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Patients who pursue brachytherapy
as their prostate
cancer treatment will undergo an important planning
stage. A radiation oncologist, urologist, and physics
team plan and map the prostate gland to ensure the seeds
are planted in the correct spots. There are currently
two widely-practiced ways that doctors plan for the
seed implantation: intra-operative
planning (also called real-time dosimetry)
and preplanning.
Preplanning is done in the weeks before the minimally
invasive surgery; intra-operative, as part of the procedure.
Internal organs tend to shift as people go about their
daily activities; some researchers therefore believe
that intra-operative is superior. There is not much
evidence however that can prove the superiority of either
one.
A radiation oncologist and a physics
team are responsible for mapping the prostate gland.
The oncologist uses the transrectal ultra sound (TRUS)
to take pictures of the prostate and surrounding organs
every five millimeters. This imaging last about 15 minutes.
After drawing the area that needs to be treated, the
oncologist writes a prescription indicating the amount
of radiation needed and gives the prescription and images
to the physics team. The physics team plans a pattern
of seeds that will create a radioactive “cloud”
that will treat the prostate
cancer.
Before undergoing brachytherapy,
some patients may use neoadjuvant hormone
therapy
to shrink the prostate gland. Brachytherapy
is more effective prostate cancer treatment for smaller
glands. Patients usually start antibiotics to help prevent
an infection and undergo mechanical bowel preparation
before the treatment. Not eating anything after midnight
or taking enemas or laxatives are all examples of bowel
preparation. Patients are put under general anesthesia
or a spinal epidural that numbs them from the waist
down and a sedative. Patients who remain awake should
not laugh, cough, or talk because these activities could
upset the precision of the treatment.
The Minimally Invasive Prostate
Cancer Treatment
The patients put into the lithotomy position, meaning
his legs are put into stirrups and his legs are lifted
to 90 degrees. This position gives the doctor a clear
view of the perineum,
which is cleaned and then possibly shaved according
to the practice of the center. The doctor inserts an
ultrasound probe into the rectum and attaches it to
a stabilizing device which holds the tool for the duration
of the treatment. Also attached to the stabilizing device
is a needle template which is 1 to 3 centimeters away
from the perineum. The template’s design corresponds
with the medical team’s planning and guides the
seed implant process.
Radioactive seeds may come pre-loaded
in the brachytherapy needles according to the oncologist’s
prescription. Permanent seed implantation uses Palladium-103-
or Iodine-125-filled
titanium seeds. The titanium casings stay in the body
but become inert as the radioactive material decays.
The number of seeds in a needle is specified for a patient.
Linked seeds are bound by a suture that is absorbed
by the body. Some researchers believe that seed strands
are easier to plant and that the link decreases the
occurrence of seed migration. Migration occurs when
seeds are dislodged and expelled in the urine or semen.
In rarer cases, a seed migrates to the lungs, but there
is no evidence that proves lung migration is harmful.
The needles are inserted percuntaneously
through the perineum. The doctor carefully plants the
seeds, which engulf the prostate gland and a 5 millimeter
margin outside the gland with a cloud of radiation.
During the procedure, most doctors looking for hot and
cold spots are continually scanning the prostate with
the TRUS. Seeds that are planted too close together
result in a hot spot of higher radioactivity and could
damage the rectum or bladder. A cold spot occurs when
seeds are planted too far apart and could leave the
tumor inadequately treated.
Most patients move around as soon
as anesthesia wears off. Doctors will prescribe antibiotics
and possibly an alpha-blocker,
which relaxes the neck of the bladder and decreases
the severity of urinary side effects. Patients may also
take over-the-counter medications to alleviate soreness
in the perineum. Some patients will use ice packs the
next day or two to reduce swelling. |
