High kV Research Articles

Optimal Spectral Performance on Pediatric Photon-Counting CT: Investigating Phantom-Based Size-Dependent kV Selection for Spectral Body Imaging.

The comprehensive evaluation of kV selection on photon-counting computed tomography (PCCT) has yet to be performed. The aim of the study is to evaluate and determine the optimal kV options for variable pediatric body sizes on the PCCT unit. In this study, 4 phantoms of variable sizes were utilized to represent abdomens of newborn, 5-year-old, 10-year-old, and adult-sized pediatric patients. One solid water and 4 solid iodine inserts with known concentrations (2, 5, 10, and 15 mg I/mL) were inserted into phantoms. Each phantom setting was scanned on a PCCT system (Siemens Alpha) with 4 kV options (70 and 90 kV under Quantum Mode, 120 and 140 kV under QuantumPlus Mode) and clinical dual-source (3.0 pitch) protocol. For each phantom setting, radiation dose (CTDIvol) was determined by clinical dose settings and matched for all kV acquisitions. Sixty percent clinical dose images were also acquired. Reconstruction was matched across all acquisitions using Qr40 kernel and QIR level 3. Virtual monoenergetic images (VMIs) between 40 and 80 keV with 10 keV interval were generated on the scanner. Low-energy and high-energy images were reconstructed from each scan and subsequently used to generate an iodine map (IM) using an image-based 2-material decomposition method. Image noise of VMIs from each kV acquisition was calculated and compared between kV options. Absolute percent error (APE) of iodine CT number accuracy in VMIs was calculated and compared. Root mean square error (RMSE) and bias of iodine quantification from IMs were compared across kV options. At the newborn size and 50 keV VMI, noise is lower at low kV acquisitions (70 kV: 10.5 HU, 90 kV: 10.4 HU), compared with high kV acquisitions (120 kV: 13.8 HU, 140 kV: 13.9 HU). At the newborn size and 70 keV VMI, the image noise from different kV options is comparable (9.4 HU for 70 kV, 8.9 HU for 90 kV, 9.7 HU for 120 kV, 10.2 HU for 140 kV). For APE of VMI, high kV (120 or 140 kV) performed overall better than low kV (70 or 90 kV). At the 5-year-old size, APE of 90 kV (median: 3.6%) is significantly higher (P < 0.001, Kruskal-Wallis rank sum test with Bonferroni correction) than 140 kV (median: 1.6%). At adult size, APE of 70 kV (median: 18.0%) is significantly higher (P < 0.0001, Kruskal-Wallis rank sum test with Bonferroni correction) than 120 kV (median: 1.4%) or 140 kV (median: 0.8%). The high kV also demonstrated lower RMSE and bias than the low kV across all controlled conditions. At 10-year-old size, RMSE and bias of 120 kV are 1.4 and 0.2 mg I/mL, whereas those from 70 kV are 1.9 and 0.8 mg I/mL. The high kV options (120 or 140 kV) on the PCCT unit demonstrated overall better performance than the low kV options (70 or 90 kV), in terms of image quality of VMIs and IMs. Our results recommend the use of high kV for general body imaging on the PCCT.

Optimizing dual-energy CT technique for iodine-based contrast-to-noise ratio, a theoretical study.

Dual-energy CT (DECT) systems provide valuable material-specific information by simultaneously acquiring two spectral measurements, resulting in superior image quality and contrast-to-noise ratio (CNR) while reducing radiation exposure and contrast agent usage. The selection of DECT scan parameters, including x-ray tube settings and fluence, is critical for the stability of the reconstruction process and hence the overall imagequality. The goal of this study is to propose a systematic theoretical method for determining the optimal DECT parameters for minimal noise and maximum CNR in virtual monochromatic images (VMIs) for fixed subject size and total radiationdose. The noise propagation in the process of projection based material estimation from DECT measurements is analyzed. The main components of the study are the mean pixel variances for the sinogram and monochromatic image and the CNR, which were shown to depend on the Jacobian matrix of the sinograms-to-DECT measurementsmap. Analytic estimates for the mean sinogram and monochromatic image pixel variances and the CNR as functions of tube potentials, fluence, and VMI energy are derived, and then used in a virtual phantom experiment as an objective function for optimizing the tube settings and VMI energy to minimize the image noise and maximize theCNR. It was shown that DECT measurements corresponding to kV settings that maximize the square of Jacobian determinant values over a domain of interest lead to improved stability of basis material reconstructions. Instances of non-uniqueness in DECT were addressed, focusing on scenarios where the Jacobian determinant becomes zero within the domain of interest despite significant spectral separation. The presence of non-uniqueness can lead to singular solutions during the inversion of sinograms-to-DECT measurements, underscoring the importance of considering uniqueness properties in parameter selection. Additionally, the optimal VMI energy and tube potentials for maximal CNR was determined. When the x-ray beam filter material was fixed at 2 mm of aluminum and the photon fluence for low and high kV scans were considered equal, the tube potential pair of 60/120 kV led to the maximal iodine CNR in the VMI at 53keV. Optimizing DECT scan parameters to maximize the CNR can be done in a systematic way. Also, choosing the parameters that maximize the Jacobian determinant over the set of expected line integrals leads to more stable reconstructions due to the reduced amplification of the measurement noise. Since the values of the Jacobian determinant depend strongly on the imaging task, careful consideration of all of the relevant factors is needed when implementing the proposedframework.

Perbandingan Dosis Radiasi Pemeriksaan Radiografi Thoraks PA Menggunakan Faktor Eksposi: Standar dan High kVp Berdasarkan Database DRL Si-INTAN BAPETEN

The usage of high kV has yet to be debated, so it is not fully used in PA chest radiographic examinations. However, The World Health Organization (WHO) and the Commission of European Communities (CEC) recommend using high kV, which can reduce the radiation dose to a minimum while maintaining the quality of the radiographic image. This study aimed to analyze the radiation dose for posterior-anterior (PA) chest radiography examinations using exposure factors: standard and high kV. This research method uses a retrospective study of the results of PA chest radiography examinations database diagnostic reference level (DRL) BAPETEN between 2018-2022. The PA chest examination data are the procedure, patient position, age, body weight, exposure factors (kVp and mAs), and ESAK dose (mGy). Then, use a standard exposure factor between 60-75 kVp and tube current-time of 6-12 mAs, while the exposure factor is high kV between 90-109 kVp and tube current-time of 0.7-4 mAs. After that, statistical analysis was carried out using IBM SPSS version 26 and Microsoft Excel. Determination of the average value and percentage difference in radiation dose of standard exposure factors and high kV. Then, proceed with statistical tests mann-whitney to determine the difference in the average radiation dose value between standard and exposure factors high kVp. The study showed that the average radiation dose for the standard kV exposure factor for the PA chest radiography examination was 0.179 mGy, while the high kV was 0.146 mGy. The dose difference between standard kV and high kV is 18.43%, with exposure factor radiation dose high kV lower than the standard exposure factor. For statistical test results, mann-whitney results p-value &lt; 0,000. High kV could be a procedure to optimize exposure factors for PA chest radiography examination. Keywords: Exposure factors, High kV, Optimization, DRL, Chest PA

Evolution of CT radiation dose in pediatric patients undergoing hybrid 2-[18F]FDG PET/CT between 2007 and 2021.

To evaluate the evolution of CT radiation dose in pediatric patients undergoing hybrid 2-[18F]fluoro-2-deoxy-D-glucose (2-[18F]FDG) PET/CT between 2007 and 2021. Data from all pediatric patients aged 0-18 years who underwent hybrid 2-[18F]FDG PET/CT of the body between January 2007 and May 2021 were reviewed. Demographic and imaging parameters were collected. A board-certified radiologist reviewed all CT scans and measured image noise in the brain, liver, and adductor muscles. 294 scans from 167 children (72 females (43%); median age: 14 (IQR 10-15) years; BMI: median 17.5 (IQR 15-20.4) kg/m2) were included. CT dose index-volume (CTDIvol) and dose length product (DLP) both decreased significantly from 2007 to 2021 (both p < 0.001, Spearman's rho coefficients -0.46 and -0.35, respectively). Specifically, from 2007 to 2009 to 2019-2021 CTDIvol and DLP decreased from 2.94 (2.14-2.99) mGy and 309 (230-371) mGy*cm, respectively, to 0.855 (0.568-1.11) mGy and 108 (65.6-207) mGy*cm, respectively. From 2007 to 2021, image noise in the brain and liver remained constant (p = 0.26 and p = 0.06), while it decreased in the adductor muscles (p = 0.007). Peak tube voltage selection (in kilovolt, kV) of CT scans shifted from high kV imaging (140 or 120kVp) to low kV imaging (100 or 80kVp) (p < 0.001) from 2007 to 2021. CT radiation dose in pediatric patients undergoing hybrid 2-[18F]FDG PET/CT has decreased in recent years equaling approximately one-third of the initial amount. Over the past 15 years, CT radiation dose decreased considerably in pediatric patients undergoing hybrid imaging, while objective image quality may not have been compromised.

PO-1846 Characterization of a Novel High Performance kV CBCT System on a Ring-Gantry Linac

PO-1846 Characterization of a Novel High Performance kV CBCT System on a Ring-Gantry Linac

PD-0902 ACR Accreditation Evaluation of a Novel High Speed Ring-Gantry Linac kV CBCT System

PD-0902 ACR Accreditation Evaluation of a Novel High Speed Ring-Gantry Linac kV CBCT System

Comparing Radiation Dose of Cerebral Angiography Using Conventional and High kV Techniques: A Retrospective Study on Intracranial Aneurysm Patients and a Phantom Study.

Evaluation of patient radiation dose after the implementation of a high kV technique during a cerebral angiographic procedure is an important issue. This study aimed to determine and compare the patient radiation dose of intracranial aneurysm patients undergoing cerebral angiography using the conventional and high kV techniques in a retrospective study and a phantom study. A total of 122 cases (61 cases with conventional technique and 61 cases with high kV technique) of intracranial aneurysm patients, who underwent cerebral angiographic procedure and met the inclusion criteria, were recruited. The radiation dose and the angiographic exposure parameters were reviewed retrospectively. The radiation dose in the phantom study was conducted using nanoDotTM optically stimulating luminescence (OSLD), which were placed on the scalp of the head phantom, the back of the neck, and the phantom skin at the position of the eyes. The standard cerebral angiographic procedure using the conventional and high kV techniques was performed following the standard protocol. The results showed that the high kV technique significantly reduced patient radiation dose and phantom skin dose. This study confirms that the implementation of a high kV technique in routine cerebral angiography for aneurysm diagnosis provides an effective reduction in radiation dose. Further investigation of radiation dose in other interventional neuroradiology procedures, particularly embolization procedure, should be performed.

Evaluation of the different exposure parameters for the accurate diagnosis of peri-implantitis severity in digital panoramic radiography

To evaluate the accuracy of the diagnosis of peri-implant bone defects' severities in digital panoramic radiographs obtained at different tube voltage and/or tube current settings. Two different sizes of peri-implant bone defects (type 1 and type 2) were prepared after the implants were inserted into 29 bovine rib blocks. Digital panoramic radiographs were obtained at eight different tube voltage and/or tube current settings for all rib blocks. Implant images were cropped separately. The average intensity value (AIV) of cropped images were analyzed using Adobe Photoshop CC software. The Kruskal-Wallis H test was used to compare AIVs. All cropped images were evaluated using a five-point Likert scale for the likelihood of a bone defect being absent or present. The weighted kappa values were calculated to compare observer agreement and ROC analysis was performed to determine the appropriate exposure parameters. The lowest AIV was obtained at 72 kV/6.3 mA (92.162±16.016), and the highest AIV was obtained at 60 kV/3.2 mA (179.050±13.823). The Kruskal-Wallis H test showed significant differences in the AIVs according to the exposure parameters (p<0.001). The kappa coefficient for the inter-observer agreement was excellent (0.864, p<0.001). The AUC values for type 1 defects ranged from 0.778 and 0.860; for type 2 defects ranged from 0.920 and 0.967. The AUC value of type 1 defects was slightly better in panoramic images obtained with high kV and low mA levels (72 kV/3.2 mA), compared to others. In daily clinical routine, peri-implant bone defects might be evaluated by panoramic radiographs obtained with all kV and mA values tested. However, to avoid misdiagnosing and for better accuracy, panoramic radiographs obtained with high kV and low mA levels suitable for patients should be used, especially in the detection of small or initial bone defects.

Pengaruh Teknik kV Tinggi pada Pemeriksaan Radiografi Thorak Terhadap Entrance Surface Air Kerma dan Dose Area Product yang Diterima oleh Pasien di RSUP Dr. Kariadi Semarang

This study aims to determine the effect of using the high kV technique on chest radiographic examination on Entrance Surface Air Kerma (ESAK), and Dose Area Product (DAP) received by patients. This is one of the optimization efforts in radiation protection and safety in ionizing radiation. This study used retrospective data from chest radiographic images generated by the Siemens Ysio Max radiograph at the Radiology Installation of RSUP Dr. Kariadi Semarang in 2021. Two voltages were used, 59.8 kV and 108.8 kV, with a total sample of 225 patients. The use of the high kV technique produces a smaller ESAK value, namely with a difference of 60.75%, and a smaller DAP value, namely with a difference of up to 74.92%, compared to using the standard kV technique. These results show a significant difference in the radiation dose produced using the high kV technique with image quality that can still use to diagnose a disease/disorder. Keywords: chest radiography, high kV technique, Entrance Surface Air Kerma, Dose Area Product

Cerebral angiographic procedure using high kV technique reduces patient radiation dose during intracranial aneurysmal diagnosis, a retrospective and phantom study

Cerebral angiographic procedure using high kV technique reduces patient radiation dose during intracranial aneurysmal diagnosis, a retrospective and phantom study

Visualization of the external flow field during a vented explosion for hydrogen-air mixtures: Effects of hydrogen concentrations and vent areas

To study the effects of hydrogen concentrations and vent areas on the vented hydrogen-air explosion, series of experiments were performed in a cylindrical tube under the conditions of 1 atm and 10 ℃. The pressure oscillation frequency is proportional to the hydrogen concentration, while the Helmholtz oscillation disappeared gradually with the increase of Kv. The position inside the container which was farther away from the vent cover would experience the higher dynamic loading. The volume concentration of the hydrogen at the external field (cExt) was always lower than the initial hydrogen concentration, that increased with the increase of the initial concentration, while it was zero at some concentrations with the increase of Kv. The external flame velocity of rich fuel was always larger than that of lean fuel. The deflagration to detonation (DDT) in the outer field was easier to achieve for the concentration near to 50 vol% and for lower Kv. The secondary explosion wave (PExt) increased firstly and then decreased with the increase of hydrogen concentration, which decreased with the increase of Kv in general. The maximum surface temperature rose with the increase of concentration and dropped with the increase of Kv in general. The high-temperature field was closer to the vent for lower concentration and higher Kv.

Investigation of newly diagnosed pneumoconiosis from artificial quartz stone manufacturers

Artificial quartz dust exposure may cause associated pneumoconiosis. From November 2019 to July 2020, a total of 27 cases of silicosis associated with artificial quartz stone manufacturers were diagnosed and treated in the Occupational disease Department of Suzhou Fifth People's Hospital. The average age of onset was (46.8±6.6) years, and the average working age of dust exposure was (5.7±1.7) years.The main feature of high KV chest radiography is P/S shadow with strip shadow. CT imaging findings showed diffuse small nodules and ground glass shadows with band shadows. The lesions were mainly distributed in the upper lung, accompanied by pleural thickening, lymphadenopathy and calcification. The pulmonary function impairment was mainly mild restrictive ventilation disorder, and the bronchial mucosa longitudinal plica was the main manifestation under tracheoscopy. The age of silicosis of workers in artificial quartz stone production enterprises is younger, the working age of dust exposure is short, the lung function and bronchial mucosa have a certain degree of damage, and effective preventive measures should be taken in time.

Compliance to radiography practice of high-kilovoltage technique for chest radiography in South South Nigeria

BackgroundThe production of a good quality chest radiograph depends on the selection of appropriate kilovoltage and current–time product while keeping the radiation dose to patients as low as possible. This study assessed radiographers’ level of compliance to the use of high kV as standard for postero-anterior (PA) chest X-ray in the South South region of Nigeria.ResultsSeventy-seven of the 82 questionnaires administered were completely filled and returned giving a response rate of 94%. Of these 77 respondents, only 74% (n = 57) were aware of high-kV technique as the recommended procedure for PA chest X-ray. Departmental protocols (technique chart with exposure factors) were also non-existent in all hospitals/diagnostic centres used in this study. Thirty-one respondents were males (40%); 44% (n = 34) working in public hospitals only and 32% (n = 25) with less than five years of working experience were aware of this technique. On the benefits, more than 50% of the respondents were familiar with the benefits of using high-kV technique as the recommended standard for PA chest X-rays. Responses on the benefits of the technique varied from 77% (n = 59) for patient dose reduction to 51% (n = 39) for better imaging of the airways. The use of high-kV technique for PA chest X-rays showed only 13% compliance. Factors influencing compliance included imaging system (film screen /digital), X-ray tube rating and X-ray unit with preset/manual exposure factors (p < 0.05).ConclusionsThe present study revealed low compliance to high-kV technique in this region, suggesting a potential increase in ionizing radiation dose to patients during chest radiography, hence the need to improve adherence to the recommended standard.

ESTIMASI DAN AUDIT DOSIS RADIASI PASIEN PADA PEMERIKSAAN RADIOGRAFI KONVENSIONAL TORAKS PA DENGAN TEKNIK HIGH KVP

Research about estimation and dose audit of patients' radiation on examination about thorax PA conventional radiography with high kV technique has been conducted in MRCCC Siloam Hospitals Semanggi. The research has been done on 305 patients aged around 15 years old who got thorax examinations. They consist of 129 male patients and 176 female patients. The characteristics of patients' age are between 18-86 years old, and their average age is 44.2 years old. Their weight range is between 38-120 kg, and their average weight is 66.8 kg. The thorax PA conventional radiography examination uses kVp 125, and the content of mAs is 0.5-1.4 mAs, with an average of 0.8 mAs. The dosage of patients with INAK and ESAK are counted from the outcome similarity graph of the radiation from the X-ray craft. Data analysis shows a linear increase of INAK and ESAK with a linear correlation consecutive of 0.9969 and 1 toward the rise in mAs. The higher the mAs, the higher the patient's dose of radiation also becomes bigger because mAs represent the quantity of radiation so that the amount of photons produced by the X-ray tube becomes bigger. The research result shows that the average increase of INAK and ESAK consecutive is 0.11 mGy and 0.15 mGy, with a typical value of INAK at 0.1 mGy and ESAK at 0.14 mGy. The average ESAK on the research is compared with some reference data, and the result of ESAK in MRCCC Siloam Hospitals Semanggi is under some reference data. The dose audit is the establishment of typical value, and it is compared with national DRL based on the regulation of the head of BAPETEN about stipulation of Indonesia Diagnostic Reference Level Value no. 1211/K/V/2021 on thorax PA examination. The examination of thorax PA about INAK and ESAK national DRL consecutive is 0.3 mGy and 0.4 mGy. Therefore, the result of the dose audit about establishing typical value on the study about thorax PA conventional radiography in MRCCCC Siloam Hospitals Semanggi is under national DRL. The follow-up of the dose audit is to keep the examination protocol and evaluate typical values periodically. The high kVp technique on the conventional radiography examination can reduce the patient's radiation dose. Keywords: Radiation Dose, Conventional Radiography, Thorax PA. High kVp Technique, Diagnostic Reference Levels

Intelligent Image Diagnosis of Pneumoconiosis Based on Wavelet Transform-Derived Texture Features.

Objective Early diagnosis and treatment of occupational pneumoconiosis can delay the development of the disease. This study is aimed at investigating the intelligent diagnosis of occupational pneumoconiosis by wavelet transform-derived entropy. Method From June 2013 to June 2020, the high KV digital radiographs (DR) and computed tomography (CT) images from a total of 60 patients with occupational pneumoconiosis in our department were selected. The wavelet transform-derived texture features were extracted from all images, and the decision tree was used for feature selection. The support vector machines (SVM) with three kernel functions were selected to classify the two kinds of images, and their diagnostic efficiency was compared. Result After eight times of wavelet decomposition, eight wavelet entropy texture features (feature set) were extracted, and six were selected to form the feature subset. The classification effect of linear kernel function SVM is better than those of other functions, with an accuracy of 84.2%. The diagnostic values of DR and CT for occupational pneumoconiosis were the same (kappa = 0.737, P < 0.001). The detection rate of CT for stage I of occupational pneumoconiosis was significantly higher than that of DR (P = 0.031). Conclusion It is helpful to improve the early diagnosis level of pneumoconiosis by using SVM to make an intelligent diagnosis based on the wavelet entropy.

An evaluation of solid state detectors for the relative dosimetry of kilovoltage X-ray beams.

Kilovoltage (kV) X-ray beams are an essential modality in radiotherapy. Solid state detectors are widely available in radiotherapy departments, but their use for kV dosimetry has been limited to date. This study aimed to evaluate the dosimetric performance of a range of solid state detectors for kV dosimetry. Percentage depth doses (PDDs) and relative output factors (ROFs) were measured on an XStrahl 300 unit (XStrahl-Ltd., UK) using 60, 100, 150, and 300 kVp X-ray beams. The fields were defined by circular applicators with field sizes of 2, 5, 8, and 10 cm diameter and square applicators of field sizes 10 × 10 and 20 × 20 cm2 . The following Physikalisch-Technische Werkstätten (PTW) dosimeters were used for measurements: Advanced Markus, PinPoint 3D and Semiflex ionization chambers; photon, electron, and stereotactic radiosurgery (SRS) diodes plus the microDiamond detector. All PDDs were normalized at 5mm depth, and ROFs were measured at 3mm depth to avoid collisions with the end of the applicators. ROFs measured using chambers were corrected for polarity and ion-recombination effects. PDD measurements for 60, 100, and 150 kVp beams exhibited good agreement between all diodes and the ionization chambers over the entire range of depths except in the first few millimeters near the surface. However, for the 300 kVp, all diode detectors exhibited an overresponding behavior compared to reference depth dose data measured with the Advanced Markus chamber. ROFs with the diodes were higher than the Advanced Markus chamber at low energy, and the magnitude of these differences is inversely proportional to the field sizes. The PTW P diode showed the highest variation of up to 15% in the output factor compared to the Advanced Markus chamber. This study evaluated the dosimetric performance of a range of solid state detectors in kV relative dosimetry. This study showed that diode detectors are a suitable replacement for ionization chambers for the PDD measurement of low energy kV beams (60-150 kVp) except for the PDD of 60 kVp with the smaller field sizes. However, an overresponding behavior of diode detectors at 300 kVp beams shows that diode detectors are not suitable for the PDD measurement of high energy kV beams. Generally, all solid state detectors overresponded to ROF measurements, indicating that it is not suitable for ROF measurements. In general, both shielded and unshielded diodes produced a similar dosimetric response, which demonstrates that the energy dependence of solid state detectors should be considered before they are used for any kV relative dosimetric measurements.

Evaluation of Varian Machine Performance Checks for Early Fault Detection

Varian Machine Performance Check (MPC) is an automated and integrated image-based tool for verification of beam and geometry performance of TrueBeam linacs. The tolerances for MPC are set by Varian. The checks involve placing an Isocal Phantom on the treatment couch and a combination of high resolution kV and MV images are taken at different collimator, gantry and couch angles. The images are analyzed and a pass/fail indication is displayed at the end of the check. Daily Beam, 6 MV, geometry checks, enhanced MLC and couch check have been performed in our clinic since April 15th 2019. The enhanced MLC check from initial baseline was 0.18 mm. This started to move beyond the tolerance of 0.2 mm and was investigated by Varian engineers leading to a decision to move the MLC carriage by 1mm yielding a new baseline of 0.03 mm for the MLC leaf offset. Another test which started to fail was the enhanced couch check. This was initially thought to be related to the couch movement but in fact was related to a flatness and symmetry error within the ion chamber which lead to replacing the ion chamber. This problem would have taken a lot longer to present if daily MPC checks were not performed. Overall MPC has been straight forward to implement. This helped us to safely schedule repairs and allowed for earlier detection of failing components.

Review of in vivo optical molecular imaging and sensing from x-ray excitation.

.Significance: Deep-tissue penetration by x-rays to induce optical responses of specific molecular reporters is a new way to sense and image features of tissue function in vivo. Advances in this field are emerging, as biocompatible probes are invented along with innovations in how to optimally utilize x-ray sources.Aim: A comprehensive review is provided of the many tools and techniques developed for x-ray-induced optical molecular sensing, covering topics ranging from foundations of x-ray fluorescence imaging and x-ray tomography to the adaptation of these methods for sensing and imaging in vivo.Approach: The ways in which x-rays can interact with molecules and lead to their optical luminescence are reviewed, including temporal methods based on gated acquisition and multipoint scanning for improved lateral or axial resolution.Results: While some known probes can generate light upon x-ray scintillation, there has been an emergent recognition that excitation of molecular probes by x-ray-induced Cherenkov light is also possible. Emission of Cherenkov radiation requires a threshold energy of x-rays in the high kV or MV range, but has the advantage of being able to excite a broad range of optical molecular probes. In comparison, most scintillating agents are more readily activated by lower keV x-ray energies but are composed of crystalline inorganic constituents, although some organic biocompatible agents have been designed as well. Methods to create high-resolution structured x-ray-optical images are now available, based upon unique scanning approaches and/or a priori knowledge of the scanned x-ray beam geometry. Further improvements in spatial resolution can be achieved by careful system design and algorithm optimization. Current applications of these hybrid x-ray-optical approaches include imaging of tissue oxygenation and pH as well as of certain fluorescent proteins.Conclusions: Discovery of x-ray-excited reporters combined with optimized x-ray scan sequences can improve imaging resolution and sensitivity.

Radiation dose reports and determinants of image quality during ECG-triggered Cardiac Computed Tomography Angiography in children

Aim: This study aimed to evaluate the radiation doses and determinants of image quality during prospective and retrospective ECG-triggered cardiac computed tomography angiography.Materials and Methods: Patients included study who underwent ECG-triggered and low radiation dose dual-source cardiac computed tomography angiography scans. Dose length product values were obtained from the computed tomography scanning protocol. Effective dose (mSv) was estimated using the dose length product method with a conversion factor (mSv/mGy × cm). All images were evaluated and scored by two pediatric radiologists. Results: 37 patients have ECG-triggered cardiac computed tomography. The ages of the patients were between 3 days to 17 years (mean 73.78 ±79.95 months). The average heart rate of the patients was 101.11±27.12 bpm. The mean DLP was 93.05 ±64.4 mGy/cm. The mean effective dose was calculated as 1.74 ±1.03 mSv. We found good agreement between observers while analyzing determinants of image quality (kappa values 0.71-0.80).Conclusion: High-quality images with a low dose can be obtained with an ECG-triggered cardiac computed tomography angiography method. Because of the high sensitivity of radiation in children, dose reduction techniques should be used effectively. Cardiac computed tomography examinations can be performed at diagnostic quality limits with prospective ECG-triggered technique in patients with high pitch, low kV, and dual source techniques.

A comparative study on diagnosis of silicosis by digital and high kV film-screen chest radiography

Objective: To explore the feasibility of soft copy image of chest digital radiography (DR(SC)) in pneumoconiosis diagnosis by observing the reading effect of DR(SC) and comparing it with high kV film-screen chest radiography (FSR(HkV)) . To provide a basis for the establishment of a regional information network platform for pneumoconiosis diagnosis. Methods: A total of 119 miners who were exposed to silica dust and engaged in copper or lead-zinc mining were collected by the Third People's Hospital of Yunnan from October 2017 to August 2019. The pulmonary X-ray findings of DRSC and FSR(HkV) in each case were independently judged and diagnosed by three experienced diagnostic physicians, and the final decision was made according to the consensus of most doctors. The consistency of the two imaging methods was analyzed by observing the main small opacity shape, the overall density, the range of distribution, the aggregation of the small opacity and the big opacity, and the diagnosis stage. Results: there were 118 males and 1 female with an average age of 46.21 years. Average exposure time 7.38 years. The pulmonary X-ray findings of 113 cases with two imaging methods were mainly the round small opacity of p,q and r,but the reticular irregular opacity were not prominent, Only one case of FSR(HkV) judgment p shape and DR(SC) judgment q shape were observed, The coincidence rate was 99.12% (112/113) . huger opacity were observed in the other 6 cases. The coincidence rate was 95.51% (4/89) between pneumoconiosis-free and stageⅠ, and there was no significant difference between stageⅡand stage Ⅲ (30/30, P>0.05) . Conclusion: The x-ray findings of Silicosis with small round shadow in lung can be used by DR(SC) in diagnosis and staging.