3D PET image reconstruction based on Maximum Likelihood Estimation Method (MLEM) algorithm

Positron emission tomographs (PET) do not measure an image directly. Instead, they measure at the boundary of the field-of-view (FOV) of PET tomograph a sinogram that consists of measurements of the sums of all the counts along the lines connecting two detectors. As there is a multitude of detectors build-in typical PET tomograph structure, there are many possible detector pairs that pertain to the measurement. The problem is how to turn this measurement into an image (this is called imaging). Decisive improvement in PET image quality was reached with the introduction of iterative reconstruction techniques. This stage was reached already twenty years ago (with the advent of new powerful computing processors). However, three dimensional (3D) imaging remains still a challenge. The purpose of the image reconstruction algorithm is to process this imperfect count data for a large number (many millions) of lines-of-responce (LOR) and millions of detected photons to produce an image showing the distribution of the labeled molecules in space.Comment: 10 pages, 7 figure

Plastic scintillators for positron emission tomography obtained by the bulk polymerization method

This paper describes three methods regarding the production of plastic scintillators. One method appears to be suitable for the manufacturing of plastic scintillator, revealing properties which fulfill the requirements of novel positron emission tomography scanners based on plastic scintillators. The key parameters of the manufacturing process are determined and discussed.Comment: 7 pages, 4 figure

Application of the compress sensing theory for improvement of the TOF resolution in a novel J-PET instrument

Nowadays, in positron emission tomography (PET) systems, a time of fl ight (TOF) information is used to improve the image reconstruction process. In TOF-PET, fast detectors are able to measure the difference in the arrival time of the two gamma rays, with the precision enabling to shorten signifi cantly a range along the line-of-response (LOR) where the annihilation occurred. In the new concept, called J-PET scanner, gamma rays are detected in plastic scintillators. In a single strip of J-PET system, time values are obtained by probing signals in the amplitude domain. Owing to compressive sensing (CS) theory, information about the shape and amplitude of the signals is recovered. In this paper, we demonstrate that based on the acquired signals parameters, a better signal normalization may be provided in order to improve the TOF resolution. The procedure was tested using large sample of data registered by a dedicated detection setup enabling sampling of signals with 50-ps intervals. Experimental setup provided irradiation of a chosen position in the plastic scintillator strip with annihilation gamma quanta

Multiple scattering and accidental coincidences in the J-PET detector simulated using GATE package

Novel Positron Emission Tomography system, based on plastic scintillators, is developed by the J-PET collaboration. In order to optimize geometrical configuration of built device, advanced computer simulations are performed. Detailed study is presented of background given by accidental coincidences and multiple scattering of gamma quanta

Leki złożone w terapii nadciśnienia tętniczego w Polsce. Stanowisko Ekspertów Polskiego Towarzystwa Nadciśnienia Tętniczego oraz Sekcji Farmakoterapii Sercowo-Naczyniowej Polskiego Towarzystwa Kardiologicznego

  The reasons for the publication of current expert consensus statement after 4 years from the previous one are: the growing number of evidence on the benefits of the use of single-pill combinations (SPCs) in hypertension (also with concomitant dyslipidaemia), the extension of indications for their use in the hypertension management algorithm and the emergence in recent years after the publication of Polish Society of Hypertension experts’ position statement in 2013 of new types of SPCs available to doctors in Poland, including triple-drug combinations of antihypertensives and the so-called “hybrids” SPCs containing not only antihypertensive drugs but also statins. The current position statement of experts summarizes the progress of knowledge and practical application of SPCs of antihy­pertensives in Poland. It seems that there will be a long gap in the introduction of new classes of antihypertensive drugs. The only noticeable progress in the pharmacotherapy of hypertension in the last 15 years, which may explain some increase in the effectiveness of blood pressure control in patients, is more common use of SPCs of antihypertensive drugs. Analysis of European Society of Hypertension (ESH) experts’ lectures during this year’s ESH 2017 Annual Meeting in Milan suggests that the next edition of the 2018 ESH Guidelines may include major changes in the antihypertensive therapy algorithm, suggesting the need for initiation of pharmacologic treatment with combination therapy, i.e. SPCs, in most patients with hypertension. Combination of an angiotensin converting enzyme (ACE) inhibitor + calcium antagonist should be considered optimal in patients with high and very high cardiovascular risk. Undoubtedly, the position of this combination is due to the ACCOM­PLISH trial in which such SPCs werefound to be more effective in reducing cardiovascular risk than SPCs composed of an ACE-inhibitor + thiazide diuretic. As a result of gradually increasing popularity of combined drugs, further SPCs that meet the criteria for optimal combination of antihypertensive drugs emerged in Poland between 2012 and 2017. Two of them provided the possibility of using SPCs in patients who do not need or should not use renin–angiotensin–aldosterone inhibitors. An interesting alternative is the SPC which contains antihypertensive agents along with other drugs used in cardiovascular prevention: statins and acetylsalicylic acid. This direction in the evolution of pharmacotherapy of hypertension is approaching the concept of “polypill”. In the opinion of the authors, the use of SPCs in antihypertensive therapy will increase in Poland, which may contribute to further improvement of pressure control in our country. At present, almost all useful anti-hypertensive agents are available in the form of two-drug SPCs. The combination of a sartan with beta-blocker for hypertensive patients with cardiac hypertrophy who do not tolerate ACE inhibitors and a “hybrid” SPCs of an ACE inhibitor + statin are still expected. Three-drug combinations: ACE inhibitor + beta-blocker + calcium antagonist, for patients with hypertension and coronary artery disease requiring intensive therapy, and ACE inhibitor + beta-blocker + statin, which will enable SPCs therapy for most patients, would also be useful

Sampling FEE and trigger-less DAQ for the J-PET scanner

In this paper, we present a complete Data Acquisition System (DAQ) together with the readout mechanisms for the J-PET tomography scanner. In general, detector readout chain is constructed out of Front-End Electronics (FEE) measurement devices such as Time-to-Digital or Analog-to-Digital Converters (TDCs or ADCs), data collectors and storage. We have developed a system capable for maintaining continuous readout of digitized data without preliminary selection. Such operation mode results in up to 8 Gbps data stream, therefore, it is required to introduce a dedicated module for on-line event building and feature extraction. The Central Controller Module, equipped with Xilinx Zynq SoC and 16 optical transceivers, serves as such true real time computing facility. Our solution for the continuous data recording (trigger-less) is a novel approach in such detector systems and assures that most of the information is preserved on the storage for further, high-level processing. Signal discrimination applies a unique method of using LVDS buffers located in the FPGA fabric

Leki złożone w terapii nadciśnienia tętniczego w Polsce. Stanowisko Ekspertów Polskiego Towarzystwa Nadciśnienia Tętniczego oraz Sekcji Farmakoterapii Sercowo-Naczyniowej Polskiego Towarzystwa Kardiologicznego

Nadciśnienie tętnicze jest podstawowym modyfikowalnym czynnikiem ryzyka chorób sercowo-naczyniowych: choroby niedokrwiennej serca, udaru mózgu, niewydolności serca i choroby niedokrwiennej tętnic kończyn dolnych, a także najistotniejszą epidemiologicznie przyczyną zgonów na świecie. Jednocześnie częstość występowania nadciśnienia tętniczego w Polsce stale rośnie — według badania NATPOL z 2002 roku — dotyczyła 29% populacji dorosłych Polaków [1], w powtórnym badaniu NATPOL 2011 wzrosła do 32% [2], a w badaniu WOBASZ II w 2014 roku wynosiła już 43% [3]