ARRT Limited Scope flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Two patient identifiers

Before any procedure, staff confirm identity using two independent sources, typically full name plus date of birth or medical record number, to prevent wrong-patient errors.

Informed consent elements

The patient must receive the procedure name, its risks and benefits, alternatives, and the right to refuse, then consent voluntarily or through a legal guardian.

Standard precautions

Infection control applied to every patient: gloves for contact with blood or body fluids, plus gown, mask, and eye protection when splashing is likely.

Normal adult pulse range

A resting adult heart rate of 60 to 100 beats per minute is considered normal; rates outside this range are reported before the examination proceeds.

Anaphylaxis first-line drug

Epinephrine is the first-line medication for an acute anaphylactic contrast reaction, given per protocol along with airway support and oxygen.

Safe lifting mechanics

Keep the load close, bend at the knees and hips rather than the waist, and avoid twisting the torso while bearing weight to protect the lumbar spine.

ALARA principle

Occupational and patient radiation exposure should be kept as low as reasonably achievable by limiting time, increasing distance, and using shielding.

Inverse square law

Radiation intensity is inversely proportional to the square of the distance from the source, so doubling distance reduces exposure to one quarter.

Annual occupational dose limit

The effective dose limit for radiation workers is 50 mSv (5 rem) per year, with a lifetime allowance related to age in years times 10 mSv.

Fetal dose limit

For a declared pregnant worker, the dose to the embryo-fetus is limited to 0.5 mSv (0.05 rem) in any single month.

Primary versus secondary barrier

Primary barriers attenuate the useful beam; secondary barriers attenuate leakage and scatter and need roughly one-thousandth the thickness of a primary barrier.

Tube leakage limit

The x-ray tube housing must restrict leakage radiation to no more than 100 mR per hour at one meter from the focal spot at maximum rated technique.

Collimation effect

Restricting the field to the anatomy of interest lowers patient dose and reduces Compton scatter reaching the receptor, improving image contrast.

Occupational dosimeter placement

The collar-level dosimeter is worn outside the lead apron; a second waist-level dosimeter under the apron estimates fetal or effective dose during fluoroscopy.

Subject versus receptor contrast

Subject contrast is the attenuation difference among tissues; receptor contrast is the visible density or pixel difference recorded on the image.

kVp and contrast scale

Raising kVp increases beam penetrability, producing a longer scale of lower contrast and generally reducing patient dose for the same receptor exposure.

mAs and receptor exposure

Milliampere-seconds controls the number of x-ray photons produced and is directly proportional to receptor exposure when other factors are held constant.

Fifteen percent rule

Increasing kVp by 15 percent approximately doubles receptor exposure, so mAs is reduced by half to maintain the same image density.

Geometric unsharpness

Blur from geometry increases with a larger focal spot, greater object-to-image receptor distance, and shorter source-to-image receptor distance.

Quantum mottle

A speckled noise pattern caused by too few photons reaching the receptor; it is corrected by increasing mAs rather than kVp alone.

Shape distortion types

Elongation results from tube angulation and foreshortening from part angulation; both alter the recorded shape of the anatomy.

PA chest positioning

Upright patient, chin elevated, shoulders rolled forward, 72-inch source-to-image distance, beam centered at T7, exposed at full inspiration.

Chest image criteria

Acceptable chest images show symmetric posterior ribs, equidistant clavicles, and 9 to 10 posterior ribs visible above the diaphragm.

Lateral chest position

Left lateral projection with arms elevated, 72-inch distance, beam centered at the midcoronal plane at T7, exposed at full inspiration.

AP elbow projection

The radial head, radial tuberosity, and capitulum are shown in profile; the lateral elbow requires 90 degrees of flexion for a true lateral.

Lateral cervical spine

Upright patient, chin elevated, shoulders depressed, 72-inch distance, beam centered at C4, demonstrating C1 through C7.

Lumbar spine AP centering

Supine patient with hips and knees flexed to reduce lordosis; beam centered at L3, about 2 inches above the iliac crests.

Caldwell skull method

PA skull with the orbitomeatal line perpendicular to the receptor and the central ray angled 15 degrees caudad, exiting at the nasion.

Towne skull method

AP skull with the central ray angled 30 degrees caudad to the orbitomeatal line and exiting the nasion, showing the occipital bone and foramen magnum.

Orbitomeatal line

A positioning line from the outer canthus of the eye to the external auditory meatus, used to set head angulation for skull projections.

Supine abdomen centering

Patient supine with arms at the sides, beam centered at the iliac crests, collimated from symphysis pubis to diaphragm, exposed at end of expiration.

AP pelvis rotation

Feet are internally rotated 15 to 20 degrees so the femoral necks are seen in profile; the beam is centered between the iliac crests and symphysis pubis.