Technical aids for the radiotherapy of Hodgkin's disease

Abstract

The modern high-energy treatment of Hodgkin's disease using extended fields (mantle-fields, inverted Y), presents technical problems due to the size and the irregular shape of the fields. Very extensive lead shielding is required in order to reduce the dose to the adjacent critical organs to a minimum, as well as to shield as much bone-marrow as possible. It is often necessary to alter the outline of the field during treatment as, for example, in the case of the patient who has regression of a mediastinal tumour or of enlarged para-aortic lymph glands. With treatment by mantle-fields, there is in addition the problem of obtaining a homogeneous dose to superficial cervical glands and to deep-lying mediastinal glands. Finally, with mantle-fields it may be difficult to obtain a completely reproducible arrangement because of the movement of the head. With these problems in mind, a special technique for the production of immobilizing forms, lead shields, and compensation filters, has been developed at the Radiumcenter in Copenhagen The steps in the production of an immobilizing form are shown in Fig. 1. The outer frame is a box constructed of three slabs of polystyrene foamplastic glued together. A hole, which is somewhat larger than the outline of the head and thorax of an adult man, is cut in the middle slab. An outline of the patient is superimposed onto the box, and a thin soldering iron is used to make an opening in the top slab, following this outline.