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Disponible en español: Qué esperar antes de empezar radiación

Beginner 7 min readSource verified

What to Expect Before Starting Radiation

What usually happens before radiation begins, including consultation, simulation, planning, tattoos or marks, schedule, side effects, and questions to ask.

AI-assisted and source verified. Not reviewed by a healthcare professional unless specifically stated.

Sources last checked: 2026-07-21Last updated: 2026-07-21Next planned review: 2027-07-21

How this page was created

Cancer Explained uses AI to organize and translate information from the authoritative sources cited on each page. Automated checks review claims, citations, clarity, duplication, and potential safety concerns before publication. Our content is not currently reviewed by physicians unless a specific qualified reviewer is named on the page. Cancer Explained provides general education and should not replace advice from your healthcare team.

Editorial status — Source verified. This page was created with AI assistance and checked against the sources listed on it. Source checking is not a medical review.

General education — varies by person. Answers genuinely differ between people. This page explains what commonly varies and points you to your care team for your situation.

Human medical review: not completed. At this time, most Cancer Explained content has not been reviewed by a physician or other healthcare professional. Pages with documented human medical review identify the reviewer, credentials, and review date directly.

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NCI source

National Cancer Institute - Radiation Therapy

Visual summary for What to Expect Before Starting Radiation

The short answer

Before radiation starts, many people have a consult, simulation, positioning plan, treatment planning period, schedule discussion, and side-effect teaching.

  • Before radiation starts, there is usually a planning phase. This may include a radiation oncology consult, simulation scan, positioning devices, skin marks or tattoos, planning time, and a treatment schedule.

  • The safest next step depends on diagnosis, treatment, symptoms, test results, and the care team's instructions.

  • Use this page to prepare questions and decide what information to bring to the visit.

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The full explanation.

The short answer

Before radiation starts, there is usually a planning phase. This may include a radiation oncology consult, simulation scan, positioning devices, skin marks or tattoos, planning time, and a treatment schedule.

This page is educational. It is meant to help you prepare for care-team conversations, not diagnose a symptom, choose a treatment, or replace medical advice.

Why this matters

Radiation is planned carefully because the target, nearby organs, dose, and schedule matter. The days before treatment are a good time to ask practical questions.

A practical way to prepare

  • Ask what area is being treated and what nearby organs are being protected.
  • Ask how many treatments are planned and whether the schedule could change.
  • Ask what skin care, fatigue, eating, bladder, bowel, or swallowing issues to expect for your treatment area.
  • Ask who to call after hours.

Questions to ask

  • What does this mean for my exact diagnosis, treatment, and current symptoms?
  • What should I do now, what can wait, and what should make me call sooner?
  • Is there a written plan, handout, or referral that would make this easier to follow?
  • Who should I contact after hours, and what information should I have ready?

What to keep in mind

Report symptoms the radiation team flags, especially severe pain, dehydration, fever, bleeding, breathing trouble, or rapidly worsening skin changes.

How this connects to the rest of care

Radiation preparation connects simulation, daily treatment routines, skin care, fatigue, transportation, and work scheduling.

Related pages

Helpful next pages include What Happens During Radiation Simulation?, What to Expect During a Radiation Therapy Session, The Radiation Therapy Timeline: What to Expect, Radiation Dermatitis: Skin Care Questions, What to Expect at a Survivorship Visit, What to Expect When Cancer Treatment Is Delayed.

Words to know

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Common questions

Does this page tell me what to do medically?

No. It explains the topic in plain language so you can ask better questions. Your care team applies it to your diagnosis, treatment, test results, and symptoms.

What should I have ready when I ask about this?

Bring your treatment name, recent dates, current medicines, symptom timing, recent reports, and the exact question you want answered.

When should I contact the care team sooner?

Use the urgent plan your oncology team gave you, especially for symptoms that are new, severe, fast-changing, or specifically listed as warning signs for your treatment.

Questions to ask your doctor

Being prepared helps you get the most out of your appointments. Save or print these questions.

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Your next step

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  1. Q1.What is the safest way to use this page about what to expect before starting radiation?
  2. Q2.Which detail often changes the next step?
  3. Q3.What is a useful question to ask?

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How this page was created

Cancer Explained uses AI to organize and translate information from the authoritative sources cited on each page. Automated checks review claims, citations, clarity, duplication, and potential safety concerns before publication. Our content is not currently reviewed by physicians unless a specific qualified reviewer is named on the page. Cancer Explained provides general education and should not replace advice from your healthcare team.

Editorial status: Source verified This page was created with AI assistance and checked against the sources listed on it. Source checking is not a medical review.

Human medical review: not completed. At this time, most Cancer Explained content has not been reviewed by a physician or other healthcare professional. Pages with documented human medical review identify the reviewer, credentials, and review date directly.

Read more about our editorial process, our use of AI, and our corrections policy.

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Related learning map

How this explanation connects to 12 other things you can explore — related topics, terms, questions, practice, and its NCI source.

What to Expect Before Starting Radiation