In brachytherapy, or internal radiation therapy, radioactive seeds or sources are placed in or near the tumor itself, delivering radiation to the tumor while reducing the radiation exposure in the surrounding healthy tissues. The term "brachy" is Greek for short distance, and brachytherapy is localized, precise radiation therapy given at a short distance.
CentraState's Radiation Oncology Department currently offers radiation seed implantation, a form of low dose rate (LDR) brachytherapy for treating prostate cancer and high dose rate (HDR) brachytherapy for treating prostate, gynecologic (vaginal and uterine) and lung cancers. We also offer HDR radiation therapy as a form of partial breast irradiation for treating certain breast cancers following a lumpectomy.
Radiation Seed Implantation
A form of brachytherapy (or internal radiation treatment), radiation seed implantation delivers radiation directly to the tumor through implants inside the body rather than from a machine outside the body (external beam radiation). Currently, CentraState uses radiation seed implantation as a treatment option for prostate cancer.
How Prostate Seed Implants Work
About 100 radioactive seeds (Iodine-125) are injected into the prostate under anesthesia where they emit low levels of radiation for a few months. That is why seed implantation is referred to as low dose rate (LDR) brachytherapy. The procedure is usually performed on a one-time, outpatient basis and takes about two hours. The seeds are distributed into the prostate using tiny implant needles that your doctor guides using an ultrasound instrument. Although the seeds eventually stop delivering radiation, they remain in the body permanently.Criteria for Use
Prostate seed implantation is not appropriate in all cases. The treatment decision is based on several important factors, including:
- Tumor stage
- Gleason grade
- PSA (prostate-specific antigen) level
- Prostate gland size
- Prior prostate surgery
During the initial outpatient consultation, the radiation oncologist will advise the patient on whether the implantation option is appropriate.
What to Expect
Prior to prostate seed implantation,the patient will undergo a transrectal ultrasound (TRUS). This allows the radiation oncologist and radiation physicists to visualize the prostate to determine where the seeds should be placed. The procedure usually takes about 15 to 25 minutes and entails placing a small ultrasound probe into the patient's anus. Pictures from the probe are displayed on the ultrasound screen. Patients typically describe the procedure as nothing more than "uncomfortable."
The implant procedure is performed in the operating room under either general or spinal anesthesia. The team uses transrectal ultrasound guidance to implant the prostate through the perineum with needles loaded with radioactive seeds. Seed placement is confirmed through fluoroscopy. The patient is monitored for several hours following the procedure and typically is discharged on the same day.
Nearly all patients undergoing radiation therapy for prostate cancer—be it external therapy or seed implant—suffer from some temporary urethritis (irritation of the urethra, the tube-like passage through which urine passes from the bladder to the outside of the body). About 5 percent of patients receiving seed implant require a temporary catheter to relieve urinary retention.
High Dose Rate (HDR) Radiation Therapy
High dose rate (HDR) radiation therapy, a form of brachytherapy, involves the placement of a high-energy radiation source inside the body near the tumor for brief periods of time. Where as low dose rate (LDR) radiation therapy, such as seed implantation places radioactive materials inside the body for extended periods of time, the high energy of the source used in HD Rradiation therapy (usually Iridium-192) means that doctors can deliver equivalent doses of radiation in just a few minutes by inserting and then removing the radioactive beads. Thus, HDR radiation therapy is usually performed as a short series of outpatient procedures.
Benefits & Uses of HDR Radiation Therapy
HDR radiation therapy allows highly localized doses of radiation to be delivered to the tumor quickly. This focused approach to radiation delivery limits the size of the treatment volume, which in turn permits higher doses of radiation. Given the precision of this technique, patients tend to experience decreased toxicity to surrounding normal tissue and fewer overall side effects from therapy.Patient convenience is also improved, since treatments can often be administered without the need for a hospital stay.
HDR radiation therapy is the standard of care for certain malignancies and is most commonly used to treat gynecologic cancers (i.e., affecting the vagina or uterus) and lung cancer alone or in combination with external beam radiation therapy (EBRT). It is also an option for treating prostate cancer in patients who are not candidates for seed implants(i.e., have previously undergone transurethral resection of the prostate (TURP)) or who prefer not to receive permanent seed implants.
A new form of HDR called MammoSite is being used in conjunction with lumpectomy to treat breast cancer via partial breast irradiation (PBI). Until recently, the entire breast has been treated with radiation therapy following lumpectomy to ensure that no cancer cells are left behind. Now, MammoSite is being used in appropriate cases to achieve the same results by treating only the surgical site.
How HDR Radiation Therapy Is Performed
HDR radiation therapy requires a sophisticated delivery system along with a dedicated HDR planning computer. The descriptions below explain what patients can expect when undergoing HDR radiation therapy, depending on the type of cancer being treated.
Prostate Cancer: Catheters are placed into the perineum in the Operating Room using ultrasound guidance. The process is similar to seed implantation. A CT (computed tomography) simulation is performed so a treatment plan can be developed, which takes approximately one hour. For the HDR delivery, highly radioactive material is robotically inserted into the catheters for pre-determined periods. The treatment takes from 15 to 30 minutes and is painless. Prostate HDR generally requires two to three procedures within a 24-hour time period (usually starting in the morning and ending the following morning). The patient waits comfortably in a hospital bed in between sessions. After the final procedure, the catheters are removed and the patient is discharged.
Gynecologic Cancer: A cylinder with cathetersis placed into the vagina or uterus. A CT (computed tomography) simulation is performed so a treatment plan can be developed, which takes approximately one hour. For the HDR, highly radioactive material is robotically inserted into the catheters for pre-determined periods. The treatment takes from 15 to 30 minutes and is painless. The cylinder containing the catheters is removed and the patient is discharged. The HDR procedure may be repeated once a week for two or three visits.
Breast Cancer: During the lumpectomy procedure, the surgeon inserts a catheter into the area of the original lump. Following recovery from the lumpectomy, the patient returns for a CT (computed tomography) simulation so the catheter position can be confirmed and a treatment plan can be developed, which takes approximately one hour. The patient is scheduled as an outpatient to receive two treatments a day for five days (for a total of 10 treatments). For each procedure, highly radioactive material is robotically inserted into the catheter for pre-determined periods. The treatment takes from 15 to 30 minutes and is painless. At the completion of the 10 treatments, the catheter is removed.
Lung Cancer: A catheter is placed into the lung in the Endoscopy Suite, usually under local anesthesia. Next, a CT (computed tomography) simulation is performed so a treatment plan can be developed, which takes approximately one hour. For the HDR delivery, highly radioactive material is robotically inserted into the catheter for pre-determined periods. The treatment takes from 15 to 30 minutes and is painless. The catheter is removed, and the patient is discharged. The procedure may be repeated once a week for two or three visits.
To contact the Radiation Oncology Department at CentraState Medical Center, call (732) 303-5290 or send an e-mail.