M.L.F. Lerch a, M. Petasecca a, A. Cullen a, I. Fuduli a, P.Fournier a, I. Cornelius a, A. Kok b, V. L.Pervertaylo c, A.B. Rosenfeld a IEEE MRT Workshop, 257 th Oct, 2013 Silicon Detectors for Real-time Monitoring of Submillimeter Synchrotron X-ray Beams a. Centre for Medical Radiation Physics, University of Wollongong, Australia b. SINTEF, Norway c. SPA BIT, Ukraine

Collaborators and Research Students Centre for Medical Radiation Physics, University of Wollongong: Michael Lerch Marco Petasecca Iwan Cornelius George Takacs Iolanda Fuduli Pauline Fournier (PhD) Ashley Cullen (MSc & PhD) Heidi Nettelbeck (PhD) Sally McKinnon (Hons& PhD) Andrew Baloglow (Hons) Daniel Mclure (Hons) SPA BIT, Ukraine: Vladimir Perevertaylo Biomedical Beamline (ID17), ESRF, Grenoble, France: Elke Bräuer-Krisch Herwig Requardt Alberto Bravin Theirry Brochard Raphael Serduc Christian Nemoz Erik Siegbahn (PhD) Institute of Pathology, University of Bern, Switzerland: Jean Laissue IMBL Beamline, AS Daniel Hausermann Chris Hall Andrew Stevenson

0.5 mm 50 mm (max) Energy (keV) Real Time Submillimeter X-ray Beam Monitoring

MRT requires a detector and readout system with: ◦ Spatial resolution: 1-10  m ◦ Dynamic range: 10,000 ◦ Tissue equivalent: QA of MRT treatment plan ◦ On-line: MRT beam set up and monitoring ◦ Fast: PVDR for all X-ray microbeams in real-time ◦ Water proof (QA procedure compatible) Silicon Detector Requirements

CMRP X-Tream : Architecture Overview

 FPGA based (Xilinx Spartan-6)  Fully USB compatible  Modular  Completely stand-alone  Setting of parameters fully remote controlled ◦ Acquisition time ◦ Set & Measure Applied Bias ◦ Hardware averaging ◦ Trigger mode  Hardware redundancy of bias functions  Linear over a wide dynamic range (0.5 nA – 150,000 nA)  Sampling rate 1.0 MHz  Global chain calibration 0.34 nA/count  Global noise 1.3 counts (no averaging) CMRP X-Tream TM Dosimetry System

Microstrip Detector  Designed by CMRP  Manufactured by SPA-BIT, Ukraine  ion implanted junction technology  Epitaxial Si construction ◦ 50 μm thick epitaxial layer p-type (100  cm) ◦ On 370 μm Si substrate, p-type (0.001  cm)  Single strip surrounded by a guard-ring  Strip dimensions are 10 µm × 900 μm  Waterproof 0.9 mm

Face-on Detector Response Map – Unirradiated Detector IBIC characterization performed at ANSTO  m spot size 4.5 MeV Alpha SSD EPI detector; Guard-ring Grounded Bias -32 V Energy window maps Energy (MeV) ADC Counts

Detector Preirradiation and Radiation Damage

Face-on Detector Response Map IBIC characterization performed at ANSTO:  m spot size 4.5 MeV Alpha SSD EPI detector; Guard-ring Grounded Bias -32 V 5  m wide x 50  m high beam scanned horizontally EPI Si single strip detector Face-on detector mode, -30 V bias 4 Bunch mode Energy (keV)

6 MV LINAC Testing Time (  m) Response (counts) Time (  m) Response (counts) Time (  m) Response (counts) 600 MU/min 20 MU/point 6000 Gy/sec 10x10cm 2 FS

Irradiation Geometry Side view of PMMA phantom

Face-on Detector Response Linearity Full MRT energy spectrum, dose rate Gy/Sec/mA (IC) 0.05 mm high x 20 mm wide beam scanned vertically Effective field size (FS) 20x20 mm 2 Face-on detector mode, 30 V bias Storage ring current ~190 mA

20 mm Depth in PMMA 412  m pitch Realtime readout Scan time ~12 sec Immediate display (Log scale) Scanning Mode Response – 0.5 mm x 20 mm MRT Field

Microbeam Array Response Edge-on detector mode, 30 V bias 4 Bunch synchrotron mode 5 mm Depth in PMMA 50  m FWHM microbeams 412  m pitch

Valley Dose Contribution Synchrotron X-rays Microbeams MSC Top view MSC Angle (degrees)

17 Microbeam Dosimetry at IMBL  Scan of the microbeams in the vertical direction (linear scale) ◦ 50 µm wide and 150 µm c-t-c, 2cm depth in solid water

18 Film Analysis of Synchrotron X-ray microbeams

Results – Peak Irradiation 10 mm

Peak vs Valley Irradiation Response and PVDR Peak Valley

Deduced PVDR in a 20mm x20mm MRT Field I. Martínez-Rovira, J. Sempau, and Y. Prezado, “Development and commissioning of a Monte Carlo photon beam model for the forthcoming clinical trials in microbeam radiation therapy.,” Medical physics, vol. 39, no. 1, pp. 119–31, Jan

PVDR – Irradiate Mode Field Size1 x 1 cm 2 2 x 2 cm 2 Depth (cm)Expt.MCExpt.MC ± 277 ± 449 ± 347 ± ± 251 ± 333 ± 328 ± ± 244 ± 422 ± 123 ± 3 I. Martínez-Rovira, J. Sempau, and Y. Prezado, “Development and commissioning of a Monte Carlo photon beam model for the forthcoming clinical trials in microbeam radiation therapy.,” Medical physics, vol. 39, no. 1, pp. 119–31, Jan

Valley Dose Contribution Synchrotron X-rays Microbeams MSC Top view MSC Angle (degrees)

Summary, Future Work and Acknowledgements  X-Tream real-time detector system for submillimeter synchrotron X- ray beams has been successfully developed and tested by CMRP, UOW at ESRF and AS  PVDR trend with number of microbeams in PMMA has been characterised.  Satellite structure observed in lateral profile of MRT radiation field is due to scattering from the face of the MSC slits and needs to be modelled  PVDR in a clinically relevant radiation field and its trend with depth in PMMA has been characterised by the “ X-Tream ” real-time synchrotron MRT dosimetry system and agrees with independent MC data for increasing irradiation field geometries.  Australian Synchrotron International Access Award #AS_IA092_ESRF MD289 (2011) & AS/IA131/6794 (2013)  Australian National Health and Medical Research Council Development Grant #