IMRT/IGRT
What is IMRT/IGRT?
Cancer cells grow and divide more rapidly than many of the normal cells around them. High doses of radiation can kill cells or damage their ability to reproduce. Radiation therapy has been shown to be particularly effective in killing cancer cells and shrinking tumors.
IMRT (intensity modulated radiotherapy) and IGRT (image-guided radiotherapy) are radiation therapy approaches that utilize multiple imaging and motion management techniques for highly accurate tumor targeting. IGRT involves using a variety of digital imaging techniques to pinpoint the exact location of a targeted tumor while the patient is in the treatment position and just prior to delivering the treatment. This precision is very important because tumors are not stationary. They can shift and move slightly between treatments, and even during treatments due to normal physiological processes, such as breathing. It is also convenient for the patient because both imaging and treatment can be done at one time on the same machine.
How does IMRT/IGRT work?
The radiation beam used to treat the tumor is created by a medical linear accelerator. Utilizing IMRT this beam is shaped by a multi-leaf collimator, which "paints" the area to be treated. The machine is outfitted with a pair of robotic arms and/or a portal imaging devise, which produce low-dose, high-resolution X-ray images for pinpointing the exact position of the tumor immediately prior to treatment. These images provide the radiation oncologist with precise information about the tumor and surrounding anatomy. When compared with existing images from a MRI, CT or other kinds of scans, they reveal changes in tumor position over a multi-week course of treatment. Because tissues and organs can settle around bones differently each time a patient lies down on a treatment table, tumors can end up in different positions from one treatment session to another. In addition, tumors can move several centimeters due to a patient's normal respiratory cycle. IMRT/IGRT enables the doctor to adjust for these changes and optimize treatments for their patients at each visit without moving them from one machine for imaging to another machine for treatment.
Why consider IMRT/IGRT for your diagnosis?
IMRT/ IGRT delivers higher doses of radiation directly to tumors and cancer cells, while surrounding organs and tissues are protected. Lower doses to healthy normal tissues may mean fewer complications or side effects. Using IMRT/IGRT allows your radiation oncologist options for treating cancer that were previously untreatable with radiation therapy including:
- IMRT/IGRT can be a non-invasive alternative to surgery in some cases.
- With early detection, IMRT/IGRT can eradicate tumors before the cancer spreads.
- IMRT/IGRT can usually be done on an outpatient basis.
- IMRT/IGRT targets the tumor and not the entire body.
What is the IMRT/IGRT process like?
Most cases require a treatment preparation session. Special molded devices that help you maintain the same position every day are sometimes developed at this point. Colored, semi-permanent ink is often used to mark your skin to assist in aligning the radiation equipment with the target area. Images may be taken in preparation for a treatment planning using a CT scan. The treatment preparation session might take from thirty minutes to an hour, and the CT scan might take an additional 15-30 minutes. The IMRT/IGRT planning process usually takes our team several days to create. When your unique plan is complete, we will contact you and arrange a series of appointments for your radiation treatments.
The first IMRT/IGRT treatment session is sometimes longer than subsequent ones so that additional X-ray films and checks can be done. A typical IMRT/IGRT treatment session lasts about 30 minutes.
In the treatment room, the radiation therapist uses the marks on your skin, called "tattoos," to locate the treatment area. The radiation therapist will position you on a treatment table. The same special devices used during the planning session are used to help with positioning. The radiation therapist will leave the treatment room and remotely controls a digital on-board imaging system rotating it around you to take digital images of the targeted area. Usually two or more images are taken from different angles. These images are then used to guide the final adjustments of the treatment couch. Receiving external radiation treatment is painless, just like having an X-ray taken.
The machine is controlled from a nearby area so the radiation therapist will leave you in the treatment room. You can be seen on a television screen and the therapist can talk with you through an intercom. During the treatments you will not see or hear the radiation and you usually do not feel anything. However, f you become uncomfortable the machine can be stopped at any time.
Who gives the treatment?
A doctor who has had special training in using radiation to treat disease--a radiation oncologist--prescribes the type and amount of treatment that best suits a particular patient's needs. The radiation oncologist works closely with other doctors, as well as heading a highly trained health care team. This team often includes:
- a radiation physicist, who participates in the planning process and ensures that the machines deliver the right dose of radiation
- a dosimetrist, who plans the treatment with the oncologist and the physicist
- a radiation therapy nurse, who provides nursing care and helps patients learn about treatment and how to manage any side effects
- a radiation therapist, who sets the patient up for treatment and runs the equipment that delivers the radiation.
How Long Is a Course of IMRT/IGRT Treatment?
Radiation therapy usually is given five days a week for five to eight weeks. When radiation is used for palliative care, the course of treatment lasts for two to three weeks. For each radiation therapy session, the patient is in the treatment room for about 15 to 30 minutes. These types of schedules, which use small amounts of daily radiation rather than a few large doses, help protect normal body tissues in the treatment area. Weekend rest breaks allow normal cells to recover. The total dose of radiation and the number of treatments a patient needs depend on the size and location of the cancer, the type of tumor, the patient's general health and other factors.
What happens when a person is treated with IMRT/IGRT?
IMRT/IGRT treatment involves three basic steps: diagnosis, treatment planning and delivery. As part of the diagnosis, physicians generate three-dimensional diagnostic images (usually CT or MRI) of the patient's anatomy and use these to specify the dose of radiation each area will receive. In some cases, treatment planning includes a simulation session to further localize the cancer and finalize the radiation treatment plan.
Patients receive the IMRT/IGRT treatment according to various schedules, usually five days a week for five to eight weeks. Each treatment takes fifteen to thirty minutes.
What Are the Effects of Treatment?
External radiation therapy does not cause a patient's body to become radioactive. Patients need not avoid being with other people because of treatment. Hugging, kissing, or having sexual relations will not pose a risk of radiation exposure.
Side effects of radiation therapy most often are related to the area that is being treated. Most side effects that occur during radiation therapy, although sometimes unpleasant, are not serious and can be controlled with medication or diet. They usually go away within a few weeks after treatment ends. With IMRT/IGRT, some patients have no side effects at all.
What locations offer IMRT/IGRT?
Redwood Regional Medical Group offers Intensity Modulated Radiotherapy (IMRT)/Image Guided Radiation Therapy (IGRT) through our radiation oncology department at the following locations:
121 Sotoyome Street, Santa Rosa, CA 95405
2555 Round Barn Circle, Santa Rosa, CA 95403
110 Lynch Creek Way, Suite A, Petaluma, CA 94954
1165 South Dora Street, Suite H, Ukiah