Reduction of Heart Absorbed Dose in Cobalt- Therapy of Stomach Cancer

The external photon beam radiotherapy should be carried out in a way to achieve an "as low as possible" a dose in healthy tissues surrounding the target. For the scope of protection against undue exposure to ionizing radiation it is necessary to determine radiation dose to specific body organs and tissues. Heart as a surrounding organ in stomach cancer radiotherapy, will be exposed to rays during this process. By considering its vital role in pumping blood to different tissues (about 2000 gallons per day), the insufficiency of exposure to gamma rays may show itself sensibly. A collimator has been suggested to reduce absorbed dose in heart about 36% and a reduction of about 85% in heart zone.