Flipping Book

Lung: what about low doses? Thread 11/2012

Dear all, does anyone have clear restrictions (e.g. for V5/V10 ...)

how you limit low dose bath

to the

lung in (arc)IMRT planning for locally advanced NSCLC/SCLC?

Any good literature or protocol recommendations? Any good/bad experiences?

We have no constraints for V5 or V10 at xy due to the

absence of literature

on that topic. The only

literature I am aware of is in mesothelioma with hemithoracic IMRT linking V5 with lung

toxicity/deaths.

Our IMRT approach in lung is generally to use ~7 equispaced field which leads to high conformality

at the expense of irradiation of the controlateral lung with low doses.

We are in the process of analysing our IMRT series (>150 patients) and to date we have seen no

correlation between V5/10 and acute/late lung toxicity which is very reassuring.

The article that helped us before embarking on IMRT was

Marco Schwartz analyses

: 3DCRT and

IMRT, homogeneous and inhomogeneous. This is the article coming up with the 7 equally spaced

beams. Using these beam set up is reducing the lung dose. we use only MLD and are not convinced

that any other single point form the DVH will be helping because reducing the V5 or V10 will increase

other Vx parameters.

We follow what x already mentioned.

It may be that with arc treatments the V5 or something similar may pop-up as a risk factor for RP. we

therefore limit the

ipsilateral V5 to< 75% and the V5 of both lungs to< 60%

in case of RapidArc.

But there is so much uncertainty on that. The main parameter is still the MLD.