TOPIC: PRINCIPLE OF RADIOGRAPHIC INTERPRETATION
🌟IMPORTANT POINTS TO REMEMBER
🔹Radiographic interpretation is based on the visualisation and analysis of opacities on a radiograph.
🔹The difference between those X-rays absorbed by the body part and those that penetrate it is known as differential absorption.
🔹The greater the tissue absorption, the fewer X-ray photons reach the film, and the whiter image will be on the film. This process is known as attenuation.
🔹Radiopaque: It applies to those substances that absorb X-rays and appear white on the exposed X-ray film.
🔹Radiolucent: It refers to substances through which X-rays penetrate more readily and appear dark or black on the film.
🔹The radiopacity depends on atomic number, physical opacity, thickness and ratio of different materials in the same plane.
🔹Radiopacities: Five radiographic opacities are visible on a radiograph, mineral opacity, soft tissue/fluid opacity, fat opacity, gas opacity and metal opacity.
🔹Radiolucencies: A longer exposure generally increases the degree of blackening on a film; too short exposure produces a generally lighter film in which it will be more difficult to spot abnormal radiolucent features as they will be less black than we would expect.
🔹Steps for interpretation of radiograph: Identify the radiograph, view images under ideal conditions, film mounting, interpret from quality radiographs only, obtain additional films if necessary, order special imaging studies if necessary, be familiar with anatomical landmarks, master pathology, interpret the radiograph entirely, interpret the radiograph independently of the clinical information, describe radiological findings precisely, compare the image with previous images, explain significance of the findings, develop a differential diagnosis, state your diagnostic impression, make appropriate recommendations and seek advice from appropriate others.
🔹Radiological findings: It should include location and size, osteolytic versus osteoblastic regions, margin, internal structure and effect on surrounding structure.
📌 Following points should be taken care of whilst interpreting the radiograph:
- Identify the radiograph.
- Understand the three-dimensional concept.
- View images under ideal conditions.
- Interpret from quality radiographs only.
- Obtain additional films as necessary.
- Order special imaging studies if necessary.
- Be familiar with anatomical landmarks.
- Master the pathology.
- Interpret the radiograph entirely.
- Interpret the radiograph independently of the clinical information.
- Describe radiological findings precisely.
- Compare the images with available previous images.
- Explain the significance of the findings.
- Develop a differential diagnosis.
- State your diagnostic impression.
- Make appropriate recommendations.
- Seek advice from appropriate others.
📌 ROENTGEN SIGNS:
- Changes in size: There may be an increase in size or a decrease in size.
- Variations in contour or shape: It can be diffuse, irregular or local.
- Variations in number: For example supernumerary teeth.
- Alterations in opacity: Increased radiopacity air-filled space, e.g. fluid-filled maxillary sinus, calcification within soft tissues, foreign body, increased lucency, gas in abnormal sites, e.g. subcutaneous emphysema; bone may appear more lucent with osteoporosis, osteomyelitis and neoplasia.
- Alterations in architectural pattern: Change bone trabeculation, alternation in normal function and transit contrast studies, e.g. barium series.
📌 MULTIPLE CHOICE QUESTIONS (MCQs)
💡The difference between X-rays absorbed by the body part and those that penetrate is known as
a. Integrated absorption
b. Differential absorbtion
c. Radiation potential
d. Potential gradient
Answer: b
💡In attenuation, the X-ray absorption is related to the thickness of matter keeping other factors constant as
a. Inversely proportional
b. Directly proportional
c. Equal
d. No relation
Answer: b
💡Air appears more radiolucent than fluid and soft tissue due to differences in
a. Specific gravity
b. Atomic number
c. Atomic mass
d. None
Answer: a
The clarity of mental foramen is greatest when the beam is directed
a. Perpendicular to axis
b. Along the axis
c. Acute angled
d. Obtuse angled
Answer: b
In a direct digital imaging system, images are captured by
a. PID
b. CCD
c. PET
d. None
Answer : b
💡 If an accurate description of the lesion has been made, it becomes to categorize it into one of the differential diagnostic groups.
a. Tunnel vision
b. Pattern matching
c. Selective selection
d. None
Answer: b
Swiss cheese effect is
a. Radiolucent summation shadow
b. Radiopaque summation shadow
c. Both a and b
d. None
Answer : a
Perceptual Phenomenon can be exemplified by
a. Grape bunch effect
b. Mach band effect
c. Drum band effect
c. Uncle Fred effect
Answer : b
Loss of clear margins of two structures of the same radiodensity is explained by,
a. Cousin Harry effect
b. Border effacement
c. Bunch of grapes
d. All the above
Answer : b