RESUMEN
Isodose curves are measured from a fiat surface and usually not exactly applicable to the contour of the patient. For irradiation of irregular surfaces, beam modification is often desirable. However, for obese patients, pelvic irradiation is more complicated specially if high energy linear accelerators are not available. The designed apparatus consists of a pair of rigid wood plates with 4 graduated metal bars. It is fabricated in such a way that allows for easy, reproducible flattening and compression of the anterior abdominal wall. It also allows for under couch irradiation. Better homogenity and depth dose data can be easily achieved with reduction of total given and total integral doses. Also, doses to the skin creases and subcutaneous tissues are minimized. Radiation course can be better tolerated by the patient