Radioactive Seed Implants
Radioactive seed implantation
is an increasingly popular choice for treating and curing prostate and other types of cancer. Implanting radioactive seeds is one of the minimally-invasive techniques that is suitable for patients whose cancer is still localized within the prostate gland, says Radiotherapist Dr. Apichart Panichchivaluck
During the implantation procedure, the doctor first measures the volume of the patient’s prostate gland to properly calculate the necessary radiation dosage. Tiny radioactive seeds are then inserted through catheter tubes into the prostate gland, where they emit radiation that destroys the cancerous cells. There are two main methods of prostate brachytherapy
: permanent seed implantation and high dose rate (HDR) temporary brachytherapy
Permanent seed implantation is typically used when the prostate cancer is the low-risk localized type, Dr. Apichart explains. Permanent seed implants involve injecting radioactive seeds which give off radiation at a low dose rate to kill cancer cells over several weeks or months, while the seeds remain in the prostate gland permanently.
High Dose Rate (HDR) Temporary Brachytherapy
For patients with an intermediate or high risk localized prostate cancer, doctors usually choose high dose rate radioactive seeds (High Dose Rate Brachytherapy, also known as temporary brachytherapy). The HDR implant employs different radiation sources than permanent seed implantation, says Dr. Apichart. There is also the probability for patients with prostate cancer at this stage that the cancer has spread beyond the capsule of the prostate gland. HDR temporary brachytherapy involves placing very small plastic catheters into the prostate gland. A series of radiation treatments is performed by pushing radioactive seeds into the catheter using a computer-controlled machine under Transrectal Ultrasound Guidance (TRUS). This helps control the radiation dose in different regions of the prostate. After the catheter is removed, no radioactive material is left in the prostate gland.
The ability to modify the radiation dose after the catheters are in place is one of the main advantages of temporary brachytherapy compared to permanent seed implants. HDR brachytherapy is highly effective in the treatment of intermediate to high risk localized prostate cancer, and is also useful in the control of localized recurrence. It has also been reported that HDR brachytherapy can achieve survival rates above 90% in prostate cancer patients, while the side effects such as urgency to urinate, frequent urination, and erectile dysfunction have been shown to be much lower than with other types of treatments.