Articles for Our Patients ~ Sri Gorty, M.D., Radiation Oncologist

Treating Prostate Cancer with Intensity Modulated Radiotherapy (IMRT)

Author: Sri Gorty, M.D., Radiation Oncologist • Language: ENG

Intensity Modulated Radiotherapy, or its commonly known acronym IMRT, is a specialized way to deliver radiation to a patient. It is probably one of the biggest recent advances in the field of Radiation Oncology.
Essentially, it allows one to control more accurately where the radiation dose will be given. For example, in the prostate, the goal is to give a high dose of radiation to the prostate while limiting the dose to the surrounding structures such as the rectum and bladder. In the past, we treated the patient's prostate based on the maximum tolerable dose to the rectum and bladder. After that, giving more radiation would probably cause more harm than good. With IMRT, we are able to increase the maximum dose of radiation to the prostate significantly while keeping the dose to the bladder and rectum the same or even less than from the previous technology. This is a huge advantage as we can now deliver much greater doses to the prostate while minimizing the long-term complications. By being able to give higher doses, we can improve our cure rates of prostate cancer.
This same concept can be used in multiple other cancer sites. The machine that we use to deliver IMRT is exactly the same, and the type of radiation is the same as standard Radiation Therapy. The only difference is, we are now sculpting the radiation dose around the prostate using much more advanced computer planning systems.
IMRT is a long process, which needs the services of many people including the radiation oncologist, physicist, dosimetrist, radiation therapist, and nurse. Each person plays a vital role in the IMRT process. The process starts when the radiation oncologist and nurse place three to four small gold seeds within the prostate. This is done under local anesthesia. Several days later, the patient is taken to a machine called a simulator, where temporary marks are made on the patient's skin. After that, the patient is taken for a CT scan. The CT scan is then downloaded to the computer and all of the critical structures are outlined (i.e. prostate, rectum, and bladder). Once this is done, the dosimetrist spends time to individualize the treatment to the unique body structure of each patient. An IMRT plan is formulated by the dosimetrist and verified by the physicist and radiation oncologist. The patient is then brought back to the simulator and the treatment is verified. Finally, the patient is taken to the treatment machine and his first treatment is delivered. It is not unusual for this process to take from one to two weeks. Most of this time is taken to sculpt the dose and to perform varying quality assurance protocols.
The disadvantages of IMRT are that it is more labor intensive for the staff and it is a more expensive treatment. The time taken to give each treatment is also doubled (standard treatment takes 15 minutes, IMRT takes approximately 1/2 hour).
This technology is currently available here at Pomona Valley Hospital Medical Center's Robert and Beverly Lewis Family Cancer Care Center. Unfortunately, not all patients are candidates for IMRT, but we do offer a variety of other technologies for those who can't have IMRT. If you have any questions about this technology or want to know if this technology can be used on you or your family member, please feel free to consult with your local radiation oncologist.We are committed to offering our community the newest and best technology in the treatment of cancer.

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