Additional Filtration Research Articles

Locomotive Wheel Slip Control Method Based on an Unscented Kalman Filter

Railway traction vehicles transfer forces between wheels and rails through an adhesion coefficient. The adhesion coefficient value can decrease abruptly during the train run. Therefore, the wheels can simply gain high value of the wheels slip velocity. Thus, the vehicles are equipped with slip controllers for this case. During the past decades, many types of slip control strategies were developed, and the new methods are also developed today. Some perspective methods are based on an estimation of the adhesion coefficient or an adhesion force. However, correct operation of these methods is not guaranteed in all cases. Moreover, these methods have some weakness that can decrease their efficiency. Therefore, a novel method based on the adhesion condition estimation is presented in this paper. The adhesion condition is estimated by an unscented Kalman filter. When the method is connected to a controller, it is possible to eliminate the rising wheel slip velocity at its beginning and limit it to the appropriate value. The output of the method is directly used as an input of the controller without any additional calculation as it is used in traditional methods. The input signal does not need any additional filtration, and the method does not require information about the actual train velocity for its proper work. The verification of the method is done with the measured data that were measured on a freight train hauled by an electric locomotive. This paper also presents simulation results of the method with a controller based on the locomotive mathematical model.

Istraživanje nanofibriranih obloženih traka za hemijsku i biološku zaštitu

Worldwide used Nuclear, Biological and Chemical (NBC) protective clothing has very limited protection against bacteria. Apart from this, NBC clothing has ample scope of improvements of some important features like comfort, better protection against CWA and weight reduction. The purpose of this research work is to establish process of integrating nanofibrous coated web with adsorbent layer of NBC clothing to achieve required biological protection and better chemical protection with reducing its weight. In this study, the developed activated carbon sphere (ACS) laminated structures are integrated with nanofibrous webs of Polyvinyl Alcohol (PVA). Design of the PVA integration process with adsorbent layer is strategically decided. PVA nanowebs of different morphological structures and coating densities (0.03-0.61 g/m2) by latest nozzle-less nanospider technology are coated on polypropylene (PP) spun bonded nonwoven fabric. Then coated PP fabric is stitched at the boarder-line with adsorbent layer for formulating the composite layer. The various attributes and functional properties of PVA nanofibrous integrated absorbent layer is characterized by using FESEM, 1,3-Dichloropropane test (stimulant for mustard gas), durability test, pore size, air permeability and water vapour transmission rate. The reported research work showed that by integrating nanofibrous coated web layers into ACS laminated adsorbent layer of NBC clothing, it's now offering various functional properties like additional bacterial filtration and chemical protection at a lighter weight.

Optimization of Dose and Image Quality in Full-fiand Computed Radiography Systems for Common Digital Radiographic Examinations

IntroductionA fine balance of image quality and radiation dose can be achieved by optimization to minimize stochastic and deterministic effects. This study aimed in ensuring that images of acceptable quality for common radiographic examinations in digital imaging were produced without causing harmful effects. Materials and MethodsThe study was conducted in three phases. The pre-optimization involved ninety physically abled patients aged between 20 to 60 years and weighed between 60 and 80 kilograms for four common digital radiographic examinations. Kerma X_plus, DAP meter was utilized to measure the entrance surface dose (ESD) while effective dose (ED) was estimated using CALDose_X 5.0 Monte Carlo software. The second phase, an experimental study utilized an anthropomorphic phantom (PBU-50) and Leeds test object TOR CDR for relative comparison of image quality. For the optimization phase, the imaging parameters with acceptable image quality and lowest ESD from the experimental study was related to patient’s body thickness. Image quality were evaluated by two radiologists using the modified evaluation criteria score lists. ResultsSignificant differences were found for image quality for all examinations. However significant difference for ESD were found for PA chest and AP abdomen only. The ESD for three of the examinations were lower than all published data. Additionally, the ESD and ED obtained for all examinations were lower than that recommended by radiation regulatory bodies. ConclusionOptimization of image quality and dose was achieved by utilizing an appropriate tube potential, calibrated automatic exposure control and additional filtration of 0.2mm copper.

Breast density and iodine quantification in spectral mammography

Breast density is known for being a parameter used in breast cancer risk models and might be measured during mammography exams. Automated methods based on grayscale values already exist, but they only allow a density estimation over the whole breast. Material decomposition approaches make it possible to define the breast density at each pixel based on a dual energy exposure. Furthermore, the use of contrast enhanced digital mammography exams is increasing and helps physicians to highlight blood vessels with higher permeability that may be related to malignant lesions. Nevertheless, this technique also requires two x-ray exposures. In this paper, we propose to take benefit of energy sensitive x-ray detectors that give access to several energy measurements in a single shot acquisition to both quantify breast density and iodine during a single mammography exam. To this purpose, a spectral mammography acquisition chain has been simulated and different material decomposition methods have been proposed and investigated using a simulated phantom under clinically achievable settings with an average absorbed dose by the mammary gland of 0.93 mGy (mimicking a 45 mm thick breast made of 50% fibroglandular tissue) using a 49 kVp with a tungsten anode, an inherent filtration of 0.8 mmBe and an additional filtration of 1.2 mmAl. Breast density is commonly defined as the ratio between glandular tissue and the sum of adipose and glandular tissues thicknesses. Standard polynomial material decomposition methods have been extended to make them compliant with 3-energy measurements in order to allow a three-material decomposition: adipose and glandular tissues as well as iodine concentration. Those methods allow to estimate iodine concentration with an average accuracy inferior to 0.15 mg ml−1 and breast density with a precision inferior to 8% (root-mean-square errors). Nevertheless, these methods are difficult to extend to more energy channels due to the least-square model inversion. To achieve better results, a maximum log-likelihood approach has been introduced to take into consideration more spectral information while improving accuracy and precision on measurements. Moreover, the use of the proposed method permits to accurately detect the absence of iodine and significantly improves the estimation of breast density compared to polynomial approaches. We also highlighted that there is a strong interest to increase the number of energy thresholds from 3 to 6, a less significant gain is still noticeable with more energy bins.

Optimisation of radiation dose and image quality in mobile neonatal chest radiography

PurposeTo optimise the radiation dose and image quality for chest radiography in the neonatal intensive care unit (NICU) by increasing the mean beam energy. MethodsTwo techniques for the acquisition of NICU AP chest X-ray images were compared for image quality and radiation dose. 73 images were acquired using a standard technique (56 kV, 3.2 mAs and no additional filtration) and 90 images with a new technique (62 kV, 2 mAs and 2 mm Al filtration). The entrance surface air kerma (ESAK) was measured using a phantom and compared between the techniques and against established diagnostic reference levels (DRL). Images were evaluated using seven image quality criteria independently by three radiologists. Images quality and radiation dose were compared statistically between the standard and new techniques. ResultsThe maximum ESAK for the new technique was 40.20 μGy, 43.7% of the ESAK of the standard technique. Statistical evaluation demonstrated no significant differences in image quality between the two acquisition techniques. ConclusionsBased on the techniques and acquisition factors investigated within this study, it is possible to lower the radiation dose without any significant effects on image quality by adding filtration (2 mm Al) and increasing the tube potential. Such steps are relatively simple to undertake and as such, other departments should consider testing and implementing this dose reduction strategy within clinical practice where appropriate.

Abstract ID: 115 A Monte Carlo-based eigenspectrum decomposition technique for computed tomography

Purpose The characterization of computed tomography (CT) X-ray spectra is important for beam-hardening correction techniques and raw-data reconstruction methods [1] , [2] . In this work, we propose a novel spectrum estimation approach based on transmission measurements and the use of Monte-Carlo (MC) to generate basis spectra. Methods The EGSnrc/BEAM MC code is used to generate basis X-ray spectra. The XTUBE component module is used to produce bremsstrahlung photon energy spectra from monoenergetic electrons transported through a tungsten target (10°), a beryllium window (1 mm) and additional filtration. To ensure that the modelled spectra cover the features of the unknown spectrum, a total of 40 spectra with various levels of filtration are generated using different thicknesses of aluminum and carbon, ranging from 2 mm to 18 mm. Principal component analysis is performed on the MC-generated model spectra to extract a set of linearly independent basis functions, each called eigenspectrum, which reduces the dimensionality of the problem and allows stable fitting. Transmission measurements of a calibration phantom are simulated using ray-tracing with an 80-kV source and added Poisson noise. The estimated spectrum is expressed as the weighted sum of eigenspectra and reconstructed through a constrained least squares technique. Results Using 8 eigenspectra, the 80-kV spectrum is reconstructed with a RMS error (RMSE) of 3.8%. The difference between the mean energy of the estimated and true spectrum is 0.01 keV. Reproducing the same methodology for a 140-kV spectrum yields a RMSE of 4.5% and mean energy difference of −0.1 keV. Conclusion The proposed method is shown promising to accurately characterize X-ray spectra with transmission data. With limited details on the X-ray tube and relying solely on calibration scans, our methodology provides robust spectrum estimation and is promising for reducing the known ill-posedness [3] , [4] of known transmission-based approaches. Applications of the technique to CT are expected to improve the accuracy of quantitative imaging for radiotherapy.

Research of the Aerodynamic Parameters in a Special Cyclone with Secondary Inlets

Special cyclone – gas treatment device which can be applied to remove the fine particulate matter bigger than 2 micrometres from aggressive gas flow at a temperature of 50–145 °C and a relative humidity of more than 95% and can be achieved the cleaning efficiency over 90%. Cyclone work is based on centrifugal forces and the resulting additional filtration process operation. Cyclone structure equipped with primary and secondary gas flow inflows through which gas dispersed flow is supplied parallel to all channels of the cyclone. Analysed modified multi-channel cyclone can be effectively treated from fine particulate matter, during the cleaning of aggressive gas flow an adhesion/cohesion phenomena could be reduced. Research of aerodynamic parameters it’s the first step of studies to determine the optimal case, at the average gas flow velocity in cyclone channels were 8, 12 and 16 m/s, the gas flow dynamics dependencies into cyclone were determined.

Molecularly imprinted magnetic nanoparticles for the micro solid-phase extraction of thiabendazole from citrus samples.

The preparation of molecularly imprinted core-shell magnetic nanoparticles and their subsequent use in the solid-phase extraction of thiabendazole from citrus sample extracts is described. Molecularly imprinted core-shell magnetic nanoparticles were prepared by the precipitation copolymerization of the imprinting polymerization mixture on the surface of vinyl-modified silica magnetic nanoparticles and were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The obtained molecularly imprinted core-shell magnetic nanoparticles exhibited a high selectivity for thiabendazole and were easily collected and separated by an external magnetic field without additional centrifugation or filtration steps. Under optimum conditions, a magnetic molecularly imprinted solid-phase extraction method was developed allowing the extraction of thiabendazole from citrus sample extracts and final determination by high-performance liquid chromatography with fluorescence detection. The detection limit was 0.2mg/kg, far lower than the maximum residue limit established within the European Union for thiabendazole in citrus samples.

Raising the efficiency of electroflotation purification of wastewater formed in production of printed-circuit boards to remove copper ions in the presence of complexing agents, surfactants, and flocculants

It was found that the solution composition, pH value, concentration, and nature of surfactants and flocculant affect the process of electroflotation extraction of copper hydroxide in the presence of an excess amount of ammonia. A relationship between the ζ-potential of the dispersed phase and the degree of copper extraction was found. It is shown that a cationic surfactant and flocculants positively affect the efficiency of the electroflotation extraction of copper. Under the optimal conditions, the degree of the electroflotation extraction reaches values of 95–96%, and that with additional filtration, 97–99%. A technological scheme for implementing the electroflotation process is suggested.

X-ray dose reduction using additional copper filtration for abdominal digital radiography: Evaluation using signal difference-to-noise ratio

PurposeX-ray dose reduction using additional copper filters (Cu-filters) for abdominal general radiography was indicated in a report using a simulation study. We validated the dose reduction effects using a clinical digital radiography system equipped with an indirect-type CsI detector and an automatic Cu-filter insertion function. MethodsThe image qualities were evaluated using signal difference-to-noise ratio (SDNR) for different radiation qualities with and without Cu-filters for a 20-cm acrylic phantom. Acrylic and bone equivalent material plates were used for contrast measurements. The dose reduction using Cu-filters was estimated from the ratios of the SDNR2 values. ResultsFor the same entrance surface dose (ESD), Cu-filters with 0.1- and 0.2-mm thicknesses increased the image quality as evaluated by SDNR2 and the estimated dose reduction without degrading the image quality. For the acrylic contrast, the dose reductions with the 0.1- and 0.2-mm-thick Cu-filters were approximately 30% and 44% at 70kV and 29% and 35% at 80kV, respectively. For the bone contrast, the reduction rates were slightly reduced. ConclusionsWe validated the dose reduction capability of additional Cu-filters without degrading the image quality for abdominal radiography. The estimated entrance surface dose reductions of the Cu-filters were approximately 30–40% and 20–30% for the acrylic and bone contrasts, respectively, and effective dose reductions for acrylic were nearly half of those for ESD. At these reduced dose conditions, the current time product values needed to be increased by factors of 1.4 and 1.8 for the 0.1- and 0.2-mm-thick Cu-filters, respectively.

Magnetic Cr(VI) Ion Imprinted Polymer for the Fast Selective Adsorption of Cr(VI) from Aqueous Solution

In this study, a novel magnetic Cr(VI) ion imprinted polymer (Cr(VI)-MIIP) was successfully synthesized and used as a selective sorbent for the adsorption of Cr(VI) ions from aqueous solution. It can be synthesized through the combination of an imprinting polymer and magnetic nanoparticles. The high selectivity achieved using MIIP is due to the specific recognition cavities for Cr(VI) ions created in Cr(VI)-MIIP. Also, the magnetic properties that could be obtained using magnetic nanoparticles, helps to separate adsorbent with an external magnetic field without either additional centrifugation or filtration procedures. The magnetic Fe3O4 nanoparticles (MNPs) were synthesized using an improved co-precipitation method and modified with tetraethylorthosilicate (TEOS) before imprinting. The magnetic Cr(VI) ion imprinted polymer was prepared through precipitation copolymerization of 4-vinylpyridine as the complexing monomer, 2-hydroxyethyl methacrylate as a co-monomer, the Cr6+ anion as a template, and ethylene glycol dimethacrylate (EGDMA) as a cross-linker in the presence of modified magnetite nanoparticles. This novel synthesized sorbent was characterized using different techniques. Batch adsorption experiments were performed to evaluate the adsorption conditions, selectivity, and reusability. The results showed that the maximum adsorption capacity was 39.3 mg g−1, which was observed at pH 3 and at 25 °C. The equilibrium time was 20 min, and the amount of adsorbent which gave the maximum adsorption capacity was 1.7 g L−1. Isotherm studies showed that the adsorption equilibrium data were fitted well with the Langmuir adsorption isotherm model and the theoretical maximum adsorption capacity was 44.86 mg g−1. The selectivity studies indicated that the synthesized sorbent had a high single selectivity sorption for the Cr(VI) ions in the presence of competing ions. Thermodynamic studies revealed that the adsorption process was exothermic ( $$\Delta H$$ < 0) and spontaneous ( $$\Delta G$$ < 0). In addition, the spent MIIP can be regenerated up to five cycles without a significant decrease in adsorption capacity.

P12. Commissioning and evaluation of a new commercial small animal radiation research platform Xstrahl XenX irradiator

Introduction The aim of this study was to perform the commissioning and acceptance tests of the commercial small animal radiation research platforms Xsthral XenX irradiator. Methods The Xstrahl-Xenx irradiator contains an X-ray tube with potentials of 20–220 kVp range. The inherent filtration of X-ray tube is 0.8 mm (Be). An additional filtration of 0.15 mm (Cu) is used in irradiation mode, and additional filtration of 1 mm (Al) is used for imaging. The source-to-axis (SAD) distance is 35 cm. Absolute dose were determined for the largest field without collimator (10 × 10 cm 2 ) following the recommendation of AAPM TG61 protocol using in air method to determine the dose-to-water at the surface of a water phantom for orthovoltage X-ray tubes. These measures were performed with an ion chamber and a calibrated dosimeter (PTW − 31013). Absolute dose for small field (10 × 10 mm 2 ) was determined using radiochromic films (Gafchromic EBT3). A calibration curve was fit to characterize the change in optical density (OD) in function of dose using mean intensities read from the red color channel. Films were irradiated with dose range from 0.5 Gy to 9 Gy. Then, films were scanned in transmission mode (positive mode), 48 bits RGB (16 bits per channel color), and 72 dpi resolution. In addition of dosimetric acceptance, other physics measurements were performed. These include measuring the beam homogeneity in the in-plan and cross-plane direction using film for large and small field. Other measurement such as reproducibility of tube voltage, dose output, accuracy of kVp, mA, time, and half value layer have been carried out. Results X-ray tube output and reproducibility for kilovoltage (difference between the measured and displayed value), dose output were performed five times. Reproducibility of kiloVoltage was ranged from −1.7% to 1%, of dose was lower than 0.1%. The maximum dose rate at SAD was 278 cGy/min for large filed without collimator and determined using an ion chamber, for small field it was 256 cGy/min and determined using gafchromic films after calibration. Homogeneity of radiation field was 6.5% and 5.4% in cross plan and in plan profile for large field. Homogeneity is better for small field with a collimator, 2.5% and 2.4% in cross plan and in plan profile respectively. Conclusions The acceptance tests and calibration of Xsthral XenX platform provide to researchers a tools to estimate doses delivered during irradiation of cells and mice in order to advance research in radiobiology. The dose calculation tool allowed us to performed RILA (Radiation-induced lymphocyte apoptosis) test from linac to Xenx irradiator.

Selective adsorption and separation of gadolinium with three-dimensionally interconnected macroporous imprinted chitosan films

We successfully prepared three-dimensionally interconnected macroporous imprinted chitosan films (3DIM-IFs) by template-assisted assembly. Imprinted chitosan films exhibiting an interconnected macroporous structure are used as adsorbents for efficient and selective adsorption of gadolinium ions (Gd(III)). Saturation adsorption capacity of 3DIM-IFs for Gd(III) is up to 51.36 mg g−1 at 298 K, which is significantly higher than adsorption capacities for most reported Gd(III) imprinted adsorbents during recent years. Because of highly selective imprinted sites, imprinted films possess significant selectivity of Gd(III) than other rare earth ions. Moreover, 3DIM-IFs can be easily and rapidly retrieved without the need of additional centrifugation or filtration, greatly facilitating the separation process. Reusability tests demonstrated that the materials can be repeatedly used without significant loss in adsorption capacity, enhancing their potential application for recovery of Gd(III).

Molecularly imprinted core-shell magnetic nanoparticles for selective extraction of triazines in soils.

In this work, a propazine-imprinted polymer was synthesized on the surface of modified magnetic nanoparticles to be used in the solid-phase extraction of triazines in soil samples. The effect of different solvents on the selective extraction of target analytes was assessed to establish the optimum rebinding conditions. The obtained magnetic molecularly imprinted particles exhibited high selectivity for triazines and were easily collected and separated by an external magnetic field without additional centrifugation or filtration steps. Under optimum conditions, a magnetic molecularly imprinted solid-phase extraction method was developed allowing the extraction of several triazines (desisopropylatrazine, desethylatrazine, simazine, atrazine, and propazine) from soil samples and their subsequent final determination by high-performance liquid chromatography with diode-array detection. Recoveries for the triazines studied were within the range 5.4% to 40.6%, with relative standard deviations lower than 7.0% (n=3). The detection limits were within 0.1 to 3ngg-1 , depending upon the triazine and the type of soil used.

Thy-1 (CD90)-Positive Hepatic Progenitor Cells, Hepatoctyes, and Non-parenchymal Liver Cells Isolated from Human Livers.

In response to liver injury, hepatic cells, especially hepatocytes, can rapidly proliferate to repair liver damage. Additionally, it was shown that under certain circumstances liver resident cells with progenitor capabilities are involved in liver cell proliferation and differentiation. These hepatic progenitor cells (HPCs), known as oval cells in rodents, are derived from the canals of Hering, which are located in the periportal region of the liver. Regarding to different cell niches, which were defined for human HPCs, several markers have been used to identify these cells such as CD34, c-kit, OV-6, and Thy-1 (CD90). The latter was shown to be expressed on HPCs in human liver tissue with histological signs of regeneration. In this chapter we describe a detailed method for the isolation of Thy-1 positive cells from human resected liver tissue. Based on a procedure for isolating primary human hepatocytes and non-parenchymal cells (NPCs) we expanded this protocol to additional enzymatic dissociation, filtration, and centrifugation steps. This results in a bile duct cell enriched fraction of NPCs from which Thy-1 (CD90) positive cells were purified by Thy-1 positivity selection using MACS technique. Bipotential progenitor cells from human liver resections can be isolated using Thy-1 and was shown to be a suitable tool for the enrichment of liver resident progenitor cells for xenotransplantation.

The research of influence of different additional filtration to image quality and radiation dose in the whole brain DSA

Objective To investigate the effect of different additional filtration thickness of DSA on image quality and radiation dose with cerebral angiography. Methods Prospective collected 90 patients with DSA examination of the whole cerebral artery, patients were divided into A, B and C group according to the time of the examination, each group included 30 cases. Patients underwent conventional DSA, the additional filtration of group A, B and C were (1.0 mmAl+ 0.1 mmCu), (1.0 mmAl+ 0.4 mmCu) and (1.0 mmAl+0.9 mmCu), respectively. Dose area product (DAP), air kerma (AK), tube current and tube voltage of anteroposterior and lateral radiography of the whole brain were recorded, and scored the image quality. Eye lens organ dose values were obtained by using simulation phantom and LiF dosemeter under A, B and C groups with three different additional filtrations for cerebral angiography. The image quality scores and the radiation dosewere analyzed by one-way ANOVA tests or Kruskal-Wallis tests. Results The image quality comprehensive score of three groups showed significant difference (F=40.07,P<0. 01), which were (3.8±0.4), (3.6±0.5) and (3.0±0.6), respectively. The DAP and AK value of anteroposterior and lateral radiography of three groups also showed significant difference (P<0.05), B and C group were lower than the A group. Left and right eye lens organ dose were decreased along with the increase of the additional filtration thickness, and the difference between the 3 groups also had significant difference (P<0.01). Conclusion Both the image quality and radiation dose can acquire when conducted the whole brain DSA with 1.0 mmAl + 0.4 mmCu additional filtration. Key words: Angiography, digital subtraction; Radiation dosage; Image quality

A MC study on the eye lens dose distribution for medical staff in interventional radiology

Introduction Recent studies showed equivalent dose at a depth of 0.07 mm, Hp (0.07) to be adequate in some cases to monitor the eye lens in interventional radiology, instead of equivalent dose at a depth of 3 mm, Hp (3). Purpose The aim of this study was to investigate by Monte Carlo calculations the dose deposition within the eye lens and contribute to the choice of the appropriate dose quantity. Materials and methods The XRayImagingSimulator was used to model the patient, the operator and the interventional diagnostic unit as well as to calculate the dose within the operators eyes by use of Monte Carlo techniques. Eye lens were placed in three different depths within the eye: 2.3 mm, 3.3 mm, 4.3 mm, representing mean depth and the limits found in a normal adult population. The primary spectra were calculated for 70 kV tube voltage, 12° tungsten target, 3 mm aluminum inherent filtration with an additional copper filtration (0.1 mm, 0.3 mm, 0.6 mm, 0.9 mm) according to IPEM 78 Publication. Results The calculated total absorbed dose in the eye lens depends on the initial incident spectra. This quantity normalized to the eye dose, is between 1.8% and 2.3% in the studied cases and increases with increasing the depth of the eye lens’ location. Comparison to experimental data is also provided. Conclusions The equivalent dose at a depth of 3 mm Hp (3) is likely to be the appropriate quantity for the best estimate of the eye lens dose. Recent studies showed equivalent dose at a depth of 0.07 mm, Hp (0.07) to be adequate in some cases to monitor the eye lens in interventional radiology, instead of equivalent dose at a depth of 3 mm, Hp (3). The aim of this study was to investigate by Monte Carlo calculations the dose deposition within the eye lens and contribute to the choice of the appropriate dose quantity. The XRayImagingSimulator was used to model the patient, the operator and the interventional diagnostic unit as well as to calculate the dose within the operators eyes by use of Monte Carlo techniques. Eye lens were placed in three different depths within the eye: 2.3 mm, 3.3 mm, 4.3 mm, representing mean depth and the limits found in a normal adult population. The primary spectra were calculated for 70 kV tube voltage, 12° tungsten target, 3 mm aluminum inherent filtration with an additional copper filtration (0.1 mm, 0.3 mm, 0.6 mm, 0.9 mm) according to IPEM 78 Publication. The calculated total absorbed dose in the eye lens depends on the initial incident spectra. This quantity normalized to the eye dose, is between 1.8% and 2.3% in the studied cases and increases with increasing the depth of the eye lens’ location. Comparison to experimental data is also provided. The equivalent dose at a depth of 3 mm Hp (3) is likely to be the appropriate quantity for the best estimate of the eye lens dose.

Derivation of total filtration thickness for diagnostic x-ray source assembly

The method defined by the IEC 60522 for determining the inherent filtration of an x-ray source device is applicable only for a limited range of tube voltage. Because the users cannot legally remove the x-ray movable diaphragm of the x-ray source device, total filtration, which is the sum of the additional filtration diaphragm movable for specific filtration and x-ray, cannot be measured. We develop a method for simply obtaining the total filtration for different tube voltage values.Total filtration can be estimated from a ratio R′ of the air kerma , which is measured with an Al plate with thickness T, and measured without an Al plate. The conditions of the target material of the x-ray source device are then entered into the Report 78 Spectrum Processor to calculate the air kerma Kx and Kx+T for Al thicknesses x and (x + T), respectively, to obtain R. The minimum value of x, which is the difference between the R and R′, is the total filtration of the x-ray source device.The total filtration calculated using the industrial x-ray source device was within ±1% in the 40–120 kV range. This method can calculate the total filtration using air kerma measurements with and without the Al plate. Therefore, the load on the x-ray tube can be reduced, and preparation of multiple Al plates is not necessary. Furthermore, for the 40–120 kV tube voltage range, the user can easily measure the total filtration.

Mammography calibration qualities establishment in a Mo- Mo clinical system

In this study the mammography calibration qualities were established in a clinical mammography system. The objective is to provide the IPEN instruments calibration laboratory with both mammography calibration methods (using a clinical and an industrial system). The results showed a good behavior of mammography equipment, in terms of kVp, PPV and exposure time. The additional filtration of molybdenum is adequate, air-kerma rates were determined and spectra were obtained.

Assessment of DSA dose effect with different combinations of parameters on brain organs: a phantom study

Objective To investigate the lens and pituitary dose impacted by additional filtration and collection field in head and neck DSA examinations. Methods All images were acquired by a Philips ALLura Xper FD 20 DSA machine. The combination of the different collection fields (48 cm, 42 cm, 31 cm, 22 cm) and additional filtrations (0.9 mmCu+1.0 mmAl, 0.4 mmCu+1.0 mmAl, 0.1 mmCu+1.0 mmAl) were adjusted when the anthropomorphic phantom filled with dosimeter was scanned in anterioposterior and lateral positions with 2D-DSA and 3D-DSA. The dose area product (DAP), air kerma (AK) and the radiation dose values of bilateral lens and pituitary were measured and recorded. The 2D and 3D-DSA regional absorption dose on lens and pituitary were analyzed using t' test, the correlations between DAP and AK parameters and different regional absorption doses were evaluated by Pearson rank correlation coefficient. Results Absorption doses of left lens, right lens and pituitary with 2D-DSA (n=12) were as following: (2.77±0.68) , (6.23±3.54), (8.65±2.62) mGy, while the parameters with 3D-DSA (n=12) were (1.78±0.82), (2.18±1.15), (3.32±0.64) mGy, respectively; the results revealed a significant difference (t'=3.20, 3.76 and 6.85, P<0.01). DAP [(8 739±5 731) mGy·cm2] had a relationship with absorption dose of pituitary, left lens and right lens [(5.988±3.299), (2.258±0.872), (4.207±3.303) mGy, r values were 0.766, 0.684, 0.727; P<0.01]. AK values was (31±23) mGy and it had a relationship with pituitary absorption dose (r value was 0.894, P<0.01). The lens dose was reduced when the additional filtration was increased and the collection field was decreased, the radiation dose of the pituitary was reduced when both the additional filtration and the collection field were increased. Conclusions In the head and neck DSA examinations, the radiation dose of the lens and the pituitary had different changes with the different additional filters and collecting fields. The organ dose with 3D-DSA was significantly less than that with 2D-DSA. Key words: Angiography, digital subtraction; Radiation dosage; Pituitary gland; Lens, crystalline