Diagnostic X-ray Energy Range Research Articles

Luminescence Efficiency and Spectral Compatibility of Cerium Fluoride (CeF3) Inorganic Scintillator with Various Optical Sensors in the Diagnostic Radiology X-ray Energy Range

Luminescence Efficiency and Spectral Compatibility of Cerium Fluoride (CeF3) Inorganic Scintillator with Various Optical Sensors in the Diagnostic Radiology X-ray Energy Range

Molecular form factor data for tissue equivalent materials

In the diagnostic X-ray energy range, elastic (Coherent) scattering is dominant and can be obtained using an appropriate form factor. When experimental Form Factor data is not available at certain momentum transfer values, molecular form factor data that can be compatible with experimental data should be theoretically obtained. Using these molecular form factor data, molecular coherent scattering coefficients can be calculated, and linear attenuation coefficients of tissue equivalent structures can be estimated. In this study, PMMA, CIRS 70/30, CIRS 50/50, CIRS 30/70, RMI 454, and BR 12, which are equivalent complex molecular structures to human breast tissue, were examined, and the theoretical molecular form factor F(x) values compatible with the experimental form factor values for each were obtained. We believe that our results will find a significant place in the literature and will be beneficial for our future studies and also in the studies of other researchers who make models.

Development of a flexible composite based on vulcanized silicon casting with bismuth oxide and characterization of its radiation shielding effectiveness in diagnostic X-ray energy range and medium gamma-ray energies

The study aims to develop a novel, lead-free, flexible and lightweight composite shielding material against ionizing radiation. For this, it was used bismuth oxide (Bi2O3) in RTV-2 silicon matrix. The shielding tests were carried out in both diagnostic X-ray energies and intermediate gamma-ray energy range of up to 662 keV to determine the radiation attenuation properties of this material in terms of attenuation ratio, half value layer, tenth value layer, mean free path and lead equivalency of samples in weight of 30%, 40%, 50% in Bi2O3. In the diagnostic X-ray energy range, half value layer, tenth value layer and lead equivalency (in mm Pb) of the produced samples were measured at 80 and 100 kVp narrow beam conditions according to the requirements of EN IEC 61331-1 standard. The results show that lead equivalent values of the produced novel sheets was measured to be 0.16 mm Pb, corresponding to a 6 mm thickness of the flexible sample when it contains 30% wt. Bi2O3 in RTV matrix. The experimental findings for durability and flexibility also indicated that this new RTV-based flexible, lead -free shielding composite can be used safely for especially for manufacturing aprons, garments and thyroid guards used in mammography, radiology, nuclear medicine and dental applications in practice.

Dose reduction using Saba thyroid shield during diagnostic X-ray energy range: a phantom study

The Saba thyroid shield is a new X-ray dose reduction tool for radiosensitive organs that can reduce the X-ray dose without degrading the image quality. This study investigated its effectiveness in reducing the X-ray dose on the thyroid surface during diagnostic X-ray. This study was conducted in the lab of the Medical Physics Department at Umm-Alqura University. The experiments were performed in the year 2022. A mixed fission product phantom and a solid-state detector were used to measure the radiation dose on the thyroid surface during diagnostic X-ray using a tube voltage within 40–120 kVp. The effectiveness of the Saba thyroid shield was examined in two settings: in-field and out-of-field. Measurements were conducted for these two settings without and with the Saba thyroid shield, and the attenuation percentages were computed. Analysis of covariance was used to test the tool’s effectiveness in X-ray dose reduction. The average in- and out-of-field dose attenuation percentages using the Saba thyroid shield were 80.12 ± 0.12% and 81.13 ± 0.18%, respectively. A significant difference was shown between the measurements done without and with the Saba thyroid shield (p = 0.000) for both the in-field and out-of-field doses. The in-field and out-of-field dose reduction levels using the shield were approximately the same. This study demonstrated that the newly developed Saba thyroid shield made of copper and bismuth effectively reduces both the in-field and out-of-field radiation doses.

Ex-vivo atherosclerotic plaque characterization using spectral photon-counting CT: Comparing material quantification to histology

Background and aimsAtherosclerotic plaques are characterized as being vulnerable to rupture based on a series of histologically defined features, including a lipid-rich necrotic core, spotty calcification and ulceration. Existing imaging modalities have limitations in their ability to distinguish between different materials and structural features. We examined whether X-ray spectral photon-counting computer tomography (SPCCT) images were able to distinguish key plaque features in a surgically excised specimen from the carotid artery with comparison to histological images. MethodsAn excised carotid plaque was imaged in the diagnostic X-ray energy range of 30–120 keV using a small-bore SPCCT scanner equipped with a Medipix3RX photon-counting spectral X-ray detector with a cadmium telluride (CdTe) sensor. Material identification and quantification (MIQ) images of the carotid plaque were generated using proprietary MIQ software at 0.09 mm volumetric pixels (voxels). The plaque was sectioned, stained and photographed at high resolution for comparison. ResultsA lipid-rich core with spotty calcification was identified in the MIQ images and confirmed by histology. MIQ showed a core region containing lipid, with a mean concentration of 260 mg lipid/ml corresponding to a mean value of −22HU. MIQ showed calcified regions with mean concentration of 41 mg Ca/ml corresponded to a mean value of 123HU. An ulceration of the carotid wall at the bifurcation was identified to be lipid-lined, with a small calcification identified near the breach of the artery wall. ConclusionsSPCCT derived material identification and quantification images showed hallmarks of vulnerable plaque including a lipid-rich necrotic core, spotty calcifications and ulcerations.

Lead-free transparent shields for diagnostic X-rays: Monte Carlo simulation and measurements.

In recent years, the preference for using lead-free radiation protection shields has increased because of concerns regarding lead poisoning and leakage. In medical and research laboratories, glass shields are preferred because of their transparency. In this study, various glass shields were examined and compared based on the international standards. One commercially available lead-based shield, four recently studied shields, and three new lead-free shields were considered, and their shielding factors were calculated. We presented three glasses based on borate, phosphate, and silicate compounds, which were named Ir1, Ir2, and Ir3, respectively. Based on the International Electrotechnical Commission standard (IEC 61331), the air-kerma ratios (attenuation ratios) and lead equivalent values were derived using Monte Carlo N-Particle eXtended (MCNPX) calculations, and mass attenuation coefficients and effective atomic numbers (Zeff) of all the shields were obtained from XCOM database, in the diagnostic X-ray energy range of 40-120keV. In addition, some measurements were performed for the reference (lead-based) glass to validate the simulations. The above-mentioned factors for silicate-bismuth-based (Ir3) and borosilicate-barium-based (Tu) glasses were found to be higher than the others and comparable to those of commercially available lead-based glass. In conclusion, Ir3 and Tu glasses were found to be the preferred lead-free transparent shields in the diagnostic X-ray energy range.

Photon fluence and dose estimation in computed tomography using a discrete ordinates Boltzmann solver

In this study, cone-beam single projection and axial CT scans are modeled with a software package—DOCTORS, which solves the linear Boltzmann equation using the discrete ordinates method. Phantoms include a uniform 35 cm diameter water cylinder and a non-uniform abdomen phantom. Series simulations were performed with different simulation parameters, including the number of quadrature angles, the order of Legendre polynomial expansions, and coarse and fine mesh grid. Monte Carlo simulations were also performed to benchmark DOCTORS simulations. A quantitative comparison was made between the simulation results obtained using DOCTORS and Monte Carlo methods. The deterministic simulation was in good agreement with the Monte Carlo simulation on dose estimation, with a root-mean-square-deviation difference of around 2.87%. It was found that the contribution of uncollided photon fluence directly from the source dominates the local absorbed dose in the diagnostic X-ray energy range. The uncollided photon fluence can be calculated accurately using a ‘ray-tracing’ algorithm. The accuracy of collided photon fluence estimation is largely affected by the pre-calculated multigroup cross-sections. The primary benefit of DOCTORS lies in its rapid computation speed. Using DOCTORS, parallel computing with GPU enables the cone-beam CT dose estimation nearly in real-time.

Dosimetric characterization of 3D printed phantoms at different infill percentages for diagnostic X-ray energy range

The aim of this paper is to characterize 3D printed phantoms and printing set-ups with different infill percentages for imaging energy X-ray beams attenuation. 3D printing performance was studied using the fused filament fabrication (FFF) technique with PLA (Polylactic Acid) and ABS (Acrylonitrile Butadiene Styrene) filaments. Phantom plates were printed and, using the Pantak Seifert X-ray system with different beam qualities in the diagnostic range, the attenuation coefficients were obtained experimentally with the transmission method and results compared with PMMA used as reference and theoretical data. Different percentages of infill of printed phantoms were also evaluated and transmission characterized. The attenuation coefficients were determined for the different beam qualities and results show that the variation in the values of attenuation coefficients decreases as the infill quality increases. Attenuation characteristics evaluated indicates the suitable equivalence of PLA to PMMA for 3D printing water/tissue equivalent most complex geometry phantoms. The different printing modes characterized together with their attenuation coefficients for the X-ray beams will be studied and used in the development of new 3D printed phantoms in our institute.

Effectiveness of a novel real-time dosimeter in interventional radiology: a comparison of new and old radiation sensors

Radiation dose management is important in interventional radiology (IR) procedures, such as percutaneous coronary intervention, to prevent radiation-induced injuries. Therefore, radiation dose should be monitored in real time during IR. This study evaluated the fundamental characteristics of a novel real-time skin dosimeter (RTSD) developed at our institution. In addition, we compared the performance of our new and old radiation sensors and that of a skin dose monitor (SDM), with ion chamber reference values. We evaluated the fundamental characteristics (e.g., energy dependence, dose dependence, and angular dependence) of the RTSD developed by us in the diagnostic X-ray energy range. The performance of our RTSD was similar to that of the SDM. In particular, the new radiation sensor of our RTSD demonstrated better dose rate dependence compared to the old sensor. In addition, the new sensor had the advantage of being small in size and thus minimally affecting the X-ray images compared to the old sensor. Therefore, the developed skin dosimeter and radiation sensor may be useful in real-time measurement of patients' exposure to and multi-channel monitoring of radiation in IR procedures. The new dosimeter system can be recommended for visualization and management of the radiation dose to which the patients' skin is exposed.

P061] Calculation of beam quality parameters for X-ray mammography spectra: A monte carlo simulation study

Purpose Breast cancer is known to be the most malignant type of cancer among women in the world. By X-ray mammographic imaging, the disease can be detected and then an early stage treatment can be started following this. For a reliable imaging, beam quality parameters should be precisely determined. However, measurement of X-ray beam quality parameters necessitates using specific equipment. An efficient way for determining these parameters is to utilize scientifically proven and verified Monte Carlo simulation codes. Methods Monte Carlo simulations are widely used in digital mammography imaging research. In this work, MCNP5 was used for simulating generation of X-ray spectrum including both bremsstrahlung and characteristic X-rays. Electron beam and target (anode) were modelled as specified in the Report of AAPM Task Group 195: Monte Carlo Reference Data Sets for Imaging Research. Results X-ray quality parameters such as Aluminum (Al) equivalent half-value layer (HVL), Al equivalent effective energy, average energy, and air kerma of the simulated polyenergetic X-ray beams were calculated and tabulated for a wide range of commercially available mammographic X-ray tube voltage (kVp) and target/filter material and thickness combinations (molybdenum/molybdenum, molybdenum/rhodium, rhodium/rhodium, tungsten/rhodium, tungsten/silver, and tungsten/aluminum). All calculated parameters were then fitted to second-degree polynomial surface equations as a function of kVp and filter thickness for each target/filter combination. Conclusions This work is essential and flexible in the sense that it provides a reliable and quick look-up database for those performing mammographic patient dose and image quality calculations. In addition, it could be taken as a starting point for generation of quality data for entire diagnostic X-ray energy range, e.g. 20–140 kVp, for any combination of target/filter. On the other hand, with this study, it can be deduced that important mammographic parameters can be precisely calculated with Monte Carlo methods, which would otherwise need for expensive and complicated experimental equipment and much more time.

Dosimetric evaluation of Rhizophora spp. binderless particleboard phantom for diagnostic X-ray energy

This research aims to evaluate the suitability of using binderless particleboard made from Rhizophora spp. mangrove wood as a dosimetric phantom for X-ray in the diagnostic energy regions. Comparative measurements of percentage depth and surface doses in Rhizophora spp. binderless particleboard phantom and similarly shaped Perspex and water phantoms were performed. Measurements were conducted in the diagnostic X-ray energy range of 50kVp to 90kVp. Results showed that the binderless particleboard phantom can be used for dosimetric measurements. For the X-ray beam at 90kVp, the binderless particleboard and water phantom showed data agreement of 1.6%, 2.7%, and 4.3% at depths of 1, 2, and 4cm, respectively, whereas the measurements in water and Perspex were 1.8%, 2.7%, and 4.4%. The surface dose differences were due to difference in the backscattering material. The doses measured at the surface were within 0.4% for binderless particleboard and water and within 0.9% for Perspex and water.

Radiation attenuation properties of shields containing micro and Nano WO3 in diagnostic X-ray energy range

Background : It has recently been shown that the parcle size of materials used for radiaon shielding can affect the magnitude of radiaon aenuaon. Over the past years, applicaon of nano-structured materials in radiaon shielding has aracted aenon world-wide. The purpose of this study was to invesgate the shielding properes of the lead-free shields containing micro and nano-sized WO3 against low energy x-rays. Materials and Methods : The radiaon shields were constructed using nano and micro WO3 parcles incorporated into an EPVC polymer matrix. The aenu aon coefficients of the designed shields were evaluated for low energy x-rays (diagnosc radiology energy range). Results : The results indicate that nano-structured WO3/PVC shields have higher photon aenuaon properes comp ared to those of the micro-sized samples. Conclusion: Our experiment clearly shows that the smaller size of nano-structured WO3 parcles can guarantee a beer radiaon shielding property. However, it is too early to draw any conclusion on the possible mechanisms of enhanced aenuaon of nano-sized WO3 parcles.

Sensitivity of HEMATEG Induced by Radiation Dose in the Diagnostic X-Ray Energy Range

The aim of this study is to determine sensitivity of new recipes polymer gel HEMATEG with varied x-ray exposure by using UV-visible spectrophotometer as an evaluation technique. The gels were irradiated by x-ray radiation and the polymerization of HEMATEG were followed. Polymerization was read based on absorption spectra in the range wavelength UV 300 nm to 700 nm. The dependency of polymerization with increasing of exposure dose was determined by changes in the band gap energy (Eg) and Urbach energy (∆E). In the UV-visible region, Eg with indirect transition of HEMATEG were decreased with increasing radiation dose while, ∆E were increased with increasing radiation dose. This observation supported the increase of structured disorder of the polymer with increasing radiation dose. This study proved that HEMATEG had a high potential to be used as a 3-dimensional dosimeter in the diagnostic x-ray.

Energy response calibration of photon-counting detectors using x-ray fluorescence: a feasibility study

Accurate energy calibration is critical for the application of energy-resolved photon-counting detectors in spectral imaging. The aim of this study is to investigate the feasibility of energy response calibration and characterization of a photon-counting detector using x-ray fluorescence. A comprehensive Monte Carlo simulation study was performed using Geant4 Application for Tomographic Emission (GATE) to investigate the optimal technique for x-ray fluorescence calibration. Simulations were conducted using a 100 kVp tungsten-anode spectra with 2.7 mm Al filter for a single pixel cadmium telluride (CdTe) detector with 3 × 3 mm2 in detection area. The angular dependence of x-ray fluorescence and scatter background was investigated by varying the detection angle from 20° to 170° with respect to the beam direction. The effects of the detector material, shape, and size on the recorded x-ray fluorescence were investigated. The fluorescent material size effect was considered with and without the container for the fluorescent material. In order to provide validation for the simulation result, the angular dependence of x-ray fluorescence from five fluorescent materials was experimentally measured using a spectrometer. Finally, eleven of the fluorescent materials were used for energy calibration of a CZT-based photon-counting detector. The optimal detection angle was determined to be approximately at 120° with respect to the beam direction, which showed the highest fluorescence to scatter ratio (FSR) with a weak dependence on the fluorescent material size. The feasibility of x-ray fluorescence for energy calibration of photon-counting detectors in the diagnostic x-ray energy range was verified by successfully calibrating the energy response of a CZT-based photon-counting detector. The results of this study can be used as a guideline to implement the x-ray fluorescence calibration method for photon-counting detectors in a typical imaging laboratory.

Higher‐order phase shift reconstruction approach

Biological soft tissues encountered in clinical and preclinical imaging mainly consists of atoms of light elements with low atomic numbers and their elemental composition is nearly uniform with little density variation. Hence, x-ray attenuation contrast is relatively poor and cannot achieve satisfactory sensitivity and specificity. In contrast, x-ray phase-contrast provides a new mechanism for soft tissue imaging. The x-ray phase shift of soft tissues is about a thousand times greater than the x-ray absorption over the diagnostic x-ray energy range, yielding a higher signal-to-noise ratio than the attenuation contrast counterpart. Thus, phase-contrast imaging is a promising technique to reveal detailed structural variation in soft tissues, offering a high contrast resolution between healthy and malignant tissues. Here the authors develop a novel phase retrieval method to reconstruct the phase image on the object plane from the intensity measurements. The reconstructed phase image is a projection of the phase shift induced by an object and serves as input to reconstruct the 3D refractive index distribution inside the object using a tomographic reconstruction algorithm. Such x-ray refractive index images can reveal structural features in soft tissues, with excellent resolution differentiating healthy and malignant tissues. A novel phase retrieval approach is proposed to reconstruct an x-ray phase image of an object based on the paraxial Fresnel-Kirchhoff diffraction theory. A primary advantage of the authors' approach is higher-order accuracy over that with the conventional linear approximation models, relaxing the current restriction of slow phase variation. The nonlinear terms in the autocorrelation equation of the Fresnel diffraction pattern are eliminated using intensity images measured at different distances in the Fresnel diffraction region, simplifying the phase reconstruction to a linear inverse problem. Numerical experiments are performed to demonstrate the accuracy and stability of the proposed approach. The proposed reconstruction formula is a generalization of the transport of intensity equation (TIE). It has the second-order accuracy compared to the linear model used in the conventional phase retrieval approach. The numerical experiments demonstrate that the accuracy and stability of the proposed phase reconstruction method outperforms the TIE-based reconstruction method. A novel approach has been proposed to retrieve an x-ray phase shift image induced by an object from intensity images measured at different distances in the Fresnel diffraction region. The authors' approach has the second-order accuracy and is able to retrieve the phase shift of an object stably, overcoming the restriction of slow phase variation assumed by the conventional phase retrieval techniques.

蛍光ガラス線量計小型素子システムにおける素子タイプ別エネルギー依存性と線量補正の検討

We studied energy characteristics and examined dose correction when using a radiophotoluminescence glass dosimeter (GD). There are two types of GD. One type of GD is called GD-352, which consists of a glass element and Sn filter. Another type of GD is called GD-302, which has no additional filter. Energy characteristics of these two types of GDs were investigated using a diagnostic X-ray energy range. The equation is as follows: Cf (correction factor) = average of GD measured value/air kerma. The compensation formula for estimating air kerma with each X-ray energy was determined from an approximation formula based on the ratio between GD system reading and air kerma with a specific X-ray energy. From compensation results obtained using the formula, the error for air kerma using GD-352 was approximately 0%, and the error using GD-302 was about 1.0%.

FLUXEN portable equipment for direct X-ray spectra measurements

The proper use of imaging equipment in radiological units is based on an appropriate knowledge of the physical characteristics of the X-ray beam used. The FLUXEN PROJECT is working on a portable apparatus which, together with dedicated software, is able to perform an exact spectral reconstruction of the radiation produced in diagnostic X-ray tubes. The apparatus characterizes the energy spectrum of radiological tubes and also provides a measurement of the emitted flux. The acquisition system is based on a commercial CZT detector (3×3×2 mm 3), produced by AMPTEK, cooled by a Peltier cell, with a high efficiency in the diagnostic X-ray energy range and modified in the shaping electronics so as to obtain a faster response. The acquiring section lies on a NuDAQ I/O card with a sampling frequency of up to 20 MHz. The signal produced by the X-ray tube is wholly acquired and an off-line analysis is made so as to make possible an accurate recognition of pile-up events and a reconstruction of the emitted spectra. The reconstructed spectra of a General Electric Senographe DMR mammographic X-ray tube are shown.

Applications of “edge-on” illuminated porous plate detectors for diagnostic X-ray imaging

Scanning X-ray imaging systems for non-invasive diagnostics have several advantages over conventional imaging systems using area detectors. They significantly reduce the detected scatter radiation, cover large areas and potentially provide high spatial resolution. Applications of one-dimensional gaseous detectors and “edge-on” illuminated silicon strip detectors for scanning imaging systems are currently under intensive investigation. The purpose of this work is to investigate “edge-on” illuminated Porous Plate (PP) detectors for applications in diagnostic X-ray imaging. MicroChannel Plate (MCP), which is a common type of PP, has previously been investigated as a detector in surface-on illumination mode for medical X-ray imaging. However, its detection efficiency was too low for medical imaging applications. In the present study, the PP are used in the “edge-on” illumination mode. Furthermore, the structural parameters of different PP types are optimized to improve the detection efficiency in the diagnostic X-ray energy range. The MCP, porous dielectrics, microspheric plates, a-Si-based MCPs, microcolumnar and microgranular dielectrics are considered as detector materials in the “edge-on” illumination mode. The following are some potential advantages of the “edge-on” PP detectors from the standpoint of medical imaging applications: direct quantum-to-charge conversion; high internal charge amplification; very low noise; total absorption of the X-ray photons; minimal strip size and variable shape of the strips. The results of the application of “edge-on” MCP detectors for 122 and 662 keV gamma-ray detection and the initial results of imaging a radioactive source are discussed.

Quantitative X-ray diffraction analysis of bone and marrow volumes in excised femoral head samples

The authors apply the technique of quantitative X-ray diffraction analysis (QXDA) to trabecular bone tissue to demonstrate that quantitative data of the ratio of bone and marrow volumes within the trabecular region can be obtained. Apparatus has been constructed for measuring energy dispersive X-ray diffraction spectra of human femoral head samples in the diagnostic X-ray energy range. Individual diffraction peaks due to bone and marrow tissue were identified in the measured spectra. The relative intensities of the two peaks within the spectra quantify the relative proportions of the two components, and so the bone to marrow peak ratio is proposed as a parameter which is capable of providing information on the osteoporotic state of trabecular tissue. Preliminary results indicate a significant correlation between this method and the bone density measurement techniques of quantitative computed tomography and Compton scatter densitometry. Results have also shown that the use of a synthetically prepared calibration curve can enable absolute measurement of bone or marrow volumes.

X-ray imaging using amorphous selenium: inherent spatial resolution.

This is a theoretical study of the inherent spatial resolution of the latent image on the surface of an amorphous selenium (a-Se) plate used for diagnostic x-ray imaging. The following effects are considered: (A) ranges of primary photoelectrons; (B) reabsorption of K fluorescence; (C) reabsorption of Compton scattered photons; (D) diffusion; (E) the geometric effect due to oblique incidence of x rays; (F) electrostatic effect; and (G) the space charge effect. The modulation transfer function of a-Se in the diagnostic x-ray energy range has been estimated. In conclusion, (A) and (E) are the main factors limiting the resolution, and for diagnostic x rays, the inherent spatial resolution of a-Se plates is much better than that of CsI layers used in x-ray image intensifiers.