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IMRT, IGRT and advanced radiotherapy in India

These are not different treatments. They are different ways of delivering the same radiotherapy more accurately, so the tumour receives full dose while your heart, lungs, bowel and spinal cord receive as little as possible. India's cancer centres use all of them as standard, and which one you receive should be decided by where your tumour is.

3DCRT
Shapes the beam to the tumour's outline. The established baseline
IMRT
Varies the intensity across the beam, so dose can bend around organs
IGRT
Imaging at each session to confirm the target is where the plan expects
RapidArc / VMAT
Delivers IMRT while rotating around you. Minutes instead of longer
Respiratory gating
Accounts for breathing movement. Includes DIBH for breast cancer
Painless
You feel nothing during any of them

Why the technique matters at all

Radiotherapy works by damaging the DNA of cancer cells. The difficulty has never been killing cancer cells; a large enough dose does that reliably. The difficulty is that healthy tissue sits in the beam's path, and some of that tissue matters enormously. The heart behind the left breast. The spinal cord behind a neck tumour. The salivary glands beside a throat tumour. The bowel in front of the prostate.

Every technique on this page exists to solve the same problem: how to give the tumour a full, curative dose while giving those structures as little as possible. Better technique does not mean a stronger treatment. It means a more precisely placed one, which usually translates into fewer long-term side effects rather than a higher chance of cure.

3DCRT: shaping the beam

Three-dimensional conformal radiotherapy was the first big step beyond simple rectangular beams. A CT scan builds a three-dimensional model of your tumour, and metal leaves inside the machine move to shape each beam to the tumour's outline as seen from that angle. Several beams come from different directions and overlap on the target.

It remains a perfectly good technique for many situations, particularly where the tumour is a simple shape with nothing critical immediately beside it. It is also quicker to plan. What it cannot do is create a concave dose shape, which matters when a tumour wraps around something you need to protect.

IMRT: varying the intensity

Intensity-modulated radiotherapy takes the next step. Instead of each beam having uniform strength across its width, the leaves move during delivery so that intensity varies from point to point within the beam. Combining many such beams lets the dose be sculpted into shapes 3DCRT cannot achieve, including concave shapes that curve around a critical organ.

This is why IMRT became standard for head and neck cancers, where sparing the salivary glands prevents lifelong dry mouth, and for prostate cancer, where the rectum sits directly behind the target. The trade-off is that IMRT spreads a low dose over a somewhat wider volume of surrounding tissue, which is one reason it is chosen deliberately rather than used for everything.

IGRT: checking before every session

Image-guided radiotherapy is not a way of shaping the dose. It is a way of confirming your anatomy is where the plan assumed. Before or during each session, imaging is taken on the treatment machine and compared with the planning scan, and your position is corrected if needed.

This matters more than it sounds. Tumours and organs shift between sessions: the bladder fills, the bowel moves, you lose weight over a six-week course, a tumour shrinks. Without imaging, plans compensate by treating a wider margin. With IGRT, that margin can be tighter, and a tighter margin means less healthy tissue irradiated. IMRT and IGRT are therefore usually used together, since the precision of IMRT is only useful if you can be certain the target is in the right place.

RapidArc and VMAT: delivering while rotating

Volumetric modulated arc therapy, of which RapidArc is one manufacturer's version, delivers IMRT continuously while the machine rotates around you, rather than stopping at fixed angles. The dose distribution is comparable to fixed-beam IMRT, sometimes better, but delivery takes a fraction of the time, often only a couple of minutes on the couch.

Shorter time is not merely comfort. The less time you spend lying still, the less chance you shift position or your breathing pattern changes, so accuracy improves too. For patients who find lying flat painful, which includes many people with bone metastases or advanced disease, it makes a real difference to whether treatment is tolerable.

Respiratory gating: treating something that moves

Everything above assumes the target stays still. In the chest and upper abdomen it does not. A lung tumour can travel a couple of centimetres with each breath, and the same applies to the liver and to the chest wall in breast cancer. Radiotherapy that ignores this must treat a margin large enough to cover the whole path of movement, which means irradiating a lot of healthy lung or liver.

Respiratory gating solves it by synchronising treatment with your breathing. Your breathing cycle is monitored, and the beam switches on only during the part of the cycle when the tumour is in the planned position, switching off automatically the rest of the time. Sessions take a little longer, and the healthy tissue spared is substantial.

DIBH for breast cancer, and why the heart matters

Deep inspiration breath-hold is the version of this that matters most for breast cancer, particularly on the left side. The heart sits directly behind the left breast, and radiation to the heart carries a small but real long-term risk of heart disease appearing years or decades later. For a woman treated in her forties and expected to live for decades, that is not a trivial consideration.

When you take a deep breath and hold it, your lungs inflate and physically push the heart away from the chest wall, opening a gap of a centimetre or more between the heart and the treatment area. Treatment is delivered only while you hold that breath, in short bursts of perhaps twenty seconds, and pauses while you breathe normally between them. Nothing is required of you except the ability to hold a breath, which is practised beforehand.

If you have left-sided breast cancer and radiotherapy is planned, ask whether DIBH will be used. It is a reasonable and specific question, and the answer tells you a good deal about the centre.

Gating for lung cancer

For lung cancer the goal is different: protecting the healthy lung around the tumour. Because a lung tumour moves so much with breathing, gating allows a far tighter margin, meaning less healthy lung receives dose. That reduces the inflammation and long-term scarring that can otherwise leave patients breathless.

For small lung tumours, this can be taken further with stereotactic body radiotherapy, delivering a very high dose in a handful of sessions. CyberKnife achieves the same end differently, by tracking the tumour continuously rather than gating the beam on and off. Which route suits you depends on the tumour's size and position.

Which technique for which cancer

A general guide. Your radiation oncologist decides from your scans, not from a table.
CancerUsually involvesWhy
Head and neckIMRT with IGRTSpares salivary glands and spinal cord
ProstateIMRT or VMAT with IGRTRectum sits directly behind the target
Left breast3DCRT or IMRT with DIBHMoves the heart out of the beam
LungIMRT or SBRT with gatingTumour moves with every breath
BrainIMRT, or radiosurgeryCritical structures within millimetres
CervixIMRT plus brachytherapyInternal dose reaches what external beams cannot
Bone metastases3DCRT or VMATSimple target, speed and comfort matter most

Sessions and how long you will stay

These techniques change how each session is delivered, not usually how many you need. A curative course commonly runs as daily weekday sessions over roughly four to seven weeks, depending on the cancer. Each individual session is short, often under fifteen minutes on the couch, and VMAT can reduce that to a few minutes.

For anyone travelling from abroad this is the crucial planning point. A full course means an extended stay, not a short trip, and a companion will usually need to stay too. Shorter hypofractionated schedules are used for some cancers, and for small targets radiosurgery may complete treatment in one to five sessions. Ask specifically how many sessions your plan requires before you book anything.

What it costs in India

These are indicative package prices for a full course of treatment from our partner hospitals, not a per-session rate. The differences between them reflect planning complexity and machine time rather than how well the treatment works.

Indicative partner-hospital package prices, USD, as at July 2026. Full course.
TechniqueIndicative costTypically
IMRT$3,000Daily sessions over several weeks
IGRT$4,200As above, with imaging at each session
Stereotactic radiation therapy$5,700A few high-dose sessions instead of many
Chemoradiation (with chemotherapy)$6,500Around 6 weeks
Reading this properly. IGRT costs more than IMRT because imaging is performed at every session, which allows tighter margins and less dose to healthy tissue. Stereotactic treatment costs more per course but compresses it into a few sessions, which for someone travelling can reduce the total trip cost considerably once accommodation is counted.

Indicative package prices as at July 2026, not a quotation. What the package includes: hospital charges, the surgeon's fee, medicines given during your stay, and any implants and consumables. Not included: pre-operative investigations, flights, visa, accommodation outside the hospital stay, or treatment for complications. Your written estimate follows the specialist's review of your scans. No part of it is a fee to us; the hospital pays us, so your bill is never marked up.

For an international patient the arithmetic that matters is course length times accommodation, added to the treatment price. Six weeks of daily radiotherapy is a materially different trip from four stereotactic sessions, even where the treatment prices look similar. Ask for both numbers, the price and the number of sessions, before you book anything.

Remember to count the whole trip: several weeks of daily sessions means accommodation for you and a companion. You receive a written estimate covering planning, treatment and follow-up before you commit, with no fee to us built in; the hospital pays us, so your bill is never marked up.

Questions patients ask

What is the difference between IMRT and IGRT?

They do different jobs and are usually used together. IMRT shapes the dose, varying beam intensity so it can curve around organs you need to protect. IGRT checks position, using imaging at each session to confirm the target is where the plan expects before the beam turns on. IMRT decides where the dose goes; IGRT makes sure you are in the right place to receive it.

Is IMRT better than 3DCRT?

For complex targets close to critical organs, yes, because it can create dose shapes 3DCRT cannot. For simpler targets with nothing vital nearby, 3DCRT does the job just as well and spreads less low dose through surrounding tissue. Better technique means better suited to your case, not universally superior.

What is RapidArc, and is it different from VMAT?

RapidArc is one manufacturer's name for volumetric modulated arc therapy, VMAT. Other manufacturers have their own names for equivalent technology. It delivers IMRT while rotating around you, so treatment takes a few minutes rather than longer. The underlying principle is the same whatever it is branded.

Do I need to hold my breath during treatment?

Only if DIBH is being used, which is mainly for left-sided breast cancer. You hold a deep breath for around twenty seconds at a time while the beam is on, then breathe normally between bursts. It is practised with you beforehand, and if you cannot hold a breath comfortably, other approaches such as gating or prone positioning are used instead.

Why does breathing matter for radiotherapy?

Because tumours in the chest and upper abdomen move with each breath, sometimes by a couple of centimetres. Without accounting for that, a wide margin must be treated to cover the whole range of movement, which irradiates far more healthy lung or liver. Gating switches the beam on only when the tumour is in the right position.

Does more advanced technique mean a better chance of cure?

Usually it means fewer side effects rather than a higher cure rate. The tumour receives a full dose either way; the advantage is that less healthy tissue does. For younger patients with decades ahead, reducing long-term effects on the heart, lungs or salivary glands is a genuine benefit worth having.

Are these techniques available in India?

Yes. IMRT, IGRT, VMAT and respiratory gating including DIBH are standard in India's accredited cancer centres rather than rare or experimental. Our partner network includes hospitals with this equipment, and we will name the hospital and consultant before you commit to anything.

How is this different from CyberKnife or Gamma Knife?

These techniques deliver a curative dose over many sessions, typically weeks. CyberKnife and Gamma Knife are radiosurgery: a very high dose to a small, well-defined target in one to five sessions. Radiosurgery suits small discrete targets; conventional radiotherapy suits larger areas and cases where lymph nodes must also be covered.