This document discusses the implementation of a stereotactic radiosurgery (SRS) program at Utah Valley Hospital using image-guided radiation therapy (IGRT) and surface-guided radiation therapy (SGRT) for confident and efficient treatment. It outlines the SRS workflow including simulation using customized masks, planning using single isocenter optimization, rigorous quality assurance procedures, and real-time surface monitoring during treatment for precise patient positioning and alignment. The detailed treatment timeline shows how these techniques allow for accurate and efficient SRS delivery in under 30 minutes on average.

1. IGRT + SGRT for
Confident and Efficient SRS
Ryan Hecox MS, DABR
Lead Medical Physicist

2. Financial Disclosure:
VisionRT provided funding to support
the creation of this presentation

3. SRS PROGRAM AT
UTAH VALLEY HOSPITAL

4. Intermountain Healthcare
Radiation Oncology
Provides care across Utah
• 9 Facilities with linacs
• As of 2018:
o 1 location with a Gamma Knife
o 1 location with linac SRS
• Access to care due to distance is
a common concern
o Guiding principle of “Cancer Care
Close to Home”

5. New Center, New Capabilities
“Normalizing SRS” was a primary clinical goal
• Complete replacement of original Radiation Oncology
department that was ~40 years old
o 2/12/2018: New center opened with TrueBeam and OSMS
o 11/6/2019: 1st SRS patient
• 31 SRS cases treated in ~1.5 years
o 82 SRS treatments to date

6. SRS Program Development
Adopting SRS Planning Approaches
Used prior SRS patient CTs UAB ring optimization technique SRS phantom dosimetry audit
Establishing SRS QA Tools
W/L Testing Isocenter Characterization Film & Ion Chamber SRS MapCheck
Learning to Use and Trust Surface Guidance
SBRT Monitoring Breast Breath Hold Initial Patient Setup
Non-SRS
Open Face Masks

7. SIM & PLANNING
WORKFLOW

8. Workflow Overview
Simulation:
• CT Sim using Qfix Encompass™ masks
o Very stiff material
o Clamshell design only requires a shallow “pull”
• Klarity SRS Masks are also now also available
• MINIMUM 2 sets of hands
o Discuss ideal mask position on the forehead before beginning
o More forehead variations than you might have guessed…
o One person holds the forehead in place and provides pressure on the chin
o The second person pulls and pins the mask
• Practice and experience matters
o Bite tab is not used
o Chin pressure is equally effective and MUCH more comfortable
• Integrated shims are a good insurance policy but rarely used clinically

9. Workflow Overview
Planning & QA:
• Plan using single isocenter, ring-based
optimization per the UAB approach
o Clark, Grant M et al. “Plan quality and treatment planning technique for single isocenter
cranial radiosurgery with volumetric modulated arc therapy.” Practical radiation
oncology vol. 2,4 (2012): 306-313.
• Patient QA using SNC SRS MapCheck®
o Very efficient and easy to use

10. Workflow Overview
Region Of Interest Creation:
• Create high accuracy body/face structure
• ROI close to mask but not including any mask
• Use SRS tolerances of +/- 1mm & 1.0°
o STOP and correct this if imported wrong!
Planning System AlignRT Advance
BAD EXTERNAL CONTOUR
Good ROI

11. TREATMENT
WORKFLOW

12. Sample Case Timeline
•Patient gets on table
12:55
•Surface guidance cameras monitoring
•Rough positioning with surface guidance
12:57
•Mask on
•Coach patient position guided by deltas
12:58
•Flip through video views
•All deltas green
12:59
•CBCT #1 acquisition start
1:00
•CBCT alignment using Bone and Soft Tissue
•Max shift 0.14cm, 0.3°
1:03
•CBCT #2 acquisition start
1:04
•Max shifts 0.02cm, 0.1°
1:06
•CAPTURE REFERENCE SURFACE
1:07
•MV AP image
1:07
•Couch = 0°
•Treatment beam delivery start
1:08
•Couch = 45°
•Max deviation during delivery: 0.04cm, 0.3°
1:10
•Couch = 315°
•Max deviation during delivery: 0.04cm, 0.3°
1:12
•Couch = 270°
•Max deviation during delivery: 0.03cm, 0.4°
1:13
•Treatment Complete
1:15
•Patient walking out of the room
1:17
24Gy in 1 fraction:
• 10FFF
• 4 couch angles
o All rotations remotely applied
• 30 min time slot
o 22 minutes door to door in this typical case
• Mid-treatment re-CBCT adds ~5 minutes if needed

13. •Patient gets on table
12:55
•Surface guidance cameras monitoring
•Rough positioning with surface guidance
12:57
•Mask on
•Coach patient position guided by deltas
12:58
•Flip through video views
•All deltas green
12:59
•CBCT #1 acquisition start
1:00
•CBCT alignment using Bone and Soft Tissue
•Max shift 0.14cm, 0.3°
1:03
•CBCT #2 acquisition start
1:04
•Max shifts 0.02cm, 0.1°
1:06
•CAPTURE REFERENCE SURFACE
1:07
•MV AP image
1:07
•Couch = 0°
•Treatment beam delivery start
1:08
•Couch = 45°
•Max deviation during delivery: 0.04cm, 0.3°
1:10
•Couch = 315°
•Max deviation during delivery: 0.04cm, 0.3°
1:12
•Couch = 270°
•Max deviation during delivery: 0.03cm, 0.4°
1:13
•Treatment Complete
1:15
•Patient walking out of the room
1:17
Sample Case Timeline
Pre-treatment:
• Thermal drift magnitude of ~0.5mm is significant at when
using 1mm tolerances!
• Stabilizes nicely after ~10 minutes
• Just turn on monitoring during setup and leave on
[mm]

14. •Patient gets on table
12:55
•Surface guidance cameras monitoring
•Rough positioning with surface guidance
12:57
•Mask on
•Coach patient position guided by deltas
12:58
•Flip through video views
•All deltas green
12:59
•CBCT #1 acquisition start
1:00
•CBCT alignment using Bone and Soft Tissue
•Max shift 0.14cm, 0.3°
1:03
•CBCT #2 acquisition start
1:04
•Max shifts 0.02cm, 0.1°
1:06
•CAPTURE REFERENCE SURFACE
1:07
•MV AP image
1:07
•Couch = 0°
•Treatment beam delivery start
1:08
•Couch = 45°
•Max deviation during delivery: 0.04cm, 0.3°
1:10
•Couch = 315°
•Max deviation during delivery: 0.04cm, 0.3°
1:12
•Couch = 270°
•Max deviation during delivery: 0.03cm, 0.4°
1:13
•Treatment Complete
1:15
•Patient walking out of the room
1:17
Sample Case Timeline
Pre-treatment:
• Initial alignment of the patient is critical at this point
o Verbally coach the patient to minimize rotational deltas
o Preferable to have the patient make the needed motions to maintain comfort
o Mask can be partially clipped in to allow more motion
• Rotational alignment is particularly important
o 6DOF couch can correct some deviation but has a limited range of motion
o Misalignment of the head with the mask could be unstable
o Single isocenter-multi-target treatments are very sensitive to rotational
misalignment

15. •Patient gets on table
12:55
•Surface guidance cameras monitoring
•Rough positioning with surface guidance
12:57
•Mask on
•Coach patient position guided by deltas
12:58
•Flip through video views
•All deltas green
12:59
•CBCT #1 acquisition start
1:00
•CBCT alignment using Bone and Soft Tissue
•Max shift 0.14cm, 0.3°
1:03
•CBCT #2 acquisition start
1:04
•Max shifts 0.02cm, 0.1°
1:06
•CAPTURE REFERENCE SURFACE
1:07
•MV AP image
1:07
•Couch = 0°
•Treatment beam delivery start
1:08
•Couch = 45°
•Max deviation during delivery: 0.04cm, 0.3°
1:10
•Couch = 315°
•Max deviation during delivery: 0.04cm, 0.3°
1:12
•Couch = 270°
•Max deviation during delivery: 0.03cm, 0.4°
1:13
•Treatment Complete
1:15
•Patient walking out of the room
1:17
Sample Case Timeline
Pre-treatment:
• CBCT acquisition using SRS protocol
o 100kV, 30mA, 540mAs
Mao, Weihua et al. “On the improvement of CBCT image quality for soft tissue-based SRS
localization.” Journal of applied clinical medical physics vol. 19,6 (2018): 177-184.
• Repeat CBCT to confirm shifts and patient stability
Plan CT CBCT

16. •Patient gets on table
12:55
•Surface guidance cameras monitoring
•Rough positioning with surface guidance
12:57
•Mask on
•Coach patient position guided by deltas
12:58
•Flip through video views
•All deltas green
12:59
•CBCT #1 acquisition start
1:00
•CBCT alignment using Bone and Soft Tissue
•Max shift 0.14cm, 0.3°
1:03
•CBCT #2 acquisition start
1:04
•Max shifts 0.02cm, 0.1°
1:06
•CAPTURE REFERENCE SURFACE
1:07
•MV AP image
1:07
•Couch = 0°
•Treatment beam delivery start
1:08
•Couch = 45°
•Max deviation during delivery: 0.04cm, 0.3°
1:10
•Couch = 315°
•Max deviation during delivery: 0.04cm, 0.3°
1:12
•Couch = 270°
•Max deviation during delivery: 0.03cm, 0.4°
1:13
•Treatment Complete
1:15
•Patient walking out of the room
1:17
Sample Case Timeline
Pre-treatment:
• CAPTURE REFERENCE SURFACE
o Cameras are warmed up
o kV arms are out of the way
o Gantry is at 180° after the CBCT
• Reference surface is the confirmed, ideal treatment position TODAY
o Eliminates uncertainty from posterior hair, settling into the mask and any
swelling of the facial tissue

17. •Patient gets on table
12:55
•Surface guidance cameras monitoring
•Rough positioning with surface guidance
12:57
•Mask on
•Coach patient position guided by deltas
12:58
•Flip through video views
•All deltas green
12:59
•CBCT #1 acquisition start
1:00
•CBCT alignment using Bone and Soft Tissue
•Max shift 0.14cm, 0.3°
1:03
•CBCT #2 acquisition start
1:04
•Max shifts 0.02cm, 0.1°
1:06
•CAPTURE REFERENCE SURFACE
1:07
•MV AP image
1:07
•Couch = 0°
•Treatment beam delivery start
1:08
•Couch = 45°
•Max deviation during delivery: 0.04cm, 0.3°
1:10
•Couch = 315°
•Max deviation during delivery: 0.04cm, 0.3°
1:12
•Couch = 270°
•Max deviation during delivery: 0.03cm, 0.4°
1:13
•Treatment Complete
1:15
•Patient walking out of the room
1:17
Sample Case Timeline
Pre-treatment:
• AP MV image acquisition
o Very quick “Sanity Check”
o Independent of CBCT accuracy and surface guidance accuracy
o No shifts are applied from this image, re-CBCT if uncertain

18. •Patient gets on table
12:55
•Surface guidance cameras monitoring
•Rough positioning with surface guidance
12:57
•Mask on
•Coach patient position guided by deltas
12:58
•Flip through video views
•All deltas green
12:59
•CBCT #1 acquisition start
1:00
•CBCT alignment using Bone and Soft Tissue
•Max shift 0.14cm, 0.3°
1:03
•CBCT #2 acquisition start
1:04
•Max shifts 0.02cm, 0.1°
1:06
•CAPTURE REFERENCE SURFACE
1:07
•MV AP image
1:07
•Couch = 0°
•Treatment beam delivery start
1:08
•Couch = 45°
•Max deviation during delivery: 0.04cm, 0.3°
1:10
•Couch = 315°
•Max deviation during delivery: 0.04cm, 0.3°
1:12
•Couch = 270°
•Max deviation during delivery: 0.03cm, 0.4°
1:13
•Treatment Complete
1:15
•Patient walking out of the room
1:17
Sample Case Timeline
Treatment Delivery:
• Total beam delivery time of 6 minutes
o Very little time for the patient to move or
become uncomfortable
• 10/22 minutes spent on positioning, alignment &
verification
o This is time well spent!

19. WHAT TO WATCH FOR

20. Video view as “zoomed in” patient view cameras

21. ACO + Cube Calibration + AlignRT Advance Stability

22. Eye Motion

23. Unexpected patient motion (aka:tapping to the music)

24. Camera Occlusion with Rotation

25. Intermountain Healthcare
Radiation Oncology
Provides care across Utah
• 9 Facilities with linacs
• As of 2021:
o 1 location with a Gamma Knife
o 3 locations with linac SRS
• SRS is now a normal procedure
o Everyone “LOVES IT!” because it
follows such a reliable process
o Confidence feels good 
"Retrieved Fri, 26 March 2021 from the Utah Department of Health, Indicator-
Based Information System for Public Health Web site: http://ibis.health.utah.gov"

26. THANK YOU