REVISION ON 4 - 7 LECTURES
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REVISION ON 4 - 7 LECTURES

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Questions and Answers

What is the spatial resolution of Solid State Receptor measured by pixel size?

  • 25 lp/mm
  • 20 μm (correct)
  • 7 lp/mm
  • 60 μm

    • Which advantage of digital imaging directly reduces the need for chemical processing?

  • Lower radiation dose
  • Post-processing capabilities
  • No chemical processing (correct)
  • Rapid image production

    • How many different greyscale values can digital imaging capture?

  • 242 (correct)
  • 128
  • 256
  • 512

    • Which statement represents a disadvantage of digital imaging?

    <p>High one-time cost for equipment</p> Signup and view all the answers

    What does a higher value in line pairs per millimeter (lp/mm) indicate in imaging?

    <p>Higher resolution</p> Signup and view all the answers

    What is the primary responsibility of the employer in relation to radiation protection?

    <p>Ensuring practitioners are adequately trained</p> Signup and view all the answers

    What does ALARA stand for in the context of patient radiation doses?

    <p>As Low As Reasonably Achievable</p> Signup and view all the answers

    Who is responsible for performing the practical aspects of an exposure in radiology?

    <p>The Operator</p> Signup and view all the answers

    What role does the Medical Physics Expert (MPE) play in radiation protection?

    <p>Providing advice on optimizing patient dose</p> Signup and view all the answers

    Which of the following statements about Diagnostic Reference Levels (DRLs) is true?

    <p>DRLs are adopted in consultation with an MPE</p> Signup and view all the answers

    What material is primarily used in film-based imaging packets to create X-ray images?

    <p>Silver halide</p> Signup and view all the answers

    Which of the following is a disadvantage of solid state receptors in X-ray imaging?

    <p>They are bulky and difficult to place in the patient's mouth.</p> Signup and view all the answers

    Which statement correctly describes the processing of film-based X-ray images?

    <p>It requires chemical processing and is time-consuming.</p> Signup and view all the answers

    How do phosphor plate receptors create an X-ray image?

    <p>Through laser stimulation of a photo-stimulable phosphor imaging plate.</p> Signup and view all the answers

    Which advantage is associated with phosphor plate receptors?

    <p>They are flexible, reusable, and typically cheaper.</p> Signup and view all the answers

    What happens to the phosphor plate after reading the X-ray image?

    <p>It is cleared using white light.</p> Signup and view all the answers

    What is a key feature of the Digora System for phosphor plate receptors?

    <p>It contains a small circular magnet.</p> Signup and view all the answers

    In film-based systems, what type of crystals are sensitized by X-rays?

    <p>Silver halide</p> Signup and view all the answers

    What is the typical radiation dose for a panoramic radiograph?

    <p>14-24 µSv</p> Signup and view all the answers

    Which radiograph type has the highest radiation dose among the following options?

    <p>Cone-Beam Computed Tomography (CBCT) of both jaws</p> Signup and view all the answers

    What is the primary principle behind the International Commission on Radiological Protection's justification of radiation exposure?

    <p>Exposure should only occur when benefits outweigh risks</p> Signup and view all the answers

    What is the recommended dose for a typical intraoral (periapical) radiograph?

    <p>2 µSv</p> Signup and view all the answers

    What does the term 'ALARP' stand for in the context of radiation optimization?

    <p>As low as reasonably practicable</p> Signup and view all the answers

    What is the difference in radiation dose between a panoramic radiograph and a cephalometric radiograph?

    <p>Panoramic has 14-24 µSv more</p> Signup and view all the answers

    What might happen if periapical X-rays were substituted with CT scans in dental practice?

    <p>Increase in cumulative population dose</p> Signup and view all the answers

    For which group is the dose limitation of 20 mSv applicable?

    <p>Classified workers in a medical setting</p> Signup and view all the answers

    What is the unit of measurement for absorbed dose?

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

    Which dose is considered the 'gold standard' in radiation measurement?

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

    How is equivalent dose calculated?

    <p>By multiplying absorbed dose by radiation weighting factor</p> Signup and view all the answers

    Which tissue is identified as the most radiosensitive?

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

    What percentage of background radiation in the UK comes from radon gas?

    <p>50%</p> Signup and view all the answers

    What is the risk of cancer induction for men receiving a dental radiograph measured in mSv?

    <p>1 in 15000 mSv</p> Signup and view all the answers

    Which factor is NOT involved in determining radiation risk?

    <p>Duration of exposure</p> Signup and view all the answers

    In which unit is effective dose measured?

    <p>Sieverts (Sv)</p> Signup and view all the answers

    What principle ensures that a new practice in radiology should only be implemented if it offers a net positive benefit?

    <p>Justification</p> Signup and view all the answers

    Which of the following is NOT an effective method for reducing radiation exposure to patients during panoramic X-rays?

    <p>Increasing exposure time</p> Signup and view all the answers

    How can staff best protect themselves from radiation exposure in a clinical setting?

    <p>Limiting exposure time</p> Signup and view all the answers

    What is the purpose of the inverse square law in radiological practice?

    <p>To decrease radiation exposure by maximizing distance</p> Signup and view all the answers

    What specific reason is given for wearing a thyroid shield during radiographic procedures?

    <p>When performing an upper occlusal radiograph</p> Signup and view all the answers

    Which of the following is a key action in putting the ALARP principle into practice?

    <p>Ensuring equipment is functioning correctly</p> Signup and view all the answers

    What is considered a negligible risk for pregnant women undergoing dental radiographs?

    <p>The pelvic area is not irradiated</p> Signup and view all the answers

    Which type of film receptor is specifically mentioned as being more sensitive and allowing for faster speeds?

    <p>F-speed films</p> Signup and view all the answers

    What is the primary purpose of a controlled area in radiological practices?

    <p>To maintain radiation exposure within safety limits for patients and staff</p> Signup and view all the answers

    When is it advisable to provide personnel dosimetry devices?

    <p>When individual doses could exceed 1 mSv per year based on risk assessment</p> Signup and view all the answers

    Who is responsible for enforcing the Ionising Radiation Regulations 2017 (IRR17)?

    <p>Health and Safety Executive (HSE)</p> Signup and view all the answers

    Which individual is NOT identified in the Ionising Radiation (Medical Exposure) Regulations 2017 (IRMER17)?

    <p>Radiation Protection Supervisor</p> Signup and view all the answers

    Which document outlines the special working conditions needed to restrict doses in a controlled area?

    <p>Local Rules</p> Signup and view all the answers

    What is one of the significant findings that must be included in the IRMER documentation?

    <p>Significant findings of risk assessment</p> Signup and view all the answers

    What is the minimum distance that dental staff should maintain from the X-ray tube during operations?

    <p>1.5 meters</p> Signup and view all the answers

    Who must read and follow the local rules established for controlled areas?

    <p>Every person working in the controlled areas</p> Signup and view all the answers

    What effect does foreshortening have on an X-ray image?

    <p>The image appears smaller than the actual object size.</p> Signup and view all the answers

    What positioning error leads to elongation in an X-ray image?

    <p>The X-ray beam is not angled enough.</p> Signup and view all the answers

    What causes distortion in an X-ray image?

    <p>The X-ray beam directed at an angle to the tooth.</p> Signup and view all the answers

    To achieve optimal image quality, how should the X-ray source and object be positioned?

    <p>The source should be as far from the detector as feasible, with the object close to the detector.</p> Signup and view all the answers

    What is a significant consequence of placing the X-ray source too close to the object?

    <p>Tendency for both foreshortening and elongation.</p> Signup and view all the answers

    How can one minimize the effects of beam divergence when creating X-ray images?

    <p>By increasing the distance from the source to the object.</p> Signup and view all the answers

    What impact does minimizing the object's magnification have on X-ray image quality?

    <p>It enhances the sharpness of the image.</p> Signup and view all the answers

    What should be avoided to prevent distortion in X-ray imaging?

    <p>Positioning the X-ray source at an angle.</p> Signup and view all the answers

    Study Notes

    Spatial Resolution

    • Spatial resolution for digital imaging can be measured by pixel size.
    • Phosphor Plates - 60 μm
    • Solid State Receptor - 20 μm

    Spatial Resolution for film-based imaging AND digital imaging

    • Can be measured via line pairs/mm (higher is better)
    • Phosphor Plates - 7 lp/mm
    • Solid State Receptor - 25 lp/mm
    • Film - 20 lp/mm

    Contrast

    • In digital imaging, we have 242 different greyscale values.

    Post-Processing

    • Advantage of digital imaging is the ability to post-process and adjust the brightness and contrast.
    • Digital imaging has a broader exposure latitude, making it more tolerant to over and under-exposure compared to film.
    • The forgiving nature of digital receptors decreases the likelihood of over or underexposed images.
    • Over or underexposed images can be corrected through post-processing techniques.

    Advantages and Disadvantages of Digital Imaging

    • Advantages:

      • Lower radiation dose
      • No chemical processing, reducing processing artifacts
      • Rapid image production
      • Can post-process images
      • Digital storage and sharing of images
      • Images can be easily magnified
      • Software tools can aid measurements

    • Disadvantages:

      • High cost (one-off fixed cost for buying equipment) - however overtime can reduce costs as you do not need to purchase consumables needed as part of the film-based imaging process.

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    Quiz Team

    Description

    Test your knowledge on digital imaging concepts, including spatial resolution, advantages of digital imaging, and greyscale values. This quiz will challenge your understanding of how digital imaging works and its benefits compared to traditional methods.

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