Transcript
Hello and welcome to a new Novalis Circle workflow video. My name is Bogdan Valcu, I'm the director of Novalis Circle. And today, I want to show you an ExacTrac Dynamic 1.0 workflow video for pre-positioning setup and monitoring of a spine radiosurgery patient.
The patient is being treated on an Elekta Versa HD linac with a full Novalis configuration. A free-breathing CT is utilized for treatment planning that consists of 3 coplanar VMAT arcs. The patient was scanned with no anterior mobilization device, in a supine position, and with the hands up. Pre-positioning will be performed with the help of the 3D SGRT, extractor light cameras of the ExacTrac Dynamic, followed by a 6D IGRT setup with the ExacTrac Dynamic X-ray System.
With enlarged 18 x 18 centimeters squared field of view of the new x-ray detector panels, the x-rays generated by the ExacTrac Dynamic are displaying enough distinct anatomy to render the fusion to DRRs to be both reliable and easy to interpret by the end-users. So no [inaudible 00:01:32] is needed in this workflow.
Patient monitoring is always live with the 4D SGRT hybrid camera solution, but also 3 sets of stereoscopic x-ray images will be acquired at predetermined imaging points for each arc at 270, 0, and 90 degrees. Lastly, the ExacTrac Dynamic patient settings are set to a 5-millimeter/5-degree threshold for SGRT. Again, this is due to the fact that the patient has no additional immobilization device, and to wear 0.7-millimeter/0.5-degree threshold for IGRT detector deviations. Beam hold control is set to on so ExacTrac will interlock the beam when motion is detected.
So let's begin the workflow. As true with every integrated setup on ExacTrac Dynamic, first, the system is waiting for the plan to be open on the linac. After the plan is also open automatically on the ExacTrac Dynamic side, the patient confirmation page opens up. Here, the user can visually verify and double-check that the correct patient and plan were indeed loaded. If the plan is correct, selecting from plan to proceed with pre-positioning. As previously mentioned, the therapists are performing the pre-positioning steps, utilizing the SGRT component of ExacTrac Dynamic. To begin by laying the patient on the treatment couch and slightly moving the couch into the field of view of the extractor light cameras.
The enlarged 100 decimeters cube scanning field of view of the camera system will quickly detect the patient in the treatment room, and generate an auto contour in real time. By using the send-shift feature, the user is able to send any residual shifts from the manual positioning to the linac couch to move the patient to the isocenter. Once all manual and automatic shifts are made, the 2 auto contours match. Please remember to correct for large rotational deviations manually to not exceed the robotic correction capability of the hack support units.
Now that the patient is positioned at isocenter based on the 3D SGRT feedback, we are defining an area of interest to be tracked by the hybrid camera system throughout the treatments. Please note that at this point the thermal signal is augmenting the structural light surface signal, in essence, creating a highly reliable 4D region of interest. The user needs to make sure that the AOI doesn't include any hardware, in this case, the medical intelligence reference board is removed, and only includes the area of the patient to be tracked during treatment.
Once the AOI is confirmed, the user will be brought to the x-ray corrections screen and the first set of stereoscopic x-ray images are acquired. The image fusion to the RRs generated from the free-breathing CT is being performed automatically by ExacTrac Dynamic and, highlighted in red, predefined areas are removed from the x-ray images to force the mutual information to lock into the desired volume of interest. As you can see ExacTrac provides a good fusion with the deviations seen here, and the results are first verified with the rubber band option. This allows the DRR to slightly be moved while holding the x-ray in place and snap it back into the fusion result once the mouse click is released.
This view is useful for validating that image fusion occurred at the right vertebral level. Furthermore, you can also utilize the crosser option that overlays the split x-ray view on to the DRR. You can easily track transition edges in this view. The region option can also be used to visualize larger areas of the x-ray overlay on to the DRR. You can use this to check on both spinal and vertebral alignments. The amber blue toggle is also useful in providing additional image cues for the evaluator.
Note how the rubber band feature is so much easier to understand with the color contrast between the blue x-ray and the amber DRR. Once the fusion is approved, the shifts are sent to the linac console and the couch motion is automatically enabled. With the shifts completed, the user is prompted to verify the new position of the patient under the x-ray verification page. Here, a second set of stereoscopic x-ray images are acquired, and ExacTrac Dynamic performs again automatic fusion to the DRRs.
You could see that fusion results show some translational deviations highlighted in red. This is most likely the result of the x-ray threshold setting being restricted to 0.7 millimeters. When such large residual shifts are still detected, a careful evaluation of the fusion result is necessary. We use, again, the rubber band and crosshair fusion evaluation options, and once happy with the correctness of the results, we send those new shifts to the console.
With the automatic couch motion enabled, the patient is finally set up to the isocenter based on the daily imaging of internal anatomy. With the setup completed, the user is now ready to track and monitor the patient during this SRS treatment. In the SGRT view, you can see the patient's free-breathing while the gantry moves into the first treatment position.
The surface image shows "In Tolerance" so the treatment begins. You can see the graph at the bottom of the ExacTrac Dynamic screen showing the live tracking of the patient. For this first arc, we have pre-set up ExacTrac Dynamic to auto-trigger stereoscopic x-ray images at gantry positions 270, 0, and 90 degrees. The first set of monitoring x-rays are automatically acquired at the first imaging point and fused to the reference DRRs.
As a deviation is detected outside of allowed tolerances, the beam is paused so the end-user can check the fusion results. Note that the ExacTrac Dynamic graphic user interface immediately shows with the red overlay that a large deviation was detected and also starts the beam hold. The user once again is prompted to review and approve the image fusion results. It is always a good idea to have appropriate physician or physicists' supervision during an SRS treatment especially when tight margins are employed.
With the detected intrafraction motion shifts approved, the couch motion is once again enabled, and the patient's position is automatically adjusted. When completed, the live tracking show the patient to be once again in tolerance and the beam hold is cleared. The treatment now continues automatically. At couch 0, a second set of stereoscopic verification x-ray images are acquired. Once again, a small auto-tolerance translational shift is detected and the beam is held. Image fusion is evaluated again and approved. Couch is automatically moved to correct for this new intrafraction motion, and when motion is completed, the treatment continues.
The third and last set of intrafraction verification x-ray images acquired at couch 90 are showing no significant patient motion. The first arc is therefore completed. The second field is a return arc, and with the patient SGRT tracking showing "In Tolerance," radiation delivery begins. Intrafraction x-ray checks for this arc are detecting no relevant patient motion, and the radiation delivery continues uninterrupted. The third and last arc is again a clockwise VMAT delivery that begins right away as the patient SGRT continues to show the patient to be in tolerance.
The first stereoscopic x-rays are detecting once again intrafraction motion, and the user verifies and approves the automatic fusion. The couch automatic motion is enabled to correct for the detected shifts, and once computed, the treatment resumes. The second and third pairs of stereoscopic x-rays detect no auto tolerance motion and the radiation beam is allowed to be delivered, once again, uninterrupted. Toward the end of the arc, a rather significant patient motion is detected, in this case, by the SGRT signal and this is most likely indicative the patient relaxing the arms. When the patient returns with "In Tolerance," the arc delivery completes.
The patient is being treated on an Elekta Versa HD linac with a full Novalis configuration. A free-breathing CT is utilized for treatment planning that consists of 3 coplanar VMAT arcs. The patient was scanned with no anterior mobilization device, in a supine position, and with the hands up. Pre-positioning will be performed with the help of the 3D SGRT, extractor light cameras of the ExacTrac Dynamic, followed by a 6D IGRT setup with the ExacTrac Dynamic X-ray System.
With enlarged 18 x 18 centimeters squared field of view of the new x-ray detector panels, the x-rays generated by the ExacTrac Dynamic are displaying enough distinct anatomy to render the fusion to DRRs to be both reliable and easy to interpret by the end-users. So no [inaudible 00:01:32] is needed in this workflow.
Patient monitoring is always live with the 4D SGRT hybrid camera solution, but also 3 sets of stereoscopic x-ray images will be acquired at predetermined imaging points for each arc at 270, 0, and 90 degrees. Lastly, the ExacTrac Dynamic patient settings are set to a 5-millimeter/5-degree threshold for SGRT. Again, this is due to the fact that the patient has no additional immobilization device, and to wear 0.7-millimeter/0.5-degree threshold for IGRT detector deviations. Beam hold control is set to on so ExacTrac will interlock the beam when motion is detected.
So let's begin the workflow. As true with every integrated setup on ExacTrac Dynamic, first, the system is waiting for the plan to be open on the linac. After the plan is also open automatically on the ExacTrac Dynamic side, the patient confirmation page opens up. Here, the user can visually verify and double-check that the correct patient and plan were indeed loaded. If the plan is correct, selecting from plan to proceed with pre-positioning. As previously mentioned, the therapists are performing the pre-positioning steps, utilizing the SGRT component of ExacTrac Dynamic. To begin by laying the patient on the treatment couch and slightly moving the couch into the field of view of the extractor light cameras.
The enlarged 100 decimeters cube scanning field of view of the camera system will quickly detect the patient in the treatment room, and generate an auto contour in real time. By using the send-shift feature, the user is able to send any residual shifts from the manual positioning to the linac couch to move the patient to the isocenter. Once all manual and automatic shifts are made, the 2 auto contours match. Please remember to correct for large rotational deviations manually to not exceed the robotic correction capability of the hack support units.
Now that the patient is positioned at isocenter based on the 3D SGRT feedback, we are defining an area of interest to be tracked by the hybrid camera system throughout the treatments. Please note that at this point the thermal signal is augmenting the structural light surface signal, in essence, creating a highly reliable 4D region of interest. The user needs to make sure that the AOI doesn't include any hardware, in this case, the medical intelligence reference board is removed, and only includes the area of the patient to be tracked during treatment.
Once the AOI is confirmed, the user will be brought to the x-ray corrections screen and the first set of stereoscopic x-ray images are acquired. The image fusion to the RRs generated from the free-breathing CT is being performed automatically by ExacTrac Dynamic and, highlighted in red, predefined areas are removed from the x-ray images to force the mutual information to lock into the desired volume of interest. As you can see ExacTrac provides a good fusion with the deviations seen here, and the results are first verified with the rubber band option. This allows the DRR to slightly be moved while holding the x-ray in place and snap it back into the fusion result once the mouse click is released.
This view is useful for validating that image fusion occurred at the right vertebral level. Furthermore, you can also utilize the crosser option that overlays the split x-ray view on to the DRR. You can easily track transition edges in this view. The region option can also be used to visualize larger areas of the x-ray overlay on to the DRR. You can use this to check on both spinal and vertebral alignments. The amber blue toggle is also useful in providing additional image cues for the evaluator.
Note how the rubber band feature is so much easier to understand with the color contrast between the blue x-ray and the amber DRR. Once the fusion is approved, the shifts are sent to the linac console and the couch motion is automatically enabled. With the shifts completed, the user is prompted to verify the new position of the patient under the x-ray verification page. Here, a second set of stereoscopic x-ray images are acquired, and ExacTrac Dynamic performs again automatic fusion to the DRRs.
You could see that fusion results show some translational deviations highlighted in red. This is most likely the result of the x-ray threshold setting being restricted to 0.7 millimeters. When such large residual shifts are still detected, a careful evaluation of the fusion result is necessary. We use, again, the rubber band and crosshair fusion evaluation options, and once happy with the correctness of the results, we send those new shifts to the console.
With the automatic couch motion enabled, the patient is finally set up to the isocenter based on the daily imaging of internal anatomy. With the setup completed, the user is now ready to track and monitor the patient during this SRS treatment. In the SGRT view, you can see the patient's free-breathing while the gantry moves into the first treatment position.
The surface image shows "In Tolerance" so the treatment begins. You can see the graph at the bottom of the ExacTrac Dynamic screen showing the live tracking of the patient. For this first arc, we have pre-set up ExacTrac Dynamic to auto-trigger stereoscopic x-ray images at gantry positions 270, 0, and 90 degrees. The first set of monitoring x-rays are automatically acquired at the first imaging point and fused to the reference DRRs.
As a deviation is detected outside of allowed tolerances, the beam is paused so the end-user can check the fusion results. Note that the ExacTrac Dynamic graphic user interface immediately shows with the red overlay that a large deviation was detected and also starts the beam hold. The user once again is prompted to review and approve the image fusion results. It is always a good idea to have appropriate physician or physicists' supervision during an SRS treatment especially when tight margins are employed.
With the detected intrafraction motion shifts approved, the couch motion is once again enabled, and the patient's position is automatically adjusted. When completed, the live tracking show the patient to be once again in tolerance and the beam hold is cleared. The treatment now continues automatically. At couch 0, a second set of stereoscopic verification x-ray images are acquired. Once again, a small auto-tolerance translational shift is detected and the beam is held. Image fusion is evaluated again and approved. Couch is automatically moved to correct for this new intrafraction motion, and when motion is completed, the treatment continues.
The third and last set of intrafraction verification x-ray images acquired at couch 90 are showing no significant patient motion. The first arc is therefore completed. The second field is a return arc, and with the patient SGRT tracking showing "In Tolerance," radiation delivery begins. Intrafraction x-ray checks for this arc are detecting no relevant patient motion, and the radiation delivery continues uninterrupted. The third and last arc is again a clockwise VMAT delivery that begins right away as the patient SGRT continues to show the patient to be in tolerance.
The first stereoscopic x-rays are detecting once again intrafraction motion, and the user verifies and approves the automatic fusion. The couch automatic motion is enabled to correct for the detected shifts, and once computed, the treatment resumes. The second and third pairs of stereoscopic x-rays detect no auto tolerance motion and the radiation beam is allowed to be delivered, once again, uninterrupted. Toward the end of the arc, a rather significant patient motion is detected, in this case, by the SGRT signal and this is most likely indicative the patient relaxing the arms. When the patient returns with "In Tolerance," the arc delivery completes.