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 and monitoring a prostate patient. The patient is being treated on a Varian TrueBeam Linac with a full Novalis configuration. A free-breathing CT is utilized for treatment planning that consists of two coplanar vena ducts. The patient was scanned with no anterior immobilization device and in a supine position. Pre-positioning will be performed with the help of the 3D SGRT structured light cameras of ExacTrac Dynamic followed by a 60-IGRT setup with the onboard cone beam CT system. ExacTrac Dynamic X-ray referencing will be performed at the completion of the setup to enable X-ray monitoring throughout the treatment arcs. Patient monitoring is always live with a 4D SGRT hybrid camera solution, and three sets of stereoscopic X-ray images will be acquired at pre-determined imaging points for each arc at 270, 0 and 90 degrees.
Lastly, the ExacTrac Dynamic patient settings are set to a 3-millimeter, 3-degree threshold for SGRT and a 2-millimeter, 2 degrees threshold for IGRT detected deviations. Beam whole control is set to off so ExacTrac Dynamic will not interlock the beam when motion is detected as this was an early patient for the site and the site was still investigating ExacTrac's Dynamic ability to track based on soft tissue setup. 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 to proceed with pre-positioning.
As previously mentioned, the therapists are performing 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 structured 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 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 set the patient to the machine isocenter.
The patient is pre-positioned automatically by activating the same shift button that triggers the linac console to move the couch based on the SGRT detected deviation. Once all automatic shifts are corrected, the live auto contour matches the CT one. Now that the patient is positioned at isocenter based on the 3D SGRT feedback, we are proceeding with a cone beam CT acquisition for setup. You can see on the screen the live feeds from the onboard imager console employing a half-end pelvis cone beam CT scan. Once acquired, a 60 fusion to the simulation CT is performed. And as you can see, the mutual information is heavily influenced by the bony anatomy. Upon careful review of the daily bladder and rectal fillings, the end user decides to perform a manual shift, as you can see here, to align the contours to the different daily soft tissue interface, in essence, accepting a new virtual isocenter that has a different correlation to the bony anatomy as defined in the treatment plan. The user verifies that the soft tissue interface is satisfactory and approves the daily cone beam CT setup.
As we want to monitor the patient throughout the treatment for internal motion too, we have to reference the ExacTrac Dynamic X-ray system to the soft tissue cone beam CT setup. To accomplish this, we must first define 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 structured light signal, in essence creating a highly reliable 4D region of interest. The area of interest is manually contoured to not include anatomy susceptible to breathing motion. Once the AOI is confirmed, the user will be brought to the X-ray acquisition for cone beam CT referencing screen and a set of stereoscopic X-ray images are acquired.
Please note that although we will accept the cone beam CT setup values, the fusion of ExacTrac Dynamic X-ray images to DRRs must be correct and carefully evaluated. Remember that for now, ExacTrac Dynamics must reference to planning CT DRRs that expects the original correlation to bony anatomy and not the daily one introduced by the soft tissue cone beam CT setup. To obtain a good result, we are removing the femoral heads and any anatomy that may move as well as apply an appropriate X-ray filter to aid with the image fusion evaluation. As you can see, ExacTrac provides a good fusion but with somewhat large deviations as seen here. The final step is critical. We will accept, in ExacTrac Dynamic, the cone beam CT fusion result and not the one defined by our X-ray to DRR fusion. In essence, this defines, for ExacTrac Dynamic, the virtual isocenter established for this fraction by the manual alignment of the cone beam CT to the soft tissue interfaces. By building this offset into ExacTrac Dynamic as well, future bony anatomy checks will be relevant for daily positions and no longer be restricted to the simulation definition.
This clear distinction must be approved by the end user by typing in personal credentials. With the setup complete, the user is now ready to begin treatment. In the SGRT view, you can see the patient free breathing while the gantry moves into the first treatment position. With the surface image showing intolerance, 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 to 70, 0 and 90 degrees. The first set of monitoring X-rays are automatically acquired at the first imaging point and fused to reference DRRs. If there's no deviations detected outside of the allowed tolerances, the treatment continues.
The second and third set of X-ray images also detect no significant motion. So, this first counterclockwise arc delivers without any interruptions. The second field is a return arc and with the patient's SGRT tracking showing intolerance, radiation delivery begins. The intra-fraction X-ray checks for this arc are detecting no relevant motion at either of the imaging points and the radiation delivery continues uninterrupted. Please note that we use stereoscopic imaging only for this patient in order to obtain a 60-fusion result every time we image with X-ray. This would allow for immediate patient realignment, if deviations were to be detected. In a separate workflow video, we will cover an implanted marker workflow with ExacTrac Dynamic and discuss imaging for prostatic drift checks. Thank you.
Lastly, the ExacTrac Dynamic patient settings are set to a 3-millimeter, 3-degree threshold for SGRT and a 2-millimeter, 2 degrees threshold for IGRT detected deviations. Beam whole control is set to off so ExacTrac Dynamic will not interlock the beam when motion is detected as this was an early patient for the site and the site was still investigating ExacTrac's Dynamic ability to track based on soft tissue setup. 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 to proceed with pre-positioning.
As previously mentioned, the therapists are performing 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 structured 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 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 set the patient to the machine isocenter.
The patient is pre-positioned automatically by activating the same shift button that triggers the linac console to move the couch based on the SGRT detected deviation. Once all automatic shifts are corrected, the live auto contour matches the CT one. Now that the patient is positioned at isocenter based on the 3D SGRT feedback, we are proceeding with a cone beam CT acquisition for setup. You can see on the screen the live feeds from the onboard imager console employing a half-end pelvis cone beam CT scan. Once acquired, a 60 fusion to the simulation CT is performed. And as you can see, the mutual information is heavily influenced by the bony anatomy. Upon careful review of the daily bladder and rectal fillings, the end user decides to perform a manual shift, as you can see here, to align the contours to the different daily soft tissue interface, in essence, accepting a new virtual isocenter that has a different correlation to the bony anatomy as defined in the treatment plan. The user verifies that the soft tissue interface is satisfactory and approves the daily cone beam CT setup.
As we want to monitor the patient throughout the treatment for internal motion too, we have to reference the ExacTrac Dynamic X-ray system to the soft tissue cone beam CT setup. To accomplish this, we must first define 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 structured light signal, in essence creating a highly reliable 4D region of interest. The area of interest is manually contoured to not include anatomy susceptible to breathing motion. Once the AOI is confirmed, the user will be brought to the X-ray acquisition for cone beam CT referencing screen and a set of stereoscopic X-ray images are acquired.
Please note that although we will accept the cone beam CT setup values, the fusion of ExacTrac Dynamic X-ray images to DRRs must be correct and carefully evaluated. Remember that for now, ExacTrac Dynamics must reference to planning CT DRRs that expects the original correlation to bony anatomy and not the daily one introduced by the soft tissue cone beam CT setup. To obtain a good result, we are removing the femoral heads and any anatomy that may move as well as apply an appropriate X-ray filter to aid with the image fusion evaluation. As you can see, ExacTrac provides a good fusion but with somewhat large deviations as seen here. The final step is critical. We will accept, in ExacTrac Dynamic, the cone beam CT fusion result and not the one defined by our X-ray to DRR fusion. In essence, this defines, for ExacTrac Dynamic, the virtual isocenter established for this fraction by the manual alignment of the cone beam CT to the soft tissue interfaces. By building this offset into ExacTrac Dynamic as well, future bony anatomy checks will be relevant for daily positions and no longer be restricted to the simulation definition.
This clear distinction must be approved by the end user by typing in personal credentials. With the setup complete, the user is now ready to begin treatment. In the SGRT view, you can see the patient free breathing while the gantry moves into the first treatment position. With the surface image showing intolerance, 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 to 70, 0 and 90 degrees. The first set of monitoring X-rays are automatically acquired at the first imaging point and fused to reference DRRs. If there's no deviations detected outside of the allowed tolerances, the treatment continues.
The second and third set of X-ray images also detect no significant motion. So, this first counterclockwise arc delivers without any interruptions. The second field is a return arc and with the patient's SGRT tracking showing intolerance, radiation delivery begins. The intra-fraction X-ray checks for this arc are detecting no relevant motion at either of the imaging points and the radiation delivery continues uninterrupted. Please note that we use stereoscopic imaging only for this patient in order to obtain a 60-fusion result every time we image with X-ray. This would allow for immediate patient realignment, if deviations were to be detected. In a separate workflow video, we will cover an implanted marker workflow with ExacTrac Dynamic and discuss imaging for prostatic drift checks. Thank you.