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Questions from the audience
•
Some careful considerations, some answers
…
Ø
Prescribing to an enveloping isodose line is fine, but what isodose
should we use? Isodose compared to what normalization point?
§
Isodose compared to isocentre dose or D
near-max
?
§
Which isodose 60%-80%, 95%?
§
Unfortunately ICRU only says “an enveloping isodose” must be used, so:
“yes it is still confusing”.
§
Fortunately, with what should be reported (D
50%
to PTV and GTV, and
D
near-max
and D
near-min
), you should be able to translate a published result
to your prescrition method.
o
eg, if you use 15 Gy to 60% of isocentre dose, it will become difficult to
compare that to a study reporting D
50%
= 15Gy, D
near-max
= 17Gy
…
Ø
Very confusing in the ICRU 91 is the concept in that the accepted
plan becomes the “prescription” for reporting, this is contradicting
daily practice
…
SBRT 2017 - D. Verellen