Radiology Book

Computerized Tomography

  • Cancer Risk due to Diagnostic Radiology

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Cancer Risk due to Diagnostic Radiology

Aka: Cancer Risk due to Diagnostic Radiology, CT-associated Radiation Exposure, Radiation Exposure in Medical Procedures, ALARA Principle of Radiation Exposure
  1. See Also
    1. Radiographic Contrast Media
    2. Intravenous Contrast Related Acute Renal Failure
    3. Contrast-Induced Nephropathy Risk Score
    4. Gadolinium-Associated Nephrogenic Systemic Fibrosis
    5. Radiation Exposure in Pregnancy
  2. Definition
    1. ALARA Principle of Radiation Exposure
      1. As low as reasonably achievable
      2. In some cases (e.g. serious Head Trauma), CT is needed (even in children)
  3. Epidemiology
    1. Comparisons
      1. Standard Chest XRay (2 view) Radiation Exposure: 0.06 to 0.25 mSv
      2. Radiation from natural sources in an entire year (Germany): 2.4 mSv/year
      3. Survivors of Hiroshima and Nagasaki Atomic bombings: 50 to 150 mSv
      4. Mean lethal dose radiation (kills 50% population within 60 days): 3500 to 4000 mSv
    2. Occupational exposure restrictions (U.S. Dept Energy)
      1. Adult medical imaging worker radiation exposure limit: 50 mSv/year
      2. Pregnant worker radiation exposure limit: 5 mSv/year
    3. Pregnancy exposure risks
      1. Exposure <100 mSv: Low risk of fetal malformation
      2. Exposure >500 mSv: Moderate to high risk of fetal malformation
    4. Interpretation
      1. Cummulative exposure risk increases after age 40
      2. Medical Imaging may cause 1% of U.S. Cancers
      3. Each 1 mSv increase in exposure leads to 5 extra malignancies per 100,000 people
      4. Thyroid radiation exposure is proportionally much higher in Chest CT
      5. Diederich (2000) Cancer 89:2457-60 [PubMed]
  4. Adverse Effects: Highest risk procedures (in descending order of risk)
    1. CT Scan (expecially CT Neck, CT Lung, CT Pelvis)
    2. Barium Enema
    3. Hip XRay
    4. Pelvis XRay
  5. Adverse Effects: Cancers associated with Radiography
    1. Colon Cancer
    2. Bladder Cancer
    3. Breast Cancer
    4. Leukemia
  6. Adverse Effects: Plain Radiograph (XRay) radiation exposures
    1. Lumbar Spine 3-view series: 1.5 mSv
    2. Hip XRay: 0.7 mSv
    3. Abdominal XRay series: 0.7 mSv
    4. Mammogram: 0.2 mSv
    5. Chest XRay (PA and Lateral): 0.1 mSv
    6. DEXA Scan: 0.04 mSv
    7. Dental Panoramic XRay: 0.012 mSv
  7. Adverse Effects: Radiation Exposure from Fluoroscopy
    1. Cardiac
      1. Coronary Angiography with stent placement: 13 mSv
      2. Electrophysiology study alone: 3.2 mSv
      3. Cardiac Catheter Ablation
        1. Atrial Tachycardia Ablation: 4.4 mSv
        2. Atrioventricular nodal reentrant Tachycardia (AVNRT) ablation: 4.8 mSv
        3. Atrial Flutter Ablation: 12.1 mSv
        4. Atrioventricular Reciprocating Tachycardia (AVRT) ablation: 12.8 mSv
        5. Atrial Fibrillation Ablation: 16.6 mSv
      4. References
        1. Efstathopoulos (2006) Europace 8(6): 443-8 [PubMed]
        2. Perisinakis (2001) Circulation 104(1): 58-62 [PubMed]
        3. Shapira (2009) Am Fam Physician 80(10): 1089-94 [PubMed]
    2. Abdomen
      1. TIPS Procedure: 70 mSv
      2. Pelvic vein embolization: 60 mSv
      3. Barium Enema: 8 mSv
      4. Intravenous pyelogram: 8 mSv
      5. Upper GI Series: 5 mSv
      6. ERCP: 4 mSv
  8. Adverse Effects: CT-related Radiation Exposure
    1. CT Radiation Exposure (average, in MilliSieverts)
      1. High dose protocols: 3-27 mSv
      2. Low dose protocols: 0.3-0.55 mSv
    2. CT radiation exposure varies by CT type
      1. CT Electron beam (EBT): 11 mSv Chest, 26 mSv Abdomen
      2. CT Sequential: 4 mSv Chest, 20 mSv Abdomen
      3. CT Spiral: 2 mSv Chest, 7 mSv Abdomen
      4. Becker (1998) Radiologe 38:726-9 [PubMed]
    3. CT radiation exposure during episodic care (e.g. Trauma)
      1. Average radiation exposure during a Trauma admission: 22.7 mSv
        1. Tien (2007) j Trauma 62:151-6 [PubMed]
      2. CT Cervical Spine is associated with significant radiation exposure (especially to Thyroid Gland)
        1. Cervical Spine XRay: 0.24 to 0.51 mSv (for comparison)
        2. CT Cervical Spine radiation dose at Thyroid averages 64 mSv in age <18 years
          1. Thyroid Cancer excess Relative Risk is 13% for males and 25% for females
        3. Muchow (2012) J Trauma Acute Care Surg 72(2):403-9 [PubMed]
    4. CT Chest Radiation Exposures (in milliSieverts)
      1. Newborn: 1.7 mSv
      2. Five year old (on low dose CF protocol): 0.55 mSv
      3. Adults: 5.4 mSv
        1. Equivalent of 20 to 90 Chest XRays
      4. Huda (2007) Proc Am Thorac Surg 4:316-20 [PubMed]
    5. CT regional relative radiation exposures (may overestimate exposures)
      1. Head and Neck
        1. CT Head and Brain: 2 mSv
        2. CT Neck: 3 mSv
      2. Chest
        1. CT Chest Coronary Angiogram
          1. CT Calcium Score (performed prior to each CCTA): 3 to 4 mSv
          2. CCTA-64 slice with Retrospective Gating of diastole: 16 mSv in men and 23 mSv in women
          3. CCTA-64 slice with Prospective Gating of diastole: 10 mSv in men and 14 mSv in women
          4. CCTA-64 slice with Dual Source of diastole: 2 to 4 mSv
        2. CT Chest Pulmonary Angiogram (for PE): 15 mSv
        3. CT Chest: 10 mSv
        4. CT Calcium scoring: 3 to 4 mSv
      3. Abdomen
        1. CT Abdomen: 10 mSv
        2. CT Pelvis: 7 mSv
        3. CT Virtual Colonoscopy: 10 mSv
        4. Radiation induced sold-tumor risk in children
          1. Girls: 1 new cancer per 300-390 CT Abdomen and Pelvis
          2. Boys: 1 new cancer per 670-760 CT Abdomen and Pelvis
          3. Miglioretti (2013) JAMA Pediatr 167(8): 700-7 [PubMed]
      4. Spine
        1. CT Cervical Spine: 5 mSv
        2. CT Lumbar Spine: 7 mSv
  9. Adverse Effects: Nuclear Medicine
    1. Cardiac
      1. Myocardial perfusion imaging with thalium: 29 mSv
      2. Myocardial perfusion imaging with sestamibi: 12 mSv
    2. Gastrointestinal
      1. Cholescintigraphy (e.g. HIDA Scan): 1-3 mSv
      2. Technetium 99m tagged Red Blood Cell study: 8 mSv
    3. Miscellaneous
      1. Bone Scan: 6 mSv
      2. Thyroid uptake scan: 2 mSv
      3. PET Scan: 14 mSv
  10. Resources
    1. XRay Risk Calculator
      1. http://xrayrisk.com/
  11. References
    1. Berrington de Gonzalez (2004) Lancet 363:345-51 [PubMed]
    2. Crownover (2013) Am Fam Physician 87(7): 494-501 [PubMed]
    3. Fazel (2009) N Engl J Med 361(9): 849-57 [PubMed]
    4. Linet (2012) CA Cancer J Clin 62(2): 75-100 [PubMed]
    5. Mettler (2009) Radiology 253(2):520-31 [PubMed]
    6. Mettler (2008) Radiology 248(1): 254-63 [PubMed]

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