Measurement of 32/spl times/8/spl times/4 LYSO crystal responses of DOI detector for jPET-RD
ABSTRACT jPET-RD is designed to achieve high sensitivity as well as high spatial resolution by the use of four-layer depth of interaction (DOI) information of the detector. We have previously proposed the DOI encoding method that enables four layers DOI identification using only single kind crystal elements. The basic idea was tested by using Gd2SiO5, and the first prototype detector was developed using Lu2(1-x)Y2xSiO5 (LYSO). In this work, we prepared a pair of jPET-RD prototype detectors composed of four layers of a 32 (transaxial)times8 (axial) LYSO (Lu: 98%, Y: 2%) crystal block and a 256-channel flat panel position sensitive photomultiplier tube (256ch FP-PMT). The size of each crystal element is 1.46 mmtimes1.46 mmtimes4.5 mm. The crystal block (46.5 mmtimes11.6 mmtimes18.0 mm) is placed on the central area of a 256ch FP-PMT (49 mmtimes49 mm useful area) and coupled with silicone rubber. First, we evaluated performance of the prototype DOI detector by uniform gamma ray irradiation. Then response functions of the prototype DOI detector were measured with collimated single gamma rays and finally coincidence responses are estimated with a pair of prototype DOI detectors in the experimental setup which simulates jPET-RD system. In the performance evaluation, the energy resolution of all events was 14.7% and the time resolution was found to be 0.66 ns. The response functions were 1.56 mm FWHM and 4.51 mm FWHM in average in transaxial and depth direction, respectively. The FWHMs of coincidence responses were 5.4 mm (non-DOI) and 3.7 mm (averaged DOI). It is confirmed that the spatial resolution is improved by using DOI information
Conference Proceeding: A four-layer depth of interaction detector block for small animal PET[show abstract] [hide abstract]
ABSTRACT: We are now planning to develop a positron emission tomograph dedicated to small animals such as rats and mice which meets the demand for higher sensitivity. We propose a new depth of interaction (DOI) detector arrangement to obtain DOI information by using a four-layer detector with all the same crystal elements. In this DOI detector, we control the behavior of scintillation photons by inserting the reflectors between crystal elements so that the DOI information of four layers can be extracted from one two-dimensional (2D) position histogram made by Anger-type calculation. As a preliminary experiment, we measured crystal identification performance of the DOI detector which consists of four layers of a 16 × 16 crystal array using Gd<sub>2</sub>SiO<sub>5</sub> crystals with Ce concentration of 0.5 mol %. Each crystal is 1.42 mm × 1.42 mm × 4.5 mm. A crystal block is optically coupled to a 256-channel flat panel position sensitive photomultiplier tube whose opening area is 52.0 mm × 52.0 mm. We obtained sufficient positioning performance for this four-layer DOI detector on the 2D position histogram. We concluded it would be a promising device to realize a small animal positron emission tomography scanner with high sensitivity and high resolution.Nuclear Science Symposium Conference Record, 2003 IEEE; 11/2003
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ABSTRACT: OBJECTIVE: To assess the relationships between diet, body composition, physical activity, parents’ obesity and adiposity in children at the age of 8 y and four years later.STUDY DESIGN: Prospective observational study of anthropometric measures initiated in 1992, follow-up examination in 1996.METHODS: 112 prepubertal (age: 8.6±1.0 y) children were studied. Energy and nutrient intakes were assessed by diet history, body composition by anthropometry and physical activity, by a questionnaire. Obesity was defined as relative body mass index (BMI) (rel BMI)>120%, where rel BMI=(BMI/BMI at 50th centile for age and gender)×100.RESULTS: Prevalence of obesity was not statistically different at baseline (22.3%) than four years later (19.8%): rel BMI at the age of 8 y was positively self-related with rel BMI at the age of 12 y (r=0.73, PInternational Journal of Obesity - INT J OBESITY. 01/1998; 22(8):758-764.
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ABSTRACT: An elevated risk for coronary artery disease and lung cancer was reported for smokers and nonsmokers exposed to environmental tobacco smoke. Particularly in nonsmokers, in addition to the adverse effects of tobacco smoke, other factors which are associated with the exposure to environmental tobacco smoke may contribute to the health risks. We investigated both by questionnaires and biochemical analyses whether smokers influence the dietary habits of nonsmokers living in the same household. The study population was a subgroup of the Prevention Education Program in Nuremberg: 817 adults aged 27-66 years were allocated to one of the four groups: Nonsmokers living with a nonsmoker (Group 1), nonsmokers living with a smoker (Group 2), smokers living with a nonsmoker (Group 3), and smokers living with a smoker (Group 4). The four groups did not differ in the body mass index, the concentration of lycopene, all-trans-retinol, and selenium in plasma. Plasma concentrations of high-density lipoprotein cholesterol, triglycerides, homocysteine, cobalamin, folate, beta-carotene, and alpha-tocopherol showed a gradient to unfavorable levels from Group 1 to Group 4. This trend was also reflected in the reported dietary intake of beta-carotene, alpha-tocopherol, ascorbic acid, fiber, and linoleic acid. Our data show that nonsmokers living with smokers indulge in less healthy dietary habits than nonsmokers living with nonsmokers. This has to be considered when evaluating the health risks of exposure to environmental tobacco smoke.Preventive Medicine 07/2002; 34(6):600-7. · 3.50 Impact Factor