Update on TG 147: QA for non-radiographic localization and

positioning systems

AAPM Anaheim, CA 2009Twyla Willoughby

Thank-You

Joerg Lehmann, Ph.D.: TG Co-ChairRadiological Associates of

Sacramento

José A. Bencomo, Ph.D.US Oncology

Shirish K. Jani, Ph.D.Sharp Metropolitan Medical Campus

Lakshmi Santanam, Ph.D.Washington University

Anil Sethi, Ph.D.Loyola University Medical Center

Timothy D. Solberg, Ph.D.UT Southwestern Medical Center

Wolfgang A. Tomé, Ph.D.University of Wisconsin

School of Medicine and Public Health

Tim Waldron, M.S.University of Iowa

IGRT• Ultrasound: Soft tissue alignment – mostly

prostate• Orthogonal MV x-rays: Bony anatomy or implanted

markers• Orthogonal kV x-rays: Bony anatomy or implanted

markers• Cone-beam CT: image quality may be an issue• MV CT: Image quality may be a concern• In room CT: Good image quality not exactly same

treatment position• Other: Video, RF, and laser alignment systems

Disclaimer

• Task Group Report has NOT beenapproved as of yet.

• Projected publication date: Late2009/Early 2010

What is Optical Tracking?• Optical tracking is a means of determining in real-time the

position of an object by tracking the positions of eitheractive or passive infrared markers attached to the object.The position of the point of reflection is determined using acamera system.

Active markers Passive markers Camera

Meeks RSNA 2002

Stereo Correspondence

How Does it Work? Optical Tracking

Meeks RSNA 2002

Calibration to Isocenter

Meeks RSNA 2002

pi’ = Rp

i +T

Vector forroomcoordinates

3x3 rotation matrix

Translation vector

Equation can be solved numerically usingoptimization algorithms (Hook and Jeeves,etc.), or closed form solutions such assingle value decomposition or Horn’smethod (quaternions)

Vector forimagecoordinates

Meeks RSNA 2002

Infrared Camera Alignments

Meeks, S.L., et al., Image localization for framelessstereotactic radiotherapy. Int J Radiat Oncol Biol Phys, 2000.46(5): p. 1291-9.

Tome, W.A., et al., Optically guided intensity modulatedradiotherapy. Radiother Oncol, 2001. 61(1): p. 33-44.

Other Alignment Systems (VisionRT)

Waldron, T. Univ of Iowa

C-Rad Sentinel™

LAP: Galaxy

Waldron, T. Univ of Iowa

Waldron, T. Univ of Iowa

Video and Laser ReferencesMoore, C., et al., Opto-electronic sensing of body surface topologychanges during radiotherapy for rectal cancer. Int J Radiat Oncol BiolPhys, 2003. 56(1): p. 248-58.

Schoffel, P.J., et al., Accuracy of a commercial optical 3D surfaceimaging system for realignment of patients for radiotherapy of thethorax. Phys Med Biol, 2007. 52(13): p. 3949-63.

Bert, C., et al., A phantom evaluation of a stereo-vision surfaceimaging system for radiotherapy patient setup. Med Phys, 2005. 32(9):p. 2753-62.

Siebert, Human Body 3D imaging by speckle texture projectionphotogrammetry. Sensor Review, 2000. 20(3).

Super Dimension: RF guidedBronchoscopy

Transpondertip

Ascension Technology products use RF sensors to track the position and orientation in real-timeof instruments including ultrasound probes. Tracking accuracy is unaffected by the nearby presenceof conductive metals including aluminum, titanium and stainless steel 300

Ascension Technology

CalypsoMedicalSystemExcitationWaveform

SourceCoil

Current

ResponseWaveform

Resonator

Current

ExcitationPhase

RingDownPhase

RF ReferencesWagner, A., et al., Quantitative analysis of factors affecting intraoperative precision andstability of optoelectronic and electromagnetic tracking systems. Med Phys, 2002. 29(5):p. 905-12.

Hummel, J.B., et al., Design and application of an assessment protocol forelectromagnetic tracking systems. Med Phys, 2005. 32(7): p. 2371-9.

Meskers, C.G., et al., Calibration of the "Flock of Birds" electromagnetic tracking deviceand its application in shoulder motion studies. J Biomech, 1999. 32(6): p. 629-33.

Santanam, L., et al., Fiducial-based translational localization accuracy of electromagnetictracking system and on-board kilovoltage imaging system. Int J Radiat Oncol Biol Phys,2008. 70(3): p. 892-9.

Willoughby, T.R., et al., Target localization and real-time tracking using the Calypso 4Dlocalization system in patients with localized prostate cancer. Int J Radiat Oncol BiolPhys, 2006. 65(2): p. 528-34.

Evaluation of Collision Space

Calypso System during Commissioning

Calibration to Isocenter

End to End test

1 Scan of Phantom2 Treatment Plan of Phantom3 Localization of Phantom4 Orthogonal Films of Central Target5 Analysis

Localization onTreatment PlanningSystem: IR Example1

Tome RSNA 2002

Setup of at Treatment Machine usingOptical Guidance: Example 1

Tome RSNA 2002

Resulting Film: Measure of TotalAccuracy of System

Overall error = 0.789mm

Predicted error:

Z-Pixel Size = 1.25mm

X-Pixel Size = 0.703 mm

Y-Pixel Size = 0.703 mm

Predicted Error = 1.59mm

Results:

Z: 0.49 mm to T

X: 0.35 mm to A

Y: 0.50 mm High

Tome RSNA 2002

Example 2: Phantom for Calypso system(Treatment plan of Implanted target)

Example 2: Phantom for Calypso system

Meeks AAPM 2000

Meeks, AAPM 2000

Test of Localization: Introduce offsets andmeasure localization system offset

Phantom

Beacon® Phantom

ValidationDigitizer

3X 1DStages

Tracking AccuracyMeasurements

Phantom at isocenterLocalizationaccuracy

PassCollision interlocksSafety

AccuracyMethodTest

Installation

Daily QA

Tracking Rage

Range of Tracking

Range of Localization

AccuracyMethodTest

Per manufacturerspecification

Move table while tracking tomaximum range

Move table while localizing tomaximum range

Localization system interferencewith radiation delivery system

Linac interference withlocalization system

Collision spaceSafety

AccuracyMethodTest

Shift phantom from isocenterAccuracy in tracking upto 10cm fromisocenter

Data transmittedcorrectly

Test patient transferred fromplanning system tolocalization system

Data transfer

Motion tableTracking accuracy overclinical range: atclinical rate ofmotion

System end-to-end test (with CTscan, treatment plan andorthogonal portal films)

Localization accuracyMachine spec.Following Linac QA TG reportsIsocenter QA

Following Linac QA TG reportsLaser localizationsystem QA

Machine interface: Gatingtermination, table auto-translation,

Safety

Monthly (in addition to Daily): Proposed

AccuracyMethodTest

Accurate motion tableSystem latency andtracking timing

Repeat system alignment atleast 10 times to localizea fixed phantom

Reproducibility

Alignment vs. timeDrift in measuredisocenter over timeof use

PassSystem mounting brackets(all cameras are secure)

PassEmergency off buttons arefunctional

PassElectrical System:Test/reset buttons &breakers are functional

Safety

Annually (in addition to Monthly)

ReferencesGierga, D.P., et al., Comparison of target registration errors formultiple image-guided techniques in accelerated partial breastirradiation. Int J Radiat Oncol Biol Phys, 2008. 70(4): p. 1239-46.

Serban, M., et al., A deformable phantom for 4D radiotherapyverification: design and image registration evaluation. MedPhys, 2008. 35(3): p. 1094-102

Kutcher, G.J., et al., Comprehensive QA for radiation oncology:report of AAPM Radiation Therapy Committee Task Group 40.Med Phys, 1994. 21(4): p. 581-618