At the Department of Radiation Oncology, our advanced technologies and therapies include the following:
CyberKnife: Treating Brain Tumors, Head & Neck Cancers, Prostate Cancer, and Other Sites
Stereotactic radiosurgery is a non-invasive treatment in which high doses of radiation beams enter the body from different angles and intersect at the tumor or lesion. This delivers a concentrated dose to the tumor while sparing surrounding healthy cells.
The CyberKnife uses a linear accelerator mounted on a robotic arm to focus multiple beams of radiation on the tumor. Currently, the CyberKnife is used to treat primary or metastatic brain tumors. It is also used to treat other tumors of the head and neck, base of skull and cervical spine. Investigational protocols are being developed for treatment in other body sites such as the pancreas and prostate.
Both radiosurgery and radiotherapy are performed on an outpatient basis at the department's Annette Strauss Stereotactic Treatment Center at University Hospital - Zale Lipshy. The patient receives an initial consultation with the radiation oncologist and neurosurgeon, during which a CT scan is performed. A CT scan is an x-ray in which a four-dimensional image of the tumor site is constructed by a computer. This 4-D image allows the physicians to see all sides of the tumor and plan for the radiation beams to be precisely focused on the unique shape of the lesion. Once the CT scan is obtained, the physicians and medical physicists create the treatment plan. This usually takes one day or less. The patient returns for the first treatment the next day. The number of treatments required depends on the location, size and shape of the tumor.
Gamma Knife: Precise, Noninvasive Brain Surgery
Also housed at the Annette Simmons Stereotactic Treatment Center, the Gamma Knife is not really a
knife at all. It uses beams of highly-focused gamma rays to treat small- to medium-size lesions, usually in the brain. Many beams of gamma radiation join to focus on the lesion under treatment, providing a very intense dose of radiation in a safe manner.
The Gamma Knife is used primarily to treat brain tumors and arteriovenous malformations (abnormal connections between arteries and veins), as well as functional problems such as trigeminal neuralgia. Patients are fitted with a head frame for this single day, typically outpatient procedure, in order to keep the head from moving during treatment. Pins designed specifically for this purpose fasten the head frame to the skull. The head frame also is a guide to focus the gamma ray beams to the exact location of the lesion being treated.
Brachytherapy: Treating Gynecological Cancer
Brachytherapy is a form of radiation therapy in which a higher dose of radiation is delivered via radioactive seeds or very small wires placed either in the tumor ("interstitial implant") or near the tumor ("intracavitary therapy"). Thus, the radiation is emitted outward from the affected area rather than from an external source across normal tissue.
High dose rate (HDR) brachytherapy is the newest form of brachytherapy treatment, and is typically given in 5 outpatient visits. A device or holder is placed into the area to be treated. The device is then connected to the HDR machine and a small but intense radiation source is loaded into it. The dose is delivered in approximately 5 to 10 minutes. Once the treatment session is complete, the radiation source is withdrawn back into the machine and the device is removed from the treatment area. The patient is discharged to return several days later for additional treatments.
Calypso "GPS for the Body": Advanced Technology for Prostate Cancer
A newer form of radiation treatment allows physicians to exactly target prostate cancer while sparing surrounding healthy tissue and structures such as the bladder. Calypso uses implantable electromagnetic transponders to continuously report the position of the tumor target during treatment.
In an outpatient procedure similar to a biopsy, the transponders are implanted into the prostate. Each transponder is about as small as a grain of rice. The transponders communicate with the Calypso 4D Localization System using safe radiofrequency waves, allowing the radiation therapist to monitor the positioning of the target and make adjustments.
Gold Seed Implants for Prostate Cancer
Radioactive seed implants for prostate cancer are also a form of brachytherapy. The physician will place radioactive seeds (about the size of a grain of rice and containing either Iodine125 or Palladium103) into the prostate gland. These seeds emit low energy x-rays that destroy the cancer cells while leaving the surrounding tissue relatively unharmed. Iodine125 and Palladium103 give up about 90 percent of their radioactivity within a short time - six months and two months respectively. By one year, the radioactivity can be considered gone.
The implant procedure is performed at Zale Lipshy University Hospital on a day-surgery basis. Spinal anesthesia is used to numb the patient from the waist down. The physician inserts the transmitters with a series of thin needles and uses an ultrasound monitor to accurately guide their placement. The patient is discharged on the same day and returns for a CT scan two days later to confirm the seed location.
Typically, the radiation oncologist will implant about 70 to 150 seeds into a patient's prostate gland. The exact number depends on the actual size of the prostate. Although the cancer may only be detectable in a portion of the prostate, there may be tiny amounts of cancer throughout the gland; therefore, the entire prostate is treated. Before the procedure is performed, the radiation oncologist and the urologist will make a map of the prostate gland, known as a volume study, from a prostate ultrasound scan. The radiation oncologist and medical physicist will then utilize a computerized treatment planning system to determine the number and location of seeds needed to treat the cancer.
MammoSite Radiation Therapy System: Treating Breast Cancer
At the time of lumpectomy, or shortly thereafter, a deflated MammoSite balloon is inserted into the tumor resection cavity in the breast; the fluid injection site and radiation source port remain outside the breast. The balloon is filled and remains inflated for the entire duration of radiation therapy. During the treatment, the prescribed radiation dose is delivered to the breast via a high-dose rate (HDR) machine under precise computer control. By internally delivering radiation directly to the tissue surrounding the original tumor, the MammoSite RTS minimizes radiation exposure to healthy tissue while treating the area at highest risk for recurrence.
Intensity Modulated Radiation Therapy (IMRT): Treating Head & Neck Cancers, Breast Cancer, Prostate
This state-of-the-art treatment allows doctors to target multiple radiation beams directly on the tumor and spare more healthy tissue. Beam intensities vary, so that the highest possible doses can be used to destroy cancerous tissue. Proper positioning of the patient is crucial to the success of IMRT.
Stereotactic Radiosurgery (SRS) - Radiotherapy (SRT): Treating Brain Tumors and Other Intracranial Cancers
SRS-SRT involves a single, high-dose application of radiation to a tumor, instead of the many smaller doses given in standard radiation treatment. Several radiation beams are precisely aimed to converge upon a small tumor. The patient lies on a couch that rotates 180 degrees for maximum targeting, while minimizing radiation to the surrounding normal tissue. It is effective in treating brain tumors, some head and neck tumors, and abnormal blood vessels in the brain.
Four-Dimensional Radiation Treatment Planning: CT Imaging
The Moncrief Radiation Oncology Center uses a state-of-the-art 4-D CT (computed tomography) scanner that reproduces the tumor size, location and movement for each patient. This simulation is used to test various treatment fields and immobilization devices used to position the patient during radiation therapy. With this picture, they can shape and mold multiple beams of radiation to fit the size and shape of a tumor and, thus, treat tumors with pinpoint accuracy.
