What is Brachytherapy
HOW IT IS PERFORMED
The brachytherapy treatment plan is created and governed by a radiation oncologist, who is a highly trained physician specializing in treating cancer with radiotherapy. The radiation oncologist will require a team, including a medical physicist, dosimetrist, radiation therapist, radiation therapy nurse and in some cases, a surgeon to conduct the procedure. However, the radiation oncologist is the one who evaluates the patient and determines the appropriate therapy, including how much radiation to deliver.
In permanent brachytherapy, needles that are pre-filled with the radioactive brachytherapy seeds are inserted into the tumor. Then the needle or device is removed, leaving the radioactive seeds behind. Sometimes these seeds may be implanted in sessions using a device that inserts them individually at regular intervals. Appropriate imaging means such as an ultrasound, X-ray, MRI or CT scan may be used to assist the physician in positioning brachytherapy seeds at the right place. After implantation, some additional imaging can be done to verify seed placement.
Temporary brachytherapy starts with placing a delivery device, such as a catheter, needle, or applicator, into the tumor. Methods of imaging such as an ultrasound, MRI, or CT scan will help position the radiation sources correctly. The delivery device can either be inserted into a body cavity such as the vagina (intracavitary brachytherapy) or applicators such as needles or catheters can be inserted into body tissues (interstitial brachytherapy). Device implantation will depend on the location of cancer.
Radiation using brachytherapy procedure can be delivered at three different levels:
High-dose-rate (HDR):
HDR brachytherapy is given for over 10 to 20 minutes per session, but it can take several hours worth of preparation, which includes device placement. HDR brachytherapy is mostly conducted as an outpatient procedure, although sometimes patients are admitted for one to two days to have several HDR brachytherapy sessions using the same applicator.
HDR brachytherapy delivers a specified dose of radiation to the tumor in a short burst using a remote-afterloading machine. This will help protect the patient from unnecessary exposure to radiation. This procedure can be repeated a couple of times on the same day.
Low-dose rate (LDR):
LDR is delivered at a continuous rate of radiation for over 20 to 50 minutes. The patient needs overnight hospitalization so the delivery device can remain in place throughout the treatment. The radiation oncologist may insert the radioactive particle manually through the delivery device and remove the material and delivery device after the treatment.
Pulsed dose rate (PDR):
PDR brachytherapy is delivered in a similar way of LDR, but the treatment takes place in periodic pulses instead of continuous radiation.
