Pixel segmented ionization chamber for therapeutical beams of photons and hadrons

Abstract A fast and precise detector to monitor on-line the dose delivered by an active scanning therapeutical beam has been built and tested

Characterization of a front-end electronics for the monitoring and control of hadrontherapy beams

Abstract An integrated 64-channel device for the read-out of parallel plate pixel and strip ionization detectors has been developed by the INFN and University of Torino. The detectors will be used for the monitoring and control of hadrontherapy beams. The ASIC has been designed in CMOS 0.8 μm technology and it is based on a current-to-frequency converter followed by a synchronous counter. In this paper, we present a detailed characterization of the device done with 113 chips

'Ionizing radiation effects on a 64-channel charge measurement ASIC designed in CMOS 0.35 μm technology'

A 64-channel circuit Application Specific Integrated Circuit (ASIC) for charge measurement has been designed in CMOS 0.35mm technology and characterized with electrical tests. The ASIC has been conceived to be used as a front-end for dosimetry and beam monitoring detector read-out. For that application, the circuitry is housed at a few centimeters from the irradiated area of the detectors and therefore radiation damages can affect the chip performances. The ASIC has been tested on an X-ray beam. In this paper, the results of the test and an estimate of the expected lifetime of the ASIC in a standard radio-therapeutical treatment environment are presented. An increase of the background current of 2 fA/Gy has been observed at low doses, whilst the gain changes by less than 3% when irradiated up to 15 kGy. Furthermore it has been assessed that, when used as an on-line beam monitor and the annealing effect has been taken into account, the background current increase is � 440 fA/year

Dosimetric characterization of a large area pixel-segmented ionization chamber.

A pixel-segmented ionization chamber has been designed and built by Torino University and INFN. The detector features a 24 x 24 cm2 active area divided in 1024 independent cylindrical ionization chambers and can be read out in 500 micros without introducing dead time; the digital charge quantum can be adjusted between 100 fC and 800 fC. The sensitive volume of each single ionization chamber is 0.07 cm3. The purpose of the detector is to ease the two-dimensional (2D) verifications of fields with complex shapes and large gradients. The detector was characterized in a PMMA phantom using 60Co and 6 MV x-ray photon beams. It has shown good signal linearity with respect to dose and dose rate to water. The average sensitivity of a single ionization chamber was 2.1 nC/Gy, constant within 0.5% over one month of daily measurements. Charge collection efficiency was 0.985 at the operating polarization voltage of 400 V and 3.5 Gy/min dose rate. Tissue maximum ratio and output factor have been compared with a Farmer ionization chamber and were found in good agreement. The dose profiles have been compared with the ones obtained with an ionization chamber in water phantom for the field sizes supplied by a 3D-Line dynamic multileaf collimator. These results show that this detector can be used for 2D dosimetry of x-ray photon beams, supplying a good spatial resolution and sensibly reducing the time spent in dosimetric verification of complex radiation fields

Electrode Strip Deposition for the CMS Barrel Drift Tube System

The full production ideation, design, set up and realization of the Electrode Strip Deposition for the entire construction of the CMS Barrel Drift Tube System are described in detail