Implementing Optimal Kidney Stone CT Protocols Using Outreach from a National Database. Purpose

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Avis Baldwin
6 years ago
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1 Implementing Optimal Kidney Stone CT Protocols Using Outreach from a National Database Melissa M. Shaw, BS 1 Karri Weisenthal, BS 1 Priyadarshini Karthik, MS Debapriya Sengupta, MPH Judy Burleson, MHSA Mythreyi Chatfield, PhD Mannudeep Kalra, MD 3 Chris L. Moore, MD 1 1 Yale University, New Haven, CT American College of Radiology, Reston, VA 3 Massachusetts General Hosptial, Boston, MA S L I D E Purpose Kidney stones (KS), are common, recurrent, and occur in young patients. Optimizing radiation dose for KS CT is highly desirable. Guidelines and evidence support use of reduced-dose protocols (DLP < mgy*cm) Despite this, reduced-dose protocols are underutilized. We sought to characterize scan level parameters that influence radiation dose as part of an ongoing effort to optimize CT radiation dose for suspected KS. B S L I D E 1 1

2 Reduced-Radiation Dose Kidney Stone CT Trends Reduced-Dose CT (RDCT) Prevalence from national samples 11-1 % KS CT exam met RDCT criteria Mean institutional DLP of 76 mgy*cm (range ) % KS CT exam met RDCT criteria Mean exam DLP of 689 mgy*cm (95% CI:667, 71) Institutions often lack a dedicated RDCT stone protocol Protocols are often the same as those for undifferentiated abdominal pain (without contrast) Dose Optimization for Stone Evaluation (DOSE) seeks to provide education and consultation to optimize CT protocols. S L I D E Methods ACR s Dose Index Registry (DIR) identified 38 institution contributing KS CT exams. Institutions were stratified by DLP and randomized 189 institutions to intervention 191 institutions to control DOSE Intervention Free access to online CME modules ( DOSE individualized consultation Data was abstracted from provided KS CT protocols (N=5) *Tube potential *Pitch *Rotation time *Tube current (TC) *Automatic Exposure Control (AEC) use *Iterative Reconstruction (IR) use *Institution s DLP (ACR DIR data) Scan parameters and DLP for KS CT protocols were analyzed by vendor. Student s t-test was used to determine if the use of iterative reconstruction allowed for a significant reduction in TC. S L I D E 3

3 15 Institutions provided KSCT protocols a Mean DLP ± 31 mgy*cm 51 KSCT protocols 8 different CT models Siemens (n=15) GE (n=9) Philips (n=3) Toshiba (n=1) b a Institutions response at time of abstract submission. To date 39 institutions have received DOSE consultation b Toshiba protocol was excluded because of incomplete data S L I D E Wide variations in KS CT protocol parameters regardless of CT vendor Tube Potential Institutions employing 1kV 11/15 Mean DLP= 798 ± 39 mgy*cm Institutions employing <1kV /15 Mean DLP = 57 ± 151 mgy*cm Pitch per CT protocol Gantry Rotation Time (sec) per CT Protocol N/A S L I D E 5 3

4 1 Automatic Exposure Controls (AEC) by Scanner Manufacturer 8 Institution DLP Associated with Iterative Reconstructions (IR) vs Filtered Back Projection (FBP) GE Siemens Facilities using IR Facilties using FBP Although all institutions applied AEC, image quality requirement was set too high for KSCT protocol resulting in higher radiation dose for KSCT in terms of mean DLP. Institutions with IR (mean DLP 73 ± 56 mgy*cm) had a statistically insignificant, higher radiation dose compared to those with FBP (mean DLP 67 ± 13 mgy.cm) (p=.7) emphasizing insufficient modification to reduce radiation dose. S L I D E 6 Overview of KSCT Protocol Settings as Provided by Institutions Compared to Recommendations Reduced-Dose KSCT Scan Parameters Provided KSCT Recommended Reduced Dose KSCT kv Siemens CareDose b (effective mas) Mean 118. kv 1 kv a Median (IQR) 1 kv (1-1) 1 kv (1-1) Mean 17 mas 1 mas Median (IQR) 175 mas (15-) 1 (1-1) (ma) b Median (IQR) 3 ma (-58) 3 ma (5-3) GE AutomA max Mean 77 ma 89 ma Philips Z-Dom (mas/slice) b Mean 13 mas 17 mas Median (IQR) 16 mas (11-17) 1 mas (1-11) a Tube current across vendors is not comparable due to different ways of representing and estimating the values. b Four scanners lacked 1 kv capability. S L I D E 7

5 Conclusion Available CT technologies (both AEC and IR techniques) are underutilized Factors responsible for higher radiation dose in KSCT include higher kv and higher tube current despite AEC This was irrespective of the CT reconstruction technique Current KSCT and general abdominal-pelvic CT protocols often have minimal variation A true KSCT can and should be performed at significantly reducedradiation dose compared to a general CT of the abdomen/pelvis S L I D E 8 Special Thanks Karri Weisenthal, BS Priyadarshini Karthik, MS Debapriya Sengupta, MPH Judy Burleson, MHSA Mythreyi Bhargavan-Chatfield, PhD Mannudeep Kalra, MD Chris Moore, MD Agency for Healthcare Research and Quality Grant#R18H53778 S L I D E 9 5

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