Direct multiplanar computed tomography in planning radiotherapy for malignant tumours of the nasopharynx

A method of direct computed tomography (CT) scanning for planning radiotherapy of malignant nasopharyngeal tumours is described. Direct multiplanar CT scanning is the imaging method of choice for the diagnosis and definition of the target volume of these tumours. The patient is positioned for treatment precisely as for direct axial model CT. By integrating the information generated by high-definition scout views, direct axial mode, and, occasionally, direct coronal mode CT, the anatomical points of reference are identified. These are then translated to the surface anatomy of the patient to define the fields accurately prior to radiotherapy treatment.