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Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd. SBRT Position Monitoring with ExacTrac Following CBCT John Wochos, MS, DABR Casey Abing, MS, DABR Gundersen Health System La Crosse, WI

SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

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Page 1: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

SBRT Position Monitoring with

ExacTrac Following CBCT

John Wochos, MS, DABR

Casey Abing, MS, DABR

Gundersen Health System

La Crosse, WI

Page 2: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

Equipment at Gundersen

• GE Lightspeed CT Sim

• RPM gating system

• Varian Clinac 21EX

• BrainLAB ExacTrac System

• BodyFix immobilization system

• Mosaiq R&V

• 4DTC

• On-Board Imaging system

Page 3: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

SBRT Workflow

1. CT Simulation (gated vs. no gating)

2. Planning (IMRT vs. non-IMRT)

3. Gantry/Couch clearance check

4. Patient specific QA

5. Treatment

Page 4: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

CT Simulation

• Arms overhead

• No respiratory coaching

• Rarely use abdominal compression

• Phase-based gated CT scan (RPM system)

• Physician and physicist review gated scan

together to determine efficacy

• Roughly 30% of patients are gated for

treatment

Page 5: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

Planning 1• Non-gated treatement: planning is done on the 0% – 90% Average

Intensity Projection (Ave-IP)

• Gated treatment: the Ave-IP of the desired phases for gating (e.g. 30% - 60%)

• Contouring is assisted using the Maximum Intensity Projection (MIP) CT

• Roughly 33% are treated “IMRT” (1-3 segments per beam, minimize interplay effect)

• Use 12-15 non-coplanar beams to conform to RTOG 0813 (couch kicks at 330°, 30°, and 90°)

• Prefer Pinnacle CC algorithm over Eclipse AAA

Page 6: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

Planning 2 – Example 1

– 13 field, non-coplanar, step and shoot IMRT, 21 total segments, non-gated, 600 MU/min, thinner patient (i.e. ideal situation)

– Patient in/out time: 25-30 minutes• Setup: 5 minutes

• CBCT, review, kV orthogs: 8 minutes

• Treatment Delivery: 12 minutes

Page 7: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

Planning 3 – Example 2

– 15 field, non-coplanar, step and shoot IMRT, 25 total segments, gated 30%-60% phases, 600 MU/min, (i.e. worst situation)

– Patient in/out time: 50-60 minutes• Setup: 5 minutes

• CBCT, review, kV orthogs: 15 minutes

• Treatment Delivery: 34 minutes

Page 8: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

ExacTrac System Background 1

Dual floor-mounted kV x-ray tubes

Ceiling-mounted

aSi flat panel

detectors

Video and IR camera

Orthogonal/oblique images at isocenter

Page 9: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

ExacTrac System Background 2

• Advantages

– Fast acquisition

– Accurate and precise with respect to BONY landmarks in 6 degrees of freedom

– Auto-fusion very good, no manual adjustment needed

– Independent of the treatment machine

– Low patient dose

• Main disadvantage

– No direct soft tissue matching

– Images are not intuitive to interpret (trust the system)

Page 10: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

OBI CBCT Background

Click Here for OBI Demo

• Advantages• High contrast images (especially for lung)

• 3D images

• Auto or manual fusion options

• Full window/level ranges

• Images are very easy to interpret

• Disadvantages• SLOW acquisition

• Data transfer to Mosaiq R&V

• Increased patient dose

Page 11: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

SBRT Treatment Workflow

• Initial patient setup

• CBCT (fuse to bone, shift to tumor using ITV from

Ave-IP 0 – 90%)

• kV orthogonal pair (double checks CBCT)

• Initial ExacTrac sets a baseline (no shifts applied)

• Follow-up ExacTrac done every 2 – 3 fields

• Re-CBCT if follow-up ExacTrac differs from

baseline ExacTrac by more than 2mm

Page 12: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

Data 1Patient: Posterior Left Lower Lobe Lung

Dose: 1000cGy x 5 fractions

ITV => PTV margin: 10mm sup/inf and 5mm radially

Treatment fields: 12 field non-coplanar 3D conformal

Gating: 30%-70% phases

Treatment time: setup (5 mins), IGRT (12 mins), beam on (20 mins)

In/Out time = around 45 mins

Baseline – First Verification Baseline – Second Verification Baseline – Third Verification Baseline – Fourth Verification

Fraction Vert Long Lat Vector Vert Long Lat Vector Vert Long Lat Vector Vert Long Lat Vector

1 0.23 -0.11 0.22 0.34 0.48 -0.10 0.37 0.61 0.45 0.26 0.18 0.55 - - - -

2 -0.02 -0.15 -0.26 0.30 -0.16 0.08 0.05 0.19 0.22 -0.14 -0.40 0.48 0.37 -0.33 -0.37 0.62

3 0.02 0.08 0.14 0.16 0.10 -0.33 0.39 0.52 0.09 -0.48 -0.15 0.51 - - - -

4 -0.07 -0.14 -0.47 0.50 -0.01 -0.20 -0.25 0.32 -0.01 -0.51 -0.06 0.51 0.06 -0.67 -0.06 0.68

Max

Deviation0.23 0.08 0.22 0.50 0.48 0.08 0.39 0.61 0.45 0.26 0.18 0.55 0.37 -0.33 -0.06 0.68

Page 13: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

Data 2Patient: Left Lower Lobe Lung

Dose: 1000cGy x 5 fractions

ITV => PTV margin: 10mm sup/inf and 5mm radially

Treatment fields: 12 field non-coplanar 3D conformal

Gating: 30%-60% phases

Treatment time: setup (5 mins), IGRT (15-20 mins), beam on (25-30 mins)

In/Out time = around 50 mins

Baseline – First Verification Baseline – Second Verification Baseline – Third Verification Baseline – Fourth Verification

Fraction Vert Long Lat Vector Vert Long Lat Vector Vert Long Lat Vector Vert Long Lat Vector

1 -0.10 -0.88 -0.24 0.92 0.29 -0.18 0.18 0.39 0.11 0.05 -0.52 0.53 - - - -

2 0.50 0.95 -0.80 1.34 0.00 4.04 -0.50 4.07 - - - - - - - -

2reCBCT -0.50 0.30 0.30 0.66 0.10 -0.80 1.00 1.28 - - - - - - - -

3 0.00 0.80 0.04 0.80 0.70 0.70 0.32 1.04 0.60 1.20 1.02 1.69 0.50 1.30 1.32 1.92

4 0.00 0.10 -0.20 0.22 -0.77 0.60 -0.90 1.33 - - - - - - - -

5 0.34 0.85 -0.40 1.00 0.85 0.70 -0.10 1.11 1.76 1.07 -0.77 2.20 1.26 1.17 -1.52 2.29

Max

Deviation0.50 0.95 0.30 1.34 0.85 4.04 1.00 4.07 1.76 1.20 1.02 2.20 1.26 1.30 1.32 2.29

Page 14: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

Conclusion

• The ExacTrac relative positioning workflow

gives us fast, accurate and precise information

regarding intra-fraction motion

• With four patients and eighteen fractions,

only one patient needed a new CBCT, indicates

our immobilization system is working well

Page 15: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

Winter is Coming

Page 16: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

2013 AAPM Summer School

• Quality & Safety in Radiotherapy

• How to Apply at Gundersen’s Radiation

Oncology Department without Physicists

becoming Safety Engineers….

Page 17: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

Gundersen Safety Initiative

• First; attempt to make better use of Incident

data

• Have been recording Incidents (Major, Minor

and in-between) for >15 years.

• Early on we found trends and made system

changes

• Over the past 5 years few obvious trends or

“system issues”

Page 18: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

Incident Data

• Re-encourage staff to report

• Determine, from AAPM recommendations the

“Causality Classifications” for each incident

• Try to determine the Root Cause of each

Incident

Page 19: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

Avoid the Next Major Incident

• How to determine what it will be?

• Survey ALL staff in the department

• Request feedback on 2 or 3 items

• Either most likely or most risky thing that is

occurring from your perspective

• This can also achieve staff involvement in a

Safety Culture. Encouraged input from

everyone.

Page 20: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

Avoiding Incidents, Results

• Over 90% of staff replied

• Over 50% of staff have volunteered to be

involved in follow-up.

• Staff at ALL levels will be involved in follow-up

(MAs, RNs, PA, Physics, Dosimetry, MD,

Therapists).

Page 21: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

Data

Item Frequency Item Frequency

Emergency Response (Code) 1 Overall communication 1

Incorrect patient 2 Wrong site/ dose SRS 1

Patient slipping, falling, transfer 2 Wrong site/ dose LDR 1

Confientiality 1 HDR Calibration 1

HDR Source gets stuck 1 Friday BIDs inconsistancy 1

HDR catheter mis-measure 1 Wrong site 1

Late , hurried dosimetry 3 Linac Miscalibration 2

Wrong Dose delivered 0 Correct bolus informatioin Dosim to treat 1

Short staff (MAs) 2 CT contrast reaction 1

ExacTrac transfer Room to room 1 Communication (human & computer) 1

Rm 1 no bar code (gate, bolus,couch angle) 7 Lifting patient On/Off table 1

Staff hour reductions 1 Bathroon doors, no auto openers 1

Technology upgrades 6 Missing / delayed boost dosimetry 1

Advanced Care Planning involvement 1 Gating incorrect 2

Patient mis identified (name only no ID#) 1 Changing MD contours or beams in dosim 1

Incomplete/Excessive scheduling on orders 2 Wrong CT coordinates Rm 1 4

Page 22: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

Categorized Data

Linac Technical Communication

Item Frequency Item Frequency

Rm 1 no bar code (gate, bolus,couch angle) 7 Incorrect patient (or misidentify) 3

Technology upgrades 6 Confidentiality 1

Wrong CT coordinates Rm 1 4 Overall communication 1

Gating incorrect 2 Friday BIDs inconsistency 1

Linac Miscalibration 2 Communication (human & computer) 1

Correct bolus informatioin Dosim to treat 1

ExacTrac transfer Room to room 1 Non-radiation safety

Item Frequency

Brachytherapy Patient slipping, falling, transfer 3

HDR Source gets stuck 1 Short staff (MAs) 2

HDR catheter mis-measure 1 Incomplete/Excessive scheduling on orders 2

HDR Calibration 1 Emergency Response (Code) 1

Wrong site/ dose LDR 1 Staff hour reductions 1

Advanced Care Planning involvement 1

Dosimetry CT contrast reaction 1

Item Frequency Bathroom doors, no auto opener 1

Late , hurried dosimetry 3

Wrong Dose delivered 1

Changing MD contours or beams in dosim 1

Wrong site/ dose SRS 1

Wrong site 1

Missed/ delayed boost 1

Page 23: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

Failure Mode & Effects Analysis

• Occurrence = Likelihood event will occur, to

the undesired result: 1=Remote/ 10=For sure

• Severity: 1=No effect, 2=Minor, 7=serious,

10=death

• Detectability: 1= always, 10=Never

Page 24: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

Evaluation of Data

Linac Technical Occurance OxSxD

Item Frequency Likelihood Severity DetectabilityRiskPriority

Number

Rm 1 no bar code (gate, bolus,couch angle) 7

Technology upgrades 6 7 8 4 224

Wrong CT coordinates Rm 1 4 3 7 2 42

Gating incorrect 2 3 6 7 126

Linac Miscalibration 2 2 10 2 40

Correct bolus informatioin Dosim to treat 1 5 3 9 135

ExacTrac transfer Room to room 1

Brachytherapy

HDR Source gets stuck 1 2 9 2 36

HDR catheter mis-measure 1 3 9 6 162

HDR Calibration 1 2 9 2 36

Wrong site/ dose LDR 1 2 7 2 28

Dosimetry

Item Frequency

Late , hurried dosimetry 3 9 9 5 405

Wrong Dose delivered 1 3 8 6 144

Changing MD contours or beams in dosim 1 3 4 5 60

Wrong site/ dose SRS 1 3 9 5 135

Wrong site 1 3 9 4 108

Missed/ delayed boost 1 2 2 2 8

Page 25: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

Safety Initiative, Conclusions

• None to date

• We’ve had an explosion in workload; what

happens to safety when extremely busy?

• Survey � same events, just more of them or

higher probability

• If this initiative is successful, we will never

know because the major event will not

happen!

Page 26: SBRT Position Monitoring with ExacTrac Following CBCTchapter.aapm.org/nccaapm/z_meetings/2013-10-10_and_10-11/fall2013/Wochos.pdf · SBRT Position Monitoring with ExacTrac Following

Gundersen Lutheran Medical Center, Inc. | Gundersen Clinic, Ltd.

Thank you

• Questions

• Comments