Technological Advances of Permanent Seed Brachytherapy Page 7

Permanent Seed Brachytherapy

Stephen W. Doggett MD
14642 Newport Ave #470
Tustin California, USA 92780
714 573 9500 Fax 714 573 9505
www.nocancer.com

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Image fusion is the ability to electronically superimpose two different types of images onto one screen for interpretation. Image fusion allows twice or three times as much information to be viewed on the imaging screen. Different types of images like ultrasound, MRI, CAT and Prostascint can be viewed simultaneously. Simultaneous image fusion allows the strong points of each type of imaging to be exploited. Dr Doggett is a leader in the use of Prostascint/MRI image fusion in the operating room which permits far greater implant accuracy.

Prostascint is a nuclear medicine test with essentially no side effects. It requires an injection on day one and then four days later about one hour of scanning time to create the images. Prostascint is an antibody against the membrane that surrounds the prostate cell. Attached to the antibody is a tiny amount of a radioactive tracer that can be detected by the scanning camera. The Prostascint antibody attaches itself to wherever there are prostate cells in the body. In turn the camera can find the radioactive tracer and localize it so the position of the cancer in the body can be pinpointed.

Until recently, Prostascint scans were somewhat difficult to interpret. This was because the physician interpreter had few anatomic landmarks to measure the uptake of antibody against. This means that the Prostascint pictures generated in the past were difficult to use to make treatment decisions. The following older Prostascint image demonstrates how indistinct and difficult to interpret such images were.

MRI scans are created with a magnetic field and like Prostascint have almost no side effects. MRI stands for Magnetic Resonance Imaging. MRI scans produce an exquisitely detailed picture, almost like that of an anatomic text book. MRI usually does not show the location of the cancer.

New and sophisticated hardware and software are used to fuse the MRI and Prostascint images together. The result is a compound image of astounding clarity containing an enormous amount of information. Dr Doggett uses this information to tell where in the gland the cancer is concentrated. Radiation seeds can therefore be planned to be placed in areas where cancer exists. If cancer is seen extending outside of the capsule of the prostate, seeds can be planned to be placed here also. If the cancer is confined to one side of the gland, then the nerve controlling erection on the opposite side can have a reduced dose of radiation planned, this is called nerve sparing brachytherapy. (Click here for home page nerve sparing brachytherapy). Image fusion has tremendously increased the accuracy and usefulness of the Prostascint examination by combining the cancer finding ability of the Prostascint examination with the anatomic clarity of the MRI examination.

Nerve sparing brachytherapy is the use of reduced amounts of radiation to the nerves that control erection that run on either side of the prostate. (nerve sparing brachytherapy) This reduction in radiation to the nerve is designed to decrease the amount of scarring to the nerve that radiation can cause. This is designed to decrease the sexual impotency that can arise with radiation. In nerve sparing surgery, one of the nerves is surgically removed with the prostate and one is left behind. With nerve sparing brachytherapy, both nerves are left intact and one nerve receives a much lower dose of radiation.

Nerve sparing brachytherapy is a technologically advanced technique that requires the use of intraoperative brachytherapy and of Prostascint/MRI image fusion. Nerve sparing brachytherapy is not possible with the old pre plan method. Dr Doggett is a leader in the use of nerve sparing brachytherapy.

The image shows an MRI fused onto an intraoperative ultrasound image. The red contour is that of the prostate as identified by intraoperative ultrasound. The nerves that control erection are labeled. The nerve on the left has been spared by sophisticated intraoperative treatment planning but the nerve on the right has been included in the treatment field because the cancer comes close to this nerve.

The neurovascular bundles that control erection run on either side of the prostate gland. These nerves cannot be seen under ultrasound but can be seen clearly with MRI. A preoperative MRI is therefore fused onto the real time ultrasound so that the nerves can be identified. Once identified, the radiation dose to one of the nerves can be reduced using intraoperative planning techniques provided that the biopsy report and Prostascint report show little or no cancer near that nerve. It is thought that radical prostatectomy nerve sparing surgery may improve potency rates. For nerve sparing brachytherapy it is thought that a reduction in dose may also improve potency rates. Nerve sparing brachytherapy is not possible with the old preplan technique. Dr Doggett is one of the first physicians in the world to use nerve sparing brachytherapy.

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