We have a vendor indicating that we need to provide an RT Structure for the images that we have acquired if they are to be used for offline image review in Varian Aria.

My initial thought is that Aria likely needs at least the external patient contour, in support of basic bounds for dose calculations. But any insights or pointers would be appreciated.

Thanks in advance,
Mike

Hi Mike, radiation oncology physicist here so I've used Offline Review a bit.

You are correct that an external contour for dose calculation is one reason they would want structures for offline review. Another calculation related use case is calculating dose volume histograms for individual contours.

The typical use of offline review is comparing patient images taken before/during/after treatment and comparing them to the patient images used for treatment planning. In this use case, sometimes you can compare anatomy directly without the need for contours (for example, does the lung tumor at treatment look ~ the same as it did at the time of treatment planning). However it often simpler to compare the treatment anatomy to the contour used for treatment planning (so in the same example you could compare the tumor at the time of treatment to the contour of the tumor from treatment planning). Also, there are geometric structures that don't have a direct anatomic partner that would require a contour to review. These are typically things like planning target volumes, which are expansions of the tumor volume that account for patient / tumor movement, patient setup variations, etc.

Hope that helps,
Andrew