The value of MRI in radiation therapy

This paper deals with MRI utilization for planning radiation therapy. There have been several reports with the same purpose, however, seem to be incomplete. Such a clinical trial should basically require the high diagnostic quality of MRI for demonstrating cancer invasion. To reach the goal, we have been working with MAGNETOM H15 and/or M10 (Siemens) newly installed in Tenri Hospital. The clinical series consists of 12 patients with head and neck tumors, and with malignancies involving the mediastinum or lung apeces. The practical method and procedure are as follows. (1) The radiation field on the patient's skin is prearranged to include the tumor in its depth. This is identified by putting markers of our own making, small plastic tubes plugged with 'cheese', at each corner on the skin. The material used is based on a specificity producing high intensity signals on T1-weighted image. (2) MR scan is performed from the skin to the depth of lesion with sequential 10 mm-slices by using T1-weighted imaging. MRI display is on the coronal or sagittal views usually vertical to the beams of radiation therapy. (3) Of all MRI acquired, several images are used for drawing the radiation field, and one of others for the optimal demonstration of the lesion. Thus, MRI can be superimposed with the radiation field on the CRT screen. These procedures only requires 30 minites or less. (author)