The role of lymphangiography in designing fields for elective pelvic node irradiation in Hodgkin's disease.

PURPOSE

We attempted to design a standard pelvic nodal treatment field such that all lymph nodes usually visualized on lymphangiogram would be irradiated with optimal midline blocking of normal tissues.

METHODS AND MATERIALS

Two standard fields for treatment of pelvic lymph nodes were designed, based on bony landmarks. The standard fields were applied to the anterior-posterior view of 35 pretherapy lymphangiograms, and the fields were then assessed for inclusion of visible lymph nodes. Measurements were done on the lymphangiograms to assess the amount of additional midline blocking that could be added.

RESULTS

All visualized nodes were included in 30 patients (86%) using Standard Field I and in 33 patients (94%) using Standard Field II, but visualized nodes plus a 1.5-cm minimum margin were included in only two patients (6%) with Field I and 24 patients (69%) with Field II. The most frequent sites of close margins were the lateral and medial borders adjacent to the external iliac nodes. Based on the lymphangiograms, a mean of 1.6 cm in male patients and 3.1 cm in female patients could be added to the width of the midline blocks.

CONCLUSION

Lymphangiography is useful in designing fields for pelvic node irradiation, both to improve coverage of nodes with a 1.5 cm margin and to increase the amount of central shielding of normal tissues.