Computed tomography in radiation therapy treatment planning of hepatic metastases

Forty-four patients with symptomatic hepatic metastases from a colon primary had CT prior to radiation therapy treatment planning. A control group of 44 patients with no evidence of liver metastases was analyzed for comparison. The objectives of planning were to deliver as homogeneous a dose to the whole liver as possible and not to treat one kidney or more than one-half of both kidneys. Conventional anteroposterior/posteroanterior portals were found to be inadequate for the treatment of 60% of patients with metastases and 10% of patients with no liver involvement. Among the metastatic group, 50% required oblique planning, 40% anteroposterior/posteroanterior and 9% posteroanterior and left lateral portals to meet the treatment planning objectives. Among the control group of patients with no liver metastases, only 9% required oblique portals and 8% could not be treated because of left hydronephrosis or a solitary right kidney. It is concluded that all patients receiving radiation therapy to the liver for symptoms or prophylaxis require CT for optimum radiation therapy treatment planning.