Transcript
Hello, and welcome to a New Novalis Circle Workflow Video. My name is Bogdan Valcu. I am the director of Novalis Circle. And today, I want to show you an ExacTrac Dynamic1.0 workflow video for pre-positioning and monitoring a left-sided Breast DIBH treatment. The patient is being treated on a variant Linac with a full Novalis configuration. A full inhalation CT is utilized for treatment planning that consists of two tangents and one arc.
The breath-hold CT is acquired with the help of an RPM system mounted in the simulation room, and the patient also has conventional AP lateral tattoos defined at full inhalation. Prior to installation of ExacTrac Dynamic, the patient would have been manually pre-positioned with the three-point technique followed by acquisition of a breath-hold cone-beam CT for setup. Patient coaching is performed based on the RPM signal with additional audio instructions provided by the therapists from the console area.
In the workflow you are about to observe, we are replacing the manual three-point setup with the ExacTrac SGRT pre-positioning keeping the breath-hold cone-beam CT for initial setup, and adding ExacTrac Dynamic SGRT and X-ray monitoring throughout the treatment. For this first version of ExacTrac Dynamic, the X-ray imaging is triggered based on observing the RPM threshold and full patient inhalation. Lastly, the ExacTrac Dynamic patient's settings are set to a 3-millimeter three-degree threshold for both SGRT and IGRT detected deviations, and beam hold is disabled as this patient was part of the site's investigational steps for adding ExacTrac Dynamic to their breast procedures.
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 opened on the Linac. After the plan is also opened 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, select confirm plan. The software will then prompt you to prepare a treatment beam on the Linac so the beam information is known for all images.
Once a beam is prepared, the user can proceed with pre-positioning the patient. Although, as previously mentioned, this patient has a classical three-point tattoo referencing that therapists are performing the pre-positioning steps utilizing the SGRT component of ExacTrac Dynamic. We begin by laying the patient on the treatment couch and slightly moving the couch top into the field of view of the structure light cameras. The enlarged 100 designators cubed scanning field of view the camera system will quickly detect the patient in the treatment room and generate an outer contour in real-time. Once accurately detected, this 3D patient surface is compared to the outer contour generated from the treatment planning CT, and positional shifts are being displayed to guide the therapist on direction and magnitude of correctional alignments that need to be performed in order to send the patient to the machine isocenter.
The live patient surface is displayed in orange and the outer contour from the treatment planning CT in white. The user will pre-position the patient until the orange contour is matched with the white contour. In parallel to the SGRT pre-positioning, the therapists are also placing the RPM block on the patient's chest and tape is being applied to hold it in place. Our next version of ExacTrac Dynamic will provide a breathing pattern visualization, part of a dedicated DIVH workflow that will actually monitor the treatment side and with that solution, the RPM block will no longer have to be utilized.
The patient may be pre-positioned both manually and automatically when activating the sense shift button that triggers the linear console to move the couch based on the SGRT detected deviation. Please note that only translations are allowed to be corrected automatically at this point and never rotations. This is done on purpose so that the therapists manually correct for angular deviations to not exceed the maximum allowed tolerances of the robotic couch tops. So, always bring the patient as close as possible to a position that reproduces the simulation posture before proceeding with IGRT. You never want the KV imaging to detect large rotations that cannot be corrected robotically and have to image twice.
In this case, the patient is manually rotated on the alpha cradle to correct for rotations. By using the send shift feature, the user is able to send any residual shifts from the manual positioning to the linear couch to move the patient to isocenter. Once all manual and automatic shifts are made, the two outer contours match. Now that the patient is positioned at isocenter, a cone-beam CT is acquired with a DIBH technique. The patient is coached to take in a deep breath and hold it while the cone-beam CT is being acquired. As you can see synchronized here, the OBI screen, audio, and visual coaching begins and with this welcome plan patient the full inhalation cone-beam CT is acquired in about 35 seconds. Image acquisition here is presented in real-time. Once the cone-beam CT is completed, it is carefully analyzed by therapists with supervisions from radiation oncology and medical physics when necessary.
During the image fusion evaluation, the patient returns to a free-breathing state. If deviations are detected, shifts are made to bring the patient to the correct treatment position. After the patient is in the final treatment position, and you can see the final correction being applied on ExacTrac Dynamic screen, the user must also accept this position on the ExacTrac Dynamic side. Switching now to the ExacTrac Dynamic side, we must first confirm the cone-beam CT setup and follow this by defining an area of interest to be tracked by the hybrid camera system throughout the treatment.
Please note that at this point, the thermal signal is augmenting the structure lights surface signal, in essence creating a highly reliable for the region of interest. The area of interest or AOI is the area of the patient to be tracked during treatment by the ExacTrac Dynamic for the hybrid camera system. The user needs to make sure that the AOI doesn't include any hardware, in our case the RPM block, and only includes the area of the patient to be tracked during treatment. As the radiation beam will be delivered only in full inhalation, we take additional steps to check the area of interest at this full inhalation phase. The patient is again coached to breathe in.
Here's the zoomed-in video feedback of the synchronized RPM signal, and we make any necessary adjustments to the area of interest in the live detected anatomical position. Once the AOI is confirmed, the user will be brought to the X-ray reference acquisition screen. Before acquiring X-rays, the patient is once again coached to take in a deep breath and hold. While the patient is holding her breath, stereoscopic X-ray images are acquired. The patient is then coached to breathe freely. The contrast in the X-rays is modified by using the contrast slider bar to show the best representative image for the breast anatomy. Once the user is satisfied with how the breast anatomy shows up in the X-ray images, the accept button is pressed to continue to the fusion screen. The image fusion to the DRRs generated from the fool inhalation CT is being performed automatically by ExacTrac Dynamic.
Although at this point ExacTrac actually provides a good fusion with the deviations in here, it is a good practice to show you the necessary steps to always generate a correct result for the left-sided breast anatomy. The first thing we can do is to aid the joint mutual information definition between the X-rays and DRRs by restricting the volume utilized for the DRR definition to the projected space of the X-ray images.
Next, you always want to remove anatomy that is susceptible to movement. Consider the patient has the arms up and then the shoulders can easily relax. We're also removing the spine, especially the cervical spine that could easily show a daily different curvature position as compared to the simulation posture. And lastly, we remove the heart from the left image as it doesn't display stereoscopically. With these changes, a new image fusion is computed and you can see the deviation results here. Once the fusion is complete, you can carefully analyze the results with various fusion tools. Here, you can see the blending tool that allows you to toggle between the X-ray images and DRRs. It is important to verify the fusion for accuracy since the DRRs are saved and used as the reference position for subsequent X-ray fusions. Furthermore, they are used as the reference to create new DRRs for subsequent couch angles.
For this particular patient, however, we are going to accept the cone-beam CT results as the side was under an investigational phase for ExacTrac Dynamic. You will always have the freedom to select which image or results you want to use for your patient setup, and this final acceptance step defines how the surface coordinates are zeroed out for the beginning of treatment and tracking. Note that as we accept the cone-beam CT setup, the positional vector is zeroed out in essence building the cone-beam CT perform corrections into a new reference surface image. Also, relevance for ongoing KV monitoring with ExacTrac Dynamic is to note that future X-ray fusion correlations will now have the cone-beam CT-defined isocenter as the new reference.
This means that for the first time the onboard and room-based imagers can be used interchangeably and that you can always perform ExacTrac X-ray monitoring after cone-beam CT setup even when fusion is done at soft-tissue borders. The user is now ready to track and monitor the patient during this DIBH treatment. The patient is currently in a free-breathing state while the gantry moves into treatment position. The surface image is currently showing as expected out of tolerance but will be intolerance when the patient enters the DIBH state. The patient is coached to take in a deep breath and hold it, ExacTrac Dynamic surface image shows intolerance, and the treatment begins. You can see the graph at the bottom of the ExacTrac Dynamic screen showing the live motion of the patient.
For this first arc, we have preset up ExacTrac Dynamic to auto-trigger stereoscopic extra images at gantry positions 0 and 90. As you can see, we are manually checking that the X-rays are taken as the patient is holding the DIBH state to ensure a meaningful check of the cone-beam CT setup. The first set of monitoring X-rays are automatically fused to the reference the DRRs and as no relevant deviation is detected, the treatment continues. The ExacTrac Dynamic SGRT tracking can now also show you when the patient goes into a free-breathing state and the treatment should be paused. If you have been hold control on, ExacTrac will assert a beam hold on the console until patient returns in full inhalation face. In this case, we are using the RPM signal to pause the beam and the patient is once again coached to take in a deep breath and hold it.
As the patient returns to full inhalation, the ExacTrac Dynamic surface image shows, again, to be intolerance and the treatment continues. Again, 390 another set of breath-hold X-rays are acquired and automatically fused. Once again, no significant deviation is detected so the treatment continues. The beam is completed, and the next beam is prepared on the console for ExacTrac Dynamic. You can once again see that the patient is in free-breathing states and the ExacTrac Dynamic surface tracking detects the motion outside the full inhalation tolerance.
The next beam to be delivered is the first tangent, the RPM signal is used to coach the patient back into inhalation phase. Once the patient reaches the DI gate state and the ExacTrac Dynamic surface shows to be intolerance, the treatment begins. Intrafraction motion for the tangent is only checked with SGRT as the cone-beam CT arms are not fully retracted. If the onboard imager obstructs the ExacTrac Dynamic extra images you may see an image like this that renders a poor fusion result. If you want to use IGRT to check the tangents, please remember to fully retract [inaudible 00:13:16.937] arms.
Finally, the second tangent beam is loaded on the console and the patient is back in a DIBH state, ExacTrac Dynamic SGRT tracking monitors the patient during beam on and detects the moment when patient can no longer hold her breath. You can also see the fluctuations in the RPM signal. The beam is held until the patient can resume a full inhalation phase and the SGRT tracking shows her again to be within treatment tolerances. With the patient back in tolerance, the treatment is completed.
The breath-hold CT is acquired with the help of an RPM system mounted in the simulation room, and the patient also has conventional AP lateral tattoos defined at full inhalation. Prior to installation of ExacTrac Dynamic, the patient would have been manually pre-positioned with the three-point technique followed by acquisition of a breath-hold cone-beam CT for setup. Patient coaching is performed based on the RPM signal with additional audio instructions provided by the therapists from the console area.
In the workflow you are about to observe, we are replacing the manual three-point setup with the ExacTrac SGRT pre-positioning keeping the breath-hold cone-beam CT for initial setup, and adding ExacTrac Dynamic SGRT and X-ray monitoring throughout the treatment. For this first version of ExacTrac Dynamic, the X-ray imaging is triggered based on observing the RPM threshold and full patient inhalation. Lastly, the ExacTrac Dynamic patient's settings are set to a 3-millimeter three-degree threshold for both SGRT and IGRT detected deviations, and beam hold is disabled as this patient was part of the site's investigational steps for adding ExacTrac Dynamic to their breast procedures.
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 opened on the Linac. After the plan is also opened 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, select confirm plan. The software will then prompt you to prepare a treatment beam on the Linac so the beam information is known for all images.
Once a beam is prepared, the user can proceed with pre-positioning the patient. Although, as previously mentioned, this patient has a classical three-point tattoo referencing that therapists are performing the pre-positioning steps utilizing the SGRT component of ExacTrac Dynamic. We begin by laying the patient on the treatment couch and slightly moving the couch top into the field of view of the structure light cameras. The enlarged 100 designators cubed scanning field of view the camera system will quickly detect the patient in the treatment room and generate an outer contour in real-time. Once accurately detected, this 3D patient surface is compared to the outer contour generated from the treatment planning CT, and positional shifts are being displayed to guide the therapist on direction and magnitude of correctional alignments that need to be performed in order to send the patient to the machine isocenter.
The live patient surface is displayed in orange and the outer contour from the treatment planning CT in white. The user will pre-position the patient until the orange contour is matched with the white contour. In parallel to the SGRT pre-positioning, the therapists are also placing the RPM block on the patient's chest and tape is being applied to hold it in place. Our next version of ExacTrac Dynamic will provide a breathing pattern visualization, part of a dedicated DIVH workflow that will actually monitor the treatment side and with that solution, the RPM block will no longer have to be utilized.
The patient may be pre-positioned both manually and automatically when activating the sense shift button that triggers the linear console to move the couch based on the SGRT detected deviation. Please note that only translations are allowed to be corrected automatically at this point and never rotations. This is done on purpose so that the therapists manually correct for angular deviations to not exceed the maximum allowed tolerances of the robotic couch tops. So, always bring the patient as close as possible to a position that reproduces the simulation posture before proceeding with IGRT. You never want the KV imaging to detect large rotations that cannot be corrected robotically and have to image twice.
In this case, the patient is manually rotated on the alpha cradle to correct for rotations. By using the send shift feature, the user is able to send any residual shifts from the manual positioning to the linear couch to move the patient to isocenter. Once all manual and automatic shifts are made, the two outer contours match. Now that the patient is positioned at isocenter, a cone-beam CT is acquired with a DIBH technique. The patient is coached to take in a deep breath and hold it while the cone-beam CT is being acquired. As you can see synchronized here, the OBI screen, audio, and visual coaching begins and with this welcome plan patient the full inhalation cone-beam CT is acquired in about 35 seconds. Image acquisition here is presented in real-time. Once the cone-beam CT is completed, it is carefully analyzed by therapists with supervisions from radiation oncology and medical physics when necessary.
During the image fusion evaluation, the patient returns to a free-breathing state. If deviations are detected, shifts are made to bring the patient to the correct treatment position. After the patient is in the final treatment position, and you can see the final correction being applied on ExacTrac Dynamic screen, the user must also accept this position on the ExacTrac Dynamic side. Switching now to the ExacTrac Dynamic side, we must first confirm the cone-beam CT setup and follow this by defining an area of interest to be tracked by the hybrid camera system throughout the treatment.
Please note that at this point, the thermal signal is augmenting the structure lights surface signal, in essence creating a highly reliable for the region of interest. The area of interest or AOI is the area of the patient to be tracked during treatment by the ExacTrac Dynamic for the hybrid camera system. The user needs to make sure that the AOI doesn't include any hardware, in our case the RPM block, and only includes the area of the patient to be tracked during treatment. As the radiation beam will be delivered only in full inhalation, we take additional steps to check the area of interest at this full inhalation phase. The patient is again coached to breathe in.
Here's the zoomed-in video feedback of the synchronized RPM signal, and we make any necessary adjustments to the area of interest in the live detected anatomical position. Once the AOI is confirmed, the user will be brought to the X-ray reference acquisition screen. Before acquiring X-rays, the patient is once again coached to take in a deep breath and hold. While the patient is holding her breath, stereoscopic X-ray images are acquired. The patient is then coached to breathe freely. The contrast in the X-rays is modified by using the contrast slider bar to show the best representative image for the breast anatomy. Once the user is satisfied with how the breast anatomy shows up in the X-ray images, the accept button is pressed to continue to the fusion screen. The image fusion to the DRRs generated from the fool inhalation CT is being performed automatically by ExacTrac Dynamic.
Although at this point ExacTrac actually provides a good fusion with the deviations in here, it is a good practice to show you the necessary steps to always generate a correct result for the left-sided breast anatomy. The first thing we can do is to aid the joint mutual information definition between the X-rays and DRRs by restricting the volume utilized for the DRR definition to the projected space of the X-ray images.
Next, you always want to remove anatomy that is susceptible to movement. Consider the patient has the arms up and then the shoulders can easily relax. We're also removing the spine, especially the cervical spine that could easily show a daily different curvature position as compared to the simulation posture. And lastly, we remove the heart from the left image as it doesn't display stereoscopically. With these changes, a new image fusion is computed and you can see the deviation results here. Once the fusion is complete, you can carefully analyze the results with various fusion tools. Here, you can see the blending tool that allows you to toggle between the X-ray images and DRRs. It is important to verify the fusion for accuracy since the DRRs are saved and used as the reference position for subsequent X-ray fusions. Furthermore, they are used as the reference to create new DRRs for subsequent couch angles.
For this particular patient, however, we are going to accept the cone-beam CT results as the side was under an investigational phase for ExacTrac Dynamic. You will always have the freedom to select which image or results you want to use for your patient setup, and this final acceptance step defines how the surface coordinates are zeroed out for the beginning of treatment and tracking. Note that as we accept the cone-beam CT setup, the positional vector is zeroed out in essence building the cone-beam CT perform corrections into a new reference surface image. Also, relevance for ongoing KV monitoring with ExacTrac Dynamic is to note that future X-ray fusion correlations will now have the cone-beam CT-defined isocenter as the new reference.
This means that for the first time the onboard and room-based imagers can be used interchangeably and that you can always perform ExacTrac X-ray monitoring after cone-beam CT setup even when fusion is done at soft-tissue borders. The user is now ready to track and monitor the patient during this DIBH treatment. The patient is currently in a free-breathing state while the gantry moves into treatment position. The surface image is currently showing as expected out of tolerance but will be intolerance when the patient enters the DIBH state. The patient is coached to take in a deep breath and hold it, ExacTrac Dynamic surface image shows intolerance, and the treatment begins. You can see the graph at the bottom of the ExacTrac Dynamic screen showing the live motion of the patient.
For this first arc, we have preset up ExacTrac Dynamic to auto-trigger stereoscopic extra images at gantry positions 0 and 90. As you can see, we are manually checking that the X-rays are taken as the patient is holding the DIBH state to ensure a meaningful check of the cone-beam CT setup. The first set of monitoring X-rays are automatically fused to the reference the DRRs and as no relevant deviation is detected, the treatment continues. The ExacTrac Dynamic SGRT tracking can now also show you when the patient goes into a free-breathing state and the treatment should be paused. If you have been hold control on, ExacTrac will assert a beam hold on the console until patient returns in full inhalation face. In this case, we are using the RPM signal to pause the beam and the patient is once again coached to take in a deep breath and hold it.
As the patient returns to full inhalation, the ExacTrac Dynamic surface image shows, again, to be intolerance and the treatment continues. Again, 390 another set of breath-hold X-rays are acquired and automatically fused. Once again, no significant deviation is detected so the treatment continues. The beam is completed, and the next beam is prepared on the console for ExacTrac Dynamic. You can once again see that the patient is in free-breathing states and the ExacTrac Dynamic surface tracking detects the motion outside the full inhalation tolerance.
The next beam to be delivered is the first tangent, the RPM signal is used to coach the patient back into inhalation phase. Once the patient reaches the DI gate state and the ExacTrac Dynamic surface shows to be intolerance, the treatment begins. Intrafraction motion for the tangent is only checked with SGRT as the cone-beam CT arms are not fully retracted. If the onboard imager obstructs the ExacTrac Dynamic extra images you may see an image like this that renders a poor fusion result. If you want to use IGRT to check the tangents, please remember to fully retract [inaudible 00:13:16.937] arms.
Finally, the second tangent beam is loaded on the console and the patient is back in a DIBH state, ExacTrac Dynamic SGRT tracking monitors the patient during beam on and detects the moment when patient can no longer hold her breath. You can also see the fluctuations in the RPM signal. The beam is held until the patient can resume a full inhalation phase and the SGRT tracking shows her again to be within treatment tolerances. With the patient back in tolerance, the treatment is completed.