I am looking for how to apply the dose constraints for OARs in the case of a RC3D hypofraction treatment.
Example; RC3D case of lung cancer treatment is a vector of 66 Gy, for the DVHS v20 is applied to the healthy lung
In my institutions there are two approachs to that problem:
- Use constraints from the literature for that fractionation. Since Hypo-fraccionated schemes are so popular it shouldn't be difficult to find them. I guess your physician didn't produce the scheme out of thin air.
- A second approach is to to rescale your whole dose distribution (f.e. 30 Gy/10 fractions would be like 38 Gy /19 fractions) acording to some alpha/beta.
Hope it helps, yours,
Eduardo Pardo (Medichal physicist).
By the way your title says hyperfractionated but the question says hypo fractionated.
I am not sure if I fully understand what you are looking for but from my experience I would say that when a clinician chooses 30 Gy in 10 fractions, the aim of treatment for that patient is palliation and not cure and so the constraints are generally very lax and the technique quite simple and would rarely involve 3D planning; whereas a dose/fractionation regime of 66 Gy in probably 30 or 32 fractions is considered radical and the aim is cure and as a result strict constraints would need to be applied for such as well as a more complex technique. A truly hypo-fractionated regime for radical and curative effect would need to be based on evidence both for the dose/fractionation and for constraints and that would require an extensive literature search.
This question is not adequate! You should go to literature.... We just don't treat patients from doses given by random people on the web! Hyperfractionation is a very wide field! Look for schemes appropriate for the pathology that you want to treat!
Timmerman has published OAR limits for hypofractionated treatments. When hypofractionating one must take into account the BED of the higher daily dose.
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