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ARRT Radiography study materials
ARRT Radiography study resources

ARRT Radiography practice questions

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Question 1Patient Care and Education

Which combination of identifiers is acceptable when confirming a patient's identity before an imaging procedure?

  1. The patient's age and current diagnosis
  2. The room number and bed assignment
  3. The examination ordered and the time scheduled
  4. The patient's full name and date of birth Correct answer.

Explanation

Institutional policy requires at least two identifiers, and the patient's own verbal statement of name plus a second identifier such as date of birth or medical record number is standard. Identifiers must be tied to the individual, not to a location, diagnosis, or schedule. The patient should state the information when possible rather than simply agreeing to a name read aloud.

Question 2Patient Care and Education

When should a radiographer perform hand hygiene?

  1. Only when the hands are visibly soiled
  2. Before and after each patient contact Correct answer.
  3. Only after contact with blood or body fluids
  4. Only before invasive procedures

Explanation

Hand hygiene is the single most effective way to prevent transmission of microorganisms and is required before and after every patient contact and after glove removal. Alcohol-based rub or soap and water is used even when gloves were worn, because gloves can have small defects and contamination occurs during removal. Visible soiling specifically requires soap and water rather than alcohol rub.

Question 3Patient Care and Education

Which range represents a normal resting respiratory rate for an adult?

  1. 8 to 11 breaths per minute
  2. 12 to 20 breaths per minute Correct answer.
  3. 24 to 30 breaths per minute
  4. 4 to 8 breaths per minute

Explanation

A normal adult respiratory rate is approximately 12 to 20 breaths per minute. Rates below 12 indicate bradypnea and rates above 20 indicate tachypnea, either of which should be reported before starting or continuing a procedure. Respiratory rate is counted for a full 60 seconds because irregular breathing is easily missed with shorter counts.

Question 4Patient Care and Education

Before assisting a patient from a wheelchair onto the radiographic table, the radiographer should:

  1. Ask the patient to stand while the brakes are still released
  2. Lock the brakes and swing the footrests to the side Correct answer.
  3. Tilt the chair back so the front wheels lift off the floor
  4. Leave the footrests down so the patient can push off them

Explanation

Locking the wheels prevents the chair from rolling as the patient shifts weight, and moving the footrests aside clears the path for the feet and avoids tripping. The chair should be positioned parallel and as close to the table as possible. A gait belt is used for patients who are unsteady.

Question 5Patient Care and Education

Which action best protects the radiographer's back when moving a patient?

  1. Twisting the trunk while lifting
  2. Bending at the waist to reach the patient
  3. Holding the patient at arm's length
  4. Keeping the patient close to the body Correct answer.

Explanation

Holding the load close to the body shortens the lever arm and reduces the compressive force on the lumbar spine. The worker should bend at the knees and hips, keep the trunk upright, and avoid twisting while loaded. Wide, stable footing and assistance or a lift device should be used whenever the load exceeds safe limits.

Question 6Patient Care and Education

Which technique best confirms that a patient understands preprocedure instructions?

  1. Asking whether the patient has any questions
  2. Having the patient restate the instructions Correct answer.
  3. Speaking slowly and loudly to the patient
  4. Giving a written brochure at the end of the visit

Explanation

Teach-back, in which the patient explains the instructions in their own words, reveals gaps in understanding that a yes or no question will miss. Patients frequently say they understand out of politeness. Written material supplements but does not replace verification of comprehension.

Question 7Patient Care and Education

A 3-year-old child is scheduled for an abdominal radiograph. Which approach is most appropriate?

  1. Having the parent leave the room to limit distraction
  2. Explaining the procedure using correct medical terminology
  3. Letting a parent stay close and using simple, concrete words Correct answer.
  4. Requiring the child to lie still without any assistance

Explanation

Preschool children think literally and respond to short, concrete explanations, and a familiar caregiver nearby reduces fear and improves cooperation. Immobilization devices and a short exposure time compensate for limited ability to hold still. Medical terminology and separation from the parent increase distress.

Question 8Patient Care and Education

A patient's coworker telephones the department and asks about the patient's examination results. What is the appropriate response?

  1. Referring the caller to the radiologist's personal telephone
  2. Confirming whether the patient is currently in the department
  3. Giving the results if the caller says he is a family member
  4. Explaining that patient information cannot be released Correct answer.

Explanation

Protected health information may be shared only with those involved in the patient's care or as authorized in writing by the patient. Even confirming that a person is present in the facility discloses protected information. The caller should be told that details cannot be discussed and directed to the patient or the ordering provider.

Question 9Patient Care and Education

Which action is the radiographer's responsibility regarding informed consent for a contrast procedure?

  1. Judging whether the patient is competent to give consent
  2. Explaining the risks and benefits and obtaining the signature
  3. Witnessing the signature only when a family member asks
  4. Confirming that a signed consent form is in the record Correct answer.

Explanation

Obtaining informed consent, including the discussion of risks, benefits, and alternatives, is the responsibility of the physician who will perform the procedure. The radiographer verifies that consent has been obtained and documented and may witness the patient's signature. Determining competence and disclosing procedural risk fall outside the radiographer's scope.

Question 10Patient Care and Education

Which precaution is required in an area where a patient is receiving oxygen by nasal cannula?

  1. Removing smoking materials and open flames from the room Correct answer.
  2. Grounding all electrical equipment to the oxygen cylinder
  3. Storing the cylinder flat on the floor beside the patient
  4. Lubricating the regulator fittings with an oil-based gel

Explanation

Oxygen supports combustion, so open flames, smoking materials, and spark-producing devices must be kept away from the patient and the equipment. Cylinders must be secured upright, not left lying on the floor. Oil and grease must never contact oxygen fittings because they can ignite.

Question 11Patient Care and Education

A patient becomes pale and diaphoretic with a falling blood pressure after standing. Which position is most appropriate?

  1. Prone with the head turned to the side
  2. Seated upright with the feet dependent
  3. Side-lying with the head lowered below the hips
  4. Supine with the legs elevated Correct answer.

Explanation

Supine positioning with the legs elevated promotes venous return to the heart and brain and is the standard response to a hypotensive or presyncopal episode. Vital signs are reassessed and the event is reported. The patient is not allowed to stand again until stable, and a safe transport method is arranged.

Question 12Patient Care and Education

Which practice is required when imaging a patient in protective (reverse) isolation?

  1. Wearing a mask on entry and keeping the door closed Correct answer.
  2. Allowing visitors with colds to enter if they wear a mask
  3. Reusing disposable supplies between visits to save cost
  4. Wearing gloves only when touching the patient's skin

Explanation

Protective isolation shields an immunocompromised patient from organisms carried by staff, visitors, and the environment. Staff wear a mask on entry, perform hand hygiene, and use dedicated equipment, and the door stays closed to limit airflow from the corridor. Anyone with symptoms of infection is excluded from the room.

Question 13Patient Care and Education

A radiographer accidentally touches a sterile drape with a bare hand. The correct action is to:

  1. Treat the field as contaminated and replace the drape Correct answer.
  2. Spray the area with disinfectant and continue
  3. Put on sterile gloves and proceed with the setup
  4. Continue if the contact lasted only a moment

Explanation

Any contact between a nonsterile object and a sterile field renders the field contaminated, and the affected items must be replaced. Sterile technique cannot be restored by spraying, and gloves worn after the break do not correct it. The contaminated material is discarded and the setup begun again.

Question 14Patient Care and Education

When administering a cleansing enema before a barium study, the solution should be:

  1. Cooled, to slow bowel motility and cramping
  2. At room temperature, with the bag held at eye level
  3. Heated to 120 degrees Fahrenheit to speed the flow
  4. Warm, with the bag 12 to 18 inches above the hip Correct answer.

Explanation

Solution warmed to about 105 degrees Fahrenheit (40.5 degrees Celsius) and delivered from a bag 12 to 18 inches above the patient allows gravity to control the rate and limits cramping. Solution that is too hot burns the mucosa and too cold causes severe cramping. Raising the bag higher increases the flow rate and cramping.

Question 15Patient Care and Education

A patient arrives with an indwelling urinary catheter and drainage bag. During the examination, the bag should be:

  1. Raised above the bladder to speed drainage
  2. Hung below the level of the bladder Correct answer.
  3. Clamped and disconnected for the examination
  4. Placed on the table beside the patient

Explanation

Gravity drainage requires the bag to remain below bladder level so that urine does not flow backward into the bladder and introduce organisms. The tubing is kept free of loops and kinks and is not disconnected. The bag is never placed on the floor or on the examining table beside the patient.

Question 16Patient Care and Education

When a restraint is applied to keep a patient safely positioned for a procedure, the radiographer must:

  1. Tie the restraint out of the patient's reach
  2. Leave the patient alone to reduce stimulation
  3. Attach the strap to the side rail of the table
  4. Check circulation and remove it as soon as possible Correct answer.

Explanation

Restraints are used only when less restrictive measures fail, must be released and removed as soon as the procedure permits, and require monitoring of pulse, color, temperature, and sensation in the restrained limb. They are secured to the frame of the table, not to movable parts. The patient is never left unattended while restrained.

Question 17Patient Care and Education

Which adjustment is most appropriate when imaging an older adult with thin, fragile skin?

  1. Applying extra tape to secure the cassette
  2. Keeping the room cool to reduce perspiration
  3. Speaking loudly in case the patient is hard of hearing
  4. Using padding and avoiding tape on the skin Correct answer.

Explanation

Aging skin is thin, loses subcutaneous padding, and tears easily, so pressure points are padded and tape is kept off the skin when possible. Shearing forces should be minimized during transfers. Hearing should be assessed individually rather than assumed to be poor.

Question 18Patient Care and Education

A patient scheduled for an upper gastrointestinal series reports eating breakfast two hours ago. The radiographer should:

  1. Give the patient water to help empty the stomach
  2. Proceed with the examination as ordered
  3. Perform the study but increase the kilovoltage
  4. Notify the radiologist and delay the procedure Correct answer.

Explanation

Recent food in the stomach obscures mucosal detail and creates a risk of vomiting and aspiration, so the procedure is rescheduled or delayed. The radiologist is informed of the deviation from preparation instructions. Giving additional fluids does not empty the stomach promptly.

Question 19Patient Care and Education

Which action is appropriate for a patient with a documented latex allergy?

  1. Using latex-free gloves, tourniquet, and cuff Correct answer.
  2. Wearing powdered latex gloves but not touching the skin
  3. Rinsing latex gloves with water before use
  4. Asking the patient to bring their own supplies

Explanation

Latex-safe care requires removing all natural rubber latex items, including gloves, tourniquets, blood pressure cuffs, and adhesive products, from the patient's environment. Aerosolized glove powder can also trigger reactions. The allergy should be flagged and the patient scheduled to minimize exposure to latex dust from previous cases.

Question 20Patient Care and Education

A patient who speaks little English needs instructions for a barium swallow. The best approach is to:

  1. Giving written English instructions and proceeding
  2. Using a trained interpreter and checking understanding Correct answer.
  3. Having the patient's young child interpret
  4. Asking a bilingual coworker to translate quickly

Explanation

Qualified medical interpreters preserve accuracy and confidentiality and are required for meaningful communication and consent. Untrained ad hoc interpreters may omit or distort instructions. Teach-back with the interpreter confirms that the patient can actually follow the directions.

Question 21Patient Care and Education

Which set of findings most suggests an anaphylactic reaction to iodinated contrast rather than a vasovagal reaction?

  1. Hives with wheezing and a rapid heart rate Correct answer.
  2. Warmth and redness confined to the injection site
  3. A slow heart rate with cold, clammy skin
  4. Nausea with a normal pulse and blood pressure

Explanation

Anaphylaxis is an immunoglobulin E mediated reaction producing urticaria, bronchospasm, and hypotension with a compensatory tachycardia. Vasovagal reactions produce bradycardia with pale, clammy skin and are self-limited once the patient is supine. Anaphylaxis requires immediate epinephrine and emergency support.

Question 22Patient Care and Education

During a power injection, a patient reports severe pain and burning at the intravenous site. The appropriate response is to:

  1. Flush the cannula with saline and complete the injection
  2. Stop, aspirate residual contrast, and notify the radiologist Correct answer.
  3. Massage the site so the contrast disperses into tissue
  4. Apply a warm compress and continue the study

Explanation

Pain and burning during injection indicate extravasation, and the injection must be stopped immediately. Gentle aspiration through the cannula removes some residual contrast, and the radiologist directs further care, which generally includes limb elevation and cold compresses. The site is documented and the patient is monitored for swelling, blistering, and neurovascular changes.

Question 23Patient Care and Education

A patient with diabetes becomes shaky, sweaty, and confused just before the examination, and the blood glucose reads 52 mg/dL. The appropriate action is to:

  1. Withholding all food and rechecking glucose in 30 minutes
  2. Giving a diet soda and continuing the examination
  3. Giving oral glucose if the patient can swallow Correct answer.
  4. Starting the examination quickly so the patient can eat afterward

Explanation

Glucose below 70 mg/dL with shakiness, diaphoresis, and altered mental status indicates hypoglycemia, which is treated with a fast-acting carbohydrate when the patient can swallow safely. Diet beverages contain no sugar and will not raise glucose. If the patient cannot swallow or is unresponsive, emergency assistance is summoned and intravenous glucose or glucagon is given.

Question 24Patient Care and Education

Which practice is correct when suctioning a patient's tracheostomy?

  1. Applying suction continuously while inserting the catheter
  2. Suctioning for 30 seconds to clear secretions fully
  3. Using the largest catheter that fits the stoma
  4. Limiting each pass to about 10 seconds Correct answer.

Explanation

Suction is applied only during withdrawal and each pass is limited to roughly 10 seconds to prevent hypoxia and mucosal trauma. The patient is allowed to recover and is oxygenated between passes. Sterile technique is used, and the catheter is rotated gently as it is withdrawn.

Question 25Patient Care and Education

A patient with a chest tube and water-seal drainage unit must be moved onto the radiographic table. The radiographer should:

  1. Keep the unit upright and below the level of the chest Correct answer.
  2. Disconnect the tubing from the patient during the move
  3. Clamp the tube during the transfer
  4. Set the unit on the table beside the patient

Explanation

The drainage unit must stay upright and below chest level so that fluid drains by gravity and does not siphon back into the pleural space. The unit travels with the patient and the tubing is kept free of kinks and dependent loops. Clamping or disconnecting the system can cause tension pneumothorax or contamination.

Question 26Patient Care and Education

When should the radiographer perform hand hygiene?

  1. Before and after contact with each patient Correct answer.
  2. Only when gloves will not be worn
  3. Only after contact with blood or body fluids
  4. At the start of the shift and before meals

Explanation

Hand hygiene is required before and after every patient contact and after touching blood, body fluids, or contaminated equipment, whether or not gloves are used. Gloves do not replace hand hygiene, and hand hygiene is not limited to the start of a shift or to visibly soiled contact.

Question 27Patient Care and Education

Which action correctly identifies a patient before a radiographic examination?

  1. Ask the patient whether this is the right department
  2. Match the name on the requisition with the room number
  3. Rely on the name printed on the examination request
  4. Verify two identifiers, such as name and date of birth Correct answer.

Explanation

The standard is active verification of two patient-specific identifiers, such as full name and date of birth, checked against the request and the identification band. Room numbers, department names, and the requisition alone are not acceptable identifiers.

Question 28Patient Care and Education

A patient seated in a wheelchair must be moved onto the radiographic table. The radiographer should first:

  1. Ask the patient to stand while the chair is moved away
  2. Lock the wheels and raise the footrests Correct answer.
  3. Tilt the chair back toward the table
  4. Have the patient push up from the armrests first

Explanation

The wheelchair is stabilized by locking the wheels and the footrests are raised so the patient's feet are not caught as the patient stands. Standing a patient beside an unlocked chair or asking for a push-up before the chair is secured invites a fall.

Question 29Patient Care and Education

A patient who is hard of hearing needs instructions for a chest radiograph. The radiographer should:

  1. Speak more slowly with the face turned away
  2. Face the patient and speak clearly, using written cues Correct answer.
  3. Use gestures only and skip verbal instructions
  4. Speak in a loud shout from behind the patient

Explanation

Facing the patient allows lip reading and visual cues, and writing key instructions reinforces understanding. Shouting, hiding the face, or relying on gestures alone reduces comprehension and cooperation.

Question 30Patient Care and Education

A patient begins to have a tonic-clonic seizure during an examination. The radiographer should:

  1. Restrain the limbs until the movements stop
  2. Insert a tongue blade between the teeth
  3. Leave the patient alone to summon the physician
  4. Protect the patient from injury and time the seizure Correct answer.

Explanation

Care during a seizure focuses on safety: lower the patient, clear nearby objects, cushion the head, and time the event while summoning help. Nothing is placed in the mouth and the limbs are not restrained, because restraint can cause injury.

Question 31Patient Care and Education

A patient of childbearing age scheduled for an abdominal radiograph says she may be pregnant. The radiographer should:

  1. Perform the examination because the physician ordered it
  2. Ask the patient to sign a waiver and then proceed
  3. Change the order to a fluoroscopic study instead
  4. Stop and consult the radiologist before proceeding Correct answer.

Explanation

When pregnancy status is uncertain, the examination is paused so that pregnancy can be verified and the radiologist can weigh the clinical benefit against fetal risk. A signed waiver or a change in modality does not resolve the underlying question.

Question 32Patient Care and Education

A radiographer sustains a needlestick injury while disposing of a needle. The radiographer should:

  1. Apply a tourniquet above the puncture site
  2. Wait to see whether symptoms develop before reporting
  3. Wash the site and report the exposure immediately Correct answer.
  4. Squeeze the site and finish the procedure first

Explanation

The site is washed with soap and water and the exposure is reported at once so that postexposure evaluation and prophylaxis can begin promptly. Delaying the report or manipulating the wound delays care and may worsen outcome.

Question 33Patient Care and Education

An unaccompanied 15-year-old arrives for an elective contrast examination. Consent for the procedure must be obtained from:

  1. A parent or legal guardian Correct answer.
  2. The patient, if the patient seems mature enough
  3. Any adult who accompanies the patient
  4. The radiographer assigned to the room

Explanation

A minor generally cannot give legal consent for an elective procedure, so consent is obtained from a parent or legal guardian unless a specific legal provision applies. The radiographer does not provide consent and does not judge a minor's maturity to consent.

Question 34Patient Care and Education

Which instruction is appropriate for a patient after a barium enema?

  1. Expect dark, tarry stools for one week
  2. Increase fluid intake and report if no bowel movement occurs Correct answer.
  3. Restrict fluids until the barium has passed
  4. Return at once if the stools are chalky white

Explanation

Barium is eliminated by drinking extra fluids and, when ordered, a laxative; retention of barium is a concern, so absence of a bowel movement must be reported. Chalky or light-colored stool is an expected finding from barium, not a reason to return.

Question 35Patient Care and Education

Which practice is correct when a patient must receive oxygen from a portable cylinder during transport?

  1. Coat the valve threads with petroleum jelly to ease connection
  2. Store the cylinder loosely beside the patient's head
  3. Secure the cylinder upright in a holder or cart Correct answer.
  4. Lay the cylinder flat on the stretcher during transport

Explanation

Cylinders are secured upright in a holder or cart so they cannot fall and damage the valve, and they are kept away from grease, oil, and heat. Petroleum products and unsecured cylinders both create fire and injury hazards.

Question 36Patient Care and Education

A female patient scheduled for a pelvic radiograph asks that a female staff member stay in the room. The radiographer should:

  1. Ask the patient to sign a release before continuing
  2. Continue the examination without addressing the request
  3. Explain that hospital policy does not allow observers
  4. Arrange for a female staff member to stay as requested Correct answer.

Explanation

Requests for a chaperone are honored whenever possible to protect the patient's privacy, comfort, and dignity, and the arrangement is documented. Dismissing the request or requiring a release ignores the patient's right to feel safe during the examination.

Question 37Patient Care and Education

Thirty minutes before a scheduled procedure, a patient asks the radiographer for pain medication. The radiographer should:

  1. Explain that an order is needed and notify the nurse Correct answer.
  2. Tell the patient that nothing can be done at this time
  3. Delay the examination until the patient feels better
  4. Provide an analgesic from the department stock

Explanation

Administering medication requires a valid order and falls outside the radiographer's independent scope, so the request is relayed to the nurse or physician responsible for the patient. Supplying stock medication or dismissing the request is inappropriate.

Question 38Patient Care and Education

A patient with suspected active pulmonary tuberculosis needs a portable chest radiograph. Which precaution does the radiographer follow?

  1. Perform the examination without added precautions
  2. Wear an N95 respirator and mask the patient Correct answer.
  3. Wear gloves and a gown but no respiratory protection
  4. Have the patient wear an N95 respirator for the exposure

Explanation

Tuberculosis spreads by the airborne route, so the radiographer wears a fit-tested N95 respirator and the patient wears a surgical mask during transport and contact; the portable examination is performed in a negative-pressure room when available. Gloves and gown alone do not protect against inhaled droplet nuclei.

Question 39Patient Care and Education

A patient with reduced kidney function who takes metformin is scheduled for a contrast-enhanced CT. The radiographer should:

  1. Proceed because metformin does not interact with contrast
  2. Cancel the study and tell the patient to stop metformin for a week
  3. Give the patient extra oral fluids before the injection
  4. Notify the physician so metformin can be withheld per protocol Correct answer.

Explanation

In patients with impaired renal function, metformin is typically withheld at the time of iodinated contrast administration and for about 48 hours afterward, with renal function rechecked before it is resumed. The decision belongs to the ordering physician, and the radiographer's role is to ensure the team is aware.

Question 40Patient Care and Education

A patient scheduled for an elective contrast study reports hives after contrast in the past. The most appropriate action is to:

  1. Administer diphenhydramine before the injection
  2. Cancel the study permanently and note the allergy
  3. Inform the radiologist so premedication can be considered Correct answer.
  4. Proceed without comment, since hives are not serious

Explanation

A prior urticarial reaction is a risk factor for a repeat reaction, so the radiologist is informed and may order premedication, an alternative agent, or a different study. Premedication reduces but does not eliminate risk, and the radiographer does not prescribe or administer drugs independently.

Question 41Image Production - Equipment and Image Acquisition

Which x-ray tube component is responsible for the thermionic emission of electrons?

  1. Rotating anode disc
  2. Induction stator
  3. Tungsten filament Correct answer.
  4. Glass envelope

Explanation

Thermionic emission occurs at the filament, which is part of the cathode; when heated by a current it releases electrons that form the tube current. Those electrons are accelerated across the tube and strike the anode to produce x-rays. The stator and envelope serve only to rotate the anode and maintain the vacuum.

Question 42Image Production - Equipment and Image Acquisition

Which exposure factor primarily controls the total number of x-rays produced during an exposure?

  1. Added filtration
  2. Milliampere-seconds Correct answer.
  3. Source-to-image distance
  4. Focal spot size

Explanation

The number of photons emitted is proportional to the product of tube current and exposure time, so mAs governs beam quantity and receptor exposure. It does not change the energy of the individual photons. Kilovoltage, by contrast, governs beam energy and penetrability.

Question 43Image Production - Equipment and Image Acquisition

An exposure of 70 kVp at 20 mAs produces acceptable receptor exposure. Using the 15% rule, what mAs maintains the same exposure if kVp is increased to approximately 80 kVp?

  1. 30 mAs
  2. 10 mAs Correct answer.
  3. 20 mAs
  4. 40 mAs

Explanation

The 15% rule states that raising kVp by about 15% roughly doubles receptor exposure, so mAs must be halved to keep exposure constant. Halving 20 mAs yields 10 mAs. Leaving mAs unchanged would double exposure.

Question 44Image Production - Equipment and Image Acquisition

The anode heel effect causes x-ray beam intensity to be greatest on which side of the beam?

  1. Anode side of the tube
  2. Central ray of the beam
  3. Cathode side of the tube Correct answer.
  4. Perpendicular to the cathode-anode axis

Explanation

Because photons are produced a short distance inside the anode, those traveling toward the cathode side pass through less anode material and are attenuated less. Beam intensity is therefore highest toward the cathode. Positioning the thicker body part toward the cathode side makes use of the more intense portion of the beam.

Question 45Image Production - Equipment and Image Acquisition

Compared with a 5:1 grid of the same frequency, a 12:1 grid will do which of the following?

  1. Remove less scatter and require lower mAs
  2. Remove more scatter and require higher mAs Correct answer.
  3. Remove more scatter and require lower mAs
  4. Remove the same amount of scatter with no mAs change

Explanation

Grid ratio is the height of the lead strips divided by the width of the interspace material. A higher ratio intercepts more scattered photons at steeper angles but also absorbs more primary photons, so mAs must be increased to preserve receptor exposure.

Question 46Image Production - Equipment and Image Acquisition

Detective quantum efficiency describes which property of an image receptor?

  1. How much it magnifies the anatomy being imaged
  2. How rapidly it can be read between successive exposures
  3. How many pixels it contains per unit area
  4. How efficiently it converts radiation into signal Correct answer.

Explanation

Detective quantum efficiency compares the signal-to-noise ratio squared at the output with that at the input of the receptor. It quantifies how effectively incident radiation is converted into useful image signal. A receptor with higher DQE can produce a diagnostic image with less radiation.

Question 47Image Production - Equipment and Image Acquisition

Increasing kVp while keeping mAs constant produces which change in the image?

  1. Unchanged contrast with reduced receptor exposure
  2. Longer-scale contrast and greater receptor exposure Correct answer.
  3. Shorter-scale contrast with increased receptor exposure
  4. Shorter-scale contrast and reduced receptor exposure

Explanation

Kilovoltage sets the maximum and average energy of the beam. A higher kVp makes the beam more penetrating, raises receptor exposure at constant mAs, and produces more scatter and more transmitted gray tones, which lengthens the contrast scale.

Question 48Image Production - Equipment and Image Acquisition

A radiograph shows a gradual loss of density from the center of the image toward one edge. Which is the most likely cause?

  1. Lateral decentering of the grid Correct answer.
  2. Patient motion during the exposure
  3. Improper collimation of the field
  4. Underexposure of the image receptor

Explanation

Grid cutoff occurs when primary photons are absorbed by the lead strips because the beam is not aligned with them, as with decentering or tilt. Because the misalignment increases with distance from the center of the grid, the density loss is progressive toward the affected edge.

Question 49Image Production - Equipment and Image Acquisition

A radiographic grid is placed between the patient and the image receptor primarily to do what?

  1. Absorb scatter before it reaches the receptor Correct answer.
  2. Improve detail by reducing focal spot blur
  3. Reduce patient dose by limiting the radiation field
  4. Increase the intensity of the primary beam

Explanation

Scattered photons carry no useful positional information and fog the receptor, lowering contrast. The lead strips of a grid are angled to transmit primary photons while absorbing those that arrive at an angle. The result is improved contrast, at the cost of higher mAs.

Question 50Image Production - Equipment and Image Acquisition

Which is the main disadvantage of using an air gap instead of a grid to control scatter?

  1. It cannot be used with automatic exposure control
  2. It substantially increases patient dose
  3. It increases magnification of the anatomy Correct answer.
  4. It reduces the spatial resolution of the image

Explanation

An air gap allows scattered photons to diverge away from the receptor before reaching it. However, the required object-to-image distance increases geometric magnification of the anatomy. Increasing SID can offset this but also requires greater mAs by the inverse square law.