Quality Assurance beam tracking Nami Saito GSI, Darmstadt, Germany biophysics department

Quality Assurance beam tracking Nami Saito GSI, Darmstadt, Germany biophysics department 1 Oct 2009 N. Saito PTCOG 48 Heidelberg 1

Introduction Beam tracking GSI beam tracking system Beam tracking QA Function QA Dosimetric QA Summary Outline example cross check method 1 Oct 2009 N. Saito PTCOG 48 Heidelberg 2

Introduction - beam tracking Irradiation technique for moving target : Ion beam tracking continuous beam adaptation in 3D Dynamic beam delivery QA need careful QA of motion-dependent beam controlling target Lung cancer 4DCT data (10 motion phases) courtesy E. Rietzel 1 Oct 2009 N. Saito PTCOG 48 Heidelberg 3

Introduction - beam tracking Irradiation technique for moving target : Ion beam tracking continuous beam adaptation in 3D Dynamic beam delivery QA need careful QA of motion-dependent beam controlling lateral beam position x+dx(t) y+dy(t) range z+dz(t) target r(t) Lung cancer 4DCT data (10 motion phases) courtesy E. Rietzel 1 Oct 2009 N. Saito PTCOG 48 Heidelberg 4

Introduction GSI beam tracking Carbon beam Scan. magnets Wedge range shifter Moving target Y Z Scanning : ~10ms/spot x',y',z' X x+dx y+dy Control system Pos +dx 4DCT data base +dz Lin. motor drive +dv motion detection device response : lat.~1 ms, long.~16 (+11)ms/5mm accuracy : lat. ~0.16mm, long~1mm Saito et al, Phys. Med. Biol. 54 (2009) 4849 1 Oct 2009 N. Saito PTCOG 48 Heidelberg 5

Beam tracking specific QA Consideration of dynamics Function QA (status, response in (status, response in motion,, interlock, etc.) Dosimery QA (beam tracking with motion signal) QA frequency Daily/Monthly/Quarterly/Yearly Installation/Commissioning GSI beam tracking is at experimental stage, BT QA is still under investigation... 1 Oct 2009 N. Saito PTCOG 48 Heidelberg 6

Function QA Response for a standard motion without beams Scan. magnets Wedge range shifter Camera LEDs power supplies Motion phantom x+dx y+dy Pos +dx Control system data base +dz Lin. motor drive motion detection device +dv 1 Oct 2009 N. Saito PTCOG 48 Heidelberg 7

QA Interface : Function QA indicators/data plot/histogram OK/warning/error time resolved data find synchronization error/slow response Device check list Static sensor power communication.. Motion motion detector scanner current range shifter.. 1 Oct 2009 N. Saito PTCOG 48 Heidelberg 8

Dosimetric QA Similar to plan verification method at GSI therapy 3D dose measurement in water phantom For beam tracking C. Karger et al. Med. phys. 26 (10) 1999 4D treatment planning* (reference plan+adaptation) motion signal * Bert and Rietzel, Radiat. Oncol. 2 (24) 2007 1 Oct 2009 N. Saito PTCOG 48 Heidelberg 9

Dosimetric QA Dose measurement with a motion signal Carbon beam Scan. magnets Wedge range shifter x',y',z' 3D dose detector X Detector without motion! Y Z x+dx y+dy Control system +dz data base Pos +dv Lin. motor drive +dx Motion phantom motion detection device 1 Oct 2009 N. Saito PTCOG 48 Heidelberg 10

Dosimetric QA Dose on static detectors without beam tracking with beam tracking scanned beams adapted scanned beams reference target volume moving target volume Beam tracking sequence unique dose pattern find mis-tracking 1 Oct 2009 N. Saito PTCOG 48 Heidelberg 11

Dosimetric QA Calculation : Dose pattern in water (a lung patient plan) Beam s s eye view Top view Side view No tracking Tracking 1 Oct 2009 N. Saito PTCOG 48 Heidelberg 12

Dosimetric QA - process 4D Treatment planning* nominal dx, dy, dz Dose calc. in water ( with recorded motion signal) * Bert and Rietzel, Radiat. Oncol.. 2 24 (2007) Beam tracking (record motion signal) Dose measu. in water Dose comparison 1 Oct 2009 N. Saito PTCOG 48 Heidelberg 13

Dosimetric QA example Treatment plan 4D-CT data lung tumor (6.5cm 3 ) 10 motion phases 4D treatment plan* 48 slices 7389 scan spots target vol. as rigid 1 Gy dx,dy,dz in LUT dx: 0~ 5 mm dy: -10~0 mm dz: -8~19 mm * Bert and Rietzel, Radiat. Oncol.. 2 24 (2007) 25 y[mm] -25 phase 0 phase 0 phase 5 reference CT Depth correction dz [mm] of a slice for 10 CT phases dz 14 phase 1-7 -25 x[mm] 25 phase 5 phase 6 0 phase 2 phase 7 phase 3 phase 4 phase 8 phase 9 1 Oct 2009 N. Saito PTCOG 48 Heidelberg 14

3D beam tracking M : 3D TR measured Nw: 3D TR calc. Dosimetric QA example Dose comparison (norm. by prescribed dose 1 Gy) Dose [Gy] 1.4 1.2 1.0 0.8 0.6 0.4 3DTR1_M 3DTR1_Nw Dose dif. 1.2 ±2.8 % 0.2 0.0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 ID of ICs Failure case M : no beam tracking Nw: 3D TR calc. Dose [Gy] 1.4 1.2 1.0 0.8 0.6 0.4 NoTR_M 3DTR1_Nw Dose dif. 7.8 ±17.5 % 0.2 0.0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 ID of ICs 1 Oct 2009 N. Saito PTCOG 48 Heidelberg 15

Dosimetric QA example Dose difference : Measured Calc. Beam TR: dose dif./1gy 50 40 30 Measured - Calculated 3DTR1(M-C(3D)) NoTR(M-C(3D)) 2DTR(M-C(3D)) 3DTR2(M-C(3D)) 3D TR1 : 1.2 ± 2.8 % No TR : 7.8 ±17.5 % 2D TR : 2.4 ± 4.7 % 3D TR2: 0.6 ± 3.7 % Dose diff [%] 20 10 0-10 -20-30 -40-50 1 3 5 7 9 11 13 15 17 19 21 23 ID of ICs 1 Oct 2009 N. Saito PTCOG 48 Heidelberg 16

Dosimetric QA - cross check 4D Treatment planning nominal dx, dy, dz Dose calc. in water ( with recorded motion signal) Beam tracking (record motion signal) dose measurement Dose comparison 1 Oct 2009 N. Saito PTCOG 48 Heidelberg 17

Dosimetric QA - cross check 4D Treatment planning nominal dx, dy, dz Dose calc. in water ( with recorded motion signal) Beam tracking x y z (record motion signal) dose measurement Dose comparison Dose calc. in CT ( with recorded motion signal & beam tracking) DVH 1 Oct 2009 N. Saito PTCOG 48 Heidelberg 18

Dosimetric QA - cross check 4D Treatment planning nominal dx, dy, dz Dose calc. in water ( with recorded motion signal) Beam tracking x y z (record motion signal) dose measurement Dose comparison Dose calc. in CT ( with recorded motion signal & beam tracking) DVH 1 Oct 2009 N. Saito PTCOG 48 Heidelberg 19

Dosimetric QA - cross check 4D Treatment planning nominal dx, dy, dz Dose calc. in water ( with recorded motion signal) Beam tracking x y z (record motion signal) dose measurement Dose comparison Dose calc. in CT ( with recorded motion signal & beam tracking) DVH 1 Oct 2009 N. Saito PTCOG 48 Heidelberg 20

Summary From experience of beam tracking validation, possible beam tracking QA was presented Importance of time resolved data check system was pointed out for dynamic beam delivery QA Dosimetrical QA method : dose measurement with beam tracking dose calculation for the recorded motion dose comparison Further cross check method to see actual beam tracking effect on CT was presented 1 Oct 2009 N. Saito PTCOG 48 Heidelberg 21

Acknowledgement Christoph Bert Alexander Gemmel Naved Chaudhri Robert Lüchtenborg Peter Steidl Jan Trautmann Daniel Richter Sebastian Hild Dirk Müssig Anna Constantinescu Gerhard Kraft Eike Rietzel Marco Durante Michael Krämer Dieter Schardt and Colleagues at GSI & HIT This work is in part funded by Siemens Healthcare. 1 Oct 2009 N. Saito PTCOG 48 Heidelberg 22

Thank you for your attention 1 Oct 2009 N. Saito PTCOG 48 Heidelberg 23