Mixed Deck — All RT Topics Flashcards

An area where a person could receive more than 1 mSv (100 mrem) in one hour at 30 cm from the source must be posted as what?

Answer: High Radiation Area

NRC defines a High Radiation Area as one exceeding 1 mSv (0.1 rem) per hour at 30 cm.

ICRU Report 83 recommends reporting which dose as the 'near-maximum' dose?

Answer: D2%

D2%, the dose received by 2% of the volume, replaces the point maximum as the near-maximum dose.

Which detail is most important to include in setup documentation for reproducing a patient's position each day?

Answer: Immobilization devices, their indexing positions, and reference mark locations

Documented immobilization and reference marks let any therapist reproduce the simulated position accurately.

Why is it important to monitor radiation exposure to the patient during therapy?

Answer: To ensure the patient’s safety and to avoid excessive radiation exposure.

Monitoring radiation exposure to the patient during therapy is paramount to ensure their safety and prevent excessive radiation exposure. This continuous oversight helps the medical team adhere to the prescribed dose limits, protecting healthy tissues from unnecessary damage and reducing the risk of severe side effects. It is a critical component of quality assurance, ensuring the patient receives the optimal therapeutic benefit with minimal harm.

A therapist sees moist desquamation in the treatment field. How should this be documented?

Answer: Describe it with a standardized grading scale such as CTCAE or RTOG and notify the physician

Standardized toxicity grading makes the documentation objective and comparable, and the physician must be told.

What is the equivalent square of a 10 cm x 20 cm rectangular field using the area/perimeter (4A/P) method?

Answer: 13.3 cm

4A/P = 4(200)/60 = 13.3 cm.

What happens on a properly functioning linac when the treatment room door is opened during beam-on?

Answer: The door interlock terminates the beam

Door interlocks immediately stop irradiation when the vault door opens.

What is the annual occupational dose limit for a 17-year-old student working with radiation?

Answer: 10% of the adult limits

NRC limits for minors are 10% of the annual adult occupational limits.

A margin added around an organ at risk to account for its motion and setup uncertainty creates the:

Answer: PRV

The planning organ at risk volume (PRV) is the OAR plus a margin, which is commonly used for serial organs like the spinal cord.

In tangential breast planning, a half-beam block or collimator rotation is mainly used to:

Answer: Remove beam divergence into the lung and match the deep field edges

Blocking half the beam or rotating the collimator makes the deep edges of the opposed tangents line up and limits divergence into the lung.

The main purpose of a field-in-field technique in breast planning is to:

Answer: Reduce hot spots and improve dose homogeneity

Small MLC-shaped subfields block high-dose regions for part of the treatment, which reduces hot spots.

Under NRC rules, which of the following must be in place before a high-dose-rate brachytherapy treatment is given?

Answer: A written directive dated and signed by an authorized user

10 CFR 35.40 requires a written directive, dated and signed by an authorized user, before brachytherapy is administered.

Which abbreviation is on the Joint Commission 'Do Not Use' list?

Answer: U (for unit)

'U' can be misread as 0, 4, or cc, so it must be written out as 'unit'.

Which type of biologic effect has a threshold dose and increases in severity as dose increases?

Answer: Deterministic (tissue reaction) effect

Deterministic effects such as skin erythema and cataracts appear above a threshold and worsen with dose.

Before the first treatment of a new plan, which verification is normally documented?

Answer: Physician review and approval of the initial setup verification images

First-day portal or IGRT images must be reviewed and approved by the physician to confirm the field placement is correct.

The PTV margin is made up of the internal margin plus the:

Answer: Setup margin

The PTV adds a setup margin to the ITV for daily positioning and machine uncertainties.

Why is it important for radiation therapists to assess the patient's physical condition before treatment?

Answer: To ensure the patient is physically able to tolerate the treatment.

Assessing a patient's physical condition before radiation treatment is crucial to ensure they can safely tolerate the therapy. This evaluation helps identify any pre-existing conditions or vulnerabilities that might be exacerbated by radiation or affect their ability to remain still during treatment. It allows the care team to make necessary adjustments or provide supportive care to optimize patient safety and treatment efficacy.

The Bergonié-Tribondeau law states that cells are MORE radiosensitive when they:

Answer: Have high mitotic activity and are less differentiated

The Bergonié-Tribondeau law (1906) states that cells with high mitotic activity, great proliferative future, and less differentiation are more radiosensitive — which is why cancer cells are generally more sensitive than mature normal cells.

A therapist forgot to chart a treatment note yesterday and is documenting it today. How should it be recorded?

Answer: Label it a late entry, with the current date and time and a reference to the date of the event

A late entry must be clearly identified and carry the actual time of documentation to keep the record honest.

What is the standard of care requirement for patient communication in clinical practice?

Answer: The level of care a reasonably competent practitioner would provide

The standard of care is defined as what a reasonably competent practitioner with similar training would provide under similar circumstances.