Screen-Film Radiographic Artifacts

What is radiographic image quality?

The exactness of representation of the patient's anatomy on a radiographic image.

Why are high-quality images important in radiography?

They allow radiologists to make accurate diagnoses.

What are the three major interrelated categories of radiographic quality?

Film factors, geometric factors, and subject factors.

What is spatial resolution in radiography?

The ability to image two separate objects and visually distinguish one from the other.

What does contrast resolution refer to?

The ability to distinguish anatomical structures of similar subject contrast.

What are the most important characteristics of radiographic image quality?

Spatial resolution, contrast resolution, noise, and artifacts.

What is noise in radiographic imaging?

Unwanted variations in the image that can obscure details.

What are the four components of radiographic noise?

Film graininess, structure mottle, quantum mottle, and scatter radiation.

What does film graininess refer to?

The distribution in size and space of silver halide grains in the emulsion.

What is quantum mottle?

The randomness with which a low number of x-ray photons interact with the intensifying screens.

What is the relationship between image receptor speed and mAs?

If the image receptor speed is doubled, mAs must be halved (inversely).

What happens to spatial resolution and noise with fast image receptors?

Fast image receptors have high noise and low spatial resolution.

What is sensitometry?

The study of the relationship between the intensity of exposure of the film and the blackness after processing.

What is a characteristic curve in radiography?

A graph that describes the relationship between optical density (OD) and radiation exposure.

What is optical density (OD)?

A logarithmic function representing the degree of blackening of a radiograph.

What does base density refer to?

The OD inherent in the base of the film, approximately 0.1.

What is fog density?

Density resulting from inadvertent exposure of film during storage or improper processing.

What is the useful range of optical density for radiographs?

Approximately 0.25 to 2.5.

What is radiographic contrast?

The differences in optical density (OD) that are obvious in the image.

What is the significance of the straight-line portion of the characteristic curve?

It is the region where small changes in exposure result in large changes in OD, indicating a properly exposed radiograph.

What does visibility of detail refer to?

The ability to visualize recorded detail when image contrast and optical density are optimized.

What happens to the quality of a radiograph if the optical density is too low?

It may be too light to contain an image.

What happens if the optical density is too high?

It requires a hot light to view the image.

What is the effect of high contrast mammography image receptors on OD?

The most useful OD range is approximately 0.25 to 2.5 with gross features.

What is the relationship between phosphor size and radiographic quality?

Smaller phosphors lead to high resolution but low density; larger phosphors lead to low resolution but high density.

What is the impact of low noise on image receptors?

It accompanies slow image receptors with high spatial resolution and high contrast resolution.

What characterizes a high-contrast radiograph?

Marked differences in optical density (OD).

What is the difference between image receptor contrast and subject contrast?

Image receptor contrast is inherent to the screen-film combination, while subject contrast is determined by the anatomy being examined and the x-ray beam energy.

What does the speed of an image receptor refer to?

Its ability to respond to low x-ray exposure.

What is par speed in relation to image receptor speed?

A reference point of 100, where numbers above indicate fast receptors and below indicate detail receptors.

How does changing image receptor speed affect mAs settings?

If speed is doubled, mAs must be halved to maintain the same OD.

What is latitude in radiography?

The range of exposures over which the image receptor responds with optical densities in the diagnostically useful range.

What is the relationship between latitude and contrast?

Wide latitude corresponds to low contrast, while narrow latitude corresponds to high contrast.

How does film processing affect image receptor contrast?

Proper processing is essential; overdevelopment increases fog and decreases contrast.

What is the relationship between development time and contrast?

They are inversely related; increased time leads to increased fog and decreased contrast.

How does development temperature affect film processing?

Higher temperatures increase fog and speed, leading to decreased contrast.

What geometric factors affect radiographic quality?

Magnification, distortion, and focal-spot blur.

What is magnification in radiography?

The condition where images on the radiograph are larger than the objects they represent.

What is the magnification factor (MF) formula?

MF = Image Size / Object Size.

How can magnification be minimized?

By using a large source-to-image receptor distance (SID) and a small object-to-image receptor distance (OID).

What is shape distortion?

Unequal magnification of different portions of the same object.

What factors contribute to image distortion?

Object thickness, object position, and object shape.

How does object thickness affect distortion?

Thicker objects increase distortion due to changes in OID.

What happens when the object plane and image plane are not parallel?

Distortion occurs.

What is foreshortening in radiography?

The reduction in image size of an inclined object.

How does the angle of inclination affect foreshortening?

Increased angle leads to increased foreshortening.

What is the standard SID for chest imaging?

180 cm.

What is the effect of increasing development time on fog level?

Fog level increases with increased development time.

What is the effect of increasing development temperature on fog level?

Fog level increases with increased development temperature.

What is the relationship between time and temperature in film processing?

A change in time can be compensated by a change in temperature within a small range.

What is the recommended development time for optimal contrast?

The time specified by the manufacturer.

What is the relationship between relative speed and development time?

Relative speed is directly proportional to development time.

What happens to image receptor contrast when development time exceeds the recommended period?

Image receptor contrast decreases.

What is focal spot blur?

A blurred region in the radiograph caused by the size of the effective focal spot, resulting in reduced image quality.

Where is focal spot blur greater in a radiograph?

On the cathode side of the image.

How does magnification affect focal spot blur?

Increased magnification results in greater focal spot blur.

What is the relationship between SOD, OID, and focal spot blur?

The ratio of SOD to OID is equal to the ratio of the sizes of the effective focal spot and the focal spot blur.

How can focal spot blur be minimized?

By using small focal spots and positioning the patient close to the image receptor.

What is subject contrast in radiography?

The contrast of a radiograph based on the image receptor contrast and the subject's characteristics.

How does patient thickness affect subject contrast?

Thicker body sections attenuate more x-rays, resulting in lower subject contrast.

What effect does tissue mass density have on subject contrast?

Higher tissue mass density increases subject contrast.

How does the effective atomic number influence subject contrast?

A greater difference in effective atomic numbers between adjacent tissues increases subject contrast.

What role does kVp play in subject contrast?

kVp controls the absolute magnitude of subject contrast; higher kVp increases the number of x-rays transmitted.

What is motion blur in radiography?

Blurring of the radiographic image caused by movement of the patient or x-ray tube during exposure.

How can motion blur be reduced?

By using the shortest exposure time and immobilizing the patient.

What is the importance of patient positioning in radiography?

Proper positioning minimizes motion blur and ensures the anatomical structure is close to the image receptor.

What types of image receptors are commonly used in radiology?

Standard screen-film image receptors are typically used for specific examinations.

What factors must a radiologic technologist select before an examination?

The optimum radiographic technique factors, including kVp, mAs, and exposure time.

How does increasing kVp affect radiographic contrast?

Increasing kVp increases the quantity and quality of x-rays but can reduce subject contrast due to increased scatter.

What is the primary control of optical density (OD) in radiography?

mAs is the primary control of OD; increasing mAs increases the number of x-rays reaching the image receptor.

What happens if mAs is set too low or too high?

Too low results in low OD and reduced contrast; too high results in high OD and loss of contrast.

What are radiographic artifacts?

Irregularities on an image not caused by proper shadowing of tissue, which can interfere with diagnosis.

What are common causes of exposure artifacts?

Incorrect screen-film match, poor screen-film contact, warped cassettes, and improper grid positioning.

What is the effect of patient preparation on radiographic artifacts?

Proper patient preparation is essential to produce artifact-free images.

What items can conceal artifacts on a patient?

Necklaces, pendants, hearing aids, chains, earrings, body and facial piercings, zippers, and various jewelry.

Why must pins, fasteners, dressings, and splints remain in place during trauma cases?

Their removal could be dangerous to the patient.

What is a common cause of blurred radiographs?

Improper patient movement or failure to follow breathing instructions.

What can cause grid cutoff artifacts?

Improper patient positioning or misalignment of the x-ray tube.

What happens if the wrong film is loaded into a cassette?

An unexpected image results due to incorrect film type.

What are common exposure artifacts?

Unexpected foreign objects, double exposure, blur, grid cut-off artifacts, and obscured detail.

What causes roller marks in radiographic film?

Improperly positioned guide shoes in the processor.

What is a pi line artifact?

A line that occurs at 3.1416 inches due to dirt or chemical stains on a roller.

What can dirty rollers cause in film processing?

Emulsion pick-off and gelatin buildup, resulting in sludge deposits.

What does chemical fog look like on a radiograph?

A uniform dull gray appearance caused by improper processing chemistry.

What is a dichroic stain?

A chemical stain that appears as a curtain effect on the radiograph, showing two colors.

What can cause wet-pressure sensitization?

Irregular or dirty rollers during development.

What are common handling and storage artifacts?

Light or radiation fog, pressure or kink marks, static, and hypo retention.

What causes light or radiation fog on a radiograph?

High temperature or humidity, inadequate shielding from radiation, or improper safelight conditions.

What is hypo retention?

A yellow-brown stain that appears due to residual thiosulfate from inadequate washing.

What are the three patterns of static artifacts?

Crown, tree, and smudge.

What does a crown static artifact indicate?

Low humidity conditions.

What is the frequency for warm-up procedures in quality control?

Daily, if idle for 2 hours.

How often should processor quality control be performed?

Daily, prior to developing films and after service.

What is the purpose of repeat rate analysis?

To categorize repeat films and calculate repeat rates for each category.

What is the acceptable repeat rate for radiographic films?

Less than 5%.

What can cause a milky appearance on a radiograph?

Underreplenished fixer during processing.

What can result from inadequate washing of radiographic film?

Yellow-brown stains due to hypo retention.

What is the cause of streaks of increased optical density on a radiograph?

Light leaks in the darkroom or cassette.

What can cause a greasy appearance on a radiograph?

Inadequate washing after processing.

What is the effect of rough handling on radiographic film?

Scratches and kink marks that appear as increased optical density.