Radiation therapist screening questions: ARRT, state licenses, treatment delivery, IGRT and safety checks
On this page
- Which radiation therapy job is it?
- Credentials and state licenses
- Knockout questions
- Treatment delivery questions
- Simulation, safety and patient care questions
- How radiation therapy experience gets overstated
- A 12-minute phone-screen flow
- Scoring
- What to put in the submittal
- Lawful phrasing
- Questions people ask
Radiation therapist screening questions should confirm the national credential (ARRT certification and registration in radiation therapy) and any license the job state requires, then test the hands-on work: simulation and immobilization, image guidance and matching, the techniques the clinic uses (for example stereotactic treatments or breath-hold), the safety checks before every fraction, and what the therapist does when something does not look right. As of October 2026, state licensing differs widely, so check the job state's agency as well as ARRT.
Diagnostic imaging roles are covered elsewhere: the radiology technologist screening questions explain ARRT and state licensing for radiographers and CT, and the MRI technologist screening questions cover MR safety, which matters in clinics that simulate on MRI. This page is for therapists who deliver treatment.
Which radiation therapy job is it?
| Setting | What changes | Ask the candidate |
|---|---|---|
| Hospital or academic center | Several machines, complex cases, inpatients, clinical trials, sometimes pediatrics | "Which machines did you treat on, and how many patients a day on each?" |
| Community or freestanding center | One or two machines, broader duties, fewer therapists per shift | "What did you do besides treating: simulation, scheduling, checks?" |
| Simulation-focused role | CT or MR simulation, immobilization devices, marks and setup notes | "Which immobilization devices did you build, and for which sites?" |
| Stereotactic program | SRS and SBRT, tight setup tolerances, more imaging, longer treatments | "How many stereotactic cases a week, and what was your part?" |
| Travel or locum | New machines and software, short orientation | "How fast did you get signed off on a new machine at your last contract?" |
Credentials and state licenses
As of October 2026. We checked these on ARRT's and Florida's own pages and in Florida's statute. Florida is one example; check the job state's own radiation control or licensing agency.
- ARRT radiation therapy. ARRT's radiation therapy credential page sets education, ethics and exam requirements, including didactic and clinical competency requirements, and ongoing requirements after certification. Check status with ARRT's Verify Credentials search, which shows certification and registration by discipline.
- A state example: Florida. Florida's section 468.302 bars using radiation on a human being unless the person is a licensed practitioner or a certificate holder working under supervision. The radiation therapy certificate carries the title "Certified Radiologic Technologist-Therapy" and covers administering X radiation and ionizing radiation from particle accelerators and external beam teletherapy from sealed sources, for therapeutic or simulation purposes. The Department of Health's radiologic technologist page lists the radiation therapy technologist category, says it uses ARRT's exams for Florida certification, and links to online license verification.
- Other states. The radiology technologist page links ARRT's state licensing resource. A therapist moving states may need a new state license before the start date; ask how far along the application is.
Knockout questions
| Question | Strong answer | Red flag |
|---|---|---|
| 1. Are you ARRT certified and registered in radiation therapy, and current? | Yes, with the ID you can verify, and continuing education up to date. | Registry-eligible presented as registered. |
| 2. Do you hold the license for [state], or when will you? | An active license, or an application filed with a date. | Has not looked at the state's rules. |
| 3. Which treatment machines and record-and-verify system have you used in the last two years? | Names them, with how long on each. | Only machines the client does not have, with no plan to learn. |
| 4. The schedule is [early starts, late shifts, weekend coverage]. Does that work? | A clear yes or a stated limit. | Expects a schedule the clinic does not run. |
Treatment delivery questions
-
"Walk me through setting up and treating a patient on their fifth fraction."
- Strong answer: identifies the patient by the department's method (for example, two identifiers and the photo in the record), confirms the site and plan in the record-and-verify system, sets up with the immobilization and setup notes, takes and matches the images to the tolerance the physician and department set, gets approval where policy requires, treats while watching the patient on camera, documents, and asks how the patient is doing.
- Red flags: skips identification for a patient they "know"; treats before images are matched.
-
"The setup images show a shift larger than your department's tolerance."
- Strong answer: does not treat, re-sets up and re-images, calls the physician or physicist per policy, documents.
- Red flags: shifts the couch beyond tolerance and treats.
-
"How do you coach a breath-hold patient, or manage motion for a lung or liver case?"
- Strong answer: explains the technique the clinic used (breath-hold with surface guidance or a monitoring device, gating, compression), practice runs and how they handle a patient who cannot hold.
- Red flags: no experience but claims stereotactic lung cases.
-
"Tell me about a time you stopped a treatment."
- Strong answer: a specific reason (patient moved, machine interlock, plan question), what they did, who they told and how it was documented.
- Red flags: has never stopped a treatment, after years on the machine.
Simulation, safety and patient care questions
| Question | Strong answer | Red flag |
|---|---|---|
| Which immobilization devices have you made at simulation, and for which sites? | Specific: thermoplastic masks for head and neck, body molds, breast boards, knee and foot supports, with setup notes and photos. | Only watched simulation. |
| What safety checks happen before the first treatment of a new plan? | Describes the department's checks: plan approval, chart review, a time-out, first-day imaging with the physician as required. | "The physicist handles all that." |
| How do you report a near miss or error? | Knows the department's incident reporting system and the culture of reporting without blame. | Would fix it quietly. |
| A patient on week four has worsening skin reaction and pain. What do you do? | Tells the nurse or physician before treating, documents, follows skin care instructions the clinic uses. | Treats and mentions it at the end of the week. |
| Pediatric patients: have you treated children, including under anesthesia? | Specific cases and how the anesthesia team and therapists coordinated. | Only adult experience, for a pediatric program. |
Who checks what varies by department. Treatment planning and physics quality assurance belong to dosimetrists and medical physicists, and the radiation oncologist approves plans and image matches as policy requires. A strong therapist knows the line and speaks up when something on the machine or the plan looks wrong.
How radiation therapy experience gets overstated
- Clinical rotations as employment. Student time on stereotactic cases counted as experience.
- Machine names without depth. Treated on a machine but never used its image guidance or motion management.
- "Did simulation" when they assisted the simulation therapist.
- Brachytherapy that was preparing the room.
- A state license claimed but pending. Check the state's lookup.
A 12-minute phone-screen flow
- Minutes 0 to 2: setting, machines, techniques and schedule.
- Minutes 2 to 4: knockouts, ARRT and state license details for verification.
- Minutes 4 to 9: the fifth-fraction walk-through, the out-of-tolerance question and one technique question.
- Minutes 9 to 12: safety reporting, patient care, pay expectations and next steps.
Scoring
Pass or fail
- ARRT radiation therapy credential, current and verified.
- Licensed in the job state, or a realistic route before the start date.
- Recent experience on comparable machines or a credible plan to learn them.
- Accepts the schedule.
Scored 0 to 2 each (10 possible)
- Patient identification and setup.
- Image guidance and tolerance decisions.
- Techniques the client uses (stereotactic, motion management, pediatrics).
- Safety culture: stops, reports, escalates.
- Patient care during a course of treatment.
What to put in the submittal
Radiation oncology managers read a submittal for machines and techniques first. Copy this block and fill it from the call, so the manager can see the match without a second screen:
Therapist: [name]
ARRT: radiation therapy, ID [number], verified [date]
State license: [state], [active / applied on date], verified [date]
Machines (last two years): [vendor and model, months on each]
Record-and-verify and imaging: [system], [kV, cone-beam CT, surface guidance]
Techniques done hands-on: [SRS / SBRT / breath-hold / gating / pediatrics / brachytherapy]
Simulation: [CT / MR], devices built: [masks, body molds, breast boards]
Stopped a treatment: [one-line summary of their example]
Schedule: [shifts accepted], start date [date]
Candidate's own gap: [e.g. "no SBRT since school; breath-hold only on one vendor's system"]The "own gap" line matters most. A therapist who names what they have not done is easier to place, and the clinic can plan the orientation before the first day.
Lawful phrasing
Ask about the job's physical tasks (helping patients onto the treatment couch, positioning, standing for long periods) and whether the candidate can perform them, with or without accommodation. Do not ask about pregnancy or radiation dose history out of concern for the candidate; radiation safety programs are the employer's job after hire. The EEOC's guidance on disability-related questions and the illegal interview questions guide cover the line. Record the credential and license details in your candidate submittal, and verify them as described in how to verify candidate certifications.
Questions people ask
Is ARRT certification enough to work as a radiation therapist?
Not on its own in every state. ARRT certification and registration in radiation therapy is the national credential, and a state can require its own license or certificate as well. Florida, for example, certifies radiation therapy technologists under Chapter 468 of its statutes and uses ARRT's exams for that certification. Check the job state's agency as well as ARRT.
What does a radiation therapist do that a dosimetrist or physicist does not?
The therapist positions the patient, acquires and matches the setup images, delivers the planned treatment and watches the patient during it, and reports changes. Treatment planning and physics quality assurance belong to dosimetrists and medical physicists, and the radiation oncologist approves the plan and image matches as the department's policy requires.
How do I verify a radiation therapist's license?
Use ARRT's Verify Credentials search for the national credential, then the job state's licensing lookup. In Florida, the Department of Health points to its online license verification for radiologic technology certificates.
Which radiation therapy experience is hardest to find?
It depends on the client's machines and programs. Ask the client which techniques it treats with, such as stereotactic body radiation therapy, breath-hold or surface guidance, pediatric cases under anesthesia or brachytherapy, and screen for recent hands-on experience in those, not just exposure during school.