LECTURE 4 ~~~~ FROM NOTES
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Questions and Answers

What is the radiation dose of a typical intraoral radiograph?

  • 2 µSv (correct)
  • 14 µSv
  • 20 µSv
  • 39 µSv

How much radiation does a complete cone-beam computed tomography (CBCT) scan of both jaws expose a patient to?

  • 84 µSv (correct)
  • 39 µSv
  • 14 µSv
  • 20 µSv

What radiation dose is associated with a cephalometric radiograph?

  • 20 µSv
  • 6 µSv (correct)
  • 2 µSv
  • 14 µSv

Which principle ensures that patients are only exposed to ionizing radiation when the benefits outweigh the risks?

<p>Justification (D)</p> Signup and view all the answers

What is the recommended radiation dose limit for non-classified workers?

<p>6 mSv (C)</p> Signup and view all the answers

What is the purpose of Diagnostic Reference Levels (DRL)?

<p>To provide a recommended dose for standard examinations. (A)</p> Signup and view all the answers

What dose would a section of jaw radiograph with cone-beam computed tomography produce?

<p>39 µSv (A)</p> Signup and view all the answers

How does substituting periapical X-rays with CT scans affect population dose in the UK?

<p>Significantly increase the cumulative population dose. (A)</p> Signup and view all the answers

What is the primary measure of absorbed dose of radiation?

<p>Gray (Gy) (A)</p> Signup and view all the answers

Which factor is NOT considered in the equivalent dose calculation?

<p>Energy of the radiation (C)</p> Signup and view all the answers

Which type of dose is considered the gold standard for assessing radiation risk?

<p>Effective dose (B)</p> Signup and view all the answers

What is the risk of cancer induction for women following a dental radiograph?

<p>1 in 18000 mSv (B)</p> Signup and view all the answers

Which tissue is identified as the most radiosensitive?

<p>Bone marrow (D)</p> Signup and view all the answers

Which ionizing radiation type has the highest radiation weighting factor?

<p>Alpha particles (C)</p> Signup and view all the answers

What is the average background radiation exposure in the UK, measured per year?

<p>2700 uSv/year (D)</p> Signup and view all the answers

How is the effective dose calculated?

<p>Sum of (equivalent dose x tissue weighting factor) (C)</p> Signup and view all the answers

Flashcards

Intraoral Radiograph Radiation Dose

Less than 2 µSv, equivalent to a fraction of a day's background radiation.

Panoramic Radiograph Dose

20 µSv, approximately equivalent to 2-3 days of typical background radiation.

Cephalometric Radiograph Dose

Less than 6 µSv, about equivalent to one day's background radiation.

CBCT Dose (Section)

39 µSv, which is equivalent to 2 panoramic radiographs.

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CBCT Dose (Full Jaw)

84 µSv, equivalent to 4 panoramic radiographs.

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Justification Principle (Radiation)

Radiation exposure must be justified by the benefit to the patient.

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Optimization Principle (Radiation)

Use the lowest possible radiation dose while achieving diagnostic needs (ALARP).

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Diagnostic Reference Levels (DRL)

Recommended radiation doses for common dental X-ray examinations, set for typical patients.

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Absorbed Dose

The amount of energy deposited per unit mass of tissue by ionizing radiation. Measured in Gray (Gy).

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Equivalent Dose

Considers both the absorbed dose and the type of radiation's ionizing potential. Measured in Sievert (Sv).

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Effective Dose

Accounts for the different radiosensitivity of varying tissues. Measured in Sievert (Sv).

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Radiation Weighting Factor

A factor used to adjust absorbed dose to account for the type of radiation's biological effect, enabling a comparison between different radiation types.

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Tissue Weighting Factor

Factors for the different radiosensitivities of various organs and tissues. Used to convert equivalent dose to effective dose.

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Risk of radiation induced cancer (Dental X-ray)

The probability of developing cancer from dental x-ray radiation exposure (1 in 15000 mSv - men, 1 in 18000 mSv - women).

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Radiosensitive tissue

Bone marrow is the most radio-sensitive tissue.

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Background Radiation (UK)

Natural radiation exposure, primarily Radon gas in the UK, totaling approximately 2700 microSieverts per year, or 7 microSieverts per day.

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Study Notes

Intraoral Radiograph

  • Less than 2 uSv and ¼ of a day's background radiation
  • Examples: intraoral (periapical/bitewing) 2D radiograph - 2 uSv, DPT 2D radiograph - 20 uSv
  • Cone-beam CT scan 3D (section) - 40 uSv
  • Cone-beam CT scan 3D (all teeth in both jaws) - 80 uSv

Panoramic Radiograph

  • 14-24 (20) uSv and 2-3 days of background radiation

Cephalometric Radiograph

  • Less than 6 uSv and 1 day of background radiation

Cone-Beam Computed Tomography (CBCT)

  • 3D image, dose depends on how big the area you image is
  • Both Jaw radiograph = 84 uSv = 39 uSv = 2 panoramic radiographs

Radiation Concerns in Dental X-Rays

  • Cumulative effects of ionizing radiation
  • Biological Harm Potential: Even low doses can increase lifetime cancer risk
  • Professional Impact: Numerous cumulative population dose
  • Comparison of Techniques: Substituting periapical X-rays with CT scans would significantly increase the UK's cumulative population dose

International Commission on Radiographical Protection (ICRP)

  • Justification: Patient should only be exposed to ionizing radiation if benefits outweigh risks
  • Optimization: Use lowest dose possible (ALARP - as low as reasonably practicable)
  • Dose Limitation: (only applies to staff and public)
    • Efforts made to reduce exposure to patients, also reduce exposure to dental staff
    • Ensure no individual is exposed to high diagnostic or therapeutic purposes
    • No dose limits for patients exposed for diagnostic or therapeutic purposes
    • Dose limit: Classified Workers – 20mSv
    • Dose limit: Non-classified Workers – 6mSv

Diagnostic Reference Levels (DRLs)

  • DLR is a dose level for typical examination on standard-sized patients
  • DLR is essentially a reference, recommended dose, for common X-ray examinations
  • Not normally exceeded without good reason
  • It can be set locally or with a medical physics expert or Public Health England

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Description

This quiz covers various types of dental radiographs, including intraoral, panoramic, cephalometric, and cone-beam CT scans. It discusses radiation doses, background radiation comparisons, and radiation concerns, as well as the potential biological harm of ionizing radiation. Test your knowledge of dental imaging and radiation safety practices.

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