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Journal Articles

Genocchi, B. Pickford Scienti, O. Darambara, D.G. (2017). Optimal configuration of a low-dose breast-specific gamma camera based on semiconductor CdZnTe pixelated detectors. Journal of physics: conference series, Vol.841, pp. 012012-012012.

Myronakis, M.E. Zvelebil, M. Darambara, D.G. (2013). Normalized mean glandular dose computation from mammography using GATE: a validation study. Phys med biol, Vol.58 (7), pp. 2247-2265. show abstract

Myronakis, M.E. Zvelebil, M. Darambara, D.G. (2012). Computational modelling of pixelated CdZnTe detectors for x- and gamma-ray imaging applications. Journal of instrumentation, Vol.7.

Myronakis, M.E. Darambara, D.G. (2011). Monte Carlo investigation of charge-transport effects on energy resolution and detection efficiency of pixelated CZT detectors for SPECT/PET applications. Med phys, Vol.38 (1), pp. 455-467. show abstract

PURPOSE: Semiconductor detectors are increasingly considered as alternatives to scintillation crystals for nuclear imaging applications such as positron emission tomography (PET) or single photon emission computed tomography (SPECT). One of the most prominent detector materials is cadmium zinc telluride (CZT), which is currently used in several application-specific nuclear imaging systems. In this work, the charge-transport effects in pixelated CZT detectors in relation to detector pixel size and thickness are investigated for pixels sizes from 0.4 up to 1.6 mm. METHODS: The determination of an optimum pixel size and thickness for use with photon energies of 140 and 511 keV, suitable for SPECT and PET studies, is attempted using photon detection efficiency and energy resolution as figures of merit. The Monte Carlo method combined with detailed finite element analysis was utilized to realistically model photon interactions in the detector and the signal generation process. The GEANT4 Application for Tomographic Emission (GATE) toolkit was used for photon irradiation and interaction simulations. The COMSOL MULTIPHYSICS software application was used to create finite element models of the detector that included charge drift, diffusion, trapping, and generation. Data obtained from the two methods were combined to generate accurate signal induction at the detector pixels. The energy resolution was calculated as the full width at half maximum of the energy spectrum photopeak. Photon detection efficiency was also calculated. The effects of charge transport within the detector and photon escape from primary pixel of interaction were investigated; the extent of diffusion to lateral pixels was also assessed. RESULTS: Charge transport and signal induction were affected by the position of a pixel in the detector. Edge and corner pixels were less susceptible to lateral diffusion than pixels located in the inner part of the detector. Higher detection efficiency and increased photon escape from primary interaction pixel were observed for thicker detectors. Energy resolution achieved better values in 0.7 and 1.0 mm pixel size for 5 mm detector thickness and 1.6 mm pixel size for 10 mm thickness. CONCLUSIONS: Selection of pixel size and thickness depends on the imaging application and photon energy utilized. For systems that integrate two nuclear imaging modalities (i.e., combined SPECT/PET), the pixel size should offer an appropriate balance of the effects that take place in the detector, based on the results of the current work. This allows for a system to be designed with the same detector material and the same geometrical configuration for both modalities..

Guerra, P. Santos, A. Darambara, D.G. (2009). An investigation of performance characteristics of a pixellated room-temperature semiconductor detector for medical imaging. Journal of physics d-applied physics, Vol.42 (17).

Ma, A.K. Gunn, S. Darambara, D.G. (2009). Introducing DeBRa: a detailed breast model for radiological studies. Phys med biol, Vol.54 (14), pp. 4533-4545. show abstract

Currently, x-ray mammography is the method of choice in breast cancer screening programmes. As the mammography technology moves from 2D imaging modalities to 3D, conventional computational phantoms do not have sufficient detail to support the studies of these advanced imaging systems. Studies of these 3D imaging systems call for a realistic and sophisticated computational model of the breast. DeBRa (Detailed Breast model for Radiological studies) is the most advanced, detailed, 3D computational model of the breast developed recently for breast imaging studies. A DeBRa phantom can be constructed to model a compressed breast, as in film/screen, digital mammography and digital breast tomosynthesis studies, or a non-compressed breast as in positron emission mammography and breast CT studies. Both the cranial-caudal and mediolateral oblique views can be modelled. The anatomical details inside the phantom include the lactiferous duct system, the Cooper ligaments and the pectoral muscle. The fibroglandular tissues are also modelled realistically. In addition, abnormalities such as microcalcifications, irregular tumours and spiculated tumours are inserted into the phantom. Existing sophisticated breast models require specialized simulation codes. Unlike its predecessors, DeBRa has elemental compositions and densities incorporated into its voxels including those of the explicitly modelled anatomical structures and the noise-like fibroglandular tissues. The voxel dimensions are specified as needed by any study and the microcalcifications are embedded into the voxels so that the microcalcification sizes are not limited by the voxel dimensions. Therefore, DeBRa works with general-purpose Monte Carlo codes. Furthermore, general-purpose Monte Carlo codes allow different types of imaging modalities and detector characteristics to be simulated with ease. DeBRa is a versatile and multipurpose model specifically designed for both x-ray and gamma-ray imaging studies..

Ma, A.K. Darambara, D.G. Stewart, A. Gunn, S. Bullard, E. (2008). Mean glandular dose estimation using MCNPX for a digital breast tomosynthesis system with tungsten/aluminum and tungsten/aluminum+silver x-ray anode-filter combinations. Med phys, Vol.35 (12), pp. 5278-5289. show abstract

Guerra, P. Santos, A. Darambara, D.G. (2008). Development of a simplified simulation model for performance characterization of a pixellated CdZnTe multimodality imaging system. Phys med biol, Vol.53 (4), pp. 1099-1113. show abstract

Visvikis, D. Lefevre, T. Lamare, F. Kontaxakis, G. Santos, A. Darambara, D. (2006). Monte Carlo based performance assessment of different animal PET architectures using pixellated CZT detectors. Nuclear instruments & methods in physics research section a-accelerators spectrometers detectors and associated equipment, Vol.569 (2), pp. 225-5.

Darambara, D.G. (2006). State-of-the-art radiation detectors for medical imaging: Demands and trends. Nuclear instruments & methods in physics research section a-accelerators spectrometers detectors and associated equipment, Vol.569 (2), pp. 153-158.

Darambara, D.G. Sellin, P.J. Maehlum, G. (2004). A low-angle X-ray scatter breast-imaging system based on a novel multi-element Si-pad array operated in spectroscopic mode. Nuclear instruments and methods in physics research section a: accelerators, spectrometers, detectors and associated equipment, Vol.525 (1-2), pp. 253-257.

Darambara, D.G. Sellin, P.J. Maehlum, G. (2004). A novel detection system consisting of a large-area sensor and a multicell Si-pad array operated in spectroscopic mode for X-ray breast imaging. Ieee transactions on nuclear science, Vol.51 (4), pp. 1641-1647.

Darambara, D.G. Taibi, A. Speller, R.D. (2002). Image-quality performance of an a-Si:H-based X-ray imaging system for digital mammography. Nuclear instruments and methods in physics research section a: accelerators, spectrometers, detectors and associated equipment, Vol.477 (1-3), pp. 521-526.

Darambara, D.G. Todd-Pokropek, A. (2002). Solid state detectors in nuclear medicine. Q j nucl med, Vol.46 (1), pp. 3-7. show abstract

Darambara, D.G. Speller, R.D. Sellin, R. (2002). Development of a dual-detector system based on a-Si:H arrays and multi-element silicon detectors for diffraction-enhanced breast imaging. Ieee transactions on nuclear science, Vol.49 (3), pp. 1012-1016.

Darambara, D.G. Taibi, A. Speller, R.D. Gambaccini, M. (2000). Contrast-detail evaluation of a full-field digital mammography system. Ieee transactions on nuclear science, Vol.47 (3), pp. 870-876.

Darambara, D.G. Harvey, S.W. Astreinidou, E.G. Spyrou, N.M. (1997). Monte Carlo simulation of possible conversion processes with respect to soft error generation in a dynamic RAM based neutron detector. Journal of radioanalytical and nuclear chemistry, Vol.215 (2), pp. 287-294.

Darambara, D.G. Papadopoulos, A.N. Spyrou, N.M. (1997). Computer simulation of positron-induced radiation effects in Dynamic RAMs. Radiation effects and defects in solids, Vol.141 (1-4), pp. 141-148.

Darambara, D.G. Spyrou, N.M. (1997). Position sensitive regions in a generic radiation sensor based on single event upsets in dynamic RAMs. Nuclear instruments and methods in physics research section a: accelerators, spectrometers, detectors and associated equipment, Vol.392 (1-3), pp. 456-460.

Darambara, D.G. Spyrou, N.M. (1994). Neutron detection using soft errors in dynamic Random Access Memories. Nuclear instruments and methods in physics research section a: accelerators, spectrometers, detectors and associated equipment, Vol.348 (2-3), pp. 491-495.

Darambara, D.G. Spyrou, N.M. (1994). Detection mechanisms employing single event upsets in dynamic random access memories used as radiation sensors. Nuclear instruments and methods in physics research section a: accelerators, spectrometers, detectors and associated equipment, Vol.353 (1-3), pp. 67-70.

Darambara, D.G. Beach, A.C. Spyrou, N.M. (1993). Development of a novel neutron detector for imaging and analysis. Journal of radioanalytical and nuclear chemistry articles, Vol.167 (1), pp. 197-208.

Conferences

Scienti, O.P.Shah, A.Bamber, J.Darambara, D.IEEE, (2016). An Assessment of Photoacoustic and Photon Counting Multispectral x-Ray Imaging Techniques for Imaging Gold Nanorods in vivo as Part of Predicting Dose Enhancing Effects, 2016 IEEE NUCLEAR SCIENCE SYMPOSIUM, MEDICAL IMAGING CONFERENCE AND ROOM-TEMPERATURE SEMICONDUCTOR DETECTOR WORKSHOP (NSS/MIC/RTSD), .

Myronakis, M.E.Zvelebil, M.Darambara, D.G.IEEE, (2013). Effect of Collimator Design and Anode Dimensions on Gamma-Cameras Based on Pixelated CdZnTe, 2013 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC), .

Myronakis, M.E.Zvelebil, M.Darambara, D.G. (2012). Pixelated CdZnTe for Imaging in Medicine: Overall Performance Assessment Using an Advanced Computational Modeling Framework, 2012 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE RECORD (NSS/MIC), , pp.4276-+.

Myronakis, M.E.Zvelebil, M.Darambara, D.G. (2012). Integrated PET/SPECT System for Breast Imaging with CdZnTe: Computational Assessment, 2012 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE RECORD (NSS/MIC), , pp.2756-2758.

Rossall, A.K.Myronakis, M.E.Eherlin, A.Radley, I.Ayoub, M.Darambara, D.G. (2012). Optimal architecture of CdZnTe detectors for photon counting, multispectral medical x-ray imaging: comparison between simulation and experiment, 2012 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE RECORD (NSS/MIC), , pp.4085-4087.

Myronakis, M.E.Zvelebil, M.Darambara, D.G.IEEE, (2011). Computational Modelling of Multi-Head PET/SPECT Imaging Systems With Thick CdZnTe Pixelated Detectors, 2011 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC), , pp.4267-4269.

Myronakis, M.E.Zvelebil, M.Darambara, D.G.IEEE, (2011). Computational investigation of CdZnTe pixelated detector performance for x-ray based medical imaging applications, 2011 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC), , pp.1745-+.

Myronakis, M.E.Darambara, D.G.IEEE, (2010). Performance of photon-counting and energy-integrating semiconductor detectors for digital breast tomosynthesis, 2010 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD (NSS/MIC), , pp.1488-1490.

Myronakis, M.E.Darambara, D.G. (2009). Effect of pixel dimensions and thickness on energy resolution and sensitivity of CZT detectors used in nuclear medicine application, Presented at 2009 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2009), 2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC), .

Ma, A.K.Gunn, S.Bullard, E.Darambara, D.G.IEEE, (2009). Demonstration of the Superiority of Digital Breast Tomosynthesis over 2D Mammography through a Series of Sophisticated Computational Breast Phantoms - A Preliminary Monte Carlo Study, 2008 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (2008 NSS/MIC), VOLS 1-9, , pp.3158-+.

Darambara, D.G.Sellin, P.J.Maehlum, G. (2004). A novel detection system consisting of a large area sensor and a multi-cell Si-pad array operated in spectroscopic mode for X-ray breast imaging, 2003 IEEE NUCLEAR SCIENCE SYMPOSIUM, CONFERENCE RECORD, VOLS 1-5, , pp.1011-1015.

Darambara, D.G.Spyrou, N.M. (1997). Position-sensitive neutron detector based on dynamic RAM devices, Presented at Fifth International Conference on Applications of Nuclear Techniques: Neutrons in Research and Industry, International Conference Neutrons in Research and Industry, .

Darambara, D.G. (1997). A generic radiation sensor based on silicon memory devices, APPLICATION OF ACCELERATORS IN RESEARCH AND INDUSTRY - PROCEEDINGS OF THE FOURTEENTH INTERNATIONAL CONFERENCE, PTS 1 AND 2, (392), pp.1063-1066.

Darambara, D.G.Spyrou, N.M. (1995). Use of single-event upsets in dynamic random access memories as the basis for a neutron detector, Presented at 4th International Conference on Applications of Nuclear Techniques: Neutrons and their Applications, International Conference on Neutrons and Their Applications, .

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