Comparison of Field-in-Field Radiotherapy with Conformal Radiotherapy for Unilateral Cervical Malignant Lymphoma

This study compared field-in-field (FIF) radiotherapy with conformal radiotherapy with physical wedges for the treatment of unilateral cervical malignant lymphoma. Two treatment plans, the FIF technique and conformal RT, were generated for each of 32 patients with unilateral cervical malignant lymphoma. To compare the 2 treatment plans, dose-volume histograms of the planning target volume (PTV), the thyroid, submandibular gland, carotid artery, mucosa, spinal cord, and surrounding normal tissue, and monitor unit (MU) were analyzed. The FIF technique showed significant reduction in the mean dose of thyroid, submandibular gland, carotid artery and mucosa, the maximum dose of the spinal cord and PTV, and the volume receiving > 107% of the prescribed dose of surrounding normal tissue (p < 0.001). In addition, there were gains in the homogeneity index of the PTV for FIF. Furthermore, the total MU was also lower for the FIF technique than for the wedge technique (p < 0.001). Compared with the wedge technique, the FIF technique improved the dose homogeneity of the PTV, reduced the dose to normal structures, and was associated with fewer MUs in the treatment of patients with cervical malignant lymphoma.