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NEET MDS Synopsis - Lecture Notes
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📖 Radiology

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Problems in Film Processing
Radiology

Common Problems in Film Processing

1. Light Radiographs

  • Causes:
    • Under Development:
      • Temperature too low
      • Time too short
      • Depleted developer solution
    • Under Exposure:
      • Insufficient milliamperage
      • Insufficient kVp
      • Insufficient exposure time
      • Film-source distance too great
      • Film packet reversed in the mouth

2. Dark Radiographs

  • Causes:
    • Over Development:
      • Temperature too high
      • Time too long
      • Accidental exposure to light
      • Improper safe lighting
      • Developer concentration too high
    • Over Exposure:
      • Excessive milliamperage
      • Excessive kVp
      • Excessive exposure time
      • Film-source distance too short

3. Insufficient Contrast

  • Causes:
    • Improper processing conditions (under or over development)
    • Depleted developer solution
    • Contaminated solutions

4. Film Fog

  • Causes:
    • Excessive kVp
    • Improper safe lighting
    • Light leaks in the darkroom
    • Contaminated developer solution

5. Dark Spots or Tines

  • Causes:
    • Contaminated solutions
    • Film contaminated with developer before processing
    • Film in contact with tank or another film during fixation

6. Light Spots

  • Causes:
    • Insufficient washing
    • Film contaminated with fixer before processing
    • Film in contact with tank or another film during development

7. Yellow or Brown Stains

  • Causes:
    • Insufficient washing after fixation
    • Depleted fixer solution
    • Contaminated solutions

8. Blurring

  • Causes:
    • Movement of the patient during exposure
    • Movement of the X-ray tube head
    • Double exposure
    • Misalignment of the X-ray tube head (cone cut)

9. Partial Images

  • Causes:
    • Top of film not immersed in developing solution
    • Film in contact with tank or another film during processing

10. Emulsion Peel

  • Causes:
    • Excessive bending of the film
    • Improper handling of the film

11. Static Discharge

  • Causes:
    • Static discharge to film before processing (results in dark lines with a tree-like image)

12. Fingerprint Contamination

  • Causes:
    • Fingerprint contamination during handling of the film

13. Excessive Roller Pressure

  • Causes:
    • Excessive roller pressure during processing can lead to artifacts on the film.
Bisecting angle technique
Radiology

Bisecting angle technique 

Bisecting angle technique is a method used in dental radiography to obtain radiographs of teeth and surrounding structures. This technique involves positioning the X-ray beam perpendicular to an imaginary line that bisects the angle formed by the long axis of the tooth and the film or sensor. Here are the general guidelines for angulations when using the bisecting angle technique:

Anterior Teeth

  1. Maxillary Central Incisors:
    • Vertical Angulation: +40 to +50 degrees
  2. Maxillary Lateral Incisors:
    • Vertical Angulation: +40 to +50 degrees
  3. Maxillary Canines:
    • Vertical Angulation: +45 to +55 degrees
  4. Mandibular Central Incisors:
    • Vertical Angulation: -15 to -25 degrees
  5. Mandibular Lateral Incisors:
    • Vertical Angulation: -15 to -25 degrees
  6. Mandibular Canines:
    • Vertical Angulation: -20 to -30 degrees

Posterior Teeth

  1. Maxillary Premolars:
    • Vertical Angulation: +30 to +40 degrees
  2. Maxillary Molars:
    • Vertical Angulation: +20 to +30 degrees
  3. Mandibular Premolars:
    • Vertical Angulation: -10 to -15 degrees
  4. Mandibular Molars:
    • Vertical Angulation: -5 to -10 degrees

Key Points

  • Positioning: The film or sensor should be placed as close to the tooth as possible, and the X-ray beam should be directed perpendicular to the bisecting line.
  • Patient Comfort: Ensure that the patient is comfortable and that the film or sensor is properly stabilized to avoid movement during exposure.
  • Technique Variability: The exact angulation may vary based on the individual patient's anatomy, so adjustments may be necessary.
Age Groups and Radiographs
Radiology

Age Groups and Radiographs

  • Age 2:

    • Anterior IOPA's: 2
    • Posterior IOPA's: 4
    • Bitewings: 2
    • Total Films: 12

  • Age 8:

    • Anterior IOPA's: 8
    • Posterior IOPA's: 4
    • Bitewings: 2
    • Total Films: 14

  • Age 8 (another entry):

    • Anterior IOPA's: 8
    • Posterior IOPA's: 8
    • Bitewings: 2
    • Total Films: 20

Summary of Total Films by Type

  • Anterior IOPA's:

    • Age 2: 2
    • Age 8: 8
    • Age 8 (another entry): 8
    • Total Anterior IOPA's: 18

  • Posterior IOPA's:

    • Age 2: 4
    • Age 8: 4
    • Age 8 (another entry): 8
    • Total Posterior IOPA's: 16

  • Bitewings:

    • Age 2: 2
    • Age 8: 2
    • Age 8 (another entry): 2
    • Total Bitewings: 6

Overall Total Films

  • Total Films for Age 2: 12
  • Total Films for Age 8 (first entry): 14
  • Total Films for Age 8 (second entry): 20
  • Grand Total Films: 12 + 14 + 20 = 46

Digital Radiology

Radiology

Digital Radiology

Advances in computer and X-ray technology now permit the use of systems that employ sensors in place of X-ray films (with emulsion). The image is either directly or indirectly converted into a digital representation that is displayed on a computer screen. 

DIGITAL IMAGE RECEPTORS

- charged coupled device (CCD) used
- Pure silicon divided into pixels.
- Electromagnetic energy from visible light or X-rays interacts with pixels to create an electric charge that can be stored.
- Stored charges are transmitted electronically and create an analog output signal and displayed via digital converter (analog to digital converter). 

ADVANTAGES OF DIGITAL TECHNIQUE

Immediate display of images.

Enhancement of image (e.g., contrast, gray scale, brightness).

Radiation dose reduction up to 60%.

Major disadvantage: High initial cost of sensors. Decreased image resolution and contrast as compared to D speed films.

DIRECT IMAGING

- CCD or complementary metal oxide semiconductor (CMOS) detector used that is sensitive to electromagnetic radiation.

- Performance is comparable to film radiography for detection of periodontal lesions and proximal caries in noncavitated teeth.

INDIRECT IMAGING

- Radiographic film is used as the image receiver (detector). 

- Image is digitized from signals created by a video device or scanner that views the radiograph.

 

Sensors

STORAGE PHOSPHOR IMAGING SYSTEMS

Phosphor screens are exposed to ionizing radiation which excites BaFBR:EU+2 crystals in the screen storing the image.

A computer-assisted laser then promotes the release of energy from the crystals in the form of blue light.

The blue light is scanned and the image is reconstructed digitally.

ELECTRONIC SENSOR SYSTEMS

X-rays are converted into light which is then read by an electronic sensor such as a CCD or CMOS.

Other systems convert the electromagnetic radiation directly into electrical impulses.

Digital image is created out of the electrical impulses.