1. Simona Giordanengo Torino January 12 2009 Study and development of the Dose Delivery System for the National Center of Oncological Hadrontherapy (CNAO)

2. 2 Introduction  Advanced Radiotherapy and Hadrontherapy  Dose delivery systems  Active scanning system  CNAO project My research activity  CNAO Dose Delivery System (Hardware and Software characteristics)  Preliminary test of the CNAO scanning performance Conclusions Overview

3. 3 Standard and advanced Radiotherapy LINAC 6 – 18 MV Dynamic Multi-Leaf Collimator (DMLC) To increase conformity To increase conformity and biological effects 3D conformal Radiotherapy (3DCRT) Intensity Modulated Radiotherapy (IMRT) Hadrontherapy Maximum dose rate: ~ 5 Gy/min [Gy] = [J/Kg]

4. 4 4 Tumors treatment with heavy particles Depth dose distribution of various radiation modalities Inelastic collision with nuclei:  neutrons production and others fragments High dE/dx High Ionization High Dose (Gy = J/Kg ) Hadrontherapy Standard Radiotherapy

5. 5 Ions vs X-rays physical advantages These are mainly dependent on the Dose Delivery System  Low dose on surface  High dose in depth  High precision on dose delivery  Minimal lateral scattering Multiple Scattering

6. 6 Patient ACCELERATOR Dose Delivery The elements and devices necessary to conform, control and adjust the beam just before the patient belong to the Dose Delivery System (DDS) Beam line Magnets (dipoles and quadrupoles), vacuum chambers and beam diagnostic devices characterize the beam transport system just before the Dose Delivery The hadrontherapy “machine”

7. 7 Vacuum chamber Pencil Beam Target Dim 1 ÷ 30 cm FWHM 2 ÷ 10 mm Two main methods have been successfully adopted to cover a large transversal area with a small native pencil beam: THE PASSIVE and the ACTIVE METHODS From the original beam dimension to the target dimension through the Dose Delivery System

8. 8 Dose Delivery elements for a PASSIVE SCATTERING system 1 st transversal beam spread 1 st energy modulation (Spread Out Bragg Peak) 2 nd energy modulation to increase homogeneity 1 st (X,Y) conformation Energy (Z) conformation 2 nd (X,Y) conformation

9. 9 y x z LL Beam Target θ Scanning magnets Y X Beam monitors ACTIVE BEAM DELIVERY SOLUTIONS Two dipole magnets smear out the particles of a beam pulse Only beam monitors between vacuum window and patient to increase efficiency and reduce unnecessary dose  reduce scattering and nuclear interactions between particles and material along the beam path Vacuum window F = q * (v Λ B)

10. 10 RASTER SCAN SOLUTION The beam is moved continuously in a pre-selected pattern over the target area and a well-defined number of particles are delivered in each line element. Scanning magnets y x z Isocenter Scanned Field Protons, Carbon ions To obtain the desired field, several scanning techniques can be adopted

11. 11 SPOT SCAN SOLUTIONS It moves a beam spot across the field in discrete steps Scanning magnets y x z Isocenter Scanned Field Very time consuming Protons, Carbon ions Requirements: fast system to switch on-off the beam y x z Isocenter Scanned Field

12. 12 y x z Isocenter Scanned Field y x z Isocenter Scanned Field VOXEL SCAN SOLUTIONS The beam is aimed to a voxel for the time necessary to reach the prescribed fluence then it is steered to the next voxel without stopping the particle delivery Scanning magnets Protons, Carbon ions

13. 13 Scanning magnets Synchrotron Linac 2 sources Nozzle and monitor system INFN and University of Torino collaborate with Fondazione CNAO z y x (X,Y) VOXEL SCANNING (Z) PARTICLE ENERGY VARIATION through the accelerator E0E0 E1E1 EnEn E 0 <E 1 <…<E n CNAO “3D” active dose delivery system Beam ON Beam OFF t 0.5 sec 1.5 sec Synchrotron time structure SLICES

14. 14 2 strip chambers1 pixel chamber Detectors characteristics Intensity Measurement  Read every 1  s Integral sensitive area Gap  5mm Gas  nitrogen HV  400 V Position Measurement  s every 80-100  s precision 100  m # strips  128 (1.65 mm pitch) Gap  5mm Gas  nitrogen HV  400 V 2D Position Measurement 2D Intensity Measurement Precision 200  m # pixels  1024 (6.6 mm pitch) Gap  5mm Gas  nitrogen HV  400 V 2 integral chambers

15. 15 CNAO - Pavia Main entrance Synchrotron vault Hospital rooms Power plant

16. 16 CNAO Centro Nazionale di Adroterapia Oncologica 3 treatment rooms: 3 horizontal lines 1 vertical line 16 To treat deep tumours (range 1-30 cm):  p (E : 60-250 MeV, I :10 10 ),  C 6 +(E : 120-400 MeV/u, I : 4*10 8 )  Gaussian Beam : 4  10 mm (FWHM)  Active Dose Delivery System  Beam position step: 1 ± 0.1 mm  Maximum field: 20 x 20 cm 2  Patient daily fraction in ~ 2 -3 min Synchrotron Treatment rooms ~26 m

17. 17 Synchrotron room

19. 19 CNAO Dose Delivery System  Hardware and Software characteristics

20. 20 Crate PXI -NI Supervision System Timing System Control Room Scanning Magnets Interlock System DATA (monitor) Dose Delivery Interfaces Treatment Planning System Chopper/Dump Based on NI products and LabVIEW Real-Time Operating System BOX 1BOX 2

21. 21 6534 1 FPGA 1 6534 2 FPGA 2 6534 4 FPGA 4 StX StY IM1 IM2 PX PXI trig bus PXI data bus Magnets X Y FPGA 3 6534 3 I/O Chopper Interlock External BUS to trasnfer data between FPGA 2-3-4 External BUS to connect FPGA1-2-3-4, interlock module and chopper module CPU O TT Control Room Master Timing CRATE PXI Supervision System and TPS Ethernet Optical Link Ethernet Optical Link

22. 22 EnEn Monitor on-line the beam (fluence, position and dimension) Set the beam position voxel by voxel through the direct connection with the scanning magnets power supplies Correct on-line the beam position (feed-back operations) Stop the beam slice by slice or when something is wrong When the beam is ON the Dose Delivery has to… BOX 1 BOX 2 PS Slice Treated voxels PXI with FPGAs Dose Delivery DAQ 5 ionization chambers 1 23 4 5 Monitors 1-4 : Integral chamber 2-3 : Strip chambers 5 : Pixel chamber Scanning magnets I DD I PS

23. 23 “TREATMENT LOADING” “START DAQ” “SPILL ON” “ LOGFILE CREATE” YES NO “DATA STORAGE” “END of SLICE or SPILL” NO YES WAIT NEXT TREATMENT “STOP DAQ” Slice Ended Treat Ended TREATMENT SEQUENCE FROM DOSE DELIVERY Implemented with NI hardware and LabVIEW Real-Time Operating System NI = National Instruments z y x E0E0 E1E1 EnEn Treatment volume

24. 24 “TREATMENT LOADING” “START DAQ” “SPILL ON” “ LOGFILE CREATE” YES NO “DATA STORAGE” “END of SLICE or SPILL” NO YES WAIT NEXT TREATMENT “STOP DAQ” Slice Ended Treat Ended The sequential beam positions for each voxel are preventively stored in a memory and are translated in a set of strip coordinates and magnet currents For each voxel: (E n, Np, X, Y) (counts, x strip, y strip, I x, I y ) z y x E0E0 E1E1 EnEn For the ionization chamber counts also Pressure and Temperature dosimetric correction is done for each patient After a trigger from Timing System the monitor data acquisition from FPGA starts

25. 25 “TREATMENT LOADING” “START DAQ” “SPILL ON” “ LOGFILE CREATE” YES NO “DATA STORAGE” “END of SLICE or SPILL” NO YES WAIT NEXT TREATMENT “STOP DAQ” Slice Ended Treat Ended Slice Treated voxels EnEn IN REAL-TIME when SPILL is ON for each voxel  FPGA1 counts particles,  FPGA2 checks the beam position and compares it with the expected one  FPGA4 corrects the currents set if necessary (feed-back operations). VOXEL END  FPGA1 sends a trigger to the others FPGAs which prepare themselves for the next voxel.  FPGA4 transmits the new voxel currents to the magnet PS.

26. 26 “TREATMENT LOADING” “START DAQ” “SPILL ON” “ LOGFILE CREATE” YES NO “DATA STORAGE” “END of SLICE or SPILL” NO YES WAIT NEXT TREATMENT “STOP DAQ” Slice Ended Treat Ended SLICE and SPILL END  DD stop the Beam and DAQ  DD rady to start new DAQ TREATMENT END  DD creates “logfiles” and send to the SS  DD ready for next treatment

27. 27 Preliminary test of the CNAO scanning performance

28. 28  Acceptance test of the communication between Dose Delivery and Power Supply  The time response of the scanning magnet field  The performance of the scanning system with a real treatment THE AIMS OF THE MEASUREMENTS

29. 29 Scanning Magnet L = 4.4 mH, R = 26 m Ω B max = 0.3 T with 606 A Homogeneity better than 0.2 % Power Supply Power rated = ±550A/±660V Rate 100 kA/s  v beam > 20 m/s Current precision = ± 100 ppm M. Incurvati et al “FAST HIGH-POWER POWER SUPPLY FOR SCANNING MAGNETS OF CNAO MEDICAL ACCELERATOR” – EPAC 08 - Genova B Designed and built in collaboration between OCEM S.p.A and INFN-CNAO SCANNING CHARACTERISTICS

30. 30 Setup for the magnetic field measurement High Linearity Hall Probe for Room and Cryogenic Temperatures Nominal control current, In : 100 mA Sensitivity : 439 mV/T Range for B : ± 3 T Linearity : < 0.2 % Active area:0.5x1.25 mm 2 Band width:~6 MHz PXIFPGA7831-R FPGA with ADC analog channels: 8 resolution :16 bit Input signal range: ±10 V DAQ rate: 200 kHz Noise : 3 counts (~0.17 A from PS) I in = 100mA V out x50

31. 31 PXI with FPGA Magnet Hall probe 40 kHz I ref, err I ref, I meas, err 200 kHz B (a.u.) 10 m Shielded cable DATA FLOW Dose Delivery System 4 Mbaud optical link Power Supply

32. 32 Acceptance test of the communication between Dose Delivery and Power Supply Set of different currents OK Set of different currents OK (-540 A  540 A) Transmission times checkOK Transmission times checkOK 4 Mbaud 40 kHz of data Simulation of a transmission error OK Simulation of a transmission error OK Detection of current out of range OK Detection of current out of range OK

33. 33 Scan from -540 A  +540 A  -540 A with the following current steps:Scan from -540 A  +540 A  -540 A with the following current steps: –1 A, 2 A, 5 A, 10 A, 15 A, 20 A, 540 A –Δt = 2 ms, 4 ms and 10 ms (= time between two steps) Probe Hall in 3 different positions within the magnet (0 cm, +20 cm, +25 cm) Slices from treatments (scan in X and scan in Y) with Δt proportional to the fluenceSlices from treatments (scan in X and scan in Y) with Δt proportional to the fluence Performance Tests

34. 34 Step planned by Dose Delivery from planned coordinate PS current Step A B Beam at position A: X A coordinate A planned I A current for PS N A # particles in A (Dose) t A time to deliver N A Scanning parameters  Position – Speed – Time – Intensity – Dose Beam at position B: X B coordinate B planned I B current for PS N B # particles in B (Dose) t B time to deliver N B t A-B = step time I A-B = current step Beam Speed = V A-B = (X A -X B )/t A-B Power Supply Current rate = dI/dt= (I A -I B )/t A-B V A-B t I PS I DD t

35. 35 I_DD (A)  Current set by the Dose Delivery. Acquisition rate 40 kHz. I_PS (A)  Current read by the Power Supply control loop. Acquisition rate 40 kHz. B (a.u.)  Hall probe measurement in arbitrary unit to normalize the field to the current. Acquisition rate 200 kHz. Scan with 10 A step every 2 ms A B V A-B

36. 36 Linearity step 10A Power Supply non-linearity negligible B-Idd Ips-Idd Hysteresis

37. 37 Beam Speed for 1 A step ΔI/Δt = 20 kA/sec Scanning speed measurements GENERAL REQUIREMENTS: if 2.5 A ≤ ΔI ≤ 15 A  ΔI/ Δt > 100 kA/sec if ΔI < 2.5A  time < 200 μs 1 A in Δt ~ 50 μs << 200 μs From linear fit between 10 %- 90 % ΔI/Δt = 0.0201 A/μs 1 A = 200 μm for C 6+ (400Mev/u) Bρ= 6.36 Tm 1 A = 1 mm for p (60 Mev) Bρ= 1.14 Tm Beam speed 4 m/sec for C 6+ max E Beam speed 20 m/sec p minima E

38. 38 2 A step in the magnet center ΔI/Δt = 31 kA/sec 2A in Δt < 70 μs From linear fit between 10 %- 90 % Slope = 0.0314 A/μs ΔI/Δt = 29 kA/sec 2A in Δt < 70 μs From linear fit between 10 %- 90 % ΔI/Δt = 0.0291 A/μs 2 A step at the magnet edge 70 μs << 200 μs required

39. 39 10 A step in the magnet center ΔI/Δt = ~ (6/35)*10 6 ~ 170 kA/sec 10 A step in the magnet edge 10 A step out of the magnet Time Time for 20%-80% A step ( for ΔI = 6A) = 35 ± 5 us 170 kA/sec >> 100 kA/sec required

40. 40 Slice from Real Patient Treatment MEASURED and PLANNED VOXELS POSITIONS

41. 41 Treatment MEDIUM, slice 9 Slice dose distributions N particles/voxel PLANNED MEASURED Maximum N particles/voxel ~ 4*10 4

42. 42 Relative maximum difference 0.008 Difference between the real distribution obtained using the measured beam positions and the ideal distribution (from TPS) better than 1 %. (Required 2.5 %)

43. 43 S. Giordaengo et al. “Performance test of the scanning system for CNAO, Italian National Center of Oncological Hadrontherapy” Soon ready to be submitted for pubblication to NIM

44. 44 CONCLUSIONS about my activity  The CNAO Dose Delivery operations defined  The DD data acquisition developed  A software prototype to interface the DD with several CNAO subsystems implemented and will be ready to start the DD debug soon  The interface with the Supervision System successfully tested  The interface with the Power Supply for scanning magnets defined, developed and successfully tested  Performance test of the scanning system successfully done FUTURE  Master Timing interface test  Interlock System interface test  DD debug at CNAO with beam  Overall software optimizations