Foundation Exposure Techniques and Charts in Radiography

Описание: Foundation Exposure Techniques and Charts in Radiography
Exposure techniques and charts are the baseline guides radiographers use to select the correct technical factors (kVp, mAs, SID, grids, etc.) for producing diagnostic-quality images while keeping patient dose as low as reasonably achievable (ALARA).

Foundation Exposure Techniques
Primary Factors

kVp (kilovoltage peak): Controls beam penetration and image contrast.

mA (milliamperage): Controls the quantity of X-rays produced.

Exposure Time: Determines how long the patient is exposed.

SID (Source-to-Image Distance): Affects magnification and image sharpness.

Secondary Factors

Focal Spot Size: Impacts image sharpness.

OID (Object-to-Image Distance): Influences magnification and resolution.

Grids: Reduce scatter radiation, improving contrast.

Beam Restriction: Limits field size, reducing patient dose.

Compensating Filters: Balance exposure in uneven anatomy.

Patient Factors

Body Habitus: Thin, average, muscular, or obese patients require adjustments.

Part Thickness: Directly influences exposure settings.

Age (pediatric/geriatric): Lower exposures often required.

Pathology: Conditions like emphysema or fluid buildup affect technique selection.

Exposure Technique Charts
Technique charts standardize exposure settings for different body parts and patient sizes, ensuring consistency and reducing repeat exams.

Types of Charts:

Variable kVp – Fixed mAs Chart

kVp adjusted based on patient thickness.

mAs kept constant.

Useful for extremities and small parts.

Fixed kVp – Variable mAs Chart

kVp remains constant for a given exam.

mAs adjusted according to patient thickness.

Common for chest and abdomen imaging.

Anatomically Programmed Radiography (APR)

Computerized system where radiographer selects anatomy on the console.

Pre-programmed exposure factors are displayed and can be fine-tuned

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