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Med Phys. 2008 Jan;35(1):77-80.

Visual sensations during megavoltage radiotherapy to the orbit attributable to Cherenkov radiation.

Author information

1
Department of Radiation Oncology, University of Colorado at Denver and Health Sciences Center, Aurora, Colorado 80045, USA. francis.newman@uchsc.edu

Abstract

During megavoltage photon and electron beam radiotherapy treatment involving the eye, patients commonly report visual sensations; "nerve stimulation" is the conventional explanation. We propose that the phenomenon can be attributed to Cherenkov radiation inside the eye. The threshold electron energy for Cherenkov radiation in water is 260 keV. The human retina is able to perceive approximately 5-14 visible photons in 0.001 s. A single 500 keV electron traversing 1 mm of water will induce nearly 15 Cherenkov visible range photons. We propose that a portal image involving the eye will produce sufficient Cherenkov radiation to be detected by the retina.

PMID:
18293564
DOI:
10.1118/1.2815358
[Indexed for MEDLINE]

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