Types of Radiation Therapy in India Explained: IMRT, IGRT, SBRT & Proton for International Patients
Radiation therapy has evolved dramatically over the past two decades. The phrase "radiotherapy" no longer describes a single treatment — it encompasses fundamentally different technologies with different levels of precision, different dose schedules, and different appropriate indications. For international patients planning cancer treatment in India, understanding the difference between conventional radiation, IMRT, IGRT, SBRT, and proton therapy determines whether you're comparing equivalent options when evaluating hospitals.
TL;DR: India's top cancer centres offer the full spectrum: IMRT (USD 5,000–10,000 for a full course), IGRT (USD 6,000–12,000), SBRT (USD 5,000–9,000 for 5–8 fractions), and proton therapy (USD 20,000–35,000 at Apollo Proton Cancer Centre, Chennai). The right modality depends entirely on tumour site, size, and proximity to critical structures (Patients Beyond Borders, 2024).
Why Radiation Technology Matters
All radiation therapy works by depositing ionising radiation energy in tumour cells, causing DNA damage that kills them. The difference between technologies is how precisely that energy is delivered — and how well normal tissue adjacent to the tumour is spared.
Higher precision = higher dose to tumour, lower dose to surrounding tissue = better tumour control with fewer side effects.
The practical significance: for a prostate cancer patient, the difference between conventional radiation and IMRT is the difference between significant bowel and bladder side effects and minimal side effects. For a paediatric brain tumour, the difference between conventional radiation and proton therapy can mean the difference between serious neurocognitive developmental impairment and relative preservation of cognitive function.
India's JCI-accredited cancer centres have invested in modern technology precisely because they treat high volumes of international patients who expect current standards.
Conventional External Beam Radiotherapy (3D-CRT)
What it is: Three-dimensional conformal radiotherapy uses CT-planned beams shaped to conform to the tumour volume from multiple angles. An improvement over older 2D techniques but less precise than IMRT.
When it's appropriate: Simple tumour geometries without critical structures immediately adjacent. Palliative intent (symptom relief rather than cure). Some adjuvant post-operative situations.
Availability: Available at all Indian radiation oncology departments.
IMRT — Intensity-Modulated Radiation Therapy
What it is: IMRT divides each radiation beam into hundreds of small segments (beamlets), each of which can be independently adjusted in intensity. A computer optimisation algorithm calculates the combination of beamlets that delivers the prescribed dose to the target while minimising dose to specified organs at risk.
When it's the standard: Head and neck cancer (sparing salivary glands and spinal cord), prostate cancer (sparing rectum and bladder), cervical cancer (sparing bowel and kidneys), and most other anatomically complex tumour locations. IMRT is the baseline standard at all JCI-accredited Indian centres — not a premium add-on.
Cost: USD 5,000–10,000 for a full course (typically 25–33 fractions over 5–7 weeks).
IGRT — Image-Guided Radiation Therapy
What it is: IGRT adds real-time imaging before each fraction to verify the tumour's position has not shifted between sessions. Soft tissue tumours (prostate, liver, lung) can move with breathing, bowel filling, and bladder filling. IGRT corrects for this positioning variation before each delivery.
When it's essential: Prostate cancer, liver tumours, lung tumours, and any site where internal organ movement is significant. IGRT is not an alternative to IMRT — it's a complement that adds positional verification.
Cost: USD 6,000–12,000 for a full IGRT course. Many centres include IGRT as part of standard IMRT delivery; confirm what's included in the quote.
VMAT — Volumetric Modulated Arc Therapy
What it is: VMAT delivers IMRT while the treatment head rotates around the patient in one or more arcs, rather than from fixed angles. This allows dose delivery in 1–3 minutes versus 15–30 minutes for conventional IMRT, without compromising dosimetric quality.
Clinical significance: Faster treatment time reduces patient movement during delivery and increases throughput. Increasingly the standard delivery technique at modern Indian centres using Varian TrueBeam and Elekta Versa HD platforms.
SBRT / SABR — Stereotactic Body Radiotherapy
What it is: SBRT (stereotactic body radiotherapy, also called SABR — stereotactic ablative radiotherapy) delivers ablative doses — doses high enough to be tumoricidal in a single fraction — over 5–10 sessions rather than 25–33. The total dose is equivalent or higher, but the hypofractionated schedule causes more direct cell death and changes the biological response.
When it's used: Early-stage inoperable lung cancer (where it's replaced surgery as the standard for some patients), liver metastases, adrenal metastases, spine and bone metastases, kidney tumours, and prostate cancer. Also used for oligometastatic disease — 1–3 metastases — in the context of systemic therapy.
What makes it different: SBRT requires highly precise image guidance, respiratory motion management (4D-CT planning, gating), and immobilisation. It's not available at every Indian centre and should only be done at centres with dedicated experience and appropriate equipment.
Cost: USD 5,000–9,000 for a full 5–8 fraction SBRT course.
SRS — Stereotactic Radiosurgery (Brain)
What it is: SRS is a single-fraction very high dose treatment for brain lesions. Not surgery — the name is historical. Gamma Knife (Leksell Gamma Knife) and CyberKnife (linear accelerator-based) are the common platforms.
When it's used: Brain metastases (multiple small metastases), acoustic neuroma, meningioma, AVM (arteriovenous malformation), and pituitary adenoma. Highly effective for lesions under 3 cm in diameter. Larger or eloquent area tumours may require fractionated stereotactic radiotherapy (FSRT) over 3–5 sessions.
Cost: USD 4,000–8,000 for single-fraction SRS. FSRT 3–5 fractions costs USD 7,000–14,000.
Centres with Gamma Knife include Fortis Memorial Gurgaon, Apollo Delhi and Chennai, and Manipal Bengaluru.
Proton Therapy
What it is: Protons are accelerated to high energy and deposit most of their energy at the tumour (the Bragg peak) before stopping, rather than continuing to irradiate tissue beyond the tumour as photons do. This dramatically reduces dose to tissues distal to the tumour.
When it offers meaningful advantage: Paediatric tumours (where sparing developing tissue is critical), base of skull tumours, spinal cord tumours, re-irradiation (where conventional photon therapy would exceed tissue tolerance), selected head and neck cancers, and thoracic tumours adjacent to spinal cord.
When the advantage is marginal: Some adult solid tumours where conventional IMRT already achieves acceptable organ-at-risk sparing. Not every cancer benefits equally — discuss with your radiation oncologist whether proton therapy changes outcomes for your specific diagnosis.
In India: The Apollo Proton Cancer Centre (APCC) in Chennai is India's first and most advanced proton therapy facility. Operational since 2019, it uses a pencil-beam scanning proton system — the most precise form of proton delivery. Available for patients from across the globe.
Cost: USD 20,000–35,000 for a full proton therapy course.
Choosing the Right Modality
The radiation oncologist at your Indian centre will recommend the appropriate technology for your specific diagnosis, tumour characteristics, and treatment intent. Use this framework to verify the recommendation makes sense:
- IMRT/VMAT: appropriate for most curative-intent solid tumour treatments
- IGRT: should be part of any IMRT course for sites with significant motion
- SBRT: appropriate for oligometastatic disease, inoperable early-stage lung cancer, liver/spine lesions
- SRS/FSRT: for brain lesions
- Proton: for paediatric cases, base of skull, re-irradiation, selected cases
For a full overview of cancer care options in India, see our oncology guide. For details on lung cancer treatment specifically, see our lung cancer treatment guide.
To discuss which radiation modality is appropriate for your diagnosis and get an estimate from an Indian radiation oncology centre, start your case review with Arodya here.
