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Figure 2. Dose–volume histogram (DVH) for the 25 mm fan beam plan. Excellent coverage of the clinical target volume (CTV) (craniospinal axis) with 36 Gy and the gross tumour in the cord and brain (gross target volume (GTV) with 45 Gy. Doses to critical structures (OAR) are below specified limits. Compared with the DVH for LINAC treatment (1b), variation within the GTV and CTV for brain and spine is much less and OAR doses are overall much lower. For paired organs (Lung, Kidney) only the side with the higher (i.e. least favourable) DVH is illustrated.
