What to Expect During Radiation Therapy
What to expect during radiation therapy is usually calmer than people fear. The beam runs for a few minutes and you won't feel it. So where does the rest of the visit go? This page walks through planning, a typical treatment day, side effects and recovery, so you know the route before you start.
Reviewed by Dr. P. Vijay Karan Reddy · Radiation Oncologist ·
Last updated October 2026
What to expect during radiation therapy: a planning visit first, then short outpatient sessions, usually Monday to Friday, over days or weeks. At Dr. Karan's centre a visit takes 60 to 90 minutes with waiting, but only 5 to 10 minutes are on the table (stereotactic sessions run longer), and the radiation is painless. Fatigue and skin changes are the most common side effects, and most ease once treatment ends.
Before Your First Session
What to expect during radiation therapy starts with a consultation. Dr. Karan reviews your scans and reports, then your case goes to a weekly tumour board. The plan is confirmed on the day the board meets and explained to you before treatment starts. It's evidence-based, never tilted toward one specialty.
Then comes simulation: a planning scan in your exact treatment position. You may be fitted with a mask, and small marks help line you up each day. Radiotherapy technologists do both. Only pelvic cases need preparation, with a full bladder before each treatment, and no medicines need to be held. Simulation is quick: about 5 minutes for the mask and 5 for the scan. If a PET-CT or MRI is added, plan on half a day, roughly 9am to 2pm. The first session follows about two days later on average.
Radiation Therapy Process Step by Step: Your First Session
- 01
Check in and settle
Arrive, confirm your name and plan, and change into a gown if the area being treated needs it. Loose, comfortable clothes make this easier. The therapists then walk you into the treatment room.
- 02
Positioning
You lie on the table in the same position as your planning scan, using any mould or mask. Small skin marks, and often a quick check scan, line you up before the beam starts.
Learn about IGRT → - 03
Delivery
The machine moves around you with a gentle buzz while the team watches on camera. You feel nothing, and for most treatments the beam is on for only a few minutes. At Dr. Karan's centre, that's a TrueBeam STx linear accelerator with HyperArc, with kV and cone-beam imaging.
- 04
Weekly rhythm
Most people come five days a week, Monday to Friday, and go home afterwards. Dr. Karan sees you on the first day and then once a week to check your skin, weight and energy, and assistant doctors monitor you daily, so small problems get caught early. For SRS or SBRT you're reviewed daily, and for anything urgent you can contact him directly.
How Many Sessions Will I Need?
How long does radiation therapy take? From a single session to about seven or eight weeks, depending on the cancer, the dose and the goal. In Dr. Karan's practice, stage 1 lung SBRT runs 3 to 5 days and early prostate 1 to 3 weeks. Most ranges follow Mayo Clinic, ASTRO and Royal College of Radiologists guidance, and the head and neck figure is Dr. Karan's own.
- Symptom relief (palliative)
- 1 to 10 sessions (up to 2 weeks)
- SBRT / SRS
- 1 to 5 sessions
- Breast cancer, shorter course
- 15 sessions (about 3 weeks)
- Head and neck, standard course
- 30 to 33 sessions (about 6 weeks)
See the IGRT, IMRT, SBRT and SRS pages for each schedule. At Dr. Karan's centre, IMRT and IGRT courses run 30 sessions for brain, 25 for breast, cervical and rectal cancer, and 25 to 30 for prostate. With IGRT, prostate can take 20 to 25. SBRT takes 3 to 5.
Managing Radiation Therapy Side Effects
Of everything in what to expect during radiation therapy, side effects vary most. Mayo Clinic says they depend on the area treated, and most fade after treatment.
Bringing Support With You
You don't have to do this alone. A family member or friend can come to consultations, take notes and keep you company afterwards. They usually wait outside during treatment, since the room is shielded. Our view: a second pair of ears catches what you miss.
Picture arriving for session one with your questions written down and a friend in the waiting area. It's a very different morning from walking in blind. Honestly, the unknown is often harder than the treatment. If worry stays heavy, counselling and support groups are available at the centre, so just ask.
Questions to Ask Your Care Team
Bring these to your appointment to learn what to expect during radiation therapy in your own case.
- What is the goal of my radiation: cure, control or symptom relief?
- How many sessions will I have, and on which days?
- Which technique will you use, and why does it suit my cancer?
- Which side effects should I watch for, and who do I call?
- Do I need a full bladder, an empty stomach or any other preparation?
- Will I have chemotherapy or other treatment alongside the radiation?
- Which scans and check-ups will follow once treatment ends?
- Can I speak to someone who has been through this treatment?
Unsure About Your Radiation Plan? Get a Second Opinion
Want to know what to expect during radiation therapy in your case? Send your scans and reports. Dr. Karan will review them, explain each step, and tell you honestly what he'd recommend. He brings eleven years in radiation oncology to every review, and treats patients at Apollo Hospital, Financial District.
After Your Last Session
Questions Patients Ask Us
It uses high-energy beams, usually X-rays, to damage the DNA of cancer cells so they can't grow or divide. Healthy cells repair themselves more easily, which is why treatment is spread over several sessions.
No, you won't feel the beam, much like having an X-ray. Tell the team if lying still becomes uncomfortable.
No, after external beam radiation you aren't radioactive and can safely be around family and children. Internal radiation (brachytherapy) is different, and your team will advise you if it applies.
Only where the beam passes. Hair loss happens at the treatment site and is sometimes permanent, so radiation to your chest or pelvis won't affect the hair on your head.
Many appear a couple of weeks in and build gradually. According to Mayo Clinic, most go away after treatment, though some late effects can appear later.
Loose, soft clothes that are easy to move away from the treated area. Leave jewellery at home and avoid tight collars or bras on treated skin.
Regular, balanced meals with enough protein and fluids, even when appetite dips. If eating becomes difficult, ask for a dietitian early.
Not always, but protons can spare more nearby healthy tissue. Dr. Karan's view: they can be used almost anywhere radiation is, and the main limit is affordability.
Proton beam therapy →Tell your team as soon as you can. A missed day is usually added at the end, though for some cancers the team makes up time sooner, so try not to skip sessions.
It depends on the technique, the number of sessions and the hospital. At Dr. Karan's centre, a course of IMRT costs ₹2.5 lakh, IGRT ₹4.5 lakh, SRS ₹3 lakh and SBRT ₹4.5 lakh.
Walk Into Your First Session Knowing What Comes Next
Book a consultation and Dr. Karan will explain what to expect during radiation therapy in your case: your plan, how many sessions, and what each visit involves. Already have a plan elsewhere? A second look is welcome. You'll leave knowing exactly what happens on day one.
Written & reviewed by Dr. P. Vijay Karan Reddy ·
Radiation Oncologist · Last reviewed October 2026