Background and purpose: Whole craniospinal irradiation cannot be achieved in one field at a normal treatment distance for adults. The aim of this newly developed technique is to minimize problems of matching fields and to maximize precision of craniospinal radiotherapy.
Patients and methods: Twelve patients (3-59 years) had craniospinal irradiation in supine position. The head was treated with lateral opposed isocentric fields with collimator rotation and isocentric table rotation. Using an extended source-skin distance of 160 cm only one dorsal field is necessary to cover the whole spinal axis. To avoid systematic under- or overdosage, junction field edges were moved twice by 1.5 cm. Treatment planning was performed based on CT scans. For visual verification of field matching an additional line laser was first adjusted to the caudal edge of one lateral light field and then checked against the light field of the spinal field under the table.
Results: Control films show good homogeneity in the junction between lateral and vertical fields. Reproducibility of table movements is acceptable. Total time needed for one fraction is about 15-20 min.
Conclusion: The described technique is now well established, feasible and leads to less risk of dose uncertainties.