Tritium digital autoradiography with a Medipix2 hybrid silicon pixel detector

Dipartimento di Scienze Fisiche, Università di Napoli Federico II and INFN, Sezione di Napoli, Via Cinthia, I-80126 Napoli, Italy
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment (Impact Factor: 1.22). 01/2004; 516(2-3):554-563. DOI: 10.1016/j.nima.2003.09.027


We report on the first measurements of 3H beta autoradiography obtained using a room temperature hybrid pixel detector, consisting of the Medipix2 single particle counting read-out chip bump-bonded to a 300 μm thick silicon pixel detector. This system has 256×256 square pixels of 55 μm pitch for a total sensitive area of 14×14 mm2. Each pixel contains a double threshold discriminator and a 13-bit counter. Using a detection threshold equivalent to less than 6 keV and a background count rate of 5×10−3 counts mm−2 s−1, with exposures up to several hours, real-time images have been obtained of tritium-labeled solution drops spotted on a thin mylar foil placed in contact with the continuous top electrode of the silicon detector, in open air condition.

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Available from: G. Mettivier, Jul 06, 2015
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    • "Our work presented here is focused in the latter area. Within solid state detectors several different technologies can be distinguished including CCD technology [8], CMOS technology [9] and hybrid detector technology [7]. "
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    ABSTRACT: CCD (charged coupled device) and CMOS imaging technologies can be applied to thin tissue autoradiography as potential imaging alternatives to using conventional film. In this work, we compare two particular devices: a CCD operating in slow scan mode and a CMOS-based active pixel sensor, operating at near video rates. Both imaging sensors have been operated at room temperature using direct irradiation with images produced from calibrated microscales and radiolabelled tissue samples. We also compare these digital image sensor technologies with the use of conventional film. We show comparative results obtained with (14)C calibrated microscales and (35)S radiolabelled tissue sections. We also present the first results of (3)H images produced under direct irradiation of a CCD sensor operating at room temperature. Compared to film, silicon-based imaging technologies exhibit enhanced sensitivity, dynamic range and linearity.
    Physics in Medicine and Biology 09/2007; 52(16):4993-5011. DOI:10.1088/0031-9155/52/16/019 · 2.76 Impact Factor
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    ABSTRACT: Progress in CMOS technology and in fine pitch bump bonding has made possible the development of single photon counting detectors for X-ray imaging with pixel pitches on the order of 50 µm giving a spatial resolution which is comparable to conventional CCD and flat panel detectors. This thesis studies the interaction of X-ray photons in the energy range of 5 keV to 70 keV with various sensor materials as well as the response of the Medipix2 readout system to both monochromatic and wide spectrum X-ray sources. Single photon processing offers the potential for spectroscopic imaging. However, this thesis demonstrates using simulations and measurements that the charge deposition and collection within the semiconductor sensor impose fundamental limits on the achievable energy resolution. In particular the discussion of charge during collection in the sensor and the generation of fluorescence photons in heavier sensor materials contribute to the appearance of a low energy tail on the detected spectrum of an incoming beam. On the other hand, with the application of appropriate flat-field correction maps, the systemem operates to the Poisson limit. As the electronic noise in a pixel channel is around 100e rms and typical energy thresholds are over 1000e excellent quality images of low contrast objects have been produced using both intense and weak X-ray sources. The Modulation Transfer Function has been measured to be 9.1 lp/mm corresponding to the pixel aperture function. The Detective Quantum Efficiency is only limited by the sensor material used and does not change as a function of dose, highlighting the enormous potential for low dose imaging with such a system. The Medipix2 system has an upper threshold in each pixel too which allows an energy window of down to 1.4 keV FWHM to be selected and scanned in the range of 4 keV to 100 keV. First images using the energy threshold window demonstrate the potential of the technique to extract a spectral image when only a broad band source of X-rays is available.
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    ABSTRACT: For large-scale applications, hybrid pixel detectors, in which sensor and read-out chip are separate entities, constitute the state of the art in pixel detector technology to date. They have been developed and start to be used as tracking detectors and also imaging devices in radiography, autoradiography, protein crystallography and in X-ray astronomy. A number of trends and possibilities for future applications in these fields with improved performance, less material, high read-out speed, large radiation tolerance, and potential off-the-shelf availability have appeared and are momentarily advanced to greater maturity. Among them are monolithic or semi-monolithic approaches which do not require complicated hybridization but come as single sensor/IC entities. Most of these are presently still in the development phase waiting to be used as detectors in experiments. The present state in pixel detector development including hybrid and (semi-) monolithic pixel techniques and their suitability for particle detection and for imaging, is reviewed.
    IEEE Transactions on Nuclear Science 07/2004; 51(3-51):1006 - 1015. DOI:10.1109/TNS.2004.829438 · 1.28 Impact Factor
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