NEET MDS Lessons
Radiology
Fractures of the Zygomatic Arch
- Structures: Zygomatic arch, zygomatic bone.
- Best Views:
- Submento-Vertex View: Provides a clear view of the zygomatic arch and helps assess fractures.
- Waters View: Useful for visualizing the zygomatic bone and maxillary sinus.
- Reverse Townes View: Can also be used to visualize the zygomatic arch.
Base of Skull
- Structures: Base of the skull, cranial fossae.
- Best Views:
- Submento-Vertex View: Effective for assessing the base of the skull and related fractures.
Maxillary Sinus
- Structures: Maxillary sinus, zygomatic bone.
- Best Views:
- Waters View: Excellent for visualizing the maxillary sinus and any associated fractures.
Fractures of Zygoma
- Structures: Zygomatic bone, zygomatic arch.
- Best Views:
- Waters View: Good for assessing zygomatic fractures.
- PA View: Provides a frontal view of the zygomatic bone.
- Reverse Townes View: Useful for visualizing the zygomatic arch.
Nasal Septum
- Structures: Nasal septum, nasal cavity.
- Best Views:
- PA View: Useful for assessing the nasal septum and any associated fractures.
Condylar Neck Fractures
- Structures: Mandibular condyle, neck of the condyle.
- Best Views:
- Lateral Oblique View (15°): Good for visualizing condylar neck fractures.
- Transpharyngeal View: Useful for assessing the condylar region.
Medially Displaced Condylar Fractures
- Structures: Mandibular condyle.
- Best Views:
- Lateral Oblique View (30°): Effective for visualizing medially displaced condylar fractures.
Coronoid Process of Mandible
- Structures: Coronoid process.
- Best Views:
- PA View of Skull: Can help visualize the coronoid process.
Fractures of Ramus and Body of Mandible
- Structures: Mandibular ramus, body of the mandible.
- Best Views:
- Lateral Oblique View (15°): Useful for assessing fractures of the ramus and body of the mandible.
Horizontal Favorable and Unfavorable Fractures of Mandible
- Structures: Mandible.
- Best Views:
- Lateral Oblique View (30°): Effective for evaluating horizontal fractures.
Bony Ankylosis of TMJ
- Structures: Temporomandibular joint.
- Best Views:
- CT Scan: Provides detailed imaging of bony structures and ankylosis.
Fibrous Ankylosis of TMJ
- Structures: Temporomandibular joint.
- Best Views:
- CT Scan: Useful for assessing fibrous ankylosis.
Internal Derangement of the Disk
- Structures: TMJ disk.
- Best Views:
- MRI: The best modality for evaluating soft tissue structures, including the TMJ disk.
Disk Perforation
- Structures: TMJ disk.
- Best Views:
- MRI: Effective for diagnosing disk perforation.
Arthrography
- Structures: TMJ.
- Best Views:
- Arthrography: Can be used to assess the TMJ and visualize the disk and joint space.
Digital Radiology
Advances in computer and X-ray technology now permit the use of systems that employ sensors in place of X-ray ?lms (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 ?lms.
DIRECT IMAGING
- CCD or complementary metal oxide semiconductor (CMOS) detector used that is sensitive to electromagnetic radiation.
- Performance is comparable to ?lm radiography for detection of periodontal lesions and proximal caries in noncavitated teeth.
INDIRECT IMAGING
- Radiographic ?lm 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.