Free ARRT RAD Exam Flashcards

60-100 bpm. Below 60 is bradycardia; above 100 is tachycardia. Trend across readings, not a single value, drives clinical concern during imaging.

12-20 breaths per minute. Counts outside this range signal respiratory distress or depression and change how you position, monitor, and pace the patient during longer studies.

Normal is 95-100%; below about 90% indicates hypoxemia. A falling SpO2 during imaging should pause the study and prompt oxygen support rather than finishing the exposure.

1-6 L/min, giving roughly 24-44% FiO2. Higher flows dry the nasal mucosa and need humidity; the cannula is for low-flow supplemental oxygen, not for high-acuity hypoxemia.

The single most effective practice. Alcohol-based rubs work for visibly clean hands; soap and water are required when spore-formers like C. diff are suspected, because alcohol does not kill spores.

Place the patient in a negative-pressure AIIR and wear a fit-tested N95 respirator. Standard surgical masks do not filter the droplet nuclei that carry TB.

Don gown, then mask or respirator, then goggles or face shield, then gloves. Remove in reverse order to avoid contaminating exposed skin and clothing.

Nonionic LOCM cause fewer and milder reactions than ionic HOCM. LOCM is preferred for high-risk patients even though it costs more per dose.

Barium outside the lumen causes peritonitis and granulomatous reaction. Use water-soluble iodinated contrast whenever perforation is on the differential.

Creatinine and eGFR screen for contrast-induced nephropathy. Abnormal renal function may require hydration, dose reduction, or switching to an alternative imaging study.

Shellfish allergy does not predict contrast reactions; a prior contrast reaction does. The relevant history is a previous iodinated-contrast event, not seafood intolerance.

Epinephrine. It reverses bronchospasm, airway edema, and hypotension within minutes; delayed epinephrine is the strongest predictor of fatal outcome in contrast reactions.

Bradycardia with hypotension, pallor, and sweating. Place the patient supine with legs elevated to restore venous return, and monitor until symptoms resolve.

Stop the injection, elevate the extremity, and apply cold or warm compresses per policy. Document volume, agent, and signs; obtain surgical consultation if compartment syndrome is suspected.

Time, distance, and shielding. Distance is the most effective because intensity drops with the inverse square of distance; doubling distance cuts dose roughly fourfold.

Gray measures absorbed dose (energy per kilogram); sievert weights that dose by biological effectiveness. Use Gy for tissue dose, Sv for stochastic-risk reporting.

Roentgen measures exposure as ionization in air; the SI equivalent is air kerma in gray. Both describe the beam before it reaches the patient, not the dose absorbed by tissue.

The SI unit of radioactivity: one disintegration per second. It is used for radiopharmaceutical activity, not for x-ray tube output.

As Low As Reasonably Achievable. Dose must be minimized without sacrificing diagnostic quality; both stochastic risk and image noise trade off against mAs and kVp choices.

Removes low-energy photons that add skin dose without reaching the receptor, hardening the beam and lowering patient surface dose. Tubes operating above 70 kVp require at least 2.5 mm Al equivalent total filtration.

Restricting the field cuts irradiated tissue volume, which lowers patient dose and scatter, improving image contrast and reducing fog.

Pulsed mode uses intermittent pulses to lower total beam-on time and dose while preserving temporal resolution. Last-image hold further reduces dose by freezing the most recent frame so radiation can be stopped.

50 mSv (5 rem) per year for whole-body exposure. The cumulative limit is 10 mSv multiplied by the worker's age in years, which often binds before the annual cap.

1 mSv (0.1 rem) per year for continuous or frequent exposure. This is far lower than the worker limit because the public includes children and has no assumed benefit from the exposure.

5 mSv (0.5 rem) total over the declared pregnancy, with a monthly cap of 0.5 mSv after declaration to avoid uneven exposure across gestation.

150 mSv per year per NCRP Report 116. The lens is more radiosensitive than once thought; skin and extremities carry a higher 500 mSv annual limit because their threshold is greater.

Receptor exposure is directly proportional to mAs; doubling mAs doubles exposure. To halve receptor dose you halve mAs, not kVp, when exposure is the only thing being adjusted.

kVp controls beam penetration and is the primary controller of contrast scale. Higher kVp lengthens the gray scale, lowers contrast, and increases scatter production.

A 15% increase in kVp roughly doubles receptor exposure; halve mAs to maintain exposure. It trades lower patient dose for lower-contrast, longer-scale images.

mAs is tube current multiplied by exposure time. 400 mA for 0.05 s equals 20 mAs; any mA/time combination giving the same mAs produces the same receptor exposure.

Exposure falls with the square of distance from the source. Doubling SID quarters the exposure at the receptor, so mAs must rise roughly fourfold to maintain receptor exposure.

EI measures receptor exposure and gives feedback on technique adequacy. It is detector-specific and not directly comparable across manufacturers or receptor types.

DI = 0 means actual exposure equals the target. Positive DI is overexposure, negative is underexposure; each +1 represents about 26% more dose, so +3 roughly doubles target exposure (dose creep).

DQE is the fraction of incident exposure that becomes useful signal. Higher DQE lets you lower dose for the same image quality, which is why direct-conversion detectors outperform screen-film.

Direct conversion uses a-Se photoconductor to turn x-rays straight into charge. Indirect uses a scintillator to make light first, then a photodiode; the light step slightly blurs the signal.

Window width sets displayed contrast; window level sets brightness. Adjusting width narrows the visible gray range in the displayed image, not the captured data.

Maps and interpolates defective pixels so they do not appear as artifacts. It is performed periodically and after detector service to keep the receptor uniform.

Selected kVp must be within about +/-5% of actual output. Reproducibility requires repeated identical exposures to vary by no more than 5% in output.

Speckled noise from too few photons reaching the receptor (low mAs). It is a statistical, not equipment, artifact; fix it by raising mAs, not by post-processing.

Absorption of useful primary beam by the grid, seen as density loss. Off-center, off-level, off-focus, or upside-down focused grids all cause characteristic cutoff patterns.

Occurs when a stationary grid's line frequency interferes with the CR detector's sampling frequency, producing wavy lines. Use a moving grid or a higher-frequency stationary grid to avoid it.

Misalignment of tube, part, and image receptor planes distorts anatomy. Magnification distortion grows with object-to-image distance and shrinks with source-to-image distance.

The standard 72-inch (180 cm) SID minimizes cardiac magnification; shorter distances exaggerate the heart shadow and can falsely suggest cardiomegaly.

A minimum of 10 posterior ribs visible above the diaphragm confirms full inspiration. Fewer ribs suggest poor inspiration or rotation rather than a true lung problem.

Place the affected (suspect-fluid) side down. Free fluid layers along the dependent lateral chest wall, where it becomes visible against the air-filled lung.

Place the affected (suspect-air) side up. Free air rises to the nondependent chest wall, where a small pneumothorax is easier to see than on a supine image.

Projects the clavicles above the lung apices so the apices are seen unobscured. Use it when apical pathology is suspected and routine PA visualization is poor.

Perpendicular to T7, level with the inferior scapular angle. Centering too high cuts off the costophrenic angles; too low cuts the apices.

Center at the iliac crests to include kidneys through bladder. An upright abdomen is centered about 2 inches above the crests to capture the diaphragm and any free air.

Taken first and must show all seven cervical vertebrae including C7-T1. Inadequate visualization of C7-T1 requires traction, a swimmer's projection, or CT rather than a repeat blind exposure.