Localization error in the radiotherapy of Hodgkin's disease and malignant lymphoma with extended mantle fields.

Abstract

In a review of 902 treatment verification films for 99 lymphoma patients receiving radiation therapy with extended mantle fields, 330 localization errors were detected. We found that 50% of the localization errors occurred in the axillae and that the axillae were the sites of most frequent clustering and recurrence. These facts suggest that localization errors caused sufficient reduction in dose to explain the recurrence of lymphoma in the axillae of several patients. Technical modifications of the blocks in relation to the axillae are discussed. Of 10 patients with local recurrence of Hodgkin's disease or malignant lymphoma, 2 had enough documented localization errors at the site of recurrence to account for a dose reduction sufficient to explain the recurrence. For the remaining 8 cases, we lacked sufficient films to determine the incidence of localization errors and thus to make estimates of reductions in dose. We observed a reduction of localization errors from 55% to 29% over the last 2 years of the study. This gratifying result is best explained by technical refinements and by the increased use of treatment verification films. On the basis of the data gathered in this study, we feel that treatment verification films are invaluable in the detection of localization errors in the treatment of lymphoma, and that they can lead to a reduction in localization errors if they are used regularly.