SGRT Forum

At my institution, we experience RTD drift at couch angles approaching 90 and 270 degrees, as discussed in some of the other Topic's in this form. We are working on controlling our processes more tightly to reduce this issue. Recently, we have discussed the roll of simulation in reducing the RTD drift and improving our performance generally.

I have heard from a few sites that it is important to ensure that the patient’s face is pitched towards feet (i.e. chin slightly tucked) at simulation. With our current vendor of open-faced mask, this turns out to be somewhat difficult to. The shape of the head-bowl that lies under the custom neck cushion encourages a pitch that is neutral or slightly tilted back.

Does your clinic focus on head tilt at simulation?
Do you strive for a face-toward-toes pitch for every treatment?
Do you have an immobilization system that helps you achieve this?
What other simulations best-practices do you use?

Warm regards,

Dustin Jacqmin

With a custom pillow you can adjust the chin tilt any way you want. We have the patient's chin up because it helps dosimetry to avoid the eyes during planning.

In our experience, RTD drift at couch 90/270 degrees seems to be patient dependent and it seems to only cause LNG drifts. It only happens in a small number of our patients. We are guessing that it may have to do with the shape and size of the nose, but we are not sure.

Make sure you determine your couch walkout to help you determine how much of the change in RTD is due to non-patient factors.