The Role of In-Room kv X-Ray Imaging for Patient Setup and Target Localization (TG104)

Transcription

1 The Role of In-Room kv X-Ray Imaging for Patient Setup and Target Localization (TG104) John Wong David Jaffray Fang-Fang Yin AAPM 20010

2 Report and Members of TG 104 Fang-Fang Yin, Co-Chair John Wong, Co-Chair James Balter Stanley Benedict Jean-Pierre Bissonnette Timothy Craig Lei Dong David Jaffray Steve Jiang Siyong Kim Charlie Ma Martin Murphy Peter Munro Timothy Solberg Q. Jackie Wu

3 Charges of TG 104 a) Review the current existing kv x-ray systems used in the radiation treatment room, including system configurations, specifications, operation principles, and functionality b) Discuss the current clinical application methods about how these systems could be used to improve treatment accuracy and their limitations. c) Discuss issues related to effective implementation in the routine clinical procedures d) Discuss issues related to acceptance testing and quality assurance

4 Objectives Understand the current existing kv x-ray systems used in the radiation treatment room, including system configurations, specifications, operation principles, and functionality Understand the principles and challenges for treatment verification Understand current clinical application methods about how these systems could be used to improve treatment accuracy and their limitations Understand issues related to effective implementation of IGRT in the routine clinical procedures as well as quality assurance

5 Commercially Available Systems for In-Room kv Imaging

6 Outlines Overview of the principles and challenges for treatment verification and image guidance Description, applications, and performance for CT-based systems Description, applications, performance, and QA for in-room projection based systems Future development

7 2-D/3-D In-room Image-Guidance On-line systems Ceiling/floor-mounted system Gantry-mounted system On-line techniques Real time 2-D radiographic imaging Real time 2-D fluoroscopic imaging 2-D to 3-D image fusion Automatic patient/beam positioning

8 2-D MV Film and CR Imaging Off-line 2-D radiographic imaging

9 Ceiling/Floor-Mounted System Cyberknife system X-ray tube X-ray tube Detector Recessed Detector Detectors above the floor Detectors under the floor Curtsey of Accuray, Inc.

10 Ceiling/Floor-Mounted System Novalis system SDD: 3.62 m SID: 2.34 m Pixel: 0.4 mm Matrix: 512x512 Digital Detector kv x-ray tube F-F Yin Med Phy 2002

11 Gantry-Mounted System

12 Hybrid Image-Guidance System NovalisTx System Duke University Medical Center Video/IR Camera OBI KV tube KV Detector OBI KV Detector MV Detector Recessed ExactTract KV tube

13 X-ray Imaging in Proton Treatment Courtesy of Loma Linda University Courtesy of Heidleberg University

14 On-Line In-room Image-Guidance Patient planning information/ Patient information system Patient setup Reference images In-room imaging I On-board images Correction? N Treatment Y In-room imaging III In-room imaging II Correct position Feedback

15 2-D vs. 3-D In-room Image-Guidance 2-D opportunities Efficient and reliable Fluoroscopic imaging Imaging during treatment Low dose 2D to 2D or 2D to 3D image fusion 2-D challenges Volume information when deformable Critical organ information Target may not visible

16 2-D Imaging: MV/MV Isocenter Check Reference image Portal image

17 2-D Imaging: kv/kv Isocenter Check

18 Image-Guidance with 6D ExacTrac 6D Robotics Frameless Radiosurgery Adaptive Gating Courtesy of brainlab

19 Use Case: Intra-fraction Imaging Example of dual x-ray imaging

20 Liver - Effect of Breath-Hold

21 Verification of Gating Windows Fluoroscopic Imaging Fluoroscopic Imaging to verify gating window for respiratory gated treatment using onboard imager. Gating window Implanted marker

22 Image-Guided Implementation Identification of a Suitable Imaging Technology Design, Implementation and Maintenance Image Performance and Objectives Image Acquisition Analysis Tools On-line and Off-line Strategies Margins, Accuracy, and Precision Decision-Making and Intervention Quality Assurance Program for Image-Guided Processes Imaging Dose Considerations Manpower and Training

23 Acceptance Testing: Imaging System Room design and shielding consideration Verification of Imaging System Installation Safety and Mechanical Configurations Geometric Calibration Localization Accuracy Image Quality Baseline for routine QA

24 Commissioning: Imaging System Experimentally determine imaging parameters for optimal image quality and localization accuracy for different anatomical sites Identify potential limitations of the imaging system Setup and document operation procedures for different localization purposes

25 Quality Assurance Programs Safety and functionality Geometric accuracy Dosimetric information Software and hardware Imaging system with delivery system alignment/coincidence Image quality TG 142 sets the frequencies and criteria

26 Daily QA Testing Collision interlocks Imaging and treatment coordinate coincidence (1 gantry angle) Positioning/repositioning Alignment of Treatment and Imaging Coordinate Systems: Example of calibration phantoms for ExacTrac system

27 Daily QA kv/mv 2D Imaging Test AP MV RLat KV S S R L P A I I Imaging Fusion Software Test

28 Monthly QA: Monthly QA Tests Imaging and treatment coordinate coincidence (4 gantry angles) Scaling Geometric distortion Spatial linearity Image quality Spatial linearity Spatial resolution Contrast Uniformity and noise Mechanical checking: Align the center of the detector

29 Monthly QA: Geometric Alignment per Gantry Rotation S S S S L R P A R L A P I G270 PA I I I G0 Rt G90 AP G180 Lt

30 Monthly QA: Scaling Check Circuit-board

31 Monthly QA: Image Quality QA for OBI MVD Image for QA analysis CT number check for CBCT

32 Annual QA: kv Beam Quality/Energy/Dose Unfors Xi Fluoro (~5sec) Radiography (single-pulse half-resolution) Measurements ma, ms, and exposure rate (R/min) for fluoro, exposure (mr) for radiography kvp and mm (Al HVL). Variation from baselines

33 New Development CBCT with a Mobile CT Dual X-Ray Tubes with Dual Detectors kv and MV Dual-Energy Imaging Digital Tomosynthesis Functional imaging

34 CBCT with a Mobile C-Arm System Challenge: How to correlate imaging coordinate with treatment unit coordinate C-arm system

35 In-Line kvision Image-Guidance System Proposed ARtISTE system by Siemens The kv x-ray axis is in parallel and coincident to the treatment beam but at the opposite direction Radiographic Fluoroscopic imaging kv CBCT Courtesy of Siemens

36 Dual X-Ray Tubes with Dual Detectors Integrated radiotherapy imaging system (IRIS): design considerations of tumour tracking with linac gantrymounted diagnostic x-ray systems with flat-panel detectors Berbeco et al Phys. Med. Biol. 2004

37 A New Hybrid Image-Guided Radiotherapy System Courtesy of Dirk Verellen, Belgium KAMINO et al, IJROBP 2006

38 DTS Imaging Fundamentals Slice # 1 Slice # 2 Slice # Slice # 4 Scan angle Slice # 5 Patient

39 On-Board 4D-DTS Imaging 30-degree gantry rotation Maurer et al AAPM 2009

40 DTS with Prior 3D Image Data CBCT:360 o CT-360 o Deform Map CBCT:60 o Ren et al Med Phys June 2008

41 kv/mv Dual-Beam CBCT Images kv+mv CBCT Diag CT Yin et al. Med Phys 2005 Zheng et al 2007 MV-CBCT kv-cbct

42 Soft Tissue Surrogate Imaging: MRI PTV Onboard verification Under development (MR + Co-60) Renaissance System % isodose line Verifying Tx isodose line relative to PTV PlanCT CBCT MRPTV

43 Opportunity: 4-D MRI Imaging More than 1 breath cycle Low dose Duke University

44 Onboard Functional Imaging Active development of on-board PRT and SPECT imaging systems which use emission kv photons.

45 On Board Imaging for On-line ART Daily CBCT Define anatomy -of-the-day Current development: overall time ~ 5 minutes Planning CT & Original Plan Fast re- Optimization Deformable registration A R T dmlc sequencer Delivery Plan Evaluation Dose accumulation Wu et al PMB 2008

46 Summary The introduction of in-room kv imaging provides new opportunities to further improve treatment accuracy and precision. At the same time, it presents new challenges for its efficient and effective implementation. Each in-room kv imaging method has its strengths and limitations. The user is well advised to match the clinical objective with the appropriate technology; or at least to apply the image guidance information to within the bounds of its validity.

47 Summary Implementation of an in-room kv imaging technology requires rigorous characterization and validation of its performance. Quality assurance measures with phantoms are requisite. Expertise must be developed and must be re-established from time to time. One must also be cognizant that in actual clinical practice, inherent uncertainties of the guidance solution exist, as each technique has its own range of uncertainties.

48 Summary There is uncertainty in the strength of the surrogate information as in the case of implanted fiducials; in the integrity of the information with time as in the case of CT guidance; and in the residual error related to the implementation of the correction. In-room kv guidance clearly offers great potential of improving treatment accuracy. The promise of in-room kv guidance can only be realized with a radiation community that applied the technology with discipline.

49 Acknowledgements: Some research works are partially supported by grants from NIH, Varian Medical Systems, and GE Health Care. Thank you for your attention.