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ARRT Radiation Therapy study materials
ARRT Radiation Therapy study resources

ARRT Radiation Therapy practice questions

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Question 1Patient Care and Education

Which two identifiers are acceptable for confirming a patient's identity before treatment?

  1. Full name and date of birth Correct answer.
  2. Room number and treatment time
  3. Diagnosis and prescribed dose
  4. Attending physician and machine number

Explanation

Two patient-specific identifiers must be matched against the treatment record before any procedure. Name combined with date of birth is a standard, unique pairing. Room numbers, machine assignments, and diagnoses are not identifiers.

Question 2Patient Care and Education

Who is responsible for obtaining informed consent for radiation therapy?

  1. The clinic nurse
  2. The dosimetrist
  3. The staff therapist
  4. The radiation oncologist Correct answer.

Explanation

Obtaining informed consent is a physician responsibility. The radiation oncologist explains the diagnosis, goals, risks, benefits, and alternatives, and documents the patient's agreement. Other team members may verify that consent is in the record but cannot obtain it.

Question 3Patient Care and Education

A patient receiving external beam therapy asks how to care for the treatment area. Which instruction is appropriate?

  1. Cover the area with an occlusive dressing
  2. Scrub the area with an antiseptic
  3. Wash gently with mild soap and water Correct answer.
  4. Apply a heating pad nightly

Explanation

Care of irradiated skin emphasizes gentle cleansing with mild soap and lukewarm water, patting dry, and avoiding friction, heat, and irritating products unless specifically prescribed. Abrasive cleansing, heat, and tightly occlusive dressings can worsen skin reactions.

Question 4Patient Care and Education

Which instruction should a therapist give about the skin markings placed for treatment?

  1. Cover them with makeup before arriving
  2. Re-draw them at home if they fade
  3. Leave them intact and keep them dry Correct answer.
  4. Scrub them off before each treatment

Explanation

Setup marks and tattoos ensure reproducible positioning for every fraction. Patients should protect them from rubbing, cosmetics, and sun, and should let staff re-apply any that fade. Therapists, not patients, replace faded markings.

Question 5Patient Care and Education

Which question best encourages a patient to describe concerns before simulation?

  1. Do you want a pill for anxiety?
  2. Are you nervous about today?
  3. You are not anxious, are you?
  4. What worries you most? Correct answer.

Explanation

Open-ended questions invite patients to express concerns in their own words and often reveal more than a yes-or-no answer. Leading or closed questions can suppress discussion or bias the response.

Question 6Patient Care and Education

A patient reports fatigue midway through a course of radiation therapy. Which advice is most appropriate?

  1. Balance rest with light activity Correct answer.
  2. Stop all physical activity until treatment ends
  3. Increase caffeine intake throughout the day
  4. Skip treatments until energy returns

Explanation

Fatigue is the most common side effect of radiation therapy and is managed with planned rest balanced against light exercise such as walking. Unnecessary bed rest and missed treatments worsen deconditioning and compromise the plan.

Question 7Patient Care and Education

Which dietary guidance is appropriate for a patient losing weight during treatment?

  1. Eat three large meals at set times each day
  2. Restrict protein to reduce nausea
  3. Eat small, frequent high-protein meals Correct answer.
  4. Replace all meals with liquid supplements

Explanation

Weight loss during therapy is addressed with small, frequent meals that are dense in calories and protein, along with a dietitian referral. Large meals are often poorly tolerated, and protein restriction worsens tissue wasting.

Question 8Patient Care and Education

A therapist recognizes a patient in the hospital cafeteria and a coworker asks about that patient's diagnosis. What is the appropriate response?

  1. Discuss it only if the patient is absent
  2. Decline to discuss the patient's information Correct answer.
  3. Confirm the diagnosis quietly
  4. Share details with staff who ask

Explanation

Protected health information may be shared only with those involved in the patient's care and only when needed. Casual discussion in public areas, even with coworkers, is a privacy breach and should be declined.

Question 9Patient Care and Education

Which precaution should be taught to a patient with treatment-related neutropenia?

  1. Delay reporting fever until the next visit
  2. Eat fresh raw vegetables daily
  3. Avoid crowds and report fever promptly Correct answer.
  4. Share food and utensils with family

Explanation

Neutropenic patients have reduced infection defenses and should avoid crowds and other sources of pathogens. Fever at or above about 100.4 degrees F (38 degrees C) must be reported immediately because infection can progress rapidly.

Question 10Patient Care and Education

Which dietary change is recommended for a patient with radiation-induced diarrhea?

  1. Choose low-fiber foods and clear fluids Correct answer.
  2. Drink milk with every meal
  3. Increase intake of bran and raw fruits daily
  4. Eat fried foods to slow transit

Explanation

Radiation-induced diarrhea is managed with a low-fiber, low-fat diet, generous fluid replacement, and limiting lactose or caffeine if they aggravate symptoms. Bulky and high-fat foods increase stool volume and symptoms.

Question 11Patient Care and Education

Which measure helps a patient with radiation-induced oral mucositis?

  1. Rinse with a commercial alcohol mouthwash
  2. Use saline rinses and avoid acidic foods Correct answer.
  3. Eat spicy foods to stimulate saliva
  4. Brush with a firm-bristled toothbrush

Explanation

Oral mucositis care includes gentle hygiene with a soft brush, saline or bicarbonate rinses, and bland, nonacidic foods. Alcohol-containing rinses, spicy foods, and abrasive brushing increase pain and mucosal injury.

Question 12Patient Care and Education

A patient begins to panic while positioned for treatment. What is the best initial action?

  1. Tell the patient to calm down
  2. Continue and finish the treatment quickly
  3. Cancel all remaining treatments
  4. Pause and coach slow breathing Correct answer.

Explanation

When anxiety escalates, treatment is paused and the patient is reassured using simple coping strategies such as slow, coached breathing. Dismissing the fear or rushing worsens panic and compromises immobilization.

Question 13Patient Care and Education

Which approach best prepares a young child for daily radiation therapy?

  1. Discourage parents from staying in the room
  2. Use simple words and allow a comfort item Correct answer.
  3. Promise the treatment will not hurt at all
  4. Withhold all information until the machine is on

Explanation

Children cope best with brief, honest explanations in simple language, preparation before entering the room, and a familiar comfort object. False reassurance and separation from caregivers increase fear and reduce cooperation.

Question 14Patient Care and Education

Which consideration is most important when positioning an older adult who has arthritis and hearing loss?

  1. Speak loudly and avoid written instructions
  2. Allow extra time and speak face-to-face Correct answer.
  3. Use the same immobilization as a younger adult
  4. Skip the skin assessment to save time

Explanation

Older adults frequently have sensory and mobility limitations, so the therapist should face the patient when speaking, speak clearly, and allow extra time for safe positioning. Immobilization may need adaptation to accommodate stiffness and pain.

Question 15Patient Care and Education

A 28-year-old patient scheduled for pelvic irradiation mentions that her period is late. What should the therapist do first?

  1. Order a urine pregnancy test independently
  2. Proceed with treatment as prescribed
  3. Notify the radiation oncologist before treatment Correct answer.
  4. Tell her pregnancy is not a concern

Explanation

Any patient of childbearing age should be asked about possible pregnancy, and a possible pregnancy must be reported to the radiation oncologist before treatment continues. The physician determines testing and any change in the plan.

Question 16Patient Care and Education

Which method best confirms that a patient understood instructions about skin care?

  1. Giving the patient a pamphlet at discharge
  2. Repeating the instructions several times
  3. Asking the patient to sign a handout
  4. Asking the patient to explain the steps back Correct answer.

Explanation

Teach-back, in which the patient restates the instructions in their own words, documents comprehension and reveals gaps. Providing materials or repeating information does not confirm that learning occurred.

Question 17Patient Care and Education

Before leaving the room during treatment, what should the therapist tell a patient who is in an immobilization device?

  1. Hold your breath for the entire treatment
  2. Remove the mask if you feel uncomfortable
  3. You can speak to me anytime through the intercom Correct answer.
  4. Do not move and there is no way to reach me

Explanation

Patients must be able to reach staff at all times during delivery, and the intercom and camera provide that link. Leaving a patient with no means of signaling distress is unsafe and increases anxiety and motion.

Question 18Patient Care and Education

During a weekly assessment the therapist observes moist desquamation in the treatment field. What is the appropriate action?

  1. Cover the area with an adhesive dressing
  2. Report the finding to the radiation oncologist Correct answer.
  3. Scrub the area to remove the exudate
  4. Apply a drying powder and continue treatment

Explanation

Moist desquamation represents epidermal breakdown and must be reported so the radiation oncologist can prescribe management and decide whether treatment needs modification. Therapists assess and document but do not independently choose topical products.

Question 19Patient Care and Education

A patient rates pain as 7 out of 10 before treatment. What is the therapist's most appropriate action?

  1. Delay treatment until the pain resolves
  2. Report the pain to the managing team Correct answer.
  3. Advise the patient to take extra medication
  4. Document the score and continue without comment

Explanation

Uncontrolled pain is reported to the managing team so analgesia can be adjusted; the therapist documents the assessment but does not prescribe or alter medications. Poorly controlled pain prevents the patient from holding position comfortably.

Question 20Patient Care and Education

A patient who speaks limited English arrives for daily treatment. How should communication be handled?

  1. Speak only to the accompanying family member
  2. Arrange a qualified medical interpreter Correct answer.
  3. Ask a bilingual housekeeper to translate
  4. Use the patient's young child as interpreter

Explanation

Qualified medical interpreters preserve accuracy and confidentiality during education and consent discussions. Untrained ad hoc interpreters introduce errors and may breach privacy or distort clinical information.

Question 21Patient Care and Education

A patient scheduled for palliative radiation is confused and cannot understand the consent discussion. Who may provide consent?

  1. The therapist assigned to the case
  2. The legally authorized health care agent Correct answer.
  3. The nursing supervisor on duty
  4. Any adult family member who is present

Explanation

When a patient lacks decision-making capacity, consent comes from a legally authorized surrogate such as a health care agent, proxy, or guardian. Staff members and relatives without legal authority cannot consent.

Question 22Patient Care and Education

A patient with an implanted cardioverter-defibrillator is scheduled for thoracic irradiation. What should the care team do?

  1. Assume the device is safe because the dose is low
  2. Coordinate with cardiology and physics Correct answer.
  3. Deactivate the device without consulting anyone
  4. Proceed and check the device after each fraction

Explanation

Radiation can damage implanted cardiac device circuitry, so the plan is reviewed with cardiology and medical physics for dose limits, shielding, and monitoring. Devices are never deactivated or repositioned without a coordinated plan.

Question 23Patient Care and Education

Which discussion should take place before pelvic irradiation begins in a 25-year-old male patient?

  1. Delay of fertility counseling until treatment ends
  2. Assurance that his fertility will not be affected
  3. Sperm banking options before treatment begins Correct answer.
  4. Fertility preservation options after treatment ends

Explanation

Fertility counseling and referral for sperm banking must occur before the first fraction, because pelvic irradiation can cause permanent sterility. Counseling after treatment is completed is too late to preserve fertility.

Question 24Patient Care and Education

Which practice verifies the correct treatment site immediately before delivery?

  1. Relying on the patient's memory of the prescription
  2. Checking the appointment schedule on the monitor
  3. Performing a time-out with the prescription Correct answer.
  4. Reviewing the plan during the previous chart round

Explanation

A formal time-out immediately before delivery confirms patient identity, site, laterality, and prescription against the approved plan. Memory, schedules, and prior reviews are not acceptable substitutes for the real-time check.

Question 25Patient Care and Education

A patient is discharged after permanent prostate brachytherapy. Which instruction should be given?

  1. Avoid all contact with adults for six months
  2. Return all clothing for radiation screening weekly
  3. Limit close contact with young children for a time Correct answer.
  4. Share a bed with an infant without restriction

Explanation

After permanent seed implantation, patients receive written precautions to limit prolonged close contact with pregnant women and young children for a defined period. Normal contact with other adults is permitted.

Question 26Patient Care and Education

A patient receiving radiation therapy to the head and neck reports persistent dry mouth. Which instruction is most appropriate?

  1. Drink several cups of coffee or cola each day to stimulate saliva.
  2. Rinse with an alcohol-based mouthwash several times a day.
  3. Sip water often and use sugar-free gum or candy. Correct answer.
  4. Limit fluid intake to reduce swelling of the salivary glands.

Explanation

Irradiation of the salivary glands reduces saliva flow, so moisture must be replaced frequently and salivary flow stimulated without adding sugar that promotes caries. Small sips of water and sugar-free sialogogues accomplish both goals. Alcohol-containing rinses are drying and irritating to irradiated mucosa.

Question 27Patient Care and Education

A patient's platelet count has fallen to 45,000/mm3 during a course of radiation therapy. Which instruction should the therapist reinforce?

  1. Use an electric razor and a soft-bristle toothbrush. Correct answer.
  2. Floss vigorously after every meal and snack.
  3. Use a hard-bristle toothbrush to clean the teeth thoroughly.
  4. Take aspirin daily to reduce the risk of clotting.

Explanation

Thrombocytopenia increases the risk of bleeding, so trauma to skin and mucosa should be minimized by using soft-bristle brushes and electric razors. Aspirin and other antiplatelet agents further impair clotting and are avoided unless specifically ordered. Any bleeding precautions are taught before invasive or abrasive habits continue.

Question 28Patient Care and Education

Which statement should the therapist include when teaching a patient about hair loss expected during cranial irradiation?

  1. Hair loss generally begins 2 to 3 weeks in and regrows after treatment. Correct answer.
  2. Wearing a snug wig cap during treatment will prevent any additional hair loss.
  3. Hair loss always begins within 24 hours after the first treatment fraction is given.
  4. Hair regrowth is unlikely to occur even after the entire course is finished.

Explanation

Epilation from irradiation occurs only in the treated field and typically begins about two to three weeks into the course. Regrowth usually starts weeks to months after treatment ends, although it may be incomplete after high doses. Hair loss is not preventable by covering the scalp, and it does not begin within a day of the first fraction.

Question 29Patient Care and Education

A patient receiving abdominal irradiation has a standing order for an oral antiemetic. Which instruction best supports control of nausea?

  1. Skip the medication on the days when you feel completely well.
  2. Take it on a schedule, including before each treatment. Correct answer.
  3. Take the medication only with the largest meal of the day.
  4. Take the medication only after vomiting has already started.

Explanation

Antiemetics work best when given prophylactically on a regular schedule so that blood levels are adequate before the emetogenic stimulus occurs. Waiting for vomiting allows nausea to become established and harder to control. Doses should not be skipped on good days, because symptoms are then more likely to break through.

Question 30Patient Care and Education

Before bringing a patient into the treatment room, the therapist confirms identity. Which practice meets the accepted standard?

  1. Confirm the patient's identity by matching the room number to the daily schedule.
  2. Check the name written on the door of the patient's changing cubicle.
  3. Verify identity by recognizing the patient from previous treatment visits.
  4. Ask the patient to state name and birth date, then compare with the record. Correct answer.

Explanation

Two identifiers must be obtained from the patient or an authorized representative and compared with the treatment record before any procedure. Room numbers, cubicle labels, and staff recognition are not reliable identifiers and can lead to treatment of the wrong site or person.

Question 31Patient Care and Education

During setup, a patient asks the therapist whether the treatment is meant to cure the cancer. Which response is most appropriate?

  1. Tell the patient that this topic cannot be discussed in the treatment room.
  2. Give your own understanding of the treatment intent from the chart.
  3. Acknowledge the question and refer the patient to the radiation oncologist. Correct answer.
  4. Suggest that the patient search the internet for statistics on the diagnosis.

Explanation

Discussion of prognosis and treatment intent falls within the radiation oncologist's scope of practice; the therapist acknowledges the concern and facilitates that conversation. Personal interpretation of the chart or internet statistics may be inaccurate and undermines the informed relationship with the physician. The question should never be dismissed as inappropriate.

Question 32Patient Care and Education

A patient mentions taking several herbal supplements and asks whether they matter for treatment. What is the appropriate response?

  1. Stop taking all supplements immediately without telling anyone.
  2. Report every supplement to the care team so the regimen can be reviewed. Correct answer.
  3. Herbal products are natural and harmless, so they do not need to be reported.
  4. Supplements matter only if a physician prescribed them.

Explanation

Herbal products can interact with medications, cause photosensitivity, or affect skin and mucosal reactions, so the full regimen must be disclosed and reviewed by the care team. Patients should not start or stop products unilaterally. Nonprescription status does not mean a product is biologically inactive.

Question 33Patient Care and Education

A patient receiving prostate irradiation is told to arrive with a full bladder. What is the main reason for this instruction?

  1. A full bladder shortens the time needed for the daily setup.
  2. A full bladder reduces the total number of treatment fractions that are required.
  3. It moves bowel out of the high-dose region and steadies the prostate. Correct answer.
  4. A full bladder prevents urinary incontinence during the treatment.

Explanation

A consistently filled bladder displaces small bowel away from the high-dose volume and reduces prostate motion, improving both normal-tissue sparing and daily reproducibility. The volume must be similar each day for the setup to be reliable. Bladder filling does not change the prescribed number of fractions.

Question 34Patient Care and Education

A patient taking opioid analgesics during pelvic irradiation reports hard stools every third day. Which instruction should the therapist reinforce?

  1. Restrict fluids so that the stool becomes less watery.
  2. Increase fluids and fiber and stay as active as tolerated. Correct answer.
  3. Take a daily iron supplement to help regulate bowel movements.
  4. Stop the opioid medication on your own without telling the care team.

Explanation

Opioids slow intestinal peristalsis, so the first-line measures are adequate fluid intake, dietary fiber, and mobility, with laxatives added as ordered. Analgesic changes must be made by the prescribing clinician because uncontrolled pain also impairs treatment. Iron supplementation is itself constipating.

Question 35Patient Care and Education

A patient whose religious beliefs require modesty asks to be treated only by a female therapist. How should the team respond?

  1. Refer the patient to another facility that shares the patient's beliefs.
  2. Explain that staffing assignments cannot be changed for personal preferences.
  3. Accommodate the request when feasible and document it in the record. Correct answer.
  4. Ask the patient to sign a waiver before treatment can continue.

Explanation

Culturally congruent care means honoring modesty and religious needs whenever staffing allows, then documenting the preference so it is consistently respected. Dismissing or transferring the patient creates an avoidable barrier to completing therapy. A waiver has no role because no safety exception exists.

Question 36Patient Care and Education

Which instruction should a patient receiving radiation therapy to the jaw receive to help prevent limitation of mouth opening?

  1. Use a hard-bristle toothbrush to massage the inside of the cheek.
  2. Limit jaw movement until the treatment course is finished.
  3. Do daily jaw-stretching exercises through the full range of motion. Correct answer.
  4. Keep the mouth closed and avoid chewing between treatments.

Explanation

Irradiation of the muscles of mastication can produce fibrosis and trismus, and prophylactic stretching through the full range of motion preserves opening. Immobility accelerates contracture, so rest and limitation of movement are counterproductive. Stretching is begun early and continued after treatment ends.

Question 37Patient Care and Education

A patient receiving head and neck irradiation says that meat tastes metallic and bitter. Which suggestion is most appropriate?

  1. Eat only very hot foods because heat masks the metallic taste.
  2. Use mild marinades, poultry, eggs, or dairy, and try cool foods. Correct answer.
  3. Avoid all protein foods until the treatment course has been completed.
  4. Add extra salt and hot spices to every meal.

Explanation

Taste alterations are common when the oral cavity is irradiated; bland marinades, alternative protein sources, and cool or room-temperature foods are usually better tolerated. Maintaining protein and calorie intake supports healing and weight maintenance. Very hot, salty, or spicy foods irritate the mucosa, and protein restriction worsens nutritional status.

Question 38Patient Care and Education

A patient with a valid do-not-resuscitate order arrives for a palliative treatment and becomes unresponsive in the waiting area. What is the appropriate action?

  1. Begin full resuscitation because a DNR order does not apply outside an inpatient unit.
  2. Follow the facility's DNR policy and activate the emergency response system. Correct answer.
  3. Wait for the family to arrive before beginning any intervention.
  4. Cancel the DNR order because the patient is now in a hospital department.

Explanation

A valid DNR order follows the patient across settings, including outpatient and treatment areas, and the team responds according to facility policy while summoning help. Therapists do not unilaterally rescind or override the order. Delay in activating the response system is never appropriate.

Question 39Patient Care and Education

A patient scheduled for the first treatment says, "I signed the consent, but I don't really know what a boost is." What is the therapist's best action?

  1. Explain the boost in detail and answer all of the patient's technical questions.
  2. Pause and arrange for the radiation oncologist to answer the questions. Correct answer.
  3. Proceed with the treatment because the consent form has already been signed.
  4. Ask the patient to sign a second consent form before continuing.

Explanation

Valid informed consent requires that the patient understand the proposed treatment, and the physician is responsible for providing that explanation. The therapist documents the patient's unanswered questions and facilitates physician follow-up rather than supplying a medical explanation. A signature alone does not establish understanding.

Question 40Patient Care and Education

A patient's adult child asks to stand inside the treatment room and hold the patient's hand during delivery. What is the best response?

  1. Explain that no one may stay in the room during beam-on and offer comfort measures. Correct answer.
  2. Allow the family member to remain if the dose rate is reduced.
  3. Permit the visit only if the patient signs a release of liability form.
  4. Allow the family member to stay if lead shielding is placed over them.

Explanation

Only the patient may occupy the treatment room while the beam is on, because any other person would receive unnecessary exposure that no practical shielding or dose reduction can justify. The therapist acknowledges the family member's wish to help and offers supportive measures before and after delivery. Facility policy governs any rare exception.

Question 41Safety

The ALARA principle requires that occupational and patient exposures be:

  1. reduced for staff members but not for patients undergoing treatment
  2. set only by the maximum limits written in federal regulations
  3. kept as low as reasonably achievable while still meeting the clinical objective Correct answer.
  4. eliminated completely no matter what effect this has on patient care

Explanation

ALARA is a optimization principle: dose is reduced to the lowest level that still accomplishes the required clinical task, taking economic and social factors into account. It applies in addition to, not instead of, regulatory dose limits.

Question 42Safety

The annual occupational effective dose limit for a radiation worker is:

  1. 150 mSv
  2. 500 mSv
  3. 50 mSv Correct answer.
  4. 5 mSv

Explanation

National radiation protection guidance sets the annual occupational effective dose limit at 50 mSv (5 rem) per year, with the cumulative lifetime dose constrained by the age-based formula.

Question 43Safety

The annual effective dose limit for an individual member of the general public exposed to radiation from a licensed facility is:

  1. 1 mSv per year Correct answer.
  2. 0.1 mSv per year
  3. 50 mSv per year
  4. 0.5 mSv per year

Explanation

The dose limit for the general public is 1 mSv (100 mrem) per year, one-tenth or less of the occupational limit, because the public includes children and others who are not monitored or trained.

Question 44Safety

A therapist who routinely handles radioactive sources should wear an extremity dosimeter:

  1. on the trunk beneath the lead apron
  2. on the finger expected to receive the highest dose, beneath the glove Correct answer.
  3. clipped to the collar outside the lead apron
  4. on the wrist of the dominant hand, over the glove

Explanation

Ring or extremity badges are worn on the finger most likely to receive the highest dose and are placed under the glove so that the measured dose reflects what the skin actually receives.

Question 45Safety

Which set of principles forms the basis of external radiation protection?

  1. Time, distance, and shielding Correct answer.
  2. Collimation, filtration, and kVp selection
  3. Ventilation, temperature, and humidity control
  4. Containment, dilution, and decay

Explanation

External exposure is controlled by minimizing time near the source, maximizing distance from it, and placing appropriate shielding between the source and the person. The inverse square law makes distance especially powerful.

Question 46Safety

The function of the treatment room door interlock is to:

  1. terminate irradiation if the door is opened during treatment Correct answer.
  2. permit staff to enter briefly while the beam remains on
  3. alert the patient that the door has been opened
  4. record each entry into the treatment room

Explanation

The interlock is a safety circuit that interrupts beam-on conditions when the door is opened, preventing anyone from entering an active radiation field. It cannot be bypassed during routine treatment.

Question 47Safety

Before treatment delivery, patient identity should be confirmed using:

  1. the appointment time listed at the treatment console
  2. the patient's room number and diagnosis
  3. two independent identifiers such as full name and date of birth Correct answer.
  4. the photograph attached to the treatment record alone

Explanation

Safe practice requires at least two independent identifiers, verified by asking the patient directly and matching them to the treatment prescription. Room numbers and schedules change and are not unique to a person.

Question 48Safety

Protective aprons used in radiation therapy typically provide attenuation equivalent to:

  1. 2 mm lead equivalent
  2. 0.5 mm lead equivalent Correct answer.
  3. 1 mm lead equivalent
  4. 0.25 mm lead equivalent

Explanation

Standard protective aprons are rated at 0.5 mm lead equivalent, which attenuates most scattered diagnostic-quality photons while keeping the garment wearable. Thicker aprons are reserved for special procedures.

Question 49Safety

A point source produces a dose rate of 40 mGy/h at 1 m. Ignoring attenuation, what is the dose rate at 2 m?

  1. 20 mGy/h
  2. 80 mGy/h
  3. 160 mGy/h
  4. 10 mGy/h Correct answer.

Explanation

Dose rate from a point source falls off with the square of distance: doubling the distance divides the rate by four. Here 40 mGy/h divided by 4 equals 10 mGy/h.

Question 50Safety

After passing through two half-value layers, the intensity of a beam is reduced to:

  1. one eighth of the original
  2. one half of the original
  3. one quarter of the original Correct answer.
  4. zero

Explanation

Each half-value layer halves the intensity, so two layers transmit 1/2 × 1/2 = 1/4 of the original beam. Attenuation is exponential and never reaches zero.