RADIATION-THERAPY OF EXTERNAL ILIAC LYMPH-NODES WITH LATERAL PELVIC PORTALS - IDENTIFICATION OF PATIENTS AT RISK FOR INADEQUATE REGIONAL COVERAGE

PURPOSE: To determine whether ''standard'' lateral pelvic radiation th erapy portals provide adequate margins for treating the external iliac lymph nodes (EILNs). MATERIALS AND METHODS: With computed tomographic (CT) data and a computerized algorithm, the course of the EILN chain was reconstructed in 48 patients. The marginal distance between a cons istently localized portion of the EILNs and the anterior field border that was placed at the front of the pubic symphysis was recorded for e ach patient. RESULTS: The EILNs were covered adequately in only 50% of both men and women. More adequate EILN margins were observed in (a) w omen older than 68 years, (b) women with small anteroposterior separat ions, (c) men older than 70 years, and (d) men and women with a low ce ntral obesity index. Less adequate margins were observed in men who we re obese or men with large anteroposterior separations. In the study p opulation, no correlation was observed for sex, race, or tumor site. C ONCLUSION: The authors recommend portals that are designed specificall y for patients rather than standard portals that may inadequately cove r the intended targets.