Frequently Asked Questions

Information on Intensity Modulated Radiation Therapy (IMRT) at Hollywood Radiation Oncology

What is IMRT and how is it different from other methods?

Intensity Modulated Radiation Therapy (IMRT) is a new technology using a computer-based inverse treatment planning system, to program the movements of a dynamic multi-leaf collimator; This system "shapes the dose," targeting the tumor by modulating the radiation beam emitted by the linear accelerator. Two parallel columns of metal bars, in constant motion throughout the treatment, selectively block sensitive areas while exposing only the tumor to high doses of radiation. This dynamic blocking feature and the ability to modify the intensity of the beam are what make the technology available at Hollywood Radiation Oncology unique.

Alfred Brandon, M.D. says IMRT exists because of three technological advances: improved 3-dimensional CT scanning techniques, faster computing, and the ability to dynamically block portions of the treatment field while the patient is on the table. "IMRT works best when we can immobilize the treatment site, as in prostate, breast, head, neck, pancreas, and brain cancers." By minimizing the radiation dose to sensitive areas such as the salivary gland, optic nerve and spinal cord, while escalating the dose to only the tumor, IMRT can result in better control of the cancer, fewer complications and improved quality of life.

What are the advantages of IMRT over other treatments?

IMRT is very cost-effective compared to other treatment options like proton beam radiotherapy, and can achieve superior outcomes. Because IMRT can change the intensity within the treatment field by controlling many beamlets, it outperforms conventional 3-D conformal radiation therapy that delivers a uniform radiation within the boundary of the treatment field.

How does IMRT work?

The IMRT procedure follows a series of steps:

1. The physicians and the healthcare team determine the best treatment for the patient based on tumor location, tumor extent and other factors.
2. A CT scan is used to verify the exact location of the tumor in the patient's body and the relationship to adjacent organs. After CT scanning, the physician prescribes the dose for the tumor and the maximum tolerated dose for normal surrounding structures as part of the treatment planning program. Using variable beam intensities, the computer then calculates the optimal dose distribution with a series of computations that formerly took several days.
3. Before the patient is treated with IMRT, a quality assurance process is completed to ensure that the prescribed treatment plan delivers the radiation dose expected.
4. During the treatment itself, the patient is properly positioned on the table and must remain still for 12 minutes while the treatment is in progress.
5. The dynamic multi-leaf collimator attached to the linear accelerator rotates around the patient and pauses at many different locations along the way, delivering varying doses of radiation designated by the treatment plan. At the computer station outside the treatment room, the radiation therapist controls the computer that directs the IMRT treatment. The therapist is able to carefully monitor the patient via a video system and the two can communicate during treatment over an intercom.

Why is IMRT safer?

Approximately a week elapses from simulation to treatment time because of the quality assurance process to ensure patient safety. The planned IMRT treatment is performed on a patient model constructed of material with a density equivalent to that of human skin and bones. Computer chips that detect radiation are embedded into the model and are analyzed 24 hours later to confirm that the radiation received is what was expected. The patient is treated with IMRT only after this quality assurance process is completed.

How long does the treatment usually last?

After the initial treatment planning is completed, the subsequent treatments are usually completed in approximately 12 minutes.

How many treatments does a patient usually need?

Patients are usually treated daily, Monday through Friday, with a six- to eight-week primary treatment plan. At Hollywood Radiation Oncology, every patient is unique and is treated individually. After your treatments are completed, your physician will discuss the exact follow-up care recommended based on your specific needs.

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