstract] [Full Text] [PDF] [PDF Plus] N. Eikefjord, Frits Thorsen, Jarle Rørvik. 2007. Comparison of Effective Radiation Doses in Patients Undergoing UnenhancedMDCT and Excretory Urography for Acute Flank Pain. American Journal of Roentgenology 188:4, 934-939. [Abstract] [Full Text][PDF] [PDF Plus] H. Mulkens, Sofie Daineffe, Roel De Wijngaert, Patrick Bellinck, André Leonard, Guido Smet, Jean-Luc Termote. y Stone Disease: Comparison of Standard-Dose and Low-Dose with 4D MDCT Tube Current Modulation. AmericanJournal of Roentgenology 188:2, 553-562. [Abstract] [Full Text] [PDF] [PDF Plus] Samih Matani, Mohammed Ahmed Al-Ghazo. 2007. Role of Helical Nonenhanced Computed Tomography in theEvaluation of Acute Flank Pain. Asian Journal of Surgery 30, 45-51. [CrossRef] C. Chan, Bonnie N. Joe, Fergus V. Coakley, Edwin L. Prien, Robert G. Gould, Sven Prevrhal, William C. Barber,Kimberley S. Kirkwood, Aliya Qayyum, Benjamin M. Yeh. 2006. Gallstone Detection at CT in Vitro: Effect of Peak VoltageSetting 1. Radiology 241, 546-553. [CrossRef]29.E. M. Coppenrath, U. G. Mueller-Lisse. 2006. Multidetector CT of the kidney. European Radiology 16, 2603-2611. [CrossRef]30.E. Coppenrath, T. Meindl, P. Herzog, R. Khalil, U. Mueller-Lisse, L. Krenn, M. Reiser, U. G. Mueller-Lisse. 2006. Dosereduction in multidetector CT of the urinary tract. Studies in a phantom model. European Radiology 16, 1982-1989. [CrossRef] Hartman, Akira Kawashima, Andrew LeRoyHelical CT in the Diagnosis of Urolithiasis 13-33. [CrossRef] Kocakoc, Shweta Bhatt, Vikram S. Dogra. 2005. Renal Multidector Row CT. Radiologic Clinics of North America 43,1021-1047. [CrossRef]eep K. Kalra, Michael M. Maher, Roy V. D’Souza, Stefania Rizzo, Elkan F. Halpern, Michael A. Blake, Sanjay Saini. ion of Urinary Tract Stones at Low-Radiation-Dose CT with Z-Axis Automatic Tube Current Modulation: Phantom andClinical Studies1. Radiology 235, 523-529. [CrossRef]l ErhardMinimally invasive management of pediatric urinary calculus disease 177-193. [CrossRef]l ErhardMinimally invasive management of pediatric urinary calculus disease 891-908. [CrossRef]o Blandino, Fabio Minutoli, Emanuele Scribano, Sergio Vinci, Carlo Magno, Stefano Pergolizzi, Nicola Settineri, IgnazioPandolfo, Michele Gaeta. 2004. Combined magnetic resonance urography and targeted helical CT in patients with renal colic: Anew approach to reduce delivered dose. Journal of Magnetic Resonance Imaging 20:10.1002/jmri.v20:2, 264-271. [CrossRef]d D. Nawfel, Philip F. Judy, A. Robert Schleipman, Stuart G. Silverman. 2004. Patient Radiation Dose at CT Urographyand Conventional Urography1. Radiology 232, 126-132. [CrossRef]ne Keyzer, Denis Tack, Viviane de Maertelaer, Pascale Bohy, Pierre Alain Gevenois, Daniel Van Gansbeke. 2004. AcuteAppendicitis: Comparison of Low-Dose and Standard-Dose Unenhanced Multi–Detector Row CT1. Radiology 232, 164-172.[CrossRef]eep K. Kalra, Michael M. Maher, Thomas L. Toth, Leena M. Hamberg, Michael A. Blake, Jo-Anne Shepard, SanjaySaini. 2004. Strategies for CT Radiation Dose Optimization1. Radiology 230, 619-628. [CrossRef]40.C. Leroy, P. Puech, D. Lagard, L. Lemaitre. 2004. Diagnostic radiologique d’une lombalgie aiguë non fébrile. Feuillets de Radiologie44, 21-31. [CrossRef]Downloaded

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P. Heneghan, Keith A. McGuire, Richard A. Leder, David M. DeLong, Terry Yoshizumi, Rendon C. Nelson. 2003. HelicalCT for Nephrolithiasis and Ureterolithiasis: Comparison of Conventional and Reduced Radiation-Dose Techniques1. Radiology229, 575-580. [CrossRef] J Kenney. 2003. CT evaluation of urinary lithiasis. Radiologic Clinics of North America 41, 979-999. [CrossRef]s S. Katz, N. Venkataramanan, Sandy Napel, F. Graham Sommer. 2003. Can Low-Dose Unenhanced Multidetector CTBe Used for Routine Evaluation of Suspected Renal Colic?. American Journal of Roentgenology 180:2, 313-315. [Citation] [FullText] [PDF] [PDF Plus]