Bootstrap Framework 3.3.6

[amnavora]

Hi All,
Just wanted to ask what your policy and procedure is for if align rt goes down and you have markerless breast patients?

[ben_allen]

Hi,

We have multiple AlignRT systems so if one unit went down we would be able to treat the patients on a matched linac. A worst case scenario (that we have had once in 5 years) is that someone would have to replace a camera and this was turned around in less than 2 days. Most issues have been solved remotely in a matter of hours. And even these issues have been very rare.

We have never lost multiple systems at once but our fall back would be to use IGRT to position the patient. You could then place penmarks for the following fraction etc. Clunky workaround but thankfully never had to do anything like this. The downtime of AlignRT has been next to nothing in all the time we have used it and we've relied solely on it for our breast patients for many years.

Hope this helps.

Ben

[nicola_mullins]

Hi
We included this in our initial risk assesment when clinically implementing tattoless treatments. As a contingency for breast treatments we record the suprasternal notch (SSN) from the lateral scale on the board in our setup records.
We have multiple systems, so in the event that a system goes down we would treat on another machine. We have a similar experience to Ben in that we have had minimal downtime.
Hope that helps
Nicola

[amnavora]

Can i ask how you would manage with Breathold patients, as we would use the align rt to check patient was reaching correct BH. And with tattoos we would have a reference point from tattoo to where the patient needed to reach to ensure they we taking adequate breath holds

[marko_laaksomaa]

Hi Amnavora

I think “tattoos or tattooless” have nothing to do with correct breath hold level.

In our practice we use now SSN (reference level) for approximate initial verification to check that patient is in correct location in CC direction at the fixation, but only at the first fraction. Even more important for initial setup is that the patient is well fixed at the head cushion, relaxed and straight. Then we daily use planned couch value in AP direction, showing the correct spine location in AP. FB surface needs to be inside 1mm and 1° thresholds, also in AP direction. If the patient is 1 cm in incorrect LNG at the fixation (which we do not want her to be), it means only 1-2 mm displacement in AP for the spine if the tilt is 10° at the fixation. More effective seems to be to correct roll and arm position to reach FB VRT inside tolerances with planned couch VRT, typically there is needs to relax the patient at the setup. ROI mostly on the rigid surface seems useful. Then the switcing to BH surface ensures the correct BHL, which is as well visible on the patient monitor, the distance between FB and BH VRT should not vary daily, I mean that if the chest chould move 8 mm from FB to BH in VRT, it should move that much daily. With RPM we use daily the same couch VRT together with tattoos. RPM (and Catalyst) measures the baseline from the current chest posture. This seems to lead to good BHL as well (measured as the errors (AP) between spine and the sternum from LAT images). So I think, concerning BHL, to daily send to couch FB VRT with AlignRT may in most cases be adequate as well with not taking care of couch planned VRT. This is the practical workflow most uses, I suppose. We have however noticed it more accurate to use daily the same couch VRT and additionally to setup FB surface inside tight thresholds as well, to daily eliminate the possibilty to allow chest being differently relaxed (comparable to interfractional baseline drift) at the FB setup. The advantage of AlignRT is that already at setup we see that the patient is taking correct BHL from rotations- and LNG- and LATs parts as well, is in correct isocenter in BH as well. I do not see it important to daily check any SSDs or indexed values to show that the patient is in correct LNG in the fixation, since the reason may as well be that the posture of the patient is different not the LNG position of the patient, which one to correct? Sometimes I see that patient is asked to come caudally on the fixation to reach reference mark at sideindex and after this patient is not at the headrest anymore. This is what we should not do, since patient has for sure been well aligned at the headrest at the CT. I think AlignRT is more accurate to tell these and everything else we need to know. Some kind of daily images tell the rest.

Best regards rtt Marko