Intensity Modulated Radiation Therapy (IMRT)

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What is IMRT and what are the advantages it offers?

IMRT stands for Intensity Modulated Radiation Therapy. Unlike conventional radiation therapy for cancer in which a single, large radiation beam passes through the body, IMRT breaks up the radiation beam into thousands of tiny “beamlets”, which enter the body from many angles and intersect on the tumor. As a result, IMRT allows precise radiotherapy treatments, resulting in a higher dose to the tumor and a lower dose to the surrounding tissue.

When is IMRT used?

IMRT is the most advanced cancer-fighting technology to date and is quickly becoming the cancer treatment of choice for organs affected by respiration. It is indicated in the accurate targeting of irregularly-shaped tumors and to minimize radiation dose to surrounding healthy organs.

Through IMRT:

  • Multiple tumors in the brain can be treated with high doses of radiation with minimal risk to the patient
  • Re-treatment of extra-cranial (outside the skull) tumors and tumors of the head and neck, abdomen and pelvis can be safely accomplished
  • Prostate cancer treatment doses can be significantly increased without increased risks or complications
  • Tumors that threaten vital organs (eyes, spinal cord) can be controlled and their symptoms reversed
  • A viable non-invasive alternative to radiosurgery is available in the treatment of benign intra-cranial (within the skull) tumors

With IMRT, doctors have greater freedom in exploring the possibility of increasing radiation dose with less risk to the patient.

Who are involved in IMRT?

A specially trained radiation therapy team performs IMRT. The radiation oncologist is a specially trained physician who heads the treatment team. Together with the medical physicist who ensures the delivery of precise radiation doses, the radiation oncologist plans an individualized course of treatment. Under the supervision of medical physicist, the dosimetrist calculates the IMRT exposures and beam configurations necessary in delivering the doses prescribed by the radiation oncologist. A highly trained technologist positions the patient on the treatment table and operates the machine.

What preparations are needed before the procedure?

Your doctor will review your medical history and conduct a thorough physical examination. Present to your doctor results of previous scan you may have undergone, including Positron Emission Tomography (PET), Magnetic Resonance Imaging (MRI) and X-ray. These scans will help the radiation oncologist to determine the precise location of your tumor.

You will undergo a preparation session in which a special device will be molded to help you maintain an exact treatment position throughout the course of treatment. This is followed by a CT scan and a simulation to obtain a 3-dimensional shape of the tumor and normal tissues; the stimulation ensures the alignment of the machine and the target tumor.

Excerpt from Intensity Modulated Radiation Therapy, a St. Luke's Medical Center advertorial.