1374

1561

(57)

Radiation Oncology 0 Biology ??Physics October 1980, Volume 6. Number 10

4 simple i3lectron Sea:? t?chni,lue :as ;een developed to ?ddrzss tClesc problems. it si:wl3’+es an .3lectron bean ar’: t”lr3ug17 t’le is2 ,:f

nultiplc fixed fields. The technique is isocun.t-ic m? i33n Jc3 i:7;) I ,3- Ten ted eas i ly on an ,3cce I erator, such ds +5c t? I i nsc :a, .4her3 the 2;ln-

+ry anjl9 can be changed remotaly from tl7e control 3ns3113. TrC_?atnent

times are conparab I? to We true arc techn i que as tiler-2 is no need if? enter the room during the procedure.

T’lls paper discusses the physical characteristics of the sil’:le Jncol I inatod fields which lead to the unifor? ‘rfose 3istribution pro- duced by the Fseudo-arc tzhni que. The dosi:wtr,{ ca Icu Istims rcqu ired to implement the technisque ?nd the ;:a+ient positioni?? tcchnizali+ies are addressed as wel I.

INDIVIDUALIZED CHEST WALL COMPENSATORS FOR ELECTRON IRRADIATION FOLLOWING MASTECTOMY: AN ULTRASOUND APPROACH

J. L. Beach and C. W. Coffey

Department of Radiation Medicine University of Kentucky, Lexington, Kentucky 40536

We are using A-mode ultrasound in a procedure to construct and test individualized tissue compensators for electron beam irradiation of tissues overlaying lung. A serious problem occurs in large field electron beam ir- radiations where the thickness of tissues over the lung may vary by as much as 3 cm. Electron energies corresponding to the thickest tissues in the