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Optimizing Patient Radiation Safety in the Era of Multidetector Helical CT. Steven Birnbaum, M.D. Staff Radiologist and Radiation Safety Officer Southern New Hampshire Medical Center Nashua, New Hampshire Parkland Medical Center Derry, New Hampshire

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Optimizing patient radiation safety in the era of multidetector helical ct
Optimizing Patient Radiation Safety in the Era of Multidetector Helical CT

  • Steven Birnbaum, M.D.

  • Staff Radiologist and Radiation Safety Officer

  • Southern New Hampshire Medical Center

  • Nashua, New Hampshire

  • Parkland Medical Center

  • Derry, New Hampshire

  • Member, American College of Radiology Blue Ribbon Panel on Radiation Dose in Medicine

  • Member, ACR Blue Ribbon Panel on Radiation Dose in Medicine and Primer on Radiation Safety, Commission in Physics of the ACR


Optimizing patient radiation safety in the era of multidetector helical ct1
Optimizing Patient Radiation Safety in the Era of Multidetector Helical CT

  • Arthur Schopenhauer

    • 19th Century German Philosopher

    • “All truth passes through three stages.

    • First, it is ridiculed.

    • Second, it is violently opposed.

    • Third, it is accepted as being self-evident.”

    • Adapted from Budoff and Shinbane, Cardiac CT Imaging, Springer Verlag, 2006


Optimizing patient radiation safety in the era of multidetector helical ct2
Optimizing Patient Radiation Safety in the Era of Multidetector Helical CT

  • Recent Events-

    • 2007: Brenner and Hall Review in NEJM/Published during RSNA

    • 2009: Cedars-Sinai CT Perfusion Overexposures for Perfusion Head CT’s

    • 2009: Smith-Bindman et al, Archives of Internal Medicine: Variable Output by 13 fold of SF Bay Area CT scanners

    • 2010: FDA Initiative to Alert Clinicians and Patients about CT Exposure Issues

    • 2010: California Legislation Requiring Dose Data on Reports

Text


Optimizing patient radiation safety in the era of multidetector helical ct3
Optimizing Patient Radiation Safety in the Era of Multidetector Helical CT

  • Radiation Risks

    • What are they?

    • There are no Answers/Only Extrapolations and Best Guesses

    • We Don’t Know

    • I am NOT a Physicist


Optimizing patient radiation safety in the era of multidetector helical ct4
Optimizing Patient Radiation Safety in the Era of Multidetector Helical CT

  • Units of Dosage

    • Millisievert

      • Measurement of effective radiation dose

      • Different organs in the body have different sensitivities to radiation

      • Effective dose takes into account these differences and averages organ absorbed doses over the entire body

      • Effective dose allows comparison between different types of exams, natural background radiation, and different types of ionizing radiation


Optimizing patient radiation safety in the era of multidetector helical ct5
Optimizing Patient Radiation Safety in the Era of Multidetector Helical CT

  • Other Units of Radiation Dose Pertinent to CT

    • C.T. Dose Index (C.T.D.I.w)

      • Measure of CT Radiation Dose Delivered

      • Manufacturer Requirement for each Scanner Placed on Console

      • Calculated using Reference Phantoms on Single Axial Image

    • C.T.D.I.vol

      • Adjusts for Scanning Parameters

      • Pitch

      • Beam Width

    • Dose Length Product (D.L.P.)

      • Calculated from CTDIvol Times Area Scanned

      • Provided on user interface of all scanners

      • Can be converted to effective dose with a table of conversion

      • Standardized dose ranges are used in ACR CT accreditation program

    • Estimated Dose

      • Can be Grossly Estimated from DLP Using “Fudge” Factor

      • Heads-0.0023/Chest-0.017/Abdomen-0.015/Pelvis-0.019


Optimizing patient radiation safety in the era of multidetector helical ct6
Optimizing Patient Radiation Safety in the Era of Multidetector Helical CT

  • Radiation Dosage and Effect

    • 10,000 mSv- Radiation sickness with immediate illness and death w/i several weeks

    • 1,000 mSv- Immediate radiation sickness , unlikely to cause death

    • 100-1000 mSv –Clear dose related increasing risk of carcinogenesis

    • 50 mSv- Clearly associated with increased cancer risk and the highest dose recommended yearly in occupational exposure

    • 20 mSv/year averaged over 5 years- Highest recommended allowable dose for radiation workers

    • 3-5 mSv/year- Typical dose rates of uranium miners in Australia and

  • Estimated Radiation Dosages of Common Medical Procedures

  • Chest X-Ray- 0.1-0.2 mSv

  • Infant VCUG- 0.8 mSv

  • Head CT- 2 mSv

  • Chest CT- 8 mSv

  • CT Pulmonary Arteriogram- 8 mSv

  • Cardiac Catheterization- 2.5 mSv

  • Helical Cardiac CT/Male- 8.8 mSv

  • Helical Cardiac CT/Female- 10.5 mSv

  • Renal Stone CT - 10 mSv

  • “Low Dose” Renal Stone CT- 6 mSv

  • Abdomen- Pelvis CT- 10 mSv

  • PET/CT Fusion-20 mSv


Optimizing patient radiation safety in the era of multidetector helical ct7
Optimizing Patient Radiation Safety in the Era of Multidetector Helical CT

  • The Scope of the Problem

    • Over 70 Million CT studies Performed in the U.S. in 2009

    • 15% of the Volume of Radiographic Procedures

    • 60% of the Estimated Population Exposure from Diagnostic Radiation Comes from CT

    • Southern New Hampshire Medical Center- 2,000 CT studies in 1985/18,000 in 2006/20,000 + in 2009

    • Outsourcing of CT Reading in Off Hours


Optimizing patient radiation safety in the era of multidetector helical ct8
Optimizing Patient Radiation Safety in the Era of Multidetector Helical CT

  • Clinical Examples From Our Practice

    • Patient 1- 14 year old with hypercalciuria and multiple episodes of renal colic was noted to have had 14 renal stone CT studies in a four year period. Total “estimated dosage”- 140 mSv.

    • Patient 2- 28 year old AIDS patient with multiple Emergency Room visits receives 8 renal stone CT studies and 2 abdomen and pelvis studies in a 2 year period. Total “estimated dosage”- 100 mSv.

    • Patient 3- 22 year old patient with multiple visits to the Emergency Room over 5 years receives 5 Head CT studies, 7 Abdomen and Pelvis CT studies, and 5 CT pulmonary arteriograms. Total “estimated dosage”- 120 mSv. The mammographic equivalent exposure for this 22 year old patient would be 50-125 2 view screening mammograms.


Optimizing patient radiation safety in the era of multidetector helical ct9
Optimizing Patient Radiation Safety in the Era of Multidetector Helical CT

  • Clinical Examples From Our Practice

    • Patient 4- 39 year old patient has 4 neck CT studies and 3 CT and globus pulmonary arteriogram studies in a one year interval for panic attacks. Total “estimated dosage”- 60 mSv.

    • Patient 5- 31 year old female with renal stones and many episodes of renal colic. She had 14 renal stone CT’s at one of our hospitals and reports an additional 20 studies done at a tertiary care hospital in Boston. Total “estimated dosage”- 340 mSv.

    • Patient 6- 46 year old female patient with multiple episodes of renal colic. She has had 23 renal stone CT’s and 73 KUB’s at one of our hospitals over a 7 year interval. Total “estimated dosage”- 370 mSv.


Optimizing patient radiation safety in the era of multidetector helical ct10
Optimizing Patient Radiation Safety in the Era of Multidetector Helical CT

  • Demographics of Frequent Exposure to CT at SNHMC, 11/2008

    • PATIENT DEMOGRAPHICNUMBER OF PATIENTS

  • ER Patients/No Insurance/Episodic Care/Multiple Medical Problems 21

  • Renal Stone Disease 19

  • Chronic Abdominal Pain w/Normal Imaging 16

  • Pulmonary Embolus Evaluation 4

  • Diverticulitis 2

  • Crohn's Disease 3

  • RIS Data Mining with Crystal Reports 156


  • Optimizing patient radiation safety in the era of multidetector helical ct11
    Optimizing Patient Radiation Safety in the Era of Multidetector Helical CT

    • Technical Factors Under Radiologist Control

      • Bismuth Breast Shields

      • Initial Scout Views Done in PA Projection in Female Patients

      • Minimize Technique (mA and kV) in order to Minimize Exposure

        • Manually or Automatically

        • Dose Modulation in One or Multiple Planes

        • Use Shielding After Scout Views with Automatic Dose Modulation

      • Center Patient in Gantry

      • Iterative Reconstruction Algorithms

      • Cardiac CTA

        • Breast Shields Cause Streak Artifact in Distribution of RCA

        • EKG Dose Modulation-Needs Very Low Heart Rates to be Effective

      • Minimize Body Area to be Scanned

      • Avoid Dual/Multiphase Imaging when Possible

      • Decrease Scan Time/Increase Pitch

      • Spot Check Dose Reports Now Sent to PACS on Most Scanners

      • Avoid Repeats, “Re-does” and “Extra” Images

        • Careful Explanation by the Technologist of Breath Holding



    Optimizing patient radiation safety in the era of multidetector helical ct13
    Optimizing Patient Radiation Safety in the Era of Multidetector Helical CT

    • Education (!!!!!!!!!!!!!): Spearheaded by Radiologists

      • Radiologists at Each Institution as “Champions”

      • Radiologists

      • Emergency Physicians

      • Cardiologists and Surgeons

      • Encourage Evidence Based Practice

      • Encourage Use of Non-ionizing Modalities as Alternatives

      • Will the Study Change Management?

        • Renal/Ureteral Stone CT Studies in Renal Colic



    Optimizing patient radiation safety in the era of multidetector helical ct15
    Optimizing Patient Radiation Safety in the Era of Multidetector Helical CT

    • Patient Identification by Radiologists

      • Patients Under the Age of 40

      • Benign Diagnoses

      • Use of 50 mSv Lifetime Threshold Dosage Estimate

      • Review of Imaging Histories by Technologists and Radiologists

        • Empowerment of CT Technologists

      • Review of Identified Patients by RSO

      • Flagging of Patient in RIS

      • Certified Letters to Providers and Patients

      • Data “Mining” in RIS

        • Crystal Reports

        • Elimination of Referring Oncologists


    Optimizing patient radiation safety in the era of multidetector helical ct16
    Optimizing Patient Radiation Safety in the Era of Multidetector Helical CT

    • Patient Identification by Radiologists

      • Imaging Consultation Required in “Flagged Patients” Prior to CT Performance

      • Index Patient- Three years and No CT Studies, 12 Renal Ultrasounds and 1 One-shot IVP

      • Regular Imaging Consultation and Excellent Clinician Acceptance



    Optimizing patient radiation safety in the era of multidetector helical ct18
    Optimizing Patient Radiation Safety in the Era of Multidetector Helical CT

    • Investigation of “Extreme Exposure” by Radiologists

      • More than 100 mSv Dose Estimate

      • Notification of Provider and Patient via Certified Mail

      • Availability of Counseling to Patients by RSO

      • Empowerment of Patient

      • Knowledge of Imaging Histories at Other Institutions by Providers and Patients



    Optimizing patient radiation safety in the era of multidetector helical ct20
    Optimizing Patient Radiation Safety in the Era of Multidetector Helical CT

    • Regional and State Efforts at Patient Radiation Protection

      • Educational Forums

      • “Tool Kits” for Hospitals, Imaging Centers and Offices

      • State Radiology Society Policy Initiative

      • Inter-specialty Cooperation

      • Modify Missions of State Radiation Protection Efforts

        • Currently Device and Occupational Exposure Emphasis

        • Change Emphasis to Patient Radiation Exposure Protection

        • Recent California Legislation Requiring DLP on report

      • Insurance Company Efforts at Radiation Protection

        • Anthem Programs

          • “Tool Kits” on Web and on Forest Products

          • Provider Notification of Frequent Exposure

          • Pay for Performance Initiatives

        • National Imaging Associates/Magellan

          • Use of Pre-certification Data to Identify Frequently Exposed Patients


    Optimizing patient radiation safety in the era of multidetector helical ct21
    Optimizing Patient Radiation Safety in the Era of Multidetector Helical CT

    • American College of Radiology Blue Ribbon Panel on Radiation Dose in Medicine

      • Followed NCRP Report, April, 2007

      • Charge: Comprehensive Review of Current Issues, Controversies and Directions of ACR Patient Radiation Protection Efforts

      • Members

        • Academic and Private Practice Radiologists

        • ACR Staff Members

        • Health Physicists

        • Equipment and NEMA Representatives

        • FDA/CDRH Representative

        • Patient Advocate


    Optimizing patient radiation safety in the era of multidetector helical ct22
    Optimizing Patient Radiation Safety in the Era of Multidetector Helical CT

    • White Paper in May, 2007

    • Recommendations

      • “…the presumption is yes” whether the increased cumulative exposure to ionizing radiation will increase population cancer incidence


    Optimizing patient radiation safety in the era of multidetector helical ct23
    Optimizing Patient Radiation Safety in the Era of Multidetector Helical CT

    • Results of the SNHMC Radiation Safety Program

      • Year 1- 52 “Flagged Patients” Had CT’s Ordered

        • 15% Cancelled

        • 15% Changed to Non-ionizing Modalities

        • 1 Study Performed at Patient Insistence

        • 30% Done at Clinician Insistence

        • 40% Done Following Clinician/Radiologist Consultation

        • Performance Variability Among Radiologists

          • “Just Do It”- The Nike Approach

          • Leave it up to the Technologists

          • Active Consultation Results in Fewer Repeat Studies

    24


    Optimizing patient radiation safety in the era of multidetector helical ct24
    Optimizing Patient Radiation Safety in the Era of Multidetector Helical CT

    • Conclusions of the ACR White Paper

      • Rapid Increase in CT and Certain Nuclear Medicine Studies Over the Last 20 Years May Result in an Increased Incidence of Radiation Related Cancer

      • We Can Do Something about this NOW Before it is too Late.

    • Is Patient Radiation Exposure in 2010 the Medical Equivalent of Climate Change and Global Warming?