How do you typically prescribe dose to a PTV for standard IMRT plans?

Each PTV has three constraints:

>/= 95% of PTV receives 100% of RX dose

Max hot spot </=110%

>/=99% of PTV receives >/= 93% of Rx Dose

For the top dose level:

95% of the PTV receives 100% of the dose

100% of the PTV receives 95% of the dose

0% of the PTV receives >105% of the dose

For patients with gross disease, additionally ask for 100% of the GTV to receive 100% of the dose.

For newer dose calculation algorithms, e.g., monte carlo, we are now using 107% as a max -- this appears to be what collapsed cone would result in when recalculated in MC.

Technically, ICRU 83 is supposed to be of guidance here.

In reality, no one I know strictly hews to the ICRU 83. We're all a bit rogue.

And remember that the PTV is strictly a geometric, non-clinical construct designed to give adequate doses to GTVs/CTVs.

Re: "When you write a prescription dose for an IMRT volume, how do you typically determine if that prescription has been fulfilled," the Rx is the Rx. How you want the dose to "be" in the PTV is how it should be. Although, some things are unachievable. For example, "PTV Rx dose of 70Gy" is unachievable because it implies ALL of the PTV gets 70 Gy, no more or no less. In reality there is always "heterogeneity" which reflects dose variability within the PTV. Again, citing the ICRU, "hot spots" ...