SGRT Forum

Dear All,

We are trying to implement SGRT breath hold in liver with VisionRT.

In particular, we would like to ask what breathing recommendations do you give on the CT, do you ask them to breathe through the chest? Do you prefer expiration or inspiration? Which ROIs do you choose? avoiding the belly?

On expiration the liver seems less deform, however there may not be much difference between the body on expiration and free breathing, then it wouldn´t be possible to do BH on the treatment. On DIBH seems a good option except for liver inferior lesions, as it pushes the liver against duodenum and bowel.

Do you find DIBH surface correlates well with the liver position on the CBCT?

Lots of questions!
Thank you in advance
Clara

Hi Clara,
We treat majority of our Liver SABR cases in EBH as this is proven to be more reproducible than DIBH. We use RPM for motion management but have also started using SGRT as well. We use SGRT for setup and also monitoring during treatment ( treat without beam hold at this stage). ROI is over the diaphragm region.It is early days but we are seeing good correlation between RPM motion management and SGRT in EBH. We are exploring using both systems concurrently to ensure EBH is maintained consistently through beam on.
At CT we use RGSC and give instructions "breath out" & "Hold". Good luck with your patients and hope this helps,
Regards
Karen

Hi Clara,

We currently use SGRT (AlignRT) for EEBH Liver for suitable patients.

The instructions can vary from patient to patient, but we will usually start with ‘breathe in, breathe out and hold your breath’.

We’ve steered away from DIBH for these patients as we weren’t finding a consistent correlation between the surface of the patient and the sup/inf position of the diaphragm compared with EEBH. The ROI we use is from TOX down inferiorly umbilicus and to approximately half AP. We use a tight tolerance of 1mm in the ant/post direction and 3mm on the other translations. We watch the breath in magnitude mode on AlignRT and set our thresholds around the expiration point.

We mock these patients up on the machine prior to CT and correlate the surface with the liver dome position by doing 5 x AP fluoroscopy scans in expiration breath hold.

Hope this helps and feel free to reach out with any questions.

Kind regards,

Megan

In contrast to previous colleagues, we use DIBH approach for liver SBRT.
Its more convienient for patients. We tried EBH, but average time of breath hold was too short, way shorter than DIBH. Reproducibility of liver posiotion is excellent in our cohort - we hope to share our first experience during the upcoming SGRT meeting in London.
In case of any questions, please do not hasitate to ask.