Y. Zoccarato

A cost-effective monitoring technique in particle therapy via uncollimated prompt gamma peak integration

For the purpose of detecting deviations from the prescribed treatment during particle therapy, the integrals of uncollimated prompt gamma-ray timing distributions are investigated. The intention is to provide information, with a simple and cost-effective setup, independent from monitoring devices of the beamline. Measurements have been performed with 65 MeV protons at a clinical cyclotron. Prompt gamma-rays emitted from the target are identified by means of time-of-flight. The proton range inside the PMMA target has been varied via a modulator wheel. The measured variation of the prompt gamma peak integrals as a function of the modulator position is consistent with simulations. With detectors covering a solid angle of 25 msr (corresponding to a diameter of 3–4 in. at a distance of 50 cm from the beam axis) and 108 incident protons, deviations of a few per cent in the prompt gamma-ray count rate can be detected. For the present configuration, this change in the count rate corresponds to a 3 mm change in the proton range in a PMMA target. Furthermore, simulation studies show that a combination of the signals from multiple detectors may be used to detect a misplacement of the target. A different combination of these signals results in a precise number of the detected prompt gamma rays, which is independent on the actual target position.

A low noise and high dynamic charge sensitive amplifier-shaper associated with Silicon Strip Detector for compton camera in hadrontherapy

An 8-channel Front End Electronics (FEE) circuit has been designed and fabricated in 0.35 11m CMOS process from Austria Micro System to be coupled with the Silicon Strip Detector (SSD) of the Compton Camera for quality control of hadrontherapy. Each channel includes a Charge Sensitive Amplifier (CSA) followed by two parallel CR-RC shapers. Slow and fast shapers, with 1 IlS and 15 ns shaping time, are used to measure the energy and to time stamp all events respectively. The two sides of the SSD are read thanks to a configurable system for holes and electrons. The CSA presents an open loop gain of 67 dB and 90 degrees phase margin assuring a high stability. The circuit has been successfully tested. The test results are in good agreement with analytic and simulation calculations. Here, we describe the principles and present measured performances of the prototype. A high linearity over the range of 3E3 to 3E6 electrons is reached with a conversion gain of 3.6 mV/fC. The circuit achieves an ENC (Equivalent Noise Charge) of 412 electrons rms. 75% of the total noise is generated by the small value of the feedback resistor chosen to avoid pile up phenomenon due to the lE5 hits/s occupancy rate. A cross-talk of 2 % was measured, 99% of which is due to the power supply disturbances. The power supply dissipation is 21 mW/channel for 3.3 V supply voltage. The area of this design is 2871x1881 μm2 including pads.

Very fast front end ASIC associated with multi-anode PMTs for a scintillating-fibre beam hodoscope

For developing a scintillating-fibre beam monitor, we have designed a front-end 16-Channel readout chip (version 2) to be associated with Multi-anode photomultipliers Ma-PMTs (Hamamatsu H8500) in a 0.35 μm BiCMOS process. Each channel of the ASIC consists of one input current conveyor driving separately a current comparator for signal event detection and a charge-sensitive amplifier (CSA) for signal charge measurement. The ASIC has brought significant improvements compared to its previous version: larger input dynamic range (53 dB against 33 dB), lower power consumption (11 mW/channel instead of 22 mW/channel under a 3.3-V supply), lower noise (4 fC versus 19 fC in Equivalent input Noise Charge, or ENC) and a better phase margin for optimizing stability and speed. This dedicated chip had been used in a beam test at HIT (Heidelberg Ion-Beam Therapy Center). System testing has shown achievements of 1 mm spatial resolution (size of the scintillating fibers) and a 4 MHz count rate. The main limitation comes from the Ma-PMTs which saturates at such a frequency. The ASIC operates normally with satisfied performances.

111: Real-time monitoring of the ion range during hadrontherapy: An update on the beam tagging hodoscope

An update on the beam tagging hodoscope J. Krimmer, L. Caponetto, X. Chen, M. Chevallier, D. Dauvergne, M. De Rydt, S. M. Deng, J.-L. Ley, H. Mathez, C. Ray, V. Reithinger, E. Testa,Y. Zoccarato Université de Lyon, Université Claude Bernard Lyon 1, CNRS/IN2P3, Institut de Physique Nucléaire de Lyon, 69622 Villeurbanne, France, Instituut voor Kernen Stralingsfysica, K.U.Leuven, Celestijnenlaan 200D, B-3001 Leuven

Charge Sensitive Amplifier (CSA) in cold gas of Liquid Argon (LAr) Time Projection Chamber (TPC)

This paper presents our work on a 8-channel low noise Front-End electronic coupled to a Liquid Argon (LAr) TPC (Time Projection Chamber). Each channel consists of a Charge Sensitive Amplifier (CSA), a band pass filter and a 50 Ohms buffer as line driver. A serial link based on a ‘i2c-like’ protocol, provides multiple configuration features to the circuit by accessing slow control registers. Only the CSA part is described in this paper. The feedback network of the CSA is made of a capacitance and a resistor. Their values are respectively 250 fF and 4 ΜΩ. An input referred noise of, at most, 1500 e-rms must be achieved at −100°C with an input detector capacitance of 250 pF to ensure a correct measurement of the minimal signal of 18000e-(2.88 fC). The power consumption in this cryogenic setup must be less than 40 mW from a 3.3 V power supply.

Absorbed energy monitoring during hadrontherapy via prompt gamma detection

An independent monitoring system aiming for the detection of deviations from the prescribed treatment in hadrontherapy is presented. The system is based on prompt gamma-ray detection via scintillation detectors and the use of time-of-flight information. Test measurements at cyclotrons show the influence of degraders used in passive beam delivery systems. A dedicated data acquisition card has been developed which is suitable to provide timing and energy information from scintillation detectors at counting rates compatible with clinical beam intensities.

3: A μTCA Data Acquisition System and its application for Hadrontherapy Monitoring using a Compton Camera

This presentation describes a data acquisition system developed within the European project Envision. Our aim is to build a device capable of monitoring dose delivery, during a patient treatment with a proton or carbon ion beam by means of prompt gamma detection using a time-of-flight Compton camera. Indeed, prompt-gamma longitudinal profiles are correlated to the ion range.

A front-end chip development for the sLHC CMS Silicon Strip Tracker

The FEAFS chip has been designed for the upgrades of the CMS Silicon Strip Tracker, which is planned in view of the LHC high luminosity upgrade. Its primary function is to provide a 40 MHz selective readout of particle hits that will be used for the generation of the 100 kHz hardware trigger of the experiment within a latency of 6.4 μs. To achieve this goal, the chip identifies clusters of limited number of activated strips and correlated in position, in a given window, in two closely superimposed sensors connected to the same chip. Finally, trigger and DAQ data are transmitted off detector via a common link. The FEAFS chip has been developed in IBM 0.13 μm technology. This paper presents the design of the chip and test results.