Radiation Therapy

What radiation therapy actually is

Radiation therapy (also called radiotherapy) is the use of carefully measured beams of high-energy X-rays — and sometimes other particles like protons or electrons — to damage the DNA of cancer cells in a defined area of the body. Damaged cancer cells can no longer divide, and they die off in the days and weeks after treatment. Healthy cells around the target absorb some dose too, but they repair themselves far more effectively than cancer cells can, which is why radiation works.

Most radiation is delivered as external beam radiation therapy — a machine called a linear accelerator (linac) directs the beams at the tumour from outside the body. You feel nothing during the few minutes of treatment. Other techniques — like brachytherapy, where a radioactive source is placed inside the body for a short time — are used for specific cancers.

"Many patients walk in expecting radiation to feel like something — heat, pain, anything. Almost always, the first comment after the first session is: 'That's it?' That's it. The work happens silently, on a microscopic scale, over the weeks that follow."

When radiation is the right tool

Radiation therapy is used in three broad situations:

Why dual-trained matters

Many cancers do best when chemotherapy and radiation are used together — sometimes at the same time (concurrent), sometimes in sequence. Because Dr. Rehan is dual-trained in both medical and radiation oncology, the two halves of your treatment are planned and adapted by the same person — the one who knows you, your scans, your side effects, your goals. There is no handover between physicians, no gap in communication, no risk that the two halves of your treatment are pulling against each other.

How a course of radiation is planned

Before the first dose is delivered, an enormous amount of planning happens behind the scenes — this is what makes modern radiation so safe and effective.

1. Consultation & decision — we discuss whether radiation is recommended, the expected benefits, the side effects to anticipate, and the alternatives. You leave with a written plan.
2. CT simulation — a planning CT scan is done in the same position you'll be treated in. Small marks (or tiny tattoo dots) are placed on the skin so we can reproduce the position exactly every day.
3. Contouring & planning — over the next few days, the tumour and the surrounding normal organs are outlined on the CT, and a physicist calculates a custom beam arrangement that maximises dose to the target while sparing nearby structures.
4. Quality checks — every plan is independently checked before treatment starts.
5. Treatment delivery — daily sessions begin, usually Monday to Friday for several weeks.

What a treatment day looks like

Each daily session is short — most of the time you spend at the centre is registration, undressing, and positioning. The actual beam is on for only a few minutes.

1. You arrive and check in.
2. You change into a gown (depending on the body area being treated).
3. The therapists position you on the treatment couch using your planning marks. You stay still — you don't need to hold your breath or do anything special unless the plan requires it.
4. The therapists step out, the machine moves around you, and the beam is delivered. You hear a buzzing sound; you feel nothing.
5. You're done — usually 10 to 20 minutes door to door. You drive yourself home, go to work, pray, do whatever you'd normally do.

Side effects — what to expect, what we'll do

Side effects from radiation are usually local — affecting only the area being treated. They build up gradually over the course of treatment and peak in the week or two after it ends, then settle. Most are manageable with simple measures:

• Skin changes in the treated area — redness, dryness, sometimes peeling. Gentle moisturisers and avoiding sun help.
• Fatigue — common, builds through the course, improves over the weeks afterwards. Pacing and short walks help more than complete rest.
• Mucosal effects — if the head & neck or pelvis is being treated, the mouth, throat, bladder or bowel inside the treated area can become sore or irritated. We pre-empt this with specific medications.
• Hair loss — only in the treated area, not all over.
• Late effects — modern planning has dramatically reduced these, but for some sites we'll discuss long-term risks (e.g. fertility, fibrosis, second cancers many years later) in detail so you can decide with full information.

Working, family life, prayer, fasting

Most patients continue much of normal life during radiation. Daily sessions are short, the side effects are usually mild to moderate, and there's no risk of you "carrying radiation home" — once you walk out of the treatment room, you are not radioactive and pose no risk to children, pregnant relatives, or anyone else. Prayer, social activities, and travel between sessions on weekends are usually fine. Fasting during Ramadan can sometimes be accommodated for shorter courses — we'll discuss this individually.

After radiation ends

The end of radiation is a milestone, but not the end of care. Side effects continue to evolve for a few weeks, then improve. The first follow-up scan typically happens two to three months later — sooner is rarely useful, because the body is still healing and an early scan can be misleading. We'll see you regularly, adjust as needed, and stay alert to the long-term things that matter. Read about life after treatment →