|
Selected data from Table 1, Table 2 used to
compare incidence of
radiation-induced optic neuropathy (RION) vs. maximum dose (Dmax) to
optic nerves. Selected studies generally used fraction sizes
with range of 1.8–2.0 Gy, assessed the dose to the nerve directly
from their best estimate of dose distribution in the structure
(i.e., not as a partial volume average), did not include pituitary
lesions (lower tolerance), and selected patient age <70 years (if
segregated). Bars illustrate range of doses for groups characterized
by incidence values. Points offset from 0% to ≤1% were shifted to
clearly show range bars. For points displayed at 0%, available range
information was outside 50–70 Gy.
Threshold for RION appears
to be 55–60 Gy. However, range bars illustrate treatment in 60–65 Gy
range for some studies without RION. Data estimated from
tables, figures, and text reported in the studies, because exact
incidence data were not always provided. The 1 patient in the study
by Parsons with an event in the 55–60-Gy range was treated to 59 Gy.
The 1 patients with an event in the study by Martel in the 55–60-Gy
range received 59.5 Gy. |
