|
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 lasts 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 a 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 patient is 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. |
