In the present paper we report the development of the Continuous Motion scanning technique and its implementation for a new generation of scanning systems. The same hardware setup has demonstrated a ...significant boost in the scanning speed, reaching 190 cm
/h. The implementation of the Continuous Motion technique in the LASSO framework, as well as a number of new corrections introduced are described in details. The performance of the system, the results of an efficiency measurement and potential applications of the technique are discussed.
Coronavirus disease 2019 (COVID-19) may affect the cognitive function and activities of daily living (ADL) of elderly patients. This study aimed to establish the COVID-19 effect on cognitive decline ...and the velocity of cognitive function and ADL changes in elderly patients with dementia followed up in an outpatient memory care facility.
In total, 111 consecutive patients (age 82 ± 5 years, 32% males) with a baseline visit before infection were divided into those who had or did not have COVID-19. Cognitive decline was defined as a five-point loss of Mini-Mental State Examination (MMSE) score and ADL comprising basic and instrumental ADL indexes (BADL and IADL, respectively). COVID-19 effect on cognitive decline was weighted for confounding variables by the propensity score, whereas the effect on change in the MMSE score and ADL indexes was analyzed using multivariate mixed-effect linear regression.
COVID-19 occurred in 31 patients and a cognitive decline in 44. Cognitive decline was about three and a half times more frequent in patients who had COVID-19 (weighted hazard ratio 3.56, 95% confidence interval 1.50-8.59,
= 0.004). The MMSE score lowered on average by 1.7 points/year, independently of COVID-19, but it lowered twice faster in those who had COVID-19 (3.3 vs. 1.7 points/year, respectively,
< 0.050). BADL and IADL indexes lowered on average less than 1 point/year, independently of COVID-19 occurrence. Patients who had COVID-19 had a higher incidence of new institutionalization than those who did not have the disease (45% versus 20%,
= 0.016, respectively).
COVID-19 had a significant impact on cognitive decline and accelerated MMSE reduction in elderly patients with dementia.
The FOOT (FragmentatiOn Of Target) experiment is an international project designed to carry out the fragmentation cross-sectional measurements relevant for charged particle therapy (CPT), a technique ...based on the use of charged particle beams for the treatment of deep-seated tumors. The FOOT detector consists of an electronic setup for the identification of
fragments and an emulsion spectrometer for
fragments. The first data taking was performed in 2019 at the GSI facility (Darmstadt, Germany). In this study, the charge identification of fragments induced by exposing an emulsion detector, embedding a
target, to an oxygen ion beam of 200 MeV/n is discussed. The charge identification is based on the controlled fading of nuclear emulsions in order to extend their dynamic range in the ionization response.
The study that we present is part of the preparation work for the setup of the FOOT (FragmentatiOn Of Target) experiment whose main goal is the measurement of the double differential cross sections ...of fragments produced in nuclear interactions of particles with energies relevant for particle therapy. The present work is focused on the characterization of the gas-filled drift chamber detector composed of 36 sensitive cells, distributed over two perpendicular views. Each view consists of six consecutive and staggered layers with three cells per layer. We investigated the detector efficiency and we performed an external calibration of the space–time relations at the level of single cells. This information was then used to evaluate the drift chamber resolution. An external tracking system realized with microstrip silicon detectors was adopted to have a track measurement independent on the drift chamber. The characterization was performed with a proton beam at the energies of 228 and 80 MeV. The overall hit detection efficiency of the drift chamber has been found to be 0.929±0.008, independent on the proton beam energy. The spatial resolution in the central part of the cell is about 150±10μ m and 300±10μ m and the corresponding detector angular resolution has been measured to be 1.62±0.16 mrad and 2.1±0.4 mrad for the higher and lower beam energies, respectively. In addition, the best value on the intrinsic drift chamber resolution has been evaluated to be in the range 60−100μ m. In the framework of the FOOT experiment, the drift chamber will be adopted in the pre-target region, and will be exploited to measure the projectile direction and position, as well as for the identification of pre-target fragmentation events.
Tritium digital autoradiography with a Medipix2 hybrid silicon pixel detector Mettivier, Giovanni; Cristina Montesi, Maria; Russo, Paolo
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2004, Letnik:
516, Številka:
2
Journal Article
Recenzirano
Odprti dostop
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
mm
2. 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.
We present the design and preliminary imaging evaluation of a bench-top apparatus for X-ray cone-beam breast computed tomography (CBBCT), assembled for technical evaluation and for laboratory tests ...of various optimization techniques for CBBCT. The prototype is characterized by the computer control of the X-ray tube (W anode, 35-80 kVp, 0.25 mA, 50 ¿m focal spot size), CsI:Tl CMOS flat panel detector (12×12 cm 2 area, 50 ¿m pitch, up to 9 fps at 4 × 4 binning), motorized translation and rotation stages with eight degrees of freedom, and fan-beam or cone-beam backprojection software. First cone-beam tomographic images of two 14-cm diameter hemiellipsoidal PMMA breast phantoms are presented.
Abstract
The goals of the FOOT (FragmentatiOn Of Target) experiment are to measure the proton double differential fragmentation cross-section on H, C, O targets at beam energies of interest for ...hadrontherapy (50–250 MeV for protons and 50–400 MeV/u for carbon ions), and also at higher energy, up to 1 GeV/u for radioprotection in space. Given the short range of the fragments, an inverse kinematic approach has been chosen, requiring precise tracking capabilities for charged particles. One of the subsystems designed for the experiment will be the MSD (Microstrip Silicon Detector), consisting of three x-y measurement planes, each one made by two single sided silicon microstrip sensors. In this document, we will present a detailed description of the first MSD prototype assembly, developed by INFN Perugia group and the subsequent characterization of the detector performance. The prototype is a wide area
(∼ 100 cm
2
) single sensor, 150 μm thick to reduce material budget and fragmentation probability along the beam path, with 50 μm strip pitch and 2 floating strip readout approach. The pitch adapter to connect strips with the readout channels of the ASIC has been implemented directly on the silicon surface. Beside the interest for the FOOT experiment, the results in terms of cluster signal, signal-to-noise ratio, dynamic range of the readout chips, as well as long-term stability studies in terms of noise, are relevant also for other experiments where the use of thin sensors is crucial.
We investigated the capability of fluorescence reflectance imaging (FRI) for the early detection of surface tumors in mice. We used a hematoporphyrin (HP) compound (HP dichlorohydrate) as a red ...fluorescent marker and a low noise, high sensitivity, digital CCD camera for fluorescence imaging. In this preliminary study, highly malignant anaplastic human thyroid carcinoma cells were implanted subcutaneously in one mouse and their growth was monitored daily for 5 days by FRI. The selective HP uptake by the tumor tissues was successfully observed: we observed the fluorescence of tumor only 3 days after cancer cells injection, i.e. when the tumor mass was neither visible (to the naked eye) or palpable. These measurements indicate that FRI is a suitable technique to detect minute subcutaneous tumor masses. This FRI system will be coupled to a radionuclide imaging system based on a CdTe detector for in vivo multimodal imaging in mice.
The use of carbon ion beams in radiotherapy presents significant advantages when compared to traditional x-ray. In fact, carbon ions deposit their energy inside the human body at the end of their ...range, the Bragg peak. Unlike x-ray beams, where the energy deposition decreases exponentially inside the irradiated volume, the shape of carbon beams is sharp and focused. Advantages are an increased energy released in the cancer volume while minimizing the irradiation to healthy tissues. Currently, the use of carbon beams is limited by the poor knowledge we have about the effects of the secondary fragments on the irradiated tissues. The secondary particles produced and their angular distribution is crucial to determine the global dose deposition. The knowledge of the flux of secondary particles plays a key role in the real time monitoring of the dose profile in hadron therapy. We present a detector based on nuclear emulsions for fragmentation measurements that performs a sub-micrometric tridimensional spatial resolution, excellent multi-particle separation and large angle track recognition. Nuclear emulsions are assembled in order to realize a hybrid detector (emulsion cloud chamber (ECC)) made of 300 μm nuclear emulsion films alternated with lead as passive material. Data reported here have been obtained by exposing two ECC detectors to the fragments produced by a 400 MeV n−1 12C beam on a composite target at the GSI laboratory in Germany. The ECC was exposed inside a more complex detector, named FIRST, in order to collect fragments with a continuous angular distribution in the range 47°-81° with respect to the beam axis. Results on the angular distribution of fragments as well as their momentum estimations are reported here.
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