Irradiation of the inguinal lymph nodes in patients of differing body habitus: A comparison of techniques and resulting normal tissue complication probabilities

The treatment of the inguinal lymph nodes with radiotherapy is strongly influenced by the body habitus of the patient. The effect of 7 radiotherapy techniques on femoral head doses was studied. Three female patients of differing body habitus (ectomorph, mesomorph, endomorph) were selected. Radiation fields included the pelvis and contiguous inguinal regions and were representative of fields used in the treatment of cancers of the lower pelvis. Seven treatment techniques were compared. In the ectomorph and mesomorph, normal tissue complication probability (NTCP) for the femoral heads was lowest with use of anteroposterior (AP) and modified posteroanterior (PA) field with inguinal electron field supplements (technique 1). In the endomorph, NTCP was lowest with use of AP and modified PA field without electron field supplements (technique 2) or a 4-field approach (technique 6). Technique 1 for ectomorphs and mesomorphs and techniques 2 and 6 for endomorphs were optimal techniques for providing relatively homogeneous dose distributions within the target area while minimizing the dose to the femoral heads.