Before an implant can be performed, the patient must undergo a volume study. This
study involves placing a transrectal ultrasound into the rectum and making measurements
and taking pictures. Unlike the biopsy no needles are used. This procedure takes a few
minutes. This measurement will provide the necessary information so that the radiation
oncologist can order the proper number of seeds for the seed implant.
The Implant Procedure
The prostate seed implant is performed by a Urologist and Radiation Oncologist,
both of who have undergone special training in prostate seed implantation. When
you arrive at the hospital, you should have already have completed your bowel prep.
After completing your registration you will go to the pre-op area and will meet with the
anesthesiologist to discuss the kind of anesthesia that is most appropriate for you.
When the time is ready to start the procedure, you are taken to an operating room that is
specially equipped for urological procedures. Your anesthesia is then administered. A
Foley catheter is placed into the bladder. The skin of the perineum, an area located
between the rectum and scrotum, is cleaned with an anti-bacterial solution. In order to
further reduce the risk of infection, the hair may be shaved from this area.
The implant procedure is initiated by placing the ultrasound probe into the rectum and
attaching it to a stabilization unit and the seed implantation system. The next step
involves a careful mapping of the prostate gland. This allows your physicians to
determine how seeds are required and where the seeds are going to be placed.
During the course of the implant, approximately 16 to 26 needles are inserted through the
perineum into the prostate. The implant needles are easily seen on the ultrasound
screen. This allows precise placement into specific locations within the prostate
under direct visualization.
A template, or guidance system, is attached to the ultrasound probe outside the patient
next to the perineum. The template is used to guide the needles into precise locations in
the prostate as is called for by the plan. The template (FIGURE 1) has a series of holes,
coded A through G horizontally and 1 through 6 vertically. The dots correspond to
holes in the template, which are used to guide the implant needles into precise locations
within the prostate.
The template coordinate grid to the left is activated so that it appears on the ultrasound
screen. The prostate is aligned so that it is superimposed onto the
template grid in such a way that the D row is centered in the central portion of the
prostate and the 1 row is aligned along the back edge of the prostate.
Example of how the template is used in a prostate implant: If the implant is to start at
the location of "F2" on the grid, the needle is placed through the "F2" aperture in the
template and, under the guidance of the ultrasound, is directed into the prostate at the
"F2" location as seen on the ultrasound screen. If the needle does not hit the "F2"
coordinate, it can be easily steered into the proper location. Depending upon the size of
the prostate, 16-26 needles are used to implant 60-140 seeds.
Once the procedure is completed, the patient is transferred to the recovery room. After
the anesthesia has worn off the patient is discharged to home. In most cases the Foley
catheter is removed prior to discharge.
Follow Up Procedure
You will be scheduled to have a CAT scan of the prostate so that computerized dose
calculations can be performed. This will allow your Radiation Oncologist to evaluate the
actual dose delivered to the prostate gland as a result of the implant. These
calculations are called post-implant dosimetry. The post-implant CAT scan does not
involve the injection of any dyes or contrast. You will not be required to drink any
barium or use any laxatives or enemas. This test only takes about 5 minutes.
As part of your follow-up, you will be instructed to see both your urologist and
radiation oncologist. They will help you to get through the side effects as comfortably
as possible. After 3 months they will perform routine DRE's.
The first PSA will be drawn about 3 months after the implant. Bone scans, CAT scans
and MRI scans are not part of the routine follow-up. They may be ordered if your PSA
rises.
