When an IMRT treatment is planned for 20 fractions and if we want to check the cumulative DVH delivered after 10 fractions such that we can do an off line adaptive planning. What is the standard procedure followed. The machine is a 6MeV linac with Kv IGRT.
If I understand well to your question...it is enough to divide your previous DVH values
Hi Dr Kamal
We do have the access for each fraction. What we have is patient position data for each fraction from the on-board kV imaging system
Hi Lukas,
This information is to provide Off line adaptive planning and to plan the remaining fractions with the new DVH values
Hi,
if you have patient position/correction which has not been applied but were recorded from kv images, there has to be an option in your planning system to adjust the isodose plan - to move the whole plan in planning CT according to patient displacement which you know from kv images.(I mean to move with isodoses, something what is used with phantom and patient plan)...it is easier with CBCT when you can generate CT slice from verification..
.I have never try this, it is only idea. Good luck.
Even using positioning info per fraction can not give you an accurate daily DVH if you simply use the original planning CT scan. On a daily basis, the organs may distort slightly, contours change, functional units of the organs ar in different locations and thus get a different dose. So we are talking about ever better, but still approximations...which will depend greatly on the body site in question...
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