Image-guided radiation therapy (IGRT) is the use of imaging during radiation therapy to improve the precision and accuracy of treatment delivery. IGRT is used to treat tumors in areas of the body that move, such as the lungs. Radiation therapy machines are equipped with imaging technology to allow your doctor to image the tumor before and during treatment. By comparing these images to the reference images taken during simulation, the patient’s position and/or the radiation beams may be adjusted to more precisely target the radiation dose to the tumor. Confidence in targeting through imaging also allows the doctor to use smaller safety margins and spare more healthy tissue.

How does it work?

IMRT utilizes beams shaped by multileaf collimators (MLCs) that move in and out of the beam’s path during treatment, varying the radiation beam intensity across the targeted field.

A combination of such beams of varying intensity allows a highly sculpted three dimensional distribution of radiation, maximizing dose to the tumour while reducing or even avoiding healthy tissues. Advanced computer planning helps to find the best combination of beams to achieve the desired results.

Benefits of IGRT

  • Treatment is delivered with precise accuracy, thus minimizing the effect on
    surrounding normal tissues and organs
  • High therapeutic ratio (maximum tumour control and minimum side effects)
  • Treated on an outpatient basis
  • As side effects are reduced, patients can resume their normal activities earlier

Am I suitable for IGRT?

Currently, IMRT is being used most extensively to treat cancers of the prostate, head and neck, gastrointestinal, gynaecologic malignancies, sarcomas and central nervous system. IMRT may also be beneficial for treating pediatric malignancies.

However, IMRT may not be suitable for all situations, so a radiation oncologist will determine the suitability based on the tumour position, age and comorbidity and recommend the most appropriate treatment technique.

Our Cancer Specialists


Dr. Jonathan Teh Yi Hui

Senior Radiation Oncologist

Stereotactic Radiosurgery (SRS/SBRT), Head & Neck, Pediatric, Urologic, Gastrointestinal Cancers & Sarcoma


Dr Daniel Tan Yat Harn

Medical Director & Senior Radiation Oncologist

Stereotactic Radiosurgery (SRS/SBRT), Brain and Spine, Breast and Prostate Cancers


Dr David Tan Boon Harn

Senior Radiation Oncologist

Stereotactic Radiosurgery (SRS/SBRT), Gynaecological, Gastrointestinal & Lung Cancers

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