Intensity-modulated radiation therapy, or IMRT, is a type of cancer treatment that uses advanced computer programs to calculate and deliver radiation directly to cancer cells from different angles. It allows people with cancer to receive higher, more effective doses of radiation while limiting damage to the healthy tissues and organs around it. This increases your chance for a cure and lessens the likelihood of side effects.

Here are answers to some of the common questions our IMRT experts hear from patients.

1. Which cancers can be treated with IMRT?

IMRT is used at MSK most often to treat prostate cancer, head and neck cancers, lung cancer, brain cancer, gastrointestinal cancers, and breast cancer, in part because these tumors tend to be located close to critical organs and tissues in the body. It may also be used to treat lymphoma, sarcoma, gynecologic cancers, and select pediatric cancers.

2. How is IMRT given?

First, you will have an imaging test called a CT scan that will map your tumor in 3-D. Then a team of radiation therapy experts, including doctors and physicists, will use advanced computer programs to calculate and deliver radiation directly to the tumor from different angles.

At the beginning of each treatment session, a radiation therapist will position you on a treatment table, placing marks on your skin to guide where he or she will deliver the radiation treatment. Treatment sessions are painless.

3. How long do IMRT sessions generally last?

Most treatment sessions take between 10 and 30 minutes.

4. How many treatments do I need?

IMRT requires multiple sessions. Typically, you will have IMRT sessions five days a week for several weeks. The total number of treatments  depends on a number of factors, including the type of cancer you have and the size and location of the tumor.

5. What are the benefits of IMRT?

IMRT allows the radiation dose to conform more precisely to the three-dimensional shape of the tumor by changing — modulating — the radiation beam into multiple smaller beams. This enables a higher dose of radiation to be delivered to the tumor while sparing healthy tissue around it. To deliver these smaller beams, the machine forms the radiation into varying shapes throughout the course of treatment.

6. Why choose Memorial Sloan Kettering for IMRT?

Our researchers developed IMRT in 1996 for the treatment of prostate cancer. Since then, we have advanced its use for many other types of cancer and made many improvements to the technology and the way that treatment is delivered. IMRT remains a powerful tool for fighting many types of cancer.

Our radiation oncologists, nurses, and therapists are trained to treat specific types of cancers. Our large team of medical physicists develops and fine-tunes each patient’s treatment plan to make sure we deliver the most targeted treatment possible. This increases our chances of controlling or curing your disease.