added radiation

[Guest guest]

I can only speak to the daily, pre-treament x-ray that is taken at

Loma . The radiation from the x-ray is factored in to the total

79.2 cobalt grey equivalent dose. It is not in addition to the total

dose. I suspect that is the case where any daily imaging is used.

Laurel

Tomography, or Image-Guided RT (IGRT) is an improvement on the IMRT

procedure accuracy in that it does, as Dan wrote, use CT (computerized

tomography) to locate the prostate and to permit shaping the beam in

order to avoid collateral damage to other organs. Of course, this

involves added radiation which may or may not be a factor for the

individual to consider

>

> (snip)

>

> > The " Tomotherapy " procedure was essentially developed here at the

UW

> > in the 90's and consists of linking IMRT to a CT, so that the

patient

> > gets a CT with each treatment to better target the prostate. In

the

> > " old days " , tatoo'ed " registration " marks were applied to the

skin to

> > help line up the equipment, along with other landmarks to position

> > the radiation delivery equipment. It has been found that the

prostate

> > can move around quite a lot (centimeters!) in reference to these

> > landmarks, so radiation treatment without " same day " imaging has

been

> > less accurate. Less accurate means more side effects from normal

> > tissue being irradiated, and less effective tumor control.

>

> Just to clarify: When treating with IMRT, the tattoo marks on lower

> abdomen and each hip are far from the only means used to orient the

beams.

>

> Before txs begin, a planning session is held. At that time, a CT

scan is

> done in order to document the location, size and shape of the

prostate.

> A mold of the lower body is also prepared and is used in each tx

session

> to help immobilize the patient.

>

> Before each tx session, the exact location of the prostate is

determined

> using ultrasound equipment, called BAT (B-mode acquisition and

targeting).

>

> Tomography, or Image-Guided RT (IGRT) is an improvement on the IMRT

> procedure accuracy in that it does, as Dan wrote, use CT

(computerized

> tomography) to locate the prostate and to permit shaping the beam in

> order to avoid collateral damage to other organs. Of course, this

> involves added radiation which may or may not be a factor for the

> individual to consider.

>

> Regards,

>

> Steve J

>

> " Never choose an Institution -- if (you do) so, you will be labeled

> as having an 'edifice complex.' Choose the doc, not the building. "

> -- B. Strum, MD

> Medical Oncologist

> (See " Oedipus Rex " by Sophocles)

>