What is high dose rate (HDR) Brachytherapy?
High dose rate (HDR) therapy is considered the most precise way delivery radiotherapy to the prostate. It is a minimally invasive form of radiotherapy. Drs. Goyal and Patel are one of the very few radiation oncologists in the world who offer with groundbreaking and revolutionary therapy.
HDR offers cure rates of over 90% (which is better than other prostate therapies) with less side-effects than radical prostatectomy, prostate seeds, or external beam radiotherapy.
HDR is similar to a prostate seed implant in that a patient is taken to the OR. While in the OR, very thin catheters are painlessly placed into the prostate under ultrasound guidance. The placement of these catheters takes approximately 30-40 minutes. No incisions are necessary.
The radiation is delivered through a high intensity radiation Iridium (Ir192) source with millimeter precision under computer guidance directly into the prostate through the catheters. The delivery of radiotherapy is completely painless and takes only 10-15 minutes.
The radiation emitted from the Ir192 radiation source kills the cancer from the inside out while avoiding injury to surrounding normal healthy tissue such as the bladder, urethra, and rectum. By varying the time the source spends inside the target, the radiation oncologist can precisely modulate the dose of radiation to both the prostate and adjacent surrounding organs.
What are the advantages of HDR Brachytherapy?
- Excellent cure rates that superior to any other form of prostate cancer therapy.
- It requires only several treatments compared to 8 weeks with external beam RT.
- Side effects resolve much quicker that external beam RT or prostate seed implant.
- The radiation coverage can extend outside the prostate to kill microscopic extension of cancer.
- The most accurate and precise way of delivering radiation.
- Almost no dose of radiation to bladder, rectum, and rectum.
- Eliminates the issue of prostate motion due to daily variation in rectum and bladder filling.
- No radiation exposure to other persons !!!
Prostate HDR Brachytherapy
HDR Brachytherapy can be used as the only treatment for prostate cancer or it can be used in combination with external beam radiation therapy (EBRT).
- HDR Monotherapy: when used as a single treatment without external beam radiotherapy.
- Combined EBRT and HDR: When HDR is given with external beam radiotherapy.
Prostate brachytherapy monotherapy, either in the form of a seed implant or prostate HDR, is generally reserved used for patients with “low risk disease”. These are patients who have the following factors:
- Gleason score of 6 or less, PSA of 10 or less
- Stages T1-T2a (palpable disease confined to one lobe of the prostate).
Our treatment schedule for prostate HDR monotherapy calls for a series of two “implant” procedures performed approximately 1-2 weeks apart. Three HDR treatments (called “fractions”) are given with each implant, thus only six fractions are required to complete a course of HDR monotherapy. Since the radiation is typically delivered in less than 20 minutes, the acute radiation reactions usually resolve within one week. Recent data have reported tumor control rates in excess of 95%.
Combined HDR Brachytherapy and External Beam Radiation Therapy
Combined HDR brachytherapy and EBRT is used for patients with intermediate or high risk prostate cancer. Appropriate candidates for this would include patients who have:
- PSA over 10 or a Gleason score of 7 or above.
- Stage T3 or above.
The main benefit of external beam radiotherapy is its ability to deliver radiotherapy beyond the prostate into other regions of the pelvis where microscopic deposits of disease may be present but undetected (extracapsular or perineural invasion). Patients who are treated with combined EBRT and HDR therapy undergo two HDR implants 1-2 weeks following five weeks of external beam radiotherapy.
Combined HDR brachytherapy offers several other advantages over EBRT alone. The cure rates and side effects compare quite favorably with external beam radiotherapy alone. In addition, patients only require half the number of treatments with external beam RT ( 22 treatments as compared to 44 treatments).
Published results on patients followed for 10 years demonstrate cure rates of over 90%.
HDR Brachytherapy Procedure
- Prior to the implant, the patient will get a physical examination and routine blood work from his primary care physician in order to obtain surgical clearance.
- In the OR, the patient is put under general anesthesia. The patient’s legs are placed in stirrups and the pelvis is positioned by the physician for access to the perineum (the space between the scrotum and anus). A radio-opaque catheter is placed in the bladder for urine drainage and urethral visualization.
- A fixed template technique is used to help guide the flexiguide catheters through the perineum and into the prostate. On average, 15-18 flexiguide needles are inserted into the prostate using transrectal ultrasound and fluoroscopy.
- Once the flexiguides are in position, the template is sutured to the perineum to stabilize the implant.
- After a brief stay in the recovery room, the patient is brought to our clinic for CT scan to confirm appropriate placement of the catheters. The catheters are adjusted prior to therapy if needed. A customized treatment plan is then generated.
- After Dr. Goyal and/or Dr. Patel has approved the treatment plan, the patient is moved into the treatment room, where the ends of the catheters are connected to the machine which contains the Ir192 radiation source. The Ir192 source delivers the radiation dose through the flexiguides and into the prostate in about 10 minutes. After the treatment, the source withdraws back safely into the afterloader. The patient is no longer radioactive.
- The template and treatment flexiguides are removed. After the catheters are removed, there may be some slight bleeding, which is stopped by the nurse or therapist by applying firm pressure to the perineal area with gauze pads. The patient is discharged home.
- The second implant is done 1-2 weeks late following the same procedure as described above.
3D CT Based Dosimetry
One of the advantages of HDR over permanent seeds is the ability to evaluate the implant in 3-D and know what the doses are going to be before any treatment is given. The ability to control the time the source spends in each dwell position allows for greater target accuracy and normal tissue sparing.
The possible post-HDR acute side effects, usually lasting less than one week, are urinary frequency, discomfort on urination, and decreased urinary flow. There may also be some usually transient rectal irritation or penile numbness (less than 5% cases). The perineal area will be tender for a few days so activities like bicycle riding that put pressure on this area should be avoided. Medications are prescribed to help alleviate these temporary side effects.
How successful is HDR Brachytherapy?
HDR has excellent cure rates compared to surgery, prostate seeds or external beam RT. Because of the unique dose distribution and radiation delivery of HDR, institutions are now reporting superior results with HDR.