High dose rate (HDR) brachytherapy is a technique that has become accepted in cancer treatment over the past 10 years. Basically, hollow plastic catheters are surgically inserted into the organ involved with cancer. A CAT scan is then completed to image the organ, the cancer, and the surrounding tissues. Based on the CAT scan results and assisted with a computer generated plan, the radiation oncologist determines the radiation dosage delivering the highest concentration of radiation to the cancer, and the lowest dose possible to the surrounding healthy tissues.

The radiation oncologist reviews computer generated plan making dose adjustments, taking into account the exact known cancer location and lowering doses further to adjacent organs which may receive too much radiation. This program is then transferred to a High Dose Radiation (HDR) machine.

The HDR unit has a single radiation source of Iridium-192 welded to a long wire of 1-meter length (over 3 feet) controlled by computer driven motor. The catheters are attached to the HDR unit via transfer tubes. Generally, most HDR systems can treat 18-25 catheters at once. In the event a patient required more than 25 catheters, the treatment is divided, delivering the first 25 catheters and then immediately after the remaining catheters. The HDR motor can be controlled to millimeter accuracy to deliver treatment at any point inside the catheter and therefore any position inside the organ / cancer.

Provided the catheters are placed evenly throughout the organ during the time of surgery, HDR treatment allows the most accurate delivery of radiation to an organ. The typical sites for treatment include: prostate, vaginal canal, rectal, bile duct, certain lung cancers, and brain tumors. HDR treatment may not be appropriate in every situation. Depending on the location of the cancer, the patient’s health, or the type of cancer, it is best to consult your physician for HDR treatment suitability.

Prostate HDR

In prostate HDR brachytherapy, 18-25 catheters are inserted through the perineum (the area behind the scrotum and in front of the anus) under anesthesia. With ultrasound guidance, the catheters are advanced into the correct position into the prostate.

A plastic template is used to "hold" and secure the catheters in the perineum. These catheters stay in place for 36-48 hours while the patient remains in the hospital. Patients are bed-bound during this time, as it is critical the catheters are not dislodged.

A CAT scan is then taken to define the position of the catheters and a treatment plan is developed. After the plan has been refined and approved by the radiation oncologist, the patient receives his first HDR treatment. The plastic catheters are connected to the HDR via flexible plastic connection tubes.

A computer program then drives the source into each catheter, each position for a specific length of time. The treatment length and catheter locations are manually checked prior to treatment. One HDR treatment typically lasts 10-15 minutes.

Patients typically receive three or four HDR treatments with each implant and treatments are spaced at least 6 hours apart. Once the final HDR treatment is delivered, the catheters are removed and the patient is discharged home with suitable (usually several hours later).

HDR treatments are usually given as a treatment prior to external beam radiotherapy. Many patients receive five weeks of external beam radiotherapy following their HDR treatment. The external beam radiotherapy is given in cases where the risk of the prostate cancer is either intermediate or high.

Treatment Selction

In select patients, where the risk is very low, patients may have a second set of HDR treatments two to three weeks later following completion of first HDR treatment. These select patients do NOT require five weeks of external beam radiotherapy. This type of approach is called prostate HDR monotherapy. Suitability for HDR monotherapy is extremely limited and requires a thorough discussion with your physician.

Low Risk: Stage T1 or T2 & PSA < 10 & Gleason score of 6 or less
Intermediate Risk: Stage T1 or T2 w/PSA 10.1 - 20, or Gleason score of 7
High Risk: Stage T3 or T4, or PSA > 20, or Gleason score of 8-10

Patients with low-risk cancer are eligible for all the major prostate cancer treatments (eg. surgery, radiation, seed implants) whereas high-risk patients are best suited to undergo hormone blockers and /or external beam radiation therapy. Intermediate-risk patients are still candidates for the major treatment choices but may require the addition of hormone blockers and / or external beam radiotherapy depending their situation, age and medical health.

Learn more about Prostate Cancer Staging.
Learn more about PSA.
Learn more about Gleason Score for prostate cancer.

Advantages of HDR Brachytherapy

1. Radiation is precisely delivered to the prostate cancer (important for intermediate or high risk cancers where precision is critical).

2. Radiation is precisely minimized to normal healthy tissues.

3. Short hospitalization (2-3 days).

4. Rapid recovery (urination & bowel irritation mild).

5. No radiation safety concerns for the patient.

Disadvantages of HDR Brachytherapy

1. Most patients will require five weeks of external beam following HDR.

2. Long term data over five years has not yet matured, however some current published data demonstrates superiority of HDR plus external treatment over external beam treatment alone.

3. Prostatectomy following HDR treatment is usually not possible in the event of recurrence.