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

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II. Definitions

  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)

III. 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. Childhood exposure risks
    1. Children appear to be most susceptible to radiation exposure related cancer risk
    2. Leukemia 1.9 cases for every 10,000 Head CTs in children
    3. Miglioretti (2013) JAM Pediatr 167(8): 700-7 [PubMed]
  5. 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 adults
    4. Thyroid radiation exposure is proportionally much higher in Chest CT
    5. Diederich (2000) Cancer 89:2457-60 [PubMed]

IV. 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

V. Adverse Effects: Cancers associated with Radiography

  1. Colon Cancer
  2. Bladder Cancer
  3. Breast Cancer
  4. Leukemia

VI. 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. Upper GI Series: 6 mSv
  5. Mammogram: 0.2 to 0.4 mSv
  6. Chest XRay (PA only): 0.02 mSv
  7. Chest XRay (PA and Lateral): 0.04 to 0.1 mSv
  8. DEXA Scan: 0.04 mSv
  9. Dental Panoramic XRay: 0.012 mSv

VII. 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

VIII. 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 to 7 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
      1. CT Head and Brain: 2 mSv
      2. CT Head and Brain Cancer Risk
        1. Age <22 years: 1 case of brain cancer in 10,000 CT Head scans
        2. Hauptmann (2023) Lancet Oncol 24(1):45-53 +PMID: 36493793 [PubMed]
      3. CT Head related Leukemia risk in children
        1. Age <5 years: 1 case of Leukemia in 5,250 CT Head scans
        2. Age 10 to 14 years: 1 case of Leukemia in 21,160 CT Head scans
        3. Miglioretti (2013) JAMA Pediatr 167(8): 700-7 [PubMed]
    2. Neck
      1. CT Neck or Cervical Spine: 3 mSv
    3. 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: 7-10 mSv
      4. CT Calcium scoring: 3 to 4 mSv
    4. Abdomen
      1. CT Abdomen and Pelvis: 14 mSv
      2. CT Abdomen: 10 mSv
      3. CT Pelvis: 7 mSv
      4. CT Virtual Colonoscopy: 10 mSv
      5. 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]
    5. Spine
      1. CT Cervical Spine: 5 mSv
      2. CT Lumbar Spine: 7 mSv

IX. Adverse Effects: Nuclear Medicine

  1. Cardiac
    1. Myocardial Perfusion Imaging with thalium: 29 to 40 mSv
    2. Myocardial Perfusion Imaging with sestamibi: 9.4 to 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

X. Resources

  1. XRay Risk Calculator
    1. http://xrayrisk.com/
  2. ACR Radiation Safety Dose Card
    1. https://www.acr.org/-/media/ACR/Files/Radiology-Safety/Radiation-Safety/Dose-Reference-Card.pdf

XI. 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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