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. Author manuscript; available in PMC: 2018 Jul 2.
Published in final edited form as: J Neurosurg. 2017 Oct 6;129(1):35–47. doi: 10.3171/2016.11.JNS161170

Figure 2. Permissible PTV Modification to Limit PRV Dose (PTVPRV).

Figure 2

Planning CT with OAR, PRV, GTV, CTV, PTV, and PTVPRV contours in a patient whose WHO grade II meningioma surrounded the anterior optic apparatus. The PTV prescription dose was 54 Gy in 30 fractions. With this example, the PTVPRV prescription was lower in order to satisfy the optic nerve point dose constraint, while still prescribing 54 Gy to the larger PTV.