Evaluation Of Transperineal Ultrasound For Image Guidance In The Treatment Of Prostate Cancer in Men Following Prostatectomy

This study is being done to find out if transperineal ultrasound (TPUS) can help define the
prostate bed for radiation treatment planning and improve upon current methods of image
guidance for the treatment of prostate cancer. For the patient, TPUS involves the placement
of an ultrasound probe on the perineum, the skin between the scrotum and anus, while they
are lying on their back in the position they will receive their treatment. Image-guidance is
required for the treatment of prostate cancer because the prostate bed shifts position
depending on how full the bladder and rectum are. Image-guided radiation therapy has been
done at Fletcher Allen Health Care for approximately three years. Most commonly,
transabdominal ultrasound images are obtained every day and compared to an ultrasound that
was done on the day of treatment planning. Adjustments in radiation field position can be
done on a daily basis by comparing these images. Transperineal ultrasound has never been
used for image-guidance. We completed two phases of an earlier study and have developed a
TPUS device and process that allow us to get clear ultrasound pictures of the prostate
gland, and now we would like to explore imaging the prostate bed left after radical
prostatectomy.The TPUS has three potential advantages over the transabdominal method we
currently use:

1. Transabdominal ultrasound can be a challenge for some men. A full bladder helps us get
clearer images, however it is difficult for some men with prostate cancer to
comfortably keep a full bladder. It is also particularly difficult to get good images
in larger men who have long distances from the skin surface to the prostate bed. TPUS
is not dependent on a man having a full bladder and should be less dependent on the
size of the man.

2. TPUS images and the planning CT images can be acquired simultaneously. This is not
possible with the abdominal probe because it gets in the way of the CT machine.
Simultaneous imaging eliminates the possibility of the prostate bed shifting positions
during the time between imaging studies.

3. TPUS can be in place and acquire images during patient treatment (the abdominal probe
gets in the way of the treatment machine) and may in the future allow us to watch the
prostate bed during treatment. If we discover that we can accurately view the prostate
bed in real time, TPUS may ultimately allow us to treat even smaller radiation fields
and possibly decrease the risk of radiation complications.

Patients in this study will be treated for their prostate cancer with the standard image
guidance technique used at Fletcher Allen Health Care: transabdominal ultrasound. In
addition, one TPUS scan will be acquired at the time of the initial simulation.

To summarize, the two objectives of this study are:

1. To determine if TPUS can acquire usable, clinically pertinent IGRT images of the
prostate bed.

2. To preliminarily compare TPUS images of the prostate bed to images obtained with CT and
TAUS.