Brain Tumours

Electrons for the spinal axis

Problems:

- Limitations on length of field (20-25 cm) - Dosimetry at junctions - Possible variations in dose to CTV because of attenuation by bone - Dose gradient in vertebrae - Increased dose to lungs - Use of energies < 22 MEV are associated with an excess of failures (Carrie, 1992) - Use with care !