RT 202: PRINCIPLES OF IMAGING
LECTURE 1: RADIOGRAPHIC QUALITY
INSTRUCTOR FOR LECTURE: ANNA MAE ABARCA | INSTRUCTOR FOR LABORATORY: JIEMAR BELA-ONG
FIRST SEMESTER | A.Y. 2022 - 2023
RADIOGRAPHIC QUALITY
Other Density Influences:
Refers to how easily details can be perceived on a
radiograph. 1. Thickness and type of tissue being radiographed.
• Need to obtain as much diagnostic information as
possible about the internal structures of the BODY HABITUS
patient.
small, frail, sometimes
Asthenic
emaciated, and often elderly
Categories in evaluating radiograph:
“strong, active”— average
1. Optimal Sthenic
patients
→ this is the standard; the “best image”
2. Within the diagnostic limit/range thin but healthy appearing;
→ qualified, but needs improvement Hyposthenic these patients require less
3. Not acceptable radiographic technique
→ too many errors; bad density, position, big in frame and usually
Hypersthenic
etc. overweight
Quality depends on:
1. Radiographic Density
2. Contrast
3. Geometric Factors that affect detail
RADIOGRAPHIC DENSITY
• Increase in thickness, means that the patient can
Defined as the degree of blackness or darkness on a absorb more x-rays which will results in a lighter
radiograph. image.
• Black areas on a developed radiograph are • Large animals absorb more x-rays, so less x-rays
produced by deposits of metallic silver in the film reach the film, so the lighter the image. To
emulsion that result from exposure to x-rays and compensate, we increase the kVp.
their subsequent processing.
• Type of tissue affects density as well. Higher
X-rays make radiographic film black density tissues will cause less x-rays to reach film,
• Degree of blackness on a radiograph depends therefore have lighter areas on the film at that
on the amount of x-rays reaching the film. place.
NOTE: Density is influenced by the quantity and quality of CONTRAST
the x-ray beam, as well as the type and thickness of the
tissue under examination. Defined as visible difference between two adjacent
radiographic densities.
Factors Affecting Radiographic Density: Is divided into:
Greater radiographic density may be produced by 1. Radiographic Contrast
increasing: 2. Subject Contrast
1. Total # of x-rays that reach the film
2. The penetrating power of the x-rays RADIOGRAPHIC CONTRAST
3. The developing time
4. The temperature of the developer Density between two adjacent areas on a radiograph.
Review: • Many black and white areas means you have
, RT 202: PRINCIPLES OF IMAGING
LECTURE 1: RADIOGRAPHIC QUALITY
INSTRUCTOR FOR LECTURE: ANNA MAE ABARCA | INSTRUCTOR FOR LABORATORY: JIEMAR BELA-ONG
FIRST SEMESTER | A.Y. 2022 - 2023
• If a radiograph has many grays and a small How should mAs be adjusted?
density difference between 2 adjacent areas,
then it has low contrast.
• Need right amount of contrast. Not desirable to
have too high or too low of contrast. Need it to
be just right. Want grays, blacks and whites so eye
can easily see detail.
Answer: _______________
KILOVOLTAGE
Affects both contrast and density
Contrast is influenced by:
1. kVp level • Increase in kVp = Increase in penetrating power.
2. Subject contrast
3. Scatter radiation • Increase in kVp = shorter wavelengths are
4. Film type produced.
5. Film fog
As penetrating power increases, so does scatter
SUBJECT CONTRAST radiation. This can alter radiographic contrast.
Defined as the difference in density and mass between kVp
two adjacent anatomic structures • If too low, will have gray and white appearance
and image will be imperceptible.
Depends on:
• Thickness of the anatomic part. • Will have low density because unable to reach
• Density of the anatomic part. film.
NOTE: Bone will have more white on the film than soft tissue. • Can causes difficulty in distinguishing anatomic
organs
BONE → HIGH CONTRAST → LOW kVp
Example:
SOFT TISSUE → LOW CONTRST → HIGH kVp
NOTE: Poor contrast is due to inappropriate exposure
factors.
EXPOSURE FACTORS
mAs – affects contrast when too little or too much is used.
• Primarily affects density so should not affect
contrast if proper kVp is used.
• If mAs is insufficient, contrast is reduced because
overall density of the radiograph is reduced.
• If quantity of x-rays reaching the film is too low, film SCATTER RADIATION
will be pale.
Radiation that does not form an image and is scattered in
• If too much mAs is applied, overall film will be all directions.
blacker but less effect on contrast.
Contrast is decreased because inappropriate areas of
LECTURE 1: RADIOGRAPHIC QUALITY
INSTRUCTOR FOR LECTURE: ANNA MAE ABARCA | INSTRUCTOR FOR LABORATORY: JIEMAR BELA-ONG
FIRST SEMESTER | A.Y. 2022 - 2023
RADIOGRAPHIC QUALITY
Other Density Influences:
Refers to how easily details can be perceived on a
radiograph. 1. Thickness and type of tissue being radiographed.
• Need to obtain as much diagnostic information as
possible about the internal structures of the BODY HABITUS
patient.
small, frail, sometimes
Asthenic
emaciated, and often elderly
Categories in evaluating radiograph:
“strong, active”— average
1. Optimal Sthenic
patients
→ this is the standard; the “best image”
2. Within the diagnostic limit/range thin but healthy appearing;
→ qualified, but needs improvement Hyposthenic these patients require less
3. Not acceptable radiographic technique
→ too many errors; bad density, position, big in frame and usually
Hypersthenic
etc. overweight
Quality depends on:
1. Radiographic Density
2. Contrast
3. Geometric Factors that affect detail
RADIOGRAPHIC DENSITY
• Increase in thickness, means that the patient can
Defined as the degree of blackness or darkness on a absorb more x-rays which will results in a lighter
radiograph. image.
• Black areas on a developed radiograph are • Large animals absorb more x-rays, so less x-rays
produced by deposits of metallic silver in the film reach the film, so the lighter the image. To
emulsion that result from exposure to x-rays and compensate, we increase the kVp.
their subsequent processing.
• Type of tissue affects density as well. Higher
X-rays make radiographic film black density tissues will cause less x-rays to reach film,
• Degree of blackness on a radiograph depends therefore have lighter areas on the film at that
on the amount of x-rays reaching the film. place.
NOTE: Density is influenced by the quantity and quality of CONTRAST
the x-ray beam, as well as the type and thickness of the
tissue under examination. Defined as visible difference between two adjacent
radiographic densities.
Factors Affecting Radiographic Density: Is divided into:
Greater radiographic density may be produced by 1. Radiographic Contrast
increasing: 2. Subject Contrast
1. Total # of x-rays that reach the film
2. The penetrating power of the x-rays RADIOGRAPHIC CONTRAST
3. The developing time
4. The temperature of the developer Density between two adjacent areas on a radiograph.
Review: • Many black and white areas means you have
, RT 202: PRINCIPLES OF IMAGING
LECTURE 1: RADIOGRAPHIC QUALITY
INSTRUCTOR FOR LECTURE: ANNA MAE ABARCA | INSTRUCTOR FOR LABORATORY: JIEMAR BELA-ONG
FIRST SEMESTER | A.Y. 2022 - 2023
• If a radiograph has many grays and a small How should mAs be adjusted?
density difference between 2 adjacent areas,
then it has low contrast.
• Need right amount of contrast. Not desirable to
have too high or too low of contrast. Need it to
be just right. Want grays, blacks and whites so eye
can easily see detail.
Answer: _______________
KILOVOLTAGE
Affects both contrast and density
Contrast is influenced by:
1. kVp level • Increase in kVp = Increase in penetrating power.
2. Subject contrast
3. Scatter radiation • Increase in kVp = shorter wavelengths are
4. Film type produced.
5. Film fog
As penetrating power increases, so does scatter
SUBJECT CONTRAST radiation. This can alter radiographic contrast.
Defined as the difference in density and mass between kVp
two adjacent anatomic structures • If too low, will have gray and white appearance
and image will be imperceptible.
Depends on:
• Thickness of the anatomic part. • Will have low density because unable to reach
• Density of the anatomic part. film.
NOTE: Bone will have more white on the film than soft tissue. • Can causes difficulty in distinguishing anatomic
organs
BONE → HIGH CONTRAST → LOW kVp
Example:
SOFT TISSUE → LOW CONTRST → HIGH kVp
NOTE: Poor contrast is due to inappropriate exposure
factors.
EXPOSURE FACTORS
mAs – affects contrast when too little or too much is used.
• Primarily affects density so should not affect
contrast if proper kVp is used.
• If mAs is insufficient, contrast is reduced because
overall density of the radiograph is reduced.
• If quantity of x-rays reaching the film is too low, film SCATTER RADIATION
will be pale.
Radiation that does not form an image and is scattered in
• If too much mAs is applied, overall film will be all directions.
blacker but less effect on contrast.
Contrast is decreased because inappropriate areas of
