Safety: Radiation Protection, Equipment Operation, and Quality Assurance (14%)

ARRT-T · 42 questions

• During a source inventory with the storage safe door open, a calibrated meter 30 cm from the exposed source reads 12 mrem per hour, and staff must enter the room to complete the check. Wipe tests show no removable contamination, and the department wants an audible warning if levels rise. Which posting and monitoring arrangement applies to this area?
• A chest wall target sits over the lung, the open 6 MV field extends 2 cm past the target on every side, and the plan shows slight dose build-up near the skin. Which beam change best limits dose to uninvolved tissue while keeping the target dose unchanged?
• A medical physicist is documenting monthly output constancy for a 6 MV beam by measuring dose at reference depth in water against the machine's saved baseline. The result must be accurate to about one percent and available immediately so any drift can be corrected before the next treatment day. Which detector is the best choice for this output measurement?
• During weekly output QA on a linac, a reading comes back outside the department's tolerance limit, and physics has placed the unit on hold for review. The therapist must finish the log entry before the shift ends, and the department requires the reading, the limit it missed, and the response in the record. What should the QA entry for this out-of-tolerance result contain?
• In a photon treatment head, a stream of electrons leaves the accelerator and must be converted into a usable x-ray beam before the collimating devices shape it. Which linear accelerator component performs this electron to photon conversion?
• The radiation safety officer reviews dose records for individuals who hold no occupational assignment. One person waits in the uncontrolled public lobby on a regular schedule, carries no occupational dosimetry badge, and has no declared pregnancy. Which annual effective dose limit applies to this person's recorded exposure?
• A shielding review of a new X-ray room maps three surfaces: the wall behind the patient sits in the direct beam, the corridor wall only receives scatter from the patient, and the floor is struck when the tube points downward. Which statement correctly classifies these barriers?
• During a treatment plan review, the pelvic field is being treated with jaws open well beyond the target plus setup margin, so a band of bowel sits inside the open beam. The oncologist wants normal tissue dose reduced while target coverage stays the same. Which beam delivery change best limits unnecessary patient dose?
• The daily treatment-linac routine covers safety-device tests, geometric checks, dosimetric measurements, and mechanical checks, and each part is logged separately. The physicist asks which item is a safety-device test. Which check belongs in that part of the daily routine?
• During an annual radiation protection survey of a linac running above 10 MV, you must record neutron dose equivalent at several gantry angles and in the treatment room maze, with a live reading at each point. Which detector should be used to perform this neutron survey?
• During commissioning of a linear accelerator vault, a calibrated survey at an accessible position 30 cm from the maze entrance measures a dose equivalent rate of 40 mrem per hour while the beam is on, and the outer corridor beyond the maze stays below 0.05 mrem per hour. Staff can reach that entrance mid-treatment if the door interlock is bypassed. Under the federal radiation-area criterion, what classification and posting apply, and what controls should this site use at the entrance?
• A therapist's annual dosimeter report shows a deep dose equivalent well below the regulatory occupational limit, yet the value has climbed steadily over the past three quarters. Machine output, room shielding and assigned procedures are identical to the earlier periods. Which conclusion about personnel dose and ALARA should the radiation safety officer reach from this report?
• During monthly linac QA, output constancy agrees with the previous baseline, MLC leaf positions sit within tolerance, and the isocenter lasers pass. The light field extends past the radiation field edge on both lateral sides beyond the applicable tolerance, while the longitudinal edges line up. What should the therapist do before the linac is cleared for patient treatments?
• During a review of a new treatment vault, the architect points out three areas: an east wall that can be struck by the useful beam at gantry 90°, a north wall several meters from the couch that never crosses the beam path, and a maze wall seen only around a corner from the target. Which classification correctly identifies the shielding basis for each area?
• A patient scheduled for MRI simulation before pelvic radiotherapy reports that he once ground steel without eye protection and may have had a spark reach his eye. He denies eye pain, sees normally, and his questionnaire shows no implants, pacemakers, or retained metal anywhere else. Which screening step must be completed before he is allowed into the magnet room?
• A radiation therapist declares her pregnancy in writing to the radiation safety officer, and her monthly badge readings will be reviewed for the rest of the pregnancy. The department must apply the correct limit to the embryo or fetus. Which dose limit governs the fetal exposure for a declared pregnancy?
• During a quarterly review, the radiation safety officer finds that a therapist's whole-body dosimeter reported zero dose even though the therapist covered treatment-assist shifts in the room every day. The badge had been kept inside a lead apron pocket, and the officer wants the therapist to monitor occupational exposure during these duties. Which personnel monitoring practice should the therapist follow when wearing the apron?
• Before the first patient of the day, a therapist walks a new hire through the morning routine: the linac warm-up runs first, then the daily output and mechanical checks are recorded, while the CT simulator check is handled separately. Which statement correctly describes what the linac warm-up accomplishes before those checks are documented?
• During monthly quality assurance, output lands inside the department's tolerance, the light and radiation field edges agree, and the MLC leaves verify, but the sagittal isocenter laser sits about 3 mm off the mechanical isocenter. Which corrective action is justified before the next patient is set up?
• A monthly output constancy measurement on the linac is outside the department's action limit but inside the manufacturer's service range. The physicist is on site, asks to be told immediately, and treatment is paused. Under the department's QA procedure, what should be documented before the machine returns to patient service?
• Before a planning MRI, a patient reports a medication patch on the upper arm, a stainless steel clip from an operation two years ago with the implant card available, and a grinding injury to the eye with no imaging on file. Which pre-scan hazard checks must be finished before this patient enters the MRI room?
• A student observing morning QA sees the accelerator's dose-monitor reading fall below tolerance while the CT simulator calibration, the light field, and the imaging panel all check out normally. Which accelerator component most directly supplies the signal behind this low reading?
• During a dosimetry review, a vault therapist tells her supervisor that she declared her pregnancy at 11 weeks of gestation. Her whole-body badge total for the year is 8 mSv, and the medical physicist asks the team to apply the correct fetal limit for the rest of the pregnancy. Which statement gives the correct NCRP-based dose limit for the fetus in this declared pregnancy?
• In the nuclear medicine hot lab, an unshielded multi-dose vial on the prep counter measures 60 mR per hour at 30 cm, and the survey at the lab doorway reads the same level. The adjoining corridor carries visitors and clerical staff all day. Which posting and survey routine correctly matches this lab's measured radiation level?
• Two lung plans deliver the same prescribed dose to the same small lung target, and the multileaf apertures are nearly identical, yet a plan quality check flags higher out-of-field dose in the plan with wider jaw openings. Which beam adjustment should be made to lower dose to healthy tissue while target coverage stays unchanged?
• During monthly output constancy QA, the team irradiates a water-equivalent phantom at the machine's reference geometry and compares the reading with the established baseline for that machine. The result must appear in the same session, be an absolute dose in cGy, and come from a detector suited to the beam energy. Which detector should the therapist use for the output measurement?
• A monthly constancy check on the treatment machine returns an ionization-chamber reading outside the tolerance listed in the department QA manual, and afternoon treatments begin in an hour. The therapist must decide what to record and who to tell. Which action correctly evaluates and documents this out-of-tolerance QA result?
• Concentric ring artifacts in a CT simulator image appear when one specific component drifts out of calibration, and the rings stay centered on the rotation axis throughout the reconstructed image. Which component generates this artifact pattern?
• A spot survey in the vault anteroom while the machine is running reads 0.6 rem accumulated in one hour at 30 cm from the accessible surface. The space is observed only intermittently while therapists walk in and out for setups. Which requirements govern how this anteroom is posted, entered and monitored?
• A shielding sketch for a new room built for a linac that rotates a full circle around the patient lists four surfaces: the wall opposite the gantry, the floor beneath the couch, the ceiling above the treatment position, and the door at the far end of the entrance maze. Which surface needs only scatter-and-leakage shielding?
• A patient reports a transdermal pain patch on the left shoulder that is labeled to contain metallic foil, a metal fragment that struck one eye years ago with no record of follow-up imaging, and an old hip implant whose paperwork was left at home. The technologist is completing MRI screening before the exam. Which safety steps must be finished before the patient enters the magnet room?
• During acceptance testing, a physicist must verify the linear accelerator's absolute absorbed dose to water under reference conditions, using a measurement traceable to a standards laboratory. The physicist asks which detector from the instrument drawer should be used. Which detector best satisfies that measurement requirement?
• A hospital is fitting out a vault for a 6 MV linear accelerator, and the physicist must classify the wall in front of the gantry, the side walls, the ceiling and the entrance maze before calculating thickness. Which statement correctly assigns the barrier type and design basis for each surface?
• A radiation therapist remains in the room during fluoroscopic imaging while wearing a wrap-around protective apron. The radiation safety officer issues one dosimeter to monitor exposure to the body parts outside the apron. Where should it be worn?
• Your independent check of an AP cervical spine plan finds the superior jaw 2 cm above the approved portal border, directly over the thyroid, while the inferior border sits exactly on the approved target margin and the monitor units match the plan. Department policy requires the delivered field to agree with the approved portal image before a fraction is treated. Which correction brings the field into agreement with the plan while keeping the prescribed target dose?
• At the start of a busy treatment day, the linac has been off overnight while the CT simulator has sat idle since yesterday. You are the first therapist in, forty patients are booked, and physics is unavailable until noon. Which morning sequence follows the applicable warm-up and daily QA procedures for both machines before they are used?
• A radiation therapist in her first trimester formally declares her pregnancy to her supervisor. She continues to run daily machine checks, position patients in the treatment room, and work at the console, and the department wants to keep her on the usual rotation. Which dosimetry practice best applies ALARA to her and the fetus during the declared pregnancy?
• During weekly QA on the treatment linac, film shows that the radiation field and the light field are the same size and shape, but the light field sits a few millimetres to one side of the radiation edge every time. The offset appears at every couch height and measurement distance, and the jaw settings match yesterday's record. Which component should be adjusted first to restore light and radiation field coincidence?
• The weekly output check on the treatment machine falls outside tolerance, and a repeat measurement confirms the deviation while the light field, MLC leaf positions, and isocenter lasers all pass. Which response to the failed output check must come before the first patient is treated?
• During MRI safety screening, a patient scheduled for a lumbar spine scan reports an MR-conditional spinal cord stimulator with its label checked, an insulin pump worn on the belt, and a nicotine patch on the upper arm. The slot is already running late. Which MRI safety actions must be completed before the patient enters the scan room?
• A radiation therapist at 14 weeks of pregnancy has formally declared her pregnancy and has a fetal dose of 0.3 mSv recorded for the past month, with shielding in place and the monthly badge readings verified. Which reference limit should this month's fetal dose be judged against?
• After the morning CT simulator warm-up and air calibration finish without error, the therapist runs the linac daily output constancy check and the reading sits outside tolerance for the second morning in a row. Which step in the daily quality-assurance routine should come next before any patient is treated?