RTT Exam Domains 2026: Complete Guide to All 3 Content Areas

What the Three Domains Actually Are

The Registered Technologist - Radiation Therapy credential is awarded by the American Registry of Radiologic Technologists (ARRT) in the Radiation Therapy (T) discipline. Candidates earn it through the primary pathway, which means it is its own examination and not a postprimary add-on to Radiography. The exam is organized around three major content categories published by ARRT: Patient Care, Safety, and Procedures.

One distinction matters before you plan anything. These three categories are official examination content categories, meaning they describe how test questions are classified. They are not chapter headings from a textbook or a curriculum map. Your program's course names (dosimetry, radiobiology, clinical practicum) will cut across them. A single exam question about patient immobilization, for example, could touch Patient Care, Safety, and Procedures depending on its focus, but it is classified under exactly one.

The controlling document for exams through January 31, 2027 is the Radiation Therapy Examination Content Specifications (board approved January 2021, effective January 1, 2022). A separate set of 2027 content specifications takes effect February 1, 2027. This article covers the current 2026 scope only. If your exam date falls after that changeover, check the newer document before you finalize your plan, and see our guide to RTT exam dates, testing windows, and deadlines for scheduling details.

How the 200 Scored Questions Are Divided

The exam contains 230 questions in total. Of those, 200 are scored and 30 are unscored pilot questions that ARRT uses to evaluate future items. You will not know which are which, so treat every question as if it counts.

The official scored-question allocations are counts, not published percentages, and it is best to keep them that way when you plan:

The pattern is easy to read: Procedures is roughly as large as the other two domains combined. A candidate who spreads study time evenly across the three domains is under-investing in the area where the exam concentrates its weight. At the subcategory level, the single largest block is Treatments (35), followed by Radiation Protection, Equipment Operation, and Quality Assurance (30) and Patient Interactions and Management (29).

Domain 1: Patient Care

Patient Care accounts for 46 of the 200 scored questions, split between Patient Interactions and Management (29) and Patient and Medical Record Management (17). In radiation oncology this domain has a particular flavor: your patients are often frightened, symptomatic, and seen daily over weeks, so the exam rewards judgment about ongoing care and not just one-time encounters.

Candidates sometimes treat Patient Care as the "easy" domain because it feels intuitive. That assumption is risky. The questions are written to separate the textbook-correct answer from the plausible-but-wrong one, so practice with realistic scenarios rather than relying on common sense.

Domain 2: Safety

Safety carries 51 scored questions across two subcategories: Radiation Physics and Radiobiology (21) and Radiation Protection, Equipment Operation, and Quality Assurance (30). This is the most quantitative-flavored domain outside dose calculation, and it uses SI units as the primary system, so be fluent in gray, sievert, and becquerel rather than leaning on legacy units.

Note the boundary on brachytherapy. The content specifications limit it to basic common-use, surrounding-tissue-dose, and radiation-protection concepts. You do not need to memorize detailed procedural steps or isotope characteristics to answer these questions, so avoid spending hours on source-by-source data tables.

Domain 3: Procedures

Procedures is where the exam is won or lost: 103 of 200 scored questions. It breaks into four subcategories, and each one corresponds to a stage of the radiation therapy workflow from diagnosis through delivery.

Treatment Sites and Tumors (26 questions)

This is applied anatomy and oncology. You need to connect a disease site to its typical anatomy, patterns of spread, common treatment approaches, and the normal tissues that limit dose. Staging appears only at the level of basic concepts. The exam does not expect site-specific staging systems, so learn what staging is and why it guides treatment, not the detailed criteria for each primary site.

Treatment Volume Localization (18 questions)

Here the focus is on how targets and organs at risk are defined and reproduced. Expect questions on simulation, immobilization, patient positioning, imaging used for planning, and the margins and volumes (gross tumor, clinical, and planning concepts) that translate a diagnosis into a treatable target.

Prescription and Dose Calculation (24 questions)

This is the math-heavy corner of the exam. Calculators are provided on-screen (basic and scientific), so the challenge is knowing which relationship to apply, not arithmetic speed. Be comfortable with prescription terminology, fractionation schemes, monitor unit and time calculations, and how factors such as depth, field size, and beam modifiers change the answer.

Treatments (35 questions)

The largest single subcategory on the whole exam. It covers the delivery of treatment itself: setup, verification, image guidance, beam modifiers and accessory devices, and the different treatment techniques and modalities. Because it is closest to your daily clinical work, it also tends to reward candidates who paid close attention during their clinical rotations.

Format, Timing, and Scoring Mechanics

Knowing the blueprint is only half the picture. The delivery rules shape how you should pace and practice.

• Delivery: Computer-based at a Pearson VUE test center.
• Length: 230 questions (200 scored plus 30 unscored pilot) with 230 minutes of answering time. The full appointment is 250 minutes once you include the tutorial, nondisclosure agreement, and survey.
• Question types: Primarily single-best-answer multiple choice. The ARRT handbook also describes possible alternative formats, including multiple-response and ordered-response items, as well as image-based questions.
• Navigation: You must answer each item before advancing, but you can flag questions and revisit them.
• Tools: Closed book. Basic and scientific on-screen calculators are available, and Pearson can supply a basic four-function calculator on request. Personal calculators are prohibited.

With 230 minutes for 230 questions, you have roughly a minute per item on average. That is enough time for careful reading but not for lingering, so practicing with timed sets matters. Our complete difficulty guide to the RTT exam goes deeper on pacing.

The passing score is a scaled score

ARRT reports results on a 1-99 scale, and the passing score is 75. This is not 75% correct. Raw performance is converted to a scaled score so that candidates are held to the same standard even if different forms vary slightly in difficulty. A revised examination cut-score standard took effect February 1, 2025, and the reported passing score stays at 75 scaled. For the full explanation, read our article on the RTT passing score. For outcome data, ARRT's 2025 Annual Exam Report lists a 77.1% first-time pass rate among 958 candidates; our RTT pass rate analysis puts that figure in context.

For a full pricing picture, see the RTT certification cost breakdown.

Where Clinical Competencies Meet the Blueprint

Before you ever sit for the exam, you must complete an ARRT-verified radiation therapy educational program and its didactic and clinical competency requirements. These clinical requirements map neatly onto the exam domains, which is one reason clinical time is also exam preparation.

• Patient care: CPR plus six other patient-care activities.
• Safety and QA: Five quality-control activities.
• Localization and planning: Six treatment-simulation procedures, dose calculations for six treatment plans, and fabrication of three accessory devices.
• Special procedures: Participation in four special treatment procedures, one specialized simulation procedure, and one specialized accessory-device construction process.
• Treatment delivery: 16 radiation treatment procedures, including at least 13 on patients and no more than three simulated.

Your program director or designee must verify clinical competency through in-person direct observation; remote or virtual observation is not accepted. Eligibility also requires an associate degree or higher from an ARRT-recognized accredited institution (any major, conferred before the exam) and compliance with ethics requirements. The degree must be earned and the application submitted no more than three years after program completion, which is a separate clock from the three-year exam-attempt window. Details live in our RTT requirements guide.

What Is Deliberately Out of Scope

Knowing what will not be asked is as valuable as knowing what will. The 2022 content specifications set several explicit limits:

• Brachytherapy is limited to basic common-use, surrounding-tissue-dose, and radiation-protection concepts, not detailed procedures or isotope characteristics.
• Staging is limited to basic concepts rather than site-specific staging systems.
• Specific CPT codes are excluded.
• SI units are the primary unit system.

It is also worth separating the 2026 scope from the next revision. The 2027 specifications become effective February 1, 2027, and should not be blended into your current study plan. If you are testing before that date, anchor to the 2022 document.

Sequencing Your Prep Around the Domains

You do not need an elaborate system, only an order that respects the weighting. A practical eight-week arrangement, adjustable to your own timeline, looks like this:

Physics comes early because dose calculation and treatment technique both depend on it, while Patient Care slots in later because its scenario logic is quicker to refresh. For a fuller week-by-week framework, our RTT study guide expands this approach, and the RTT cheat sheet works well for the final review pass. When you are ready to test yourself against realistic items, start with the RTT practice test and track results by subcategory.

Frequently Asked Questions