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With the upgradation of detector components, such as scintillators and photodetectors , the PET-image signal-to-noise ratio of time-of-flight positron emission tomography (TOF-PET) systems has been improved, compared to those of ordinary nonTOF-PET systems. A TOF-PET with an ultrahigh time resolution, for example a coincidence time resolution (CTR) better than few tens of picoseconds, can not only improve the image quality, but also remove the image reconstruction process, significantly impacting medical imaging. Therefore, it is crucial to develop a high-time resolution PET detector. We focus on the prompt emission of Cherenkov radiation , owing to the instantaneousness of which, a high time resolution can be expected. One of the candidates for the Cherenkov radiator is lead fluoride (PbF 2 ) due it has excellent properties, including transparency toward the ultraviolet region, high refractive index (n = 1.82), and high density (7.77 g/cm 3). Moreover, it does not contain radioisotopes, unlike lutetium-based scintillators, which are commonly used in the currently available TOF-PET detectors. In this work, we experimentally investigate the timing performance of PbF2-based Cherenkov detectors, breaking down the timing performance into physical components. 3 × 3 × 5 mm3 and 9.6 × 9 . 6 × 5 mm3 PbF2 crystals are used as Cherenkov radiators; both are attached to a microchannel plate photomultiplier tube (MCP-PMT) because the single channel MCP-PMT is one of the best photodetectors in terms of the SPTR, which is 25 ps full width at half maximum (FWHM). All the surfaces, except the end surface where the MCP-PMT is connected, are wrapped in black tape to suppress the reflections of the Cherenkov photons in the crystal. The CTR is measured by placing a detector pair face-to-face, using an 22 Na point source, and an oscilloscope at 20 GS/s with a set bandwidth of 4.2 GHz. A CTR of 46.9 ps FWHM, corresponding to a position resolution of 7.0 mm, is obtained, consistent with our simulation results.

Genetic variability in Plasmodium falciparum malaria parasites hampers current malaria vaccine development efforts. Here, we hypothesize that to address the impact of genetic variability on vaccine efficacy in clinical trials, conserved antigen targets should be selected to achieve robust host immunity across multiple falciparum strains. Therefore, suitable vaccine antigens should be assessed for levels of polymorphism and genetic diversity. Using a total of one hundred and two clinical isolates from a region of high malaria transmission in Uganda, we analyzed extent of polymorphism and genetic diversity in four recently reported novel blood-stage malaria vaccine candidate proteins: Rh5 interacting protein (PfRipr), GPI anchored micronemal antigen (PfGAMA), rhoptry-associated leucine zipper-like protein 1 (PfRALP1) and Duffy binding-like merozoite surface protein 1 (PfMSPDBL1). In addition, utilizing the wheat germ cell-free system, we expressed recombinant proteins for the four candidates based on P. falciparum laboratory strain 3D7 sequences, immunized rabbits to obtain specific antibodies (Abs) and performed functional growth inhibition assay (GIA). The GIA activity of the raised Abs was demonstrated using both homologous 3D7 and heterologous FVO strains in vitro. Both pfripr and pfralp1 are less polymorphic but the latter is comparatively more diverse, with varied number of regions having insertions and deletions, asparagine and 6-mer repeats in the coding sequences. Pfgama and pfmspdbl1 are polymorphic and genetically diverse among the isolates with antibodies against the 3D7-based recombinant PfGAMA and PfMSPDBL1 inhibiting merozoite invasion only in the 3D7 but not FVO strain. Moreover, although Abs against the 3D7-based recombinant PfRipr and PfRALP1 proteins potently inhibited merozoite invasion of both 3D7 and FVO, the GIA activity of anti-PfRipr was much higher than that of anti-PfRALP1. Thus, PfRipr is regarded as a promising blood-stage vaccine candidate for next-generation vaccines against P. falciparum.

A new standardization method for a sealed (22)Na point source was developed utilizing two NaI(Tl) scintillation detectors. In the proposed method, the count rates of annihilation radiation, gamma rays, their coincidence sum, and the coincidences between the two detectors are used. The equations from which the source activity can be deduced are derived in this work. A series of EGS-5 Monte Carlo calculations were conducted to test the validity of the expressions. The calculated activity agreed within approximately 1 percent with the literature data used as input in the simulations.

A tritium radioactivity source was measured by triple-to-double coincidence ratio (TDCR) equipment of the National Metrology Institute of Japan (NMIJ), and measured data were fitted using polynomial approximation and the Newton-Raphson method, a technique whereby equations are solved numerically by successive approximations. The method used to obtain the activity minimizes the difference between statistically calculated data and experimental data. In the fitting, since calculated statistical efficiency and TDCR values are discrete, the calculated efficiencies are approximated by quadratic functions around experimental values and the Newton-Raphson method is used for convergence at the minimal difference between experimental data and calculated data. In this way, the activity of tritium was successfully obtained.

Electronic portal imaging device (EPID) is a popular tool for a verification of the patient setup for radiation therapy. Recently, it is grabbing attention as a tool for in vivo dosimetry. It detects therapeutic photons which penetrated the patient body to acquire an image. Conversion to absorbed dose is required from the digital pixel value. However, the response of the EPID is susceptible to the energy spectrum changes through the body [1] , [2] . The purpose of this study was to perform the energy response correction of the EPID image using Monte Carlo simulation (MC) to improve the accuracy of the EPID dosimetry. Geant4.9.6 patch04 was used for the MC with a combination of a HTCondor 7.6 parallel computing software. The MC simulated the 6 and 10 MV photon beams from Trilogy (Varian Medical Systems) linear accelerator. The EPID response to the energy spectrum was evaluated. CT DICOM data set of a chest phantom was imported to the MC, and the simulated EPID images were acquired after irradiating 6 and 10 MV photon beams. The measurement was performed with the same setup as the MC and obtained the EPID images. The energy response was corrected to obtain the absorbed dose and compared with that measured with 2D array detector (PTW) as a reference. EPID was more sensitive to the photons penetrated the mediastinum than those penetrated the lung due to the contamination of the scattered photons with the energy of

Low-temperature fabrication of Pb 0.95 Ba 0.05 [(Mg 1/3 Nb 2/3 ) 0.125 Zr 0.445 Ti 0.43 ]O 3 (PBMNZT) ceramics was investigated, and their microstructure, ferroelectric and piezoelectric properties were examined. In order to improve the sinterability and piezoelectric properties, LiBiO 2 sintering aid was uniformly added to PBMNZT powders with surface chemical modification using hydrolysis of alkoxides. PBMNZT powders without LiBiO 2 could not be fully densified at sintering temperatures lower than 1100 °C. However, an addition of LiBiO 2 considerably improved the sinterability of PBMNZT powders, and sintering temperature consequently decreased from 1100 to 850 °C. This may be attributable to the promotion of liquid-phase sintering. And also, 0.7 wt.% LiBiO 2 -added PBMNZT ceramics could be fabricated without deteriorating the piezoelectric properties in the sintering temperatures below 1000 °C. A high electromechanical coupling factor ( k p ) of 61.7%, as well as a large field-induced strain of ∼0.17% (40 kV/cm) was obtained for 950 °C-sintered specimens with 0.7 wt.% LiBiO 2 additive.

Objective To study the effects of trabeculectomy and needling revision of poorly functioning blebs on the optic nerve head (ONH) circulation in patients with primary open-angle glaucoma (POAG). Design Prospective, nonrandomized, self-controlled trial. Participants Nineteen POAG patients (age range, 52 ± 12 years; mean ± standard deviation) undergoing trabeculectomy and six POAG patients (age range, 62 ± 14 years) undergoing needling revision of the bleb. Methods Using the laser speckle method, the normalized blur (NB) value, a quantitative index of blood velocity, was determined every 0.125 seconds and averaged more than three cardiac pulses in the optic nerve head (NB ONH ). Main outcome measures The NB ONH and intraocular pressure (IOP) in both eyes, and blood pressure (BP) and pulse rate (PR) were measured before and 2 days and 1, 4, and 8 weeks after trabeculectomy, and also before and 10 and 40 min after needling procedures. Results Intraocular pressure in the operated eye was significantly decreased after trabeculectomy or needling procedures, and the ocular perfusion pressure was significantly increased by a maximum of 38%. The IOP in the unoperated eye, BP, and PR did not significantly change. The NB ONH did not significantly change in either the operated or unoperated eye. Conclusions Trabeculectomy and needling procedures induced little change in the ONH circulation.

Low-temperature sintering of Pb(Ni1/3Nb2/3)O3–Pb(Zr0.3Ti0.7)O3 was investigated using LiBiO2 (LBiO) as a sintering aid. LBiO-added PNN–PZT powders could be fully densified to 97% relative density at a temperature as low as 800 °C. An addition of LBiO was effective for improving the sinterability of PNN–PZT powders. However, LBiO was not useful to promote the grain growth. LBiO-added PNN–PZT bodies sintered at 800 and 1100 °C exhibited an electromechanical coupling factor, kp, of approximately 20 and 60%, respectively.