External Beam
Three-Dimensional Conformal Radiation Therapy (3D-CRT)
Tumors usually have an irregular shape. Three-dimensional conformal radiation therapy (3D-CRT) uses sophisticated computers and computer assisted tomography scans (CT or CAT scans) and/or magnetic resonance imaging scans (MR or MRI scans) to create detailed, three-dimensional representations of the tumor and surrounding organs. Your radiation oncologist can then shape the radiation beams exactly to the size and shape of your tumor. The tools used to shape the radiation beams are multileaf collimators or blocks. Because the radiation beams are very precisely directed, nearby normal tissue receives less radiation exposure.
Intensity Modulated Radiation Therapy (IMRT)
IMRT/IGRT Informational Brochure
Intensity modulated radiation therapy (IMRT) is a specialized form of 3D-CRT that allows radiation to be more exactly shaped to fit your tumor. With IMRT, the radiation beam can be broken up into many “beamlets,” and the intensity of each beamlet can be adjusted individually. Using IMRT, it may be possible to further limit the exact amount of radiation that is received by normal tissues that are near the tumor. In some situations, this may also allow a higher dose of radiation to be delivered to the tumor, increasing the chance of a cure.
Image-Guided Radiation Therapy (IGRT)
IMRT/IGRT Informational Brochure
The Radiation Oncologists are using image-guided radiation therapy (IGRT) to help them better deliver the radiation dose to the cancer. Normal structures and tumors can move between treatments due to differences in organ filling or movements while breathing. IGRT is conformal radiation treatment guided by imaging equipment, such as ultrasound. During Simulation ultrasound images are acquired and used as part of the planning process. These images are also then used in comparison on a daily basis while on the treatment unit. During IGRT, doctors “fuse” these images to see if the treatment needs to be changed. This allows doctors to better target the cancer while avoiding nearby healthy tissue. In some cases, doctors will implant a tiny piece of material called a fiducial marker near or in the tumor to help them localize the tumor during IGRT.
Radiosurgery-(more information)
Stereotactic Radiotherapy
Stereotactic Radiotherapy is a technique that allows your Radiation Oncologist work closely with nurosurgeons to precisely focus beams of radiation to destroy certain types of tumors. Since the beam is so precise, your Radiation Oncologist may be able to spare more normal tissue than with conventional external beam therapy. This additional precision is achieved through rigid immobilization, such as with a head frame as is used in the treatment of brain tumors. Although often performed in a single treatment, fractionated radiotherapy, where patients receive up to five treatments, is sometimes necessary. Stereotactic radiotherapy may be the only treatment if a very small area is affected. In addition to treating tumors, it can also be used to treat malformations in the brain’s blood vessels and certain noncancerous (benign) brain tumors.
Prostate Seed Implant (PSI)
The treatment of prostate cancer has changed a great deal over the last ten years with the widespread adoption of prostate seed implantation. With the use of ultrasound guidance, the Radiation Oncologist working with a Urologist inserts approximately 100 radioactive seeds into the prostate gland. Each seed is about the size of a grain of rice and usually contains a radioactive iodine isotope. Some men will have an implant as their only treatment, while others will have this done in conjunction with external beam radiation treatment. The radioactive implants deliver a very high dose of radiation to the prostate gland and great care is given to selecting the appropriate patients for this procedure. This high dose of radiation always leads to some side effects, most of them temporary and treatable but they can last for a year or longer.
High Dose Rate
High dose rate implants are used for prostate and many other types of cancer. A small radioactive source at the end of a wire can be inserted into various applicators or catheters. In order to treat prostate cancer a Urologist and Radiation Oncologist use ultrasound to help place about a dozen catheters into the prostate gland. A CAT scan is done to develop a specific computer plan that varies the length of time the radioactive source is in each catheter. The patients is given two separate treatments, and frequently requires an overnight stay in the hospital.
[Glossary of Radiation Oncology Terms]
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