Thallium bromide (TlBr) has been under development for room temperature gamma ray spectroscopy due to high density, high Z and wide bandgap of the material. Furthermore, its low melting point (460 °C), cubic crystal structure and congruent melting with no solid-solid phase transitions between the melting point and room temperature, TlBr can be grown by relatively simple melt based methods. As a result of improvements in material processing and detector fabrication over the last several years, TlBr with electron mobility-lifetime products (μ_eτ_e) in the mid 10^-3 cm²/V range has been obtained. In this paper we are going to report on our unipolar charging TlBr results for the application as a small animal imaging. For SPECT application, about 5 mm thick pixellated detectors were fabricated and tested. About 1 % FWHM at 662 keV energy resolution was estimated at room temperature. By applying the depth correction technique, less than 1 % energy resolution was estimated. We are going to report the results from orthogonal strip TlBr detector for PET application. In this paper we also present our latest detector highlights and recent progress made in long term stability of TlBr detectors at or near room temperature. This work is being supported by the Domestic Nuclear Detection Office (DNDO) and the Department of Energy (DOE).

Developments in room temperature solid state imaging arrays for energy-resolved single photon counting in medical x-ray imaging are discussed. A number of x-ray imaging applications can benefit from these developments including mammography which requires very good spatial resolution. Energy resolved photon counting can provide reduced dose through optimal energy weighting and compositional analysis through multiple basis function material decomposition. Extremely high flux can occur in x-ray imaging and energy integrating detectors with a large dynamic range and good detection efficiency have been conventionally used. To achieve the benefits of energy resolved photon counting, imaging arrays with a large count rate range and good detection efficiency are required. Si based semiconductor radiation detectors with strip anode arrays electrically connected to application specific integrated circuits (ASICs) can provide fast, efficient, low-noise performance with good energy and spatial resolution for use in mammography however this can only be achieved with a careful optimization of the Si sensors and ASICs together. We have designed and constructed a Si imaging array, with a 1 x 1024 grid of electrical 100 micron wide strip contacts inter connected to multi channel ASICs, with a counting range up to 1 x 10⁶ counts per second per pixel.

A high-sensitive X-ray computed tomography (CT) system is useful for decreasing absorbed dose for patients, and a dark-count-less photon-counting CT system was developed. X-ray photons are detected using a YAP(Ce) [cerium-doped yttrium aluminum perovskite] single crystal scintillator and an MPPC (multipixel photon counter). Photocurrents are amplified by a high-speed current-voltage amplifier, and smooth event pulses from an integrator are sent to a high-speed comparator. Then, logical pulses are produced from the comparator and are counted by a counter card. Tomography is accomplished by repeated linear scans and rotations of an object, and projection curves of the object are obtained by the linear scan. The image contrast of gadolinium medium slightly fell with increase in lower-level voltage (V_l) of the comparator. The dark count rate was 0 cps, and the count rate for the CT was approximately 250 kcps.

A low-dose-rate X-ray computed tomography (CT) system is useful for reducing absorbed dose for patients. The CT system with a tube current of 1.91 mA was developed using a silicon-PIN X-ray diode (Si-PIN-XD). The Si-PIN-XD is a selected high-sensitive Si-PIN photodiode (PD) for detecting X-ray photons. X-ray photons are detected directly using the Si-PIN-XD without a scintillator, and the photocurrent from the diode is amplified using current-voltage and voltage-voltage amplifiers. The output voltage is converted into logical pulses using a voltage-frequency converter with maximum frequency of 500 kHz, and the frequency is proportional to the voltage. The pulses from the converter are sent to differentiator with a time constant of 1 μs to generate short positive pulses for counting, and the pulses are counted using a counter card. Tomography is accomplished by repeated linear scans and rotations of an object, and projection curves of the object are obtained by the linear scan. The exposure time for obtaining a tomogram was 5 min at a scan step of 0.5 mm and a rotation step of 3.0°. The tube current and voltage were 1.91 mA and 100 kV, respectively, and gadolinium K-edge CT was carried out using filtered X-ray spectra with a peak energy of 52 keV.

Columnar, amorphous CsI:Tl scintillators are attractive for biomedical imaging applications because they allow high spatial resolution with EMCCD detectors and BazookaSPECT. But these scintillators have a serious practical limitation, they are not useful in thickness larger than 0.5 mm, because of attenuation; this means that detection efficiencies are very poor for ≥100 keV gamma rays. The development of a new crystalline microcolumnar scintillator (CMS) of CsI:Tl is described. CMS CsI:Tl has high density and greatly improved light transmission properties. CMS films were prepared in three thicknesses (0.5 mm, 1.0 mm and 4.0 mm), and test results for these films are described. The light yield and energy resolution for 0.5 mm, CMS CsI:Tl films was equivalent to that of conventional bulk CsI:Tl scintillators; while some light attenuation was seen in 4 mm-thick CMS CsI:Tl samples, useable photopeaks were obtained at 122 keV. The spatial resolution measured for the 0.5 mm and 1.0 mm films in a BazookaSPECT system was excellent, 150-200 μm. Imaging tests with the 4 mm-thick CMS CsI:Tl films in a BazookaSPECT system with 662 keV gamma rays showed progressive broadening of the signal clusters on the CCD camera with depth of interaction (DOI), indicating that DOI determination should be possible with these detectors, i.e. 3D detector operation. Future planned investigations are described.

To mitigate image degradation due to the finite spatial resolution of detectors, a new theory is developed that allows Compton cameras to be comprised of detectors that have no spatial resolution at all. The results of a computer simulation indicate that the new theory can be used to produce reasonable images at least when noiseless simulated data is used. Camera designs that can exploit the new theory for use in areas such as medicine and homeland security are presented. Although the results presented here are promising, further effort is needed to establish their usefulness with real data.

This paper presents an approach to Noise Power Spectrum (NPS) assessment of color medical displays without using an expensive imaging colorimeter. The R, G and B color uniform patterns were shown on the display under study and the images were taken using a high resolution monochromatic camera. A colorimeter was used to calibrate the camera images. Synthetic intensity images were formed by the weighted sum of the R, G, B and the dark screen images. Finally the NPS analysis was conducted on the synthetic images. The proposed method replaces an expensive imaging colorimeter for NPS evaluation, which also suggests a potential solution for routine color medical display QA/QC in the clinical area, especially when imaging of display devices is desired

In this paper, we present a family of large format CIS’s designed for dental x-ray applications. The CIS areas vary from small 31.5mm x 20.1mm, to medium 34.1mm x 26.3mm, to large 37.1mm x 26.3mm. Pixel size is 19.5um x 19.5um. The sensor family was fabricated in a 0.18um CIS process. Stitching is used in the CIS fabrication for the medium and large size sensors. We present the CIS and detector system design that includes pixel circuitry, readout circuitry, x-ray trigger mechanism, scintillator, and the camera electronics. We also present characterization results including the detector performances under both visible light and x-ray radiation.

In this paper, we present a design of a multi optical modalities blood glucose monitor. The Monte Carlo tissues optics simulation with typical human skin model suggests the SNR ratio for a detector sensor is 104 with high sensitivity that can detect low blood sugar limit at 1 mMole/dL ( <20 mg/dL). A Bayesian filtering algorithm is proposed for multisensor fusion to identify whether e user has the danger of having diabetes. The new design has real time response (on the average of 2 minutes) and provides great potential to perform real time monitoring for blood glucose.

We present recent progress in BazookaSPECT, a high-resolution, photon-counting gamma-ray detector. It is a new class of scintillation detector that combines columnar scintillators, image intensifiers, and CCD (charge- coupled device) or CMOS (complementary metal-oxide semiconductors) sensors for high-resolution imaging. A key feature of the BazookaSPECT paradigm is the capability to easily design custom detectors in terms of the desired intrinsic detector resolution and event detection rate. This capability is possible because scintillation light is optically amplfied by the image intensifier prior to being imaging onto the CCD/CMOS sensor, thereby allowing practically any consumer-grade CCD/CMOS sensor to be used for gamma-ray imaging. Recent efforts have been made to increase the detector area by incorporating fiber-optic tapers between the scintillator and image intensi_er, resulting in a 16x increase in detector area. These large-area BazookaSPECT detectors can be used for full-body imaging and we present preliminary results of their use as dynamic scintigraphy imagers for mice and rats. Also, we discuss ongoing and future developments in BazookaSPECT and the improved event- detection rate capability that is achieved using Graphics Processing Units (GPUs), multi-core processors, and new high-speed, USB 3.0 CMOS cameras.

The purpose of this presentation is to demonstrate the means which permit examining the accuracy of Image Quality with respect to MTF (Modulation Transfer Function) and NPS (Noise Power Spectrum) of Color Displays and Monochrome Displays. Indications were in the past that color displays could affect the clinical performance of color displays negatively compared to monochrome displays. Now colorimeters like the PM-1423 are available which have higher sensitivity and color accuracy than the traditional cameras like CCD cameras. Reference (1) was not based on measurements made with a colorimeter. This paper focuses on the measurements of physical characteristics of the spatial resolution and noise performance of color and monochrome medical displays which were made with a colorimeter and we will after this meeting submit the data to an ROC study so we have again a paper to present at a future SPIE Conference.Specifically, Modulation Transfer Function (MTF) and Noise Power Spectrum (NPS) were evaluated and compared at different digital driving levels (DDL) between the two medical displays. This paper focuses on the measurements of physical characteristics of the spatial resolution and noise performance of color and monochrome medical displays which were made with a colorimeter and we will after this meeting submit the data to an ROC study so we have again a paper to present at a future Annual SPIE Conference. Specifically, Modulation Transfer Function (MTF) and Noise Power Spectrum (NPS) were evaluated and compared at different digital driving levels (DDL) between the two medical displays. The Imaging Colorimeter. Measurement of color image quality needs were done with an imaging colorimeter as it is shown below. Imaging colorimetry is ideally suited to FPD measurement because imaging systems capture spatial data generating millions of data points in a single measurement operation. The imaging colorimeter which was used was the PM-1423 from Radiant Imaging. It uses full-frame CCDs with 100% fill factor which makes it very suitable to measure luminance and chrominance of individual LCD pixels and sub-pixels on an LCD display. The CCDs used are 14-bit thermoelectrically cooled and temperature stabilized , scientific grade.

Results are presented of investigations into the composition, uniformity and gamma-ray imaging performance of new ceramic scintillators with synthetic garnet structure. The ceramic scintillators were produced by a process that uses flame pyrolysis to make nanoparticles which are sintered into a ceramic and then compacted by hot isostatic compression into a transparent material. There is concern that the resulting ceramic scintillator might not have the uniformity of composition necessary for use in gamma-ray spectroscopy and gamma-ray imaging. The compositional uniformity of four samples of three ceramic scintillator types (GYGAG:Ce, GLuGAG:Ce and LuAG:Pr) was tested using an electron microprobe. It was found that all samples were uniform in elemental composition to the limit of sensitivity of the microprobe (few tenths of a percent atomic) over distance scales from ~ 1 cm to ~ 1 um. The light yield and energy resolution of all ceramic scintillator samples were mapped with a highly collimated 57Co source (122 keV) and performance was uniform at mapping scale of 0.25 mm. Good imaging performance with single gamma-ray photon detection was demonstrated for all samples using a BazookaSPECT system, and the imaging spatial resolution, measured as the FWHM of a LSF was 150 um.

This article presents the principles of laser fluorescence diagnostic method used to diagnose pathological conditions of the stomach. In it, the new criteria are proposed - the total area and integrated fluorescence intensity as the differentiation of pathological conditions. The results of investigating the interrelation between the values of intensity and area of laser fluorescence are presented. They characterize the coordinate distributions of reradiation in the points of polarizationally filtered laser images of stomach histological sections. The criteria of laser polarization fluorescent diagnostics of stomach cancer nascency and its severity degree differentiation are determined.