FlashDiamond Review and Outlook at 2nd Stakeholder Meeting January 2023

2nd stakeholder meeting january 2023 n.w
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Explore the latest updates from the 2nd Stakeholder Meeting in January 2023, focusing on the FlashDiamond technology. Discover insights on ultra-high dose rates, fundamental investigations on microDiamond, and the Varian eFLASH upgrade for Clinac systems. Learn about the potential applications in commissioning FLASH RT electron beams and advancements in dose per pulse measurements.

  • FlashDiamond
  • Stakeholder Meeting
  • Technology
  • Dose Rates
  • Radiation
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  1. 2nd Stakeholder Meeting January 2023 flashDiamond Review and Outlook R. Kranzer, M. Marinelli, G. Verona Rinati, A. Sch ller, HK. Looe, B. Poppe 1

  2. flashDiamond Starting point Challenge of ultra-high dose rates (UHDR) > 40 Gy/s as investigated for FLASH-RT Reasoning in the UHDpulse introduction paper (Sch ller et al. 2020 DOI:10.1016/j.ejmp.2020.09.020) Key features Suitable for clinical electron beam dosimetry in conventional RT and IORT Radiation hardness with accumulated dose 2

  3. flashDiamond Fundamental investigations Investigations of the microDiamond presented in the following papers Marinelli et al. 2022 (DOI: 10.1002/mp.15473) Kranzer et al. 2022 (DOI: 10.1088/1361-6560/ac594e) Key findings The microDiamond is not generally suitable for UH-DPP The crucial properties with respect to the linearity are Sensitivity Doping concentration in the p-type layer of the diamond Schottky-diode respectively the total series resistance The optimization of these parameters leads to a novel type of detector, the flashDiamond 3

  4. flashDiamond Fundamental investigations The applicability for the commissioning of FLASH RT electron beams was shown in the following work G. Verona Rinati et al. 2022 (DOI: 10.1002/mp.15782) Successfully tested in terms of: Linearity with ultra-high dose per pulse (UH-DPP) Depth dose curves (PDD) Lateral dose profiles Output factors So far, all measurements were done at the PTB research accelerator or a SIT machines 4

  5. flashDiamond Varian eFLASH Upgrade of Clinac systems (eFLEX) Beam parameters Beam quality 16 MeV Pulse duration 4.2 s Pulse repetition frequency 180 Hz 2.5 fD7609 (Palo Alto) SN220445 (Zurich) SN220442 (Zurich) Charge per pulse flashDiamond (nC) 2.0 1.5 1.0 0.5 Linearity up to 6 Gy per pulse 0.0 0 1 2 3 4 5 6 7 Dose per pulse reference (Gy) PRELIMINARY DATA WITH PERMISSION FROM VARIAN MEDICAL SYSTEMS AND UNIVERSITY HOSPITAL ZURICH ! 5

  6. flashDiamond Varian eFLASH 110 110 110 Depth dose curves 100 100 100 Conventional mode FLASH mode flashDiamond Conventional mode 90 90 90 flashDiamond Adv.Markus flashDiamond Adv.Markus CONV FLASH Comparison against Advanced Markus chamber (dose converted) 80 80 80 Relative dose (%) Relative dose (%) Relative dose (%) 70 70 70 FLASH mode 60 60 60 Comparison against Advanced Markus chamber (dose converted and corrected for recombination) 50 50 50 40 40 40 30 30 30 flashDiamond enables PDD measurement in CONV and FLASH mode without dose conversion and corrections Differences in the bremsstrahlung background between CONV and FLASH can be attributed to different scattering foils 20 20 20 10 10 10 0 0 0 0 0 0 20 20 20 40 40 40 60 60 60 80 80 80 100 100 100 120 120 120 140 140 140 Depth (mm) Depth (mm) Depth (mm) PRELIMINARY DATA WITH PERMISSION FROM UNIVERSITY HOSPITAL ZURICH ! 6

  7. flashDiamond IntraOp FLASH Mobetron Beam parameters Beam quality 9 MeV Pulse duration 0.5 to 4 s Pulse repetition frequency 30 Hz SSD 50 cm Field size 10 cm diameter 1.6 1.6 1.6 1.4 1.4 1.4 Nominal pulse duration Nominal pulse duration Linear Regr. R =0.9611 Real pulse duration Nominal pulse duration Linear Regr. R =0.9611 Linear Regr. R =0.9611 Real pulse duration Linear Regr. R =0.9968 Linear Regr. R =0.9968 FWHM pulse duration Linear Regr. R =0.9988 1.2 1.2 1.2 Dose per pulse (Gy) Dose per pulse (Gy) Dose per pulse (Gy) 1.0 1.0 1.0 0.8 0.8 0.8 0.6 0.6 0.6 0.4 0.4 0.4 Linearity with varying pulse duration Pure using the nominal pulse duration 0.2 0.2 0.2 0.0 0.0 0.0 Good using the real pulse duration Further improved using FWHM Precise knowledge of the pulse duration is required for the determination of the linearity Tools with high temporal resolution needed 0 0 0 1 1 1 2 2 2 3 3 3 4 4 4 5 5 5 Pulse duration ( s) Pulse duration ( s) Pulse duration ( s) PRELIMINARY DATA WITH PERMISSION FROM UNIVERSITY HOSPITAL HEIDELBERG ! 7

  8. flashDiamond IntraOp FLASH Mobetron 110 110 Beam parameters Beam quality 9 MeV Pulse duration 1 s Pulse repetition frequency 15 Hz SSD 18.4 cm (max. 3 Gy per pulse) Field size 6 cm diameter 100 100 flashDiamond flashDiamond 90 90 CONV FLASH CONV FLASH 80 80 Relative dose (%) Relative dose (%) 70 70 60 60 50 50 40 40 30 30 Depth dose curves Lateral dose profiles 20 20 10 10 0 0 0 20 -40 40 60 80 40 100 -60 -20 0 20 60 Depth (mm) Position (mm) flashDiamond enables measurements of 3D dose distribution in CONV and FLASH mode without dose conversion and corrections PRELIMINARY DATA WITH PERMISSION FROM UNIVERSITY HOSPITAL HEIDELBERG ! 8

  9. flashDiamond - Applications Relative Dosimetry Measurement of three-dimensional dose distribution with high spatial resolution Direct measurement of absorbed dose to water, no need to convert depth dose curves Consistency check (beam stability) Time resolved measurements (see talk of G. Verona Rinati) Absolute dose measurements After cross-calibration against a suitable reference A methodology for the determination of absorbed dose to water is still missing 9

  10. flashDiamond - Proposal Secondary standard for absorbed dose to water ??determination in conventional RT are ion chambers ??= ? ?0 ???60 ?? ??= ?? ?h ?S ?P ?? ?? ?? Absorbed dose to water determination with diamond detectors? ?? ??= ? ?0 ???60 ?? ??= ???60 10

  11. flashDiamond - Proposal Absorbed dose to water determination with diamond detectors 1.05 1.05 ??= ? ?0 ???60 ?? flashDiamond MC simulation flashDiamond MC simulation Fit Fit Verona Rinati et al. 2022 PTB 1.04 1.04 1.03 1.03 Beam quality correction factors for electron beams ?E kE kE 1.02 1.02 1.01 1.01 1.00 1.00 0.99 0.99 0.98 0.98 0.97 0.97 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 11 11 Beam specifier R50 (g/cm ) Beam specifier R50 (g/cm ) VERY PRELIMINARY DATA ! 11

  12. flashDiamond - Conclusion Usability and properties validated on four different UHDPP electron accelerators types three of them are commercially available for research in FLASH RT Methodology for the determination of absorbed dose to water ?? Should be studied in more detail Determination of the beam quality correction factors ??and its uncertainty under reference conditions is in progress The flashDiamond Type 60025 is commerciallized as a laboratory device for research purposes and thus available for further users and a variety of dosimetric applications 12

  13. Thank you! Questions? Wishes? Notes? 13

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