The pads were used to help direct the radiation beam and shield healthy tissue.
The radiation program, derived from a CT scan, divides each radiation beam into thousands of smaller, targeted beams that hit the tumor and avoid healthy tissue.
A lone primary tumour can be tackled by knife or radiation beam, as well as drugs, with a reasonable hope of success.
I.M.R.T. uses what is called a multileaf collimator, tiny metal leaves that can move during treatment, shaping and modulating the radiation beam.
The radiation beam can also come from multiple directions, each beam being focused on the deep tumour, delivering a smaller dose to surrounding organs and tissues.
Mr. Giuliani's doctors said that after two months, Mr. Giuliani would begin receiving doses of radiation from a radiation beam aimed at his prostate for 15 minutes a day, Monday through Friday, for five weeks.
The solution, the advertisement said, was a linear accelerator with 120 computer-controlled metal leaves, called a multileaf collimator, which could more precisely shape and modulate the radiation beam.
In Missouri, for example, 76 patients were overradiated because a medical physicist did not realize that the smaller radiation beam used in radiosurgery had to be calibrated differently than the larger beam used for more traditional radiation therapy.
For 30 seconds the radiation beam morphs in size and shape as it goes, deftly avoiding burning his nearby organs.
It should consider the effects of variations in object/attenuator thickness and radiation beam quality.
A radiation beam was selected to provide the most homogeneous dose to blood samples.
