Cranial stereotactic multiple arc radiotherapy; treatment planning using angiographic images

Stereotactic multiple arc radiotherapy (SMART) is an irradiation technique developed to treat small intracranial lesions. Calculation of absorbed-dose patterns for this treatment has traditionally involved complex computer programs incorporating algorithms designed to reconstruct the shape of the patient's head from computerized tomography (CT) images. A large proportion of the patients treated with SMART, however, have arteriovenous malformations for which angiography provides a better idea of lesion size and position than CT. This paper describes a computer program developed at St Bartholomew's Hospital which enables calculation of absorbed dose for a SMART treatment directly from angiographic radiographs, avoiding the need for CT. The program is compared with the existing CT-based treatment planning program.