scholarly journals What validation tests can be done by the clinical medical physicist while waiting for the standardization of quantitative SPECT/CT imaging?

2020 ◽  
Author(s):  
Hanna Piwowarska-Bilska ◽  
Aleksandra Supińska ◽  
Bożena Birkenfeld
Keyword(s):  
Nuclear Medicine ◽  
Activity Concentration ◽  
Total Activity ◽  
Ct Imaging ◽  
Calibration Factor ◽  
Recovery Coefficient ◽  
Quantitative Spect ◽  
Gamma Cameras ◽  
Reconstruction Methods ◽  
Accuracy Of Measurements

Abstract Objective The aim of the study was to assess the accuracy of quantitative SPECT/CT imaging in a clinical setting and to compare test results from two nuclear medicine departments.Methods Phantom studies were carried out with two gamma cameras manufactured by GE Healthcare: Discovery NM/CT 670 and NM/CT 850, used in two nuclear medicine departments.Results The convergence of activity concentration recovery was validated for the two gamma cameras operating in two medical centres using a homogeneous 3D phantom. The comparison of results revealed a 5% difference in the calibration factor Bg. cal; 6% difference in COV, and a 0.6% difference in total activity deviation ∆Atot.Recovery coefficients (RCmax) for activity concentration in spheres of the anthropomorphic phantom was measured for different image reconstruction techniques. RCmax was in the range of 0.2-0.4 for the smallest sphere (ϕ10 mm), and 1.3-1.4 for the largest sphere (ϕ37 mm). Conversion factors for SUVmax and SUVmean for the gamma camera systems used were 0.99 and 1.13, respectively.Conclusions 1) Measurements taken in our study confirmed the clinical suitability of 5 parameters of image quality (Bg. cal- background calibration factor, ∆Atot- total activity deviation, COV- noise level estimation, QH- hot contrast, AM-accuracy of measurements or RC- recovery coefficient) for the validation of SPECT/CT system performance in terms of correct quantitative acquisitions of images. 2) This work shows that absolute SPECT/CT quantification is achievable in clinical nuclear medicine centers. Results variation of quantitative analyzes between centers is mainly related to the use of different reconstruction methods. 3) It is necessary to standardize the technique of measuring the SUV conversion factor obtained with different SPECT/CT scanners.

scholarly journals Quantitative imaging of bone remodeling in patients with a unicompartmental joint unloading knee implant (ATLAS Knee System)—effect of metal artifacts on a SPECT-CT-based quantification

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Oliver S. Grosser ◽  
Marcus Klutzny ◽  
Heiko Wissel ◽  
Dennis Kupitz ◽  
Michael Finger ◽  
...  
Keyword(s):  
Activity Concentration ◽  
Ct Imaging ◽  
Slice Thickness ◽  
Systematic Bias ◽  
Ct Reconstruction ◽  
Reference Region ◽  
Metal Artifacts ◽  
System Effect ◽  
Quantitative Spect ◽  
X Ray

Abstract Background SPECT-CT using radiolabeled phosphonates is considered a standard for assessing bone metabolism (e.g., in patients with osteoarthritis of knee joints). However, SPECT can be influenced by metal artifacts in CT caused by endoprostheses affecting attenuation correction. The current study examined the effects of metal artifacts in CT of a specific endoprosthesis design on quantitative hybrid SPECT-CT imaging. The implant was positioned inside a phantom homogenously filled with activity (955 MBq 99mTc). CT imaging was performed for different X-ray tube currents (I = 10, 40, 125 mA) and table pitches (p = 0.562 and 1.375). X-ray tube voltage (U = 120 kVp) and primary collimation (16 × 0.625 mm) were kept constant for all scans. The CT reconstruction was performed with five different reconstruction kernels (slice thickness, 1.25 mm and 3.75 mm, each 512 × 512 matrix). Effects from metal artifacts were analyzed for different CT scans and reconstruction protocols. ROI analysis of CT and SPECT data was performed for two slice positions/volumes representing the typical locations for target structures relative to the prosthesis (e.g., femur and tibia). A reference region (homogenous activity concentration without influence from metal artifacts) was analyzed for comparison. Results Significant effects caused by CT metal artifacts on attenuation-corrected SPECT were observed for the different slice positions, reconstructed slice thicknesses of CT data, and pitch and CT-reconstruction kernels used (all, p < 0.0001). Based on the optimization, a set of three protocols was identified minimizing the effect of CT metal artifacts on SPECT data. Regarding the reference region, the activity concentration in the anatomically correlated volume was underestimated by 8.9–10.1%. A slight inhomogeneity of the reconstructed activity concentration was detected inside the regions with a median up to 0.81% (p < 0.0001). Using an X-ray tube current of 40 mA showed the best result, balancing quantification and CT exposure. Conclusion The results of this study demonstrate the need for the evaluation of SPECT-CT protocols in prosthesis imaging. Phantom experiments demonstrated the possibility for quantitative SPECT-CT of bone turnover in a specific prosthesis design. Meanwhile, a systematic bias caused by metal implants on quantitative SPECT data has to be considered.

Aktivitätskonzentration der vom Personal einer Radiojodtherapiestation eingeatmeten Luft

1987 ◽  
Vol 26 (03) ◽  
pp. 143-146 ◽  
Author(s):  
H. Fill ◽  
M. Oberladstätter ◽  
J. W. Krzesniak
Keyword(s):  
Nuclear Medicine ◽  
Length Of Stay ◽  
Activity Concentration ◽  
Threshold Value ◽  
Whole Body ◽  
Therapeutic Activity ◽  
External Radiation ◽  
Oral Application ◽  
Exhaled Air ◽  
The Mean

The mean activity concentration of1311 during inhalation by the nuclear medicine personnel was measured at therapeutic activity applications of 22 GBq (600 mCi) per week. The activity concentration reached its maximum in the exhaled air of the patients 2.5 to 4 hours after oral application. The normalized maximum was between 2 • 10−5 and 2 • 10−3 Bq-m−3 per administered Bq. The mean activity concentration of1311 inhaled by the personnel was 28 to 1300 Bq-m−3 (0.8 to 35 nCi-rrf−3). From this the1311 uptake per year was estimated to be 30 to 400 kBq/a (x̄ = 250, SD = 50%). The maximum permitted uptake from air per year is, according to the German and Austrian radiation protection ordinances 22/21 µiCi/a (= 8 • 105 Bq/a). At maximum 50% and, on the average, 30% of this threshold value are reached. The length of stay of the personnel in the patient rooms is already now limited to such an extent that 10% of the maximum permissible whole-body dose for external radiation is not exceeded. Therefore, increased attention should be paid also to radiation exposure by inhalation.

scholarly journals Assessment of cardiac amyloidosis with 99mTc-pyrophosphate (PYP) quantitative SPECT

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Chao Ren ◽  
Jingyun Ren ◽  
Zhuang Tian ◽  
Yanrong Du ◽  
Zhixin Hao ◽  
...  
Keyword(s):  
Cardiac Amyloidosis ◽  
Activity Concentration ◽  
Standardized Uptake Value ◽  
Blood Pool ◽  
Systematic Difference ◽  
Repeated Measurements ◽  
Quantitative Spect ◽  
Phantom Studies ◽  
Grade 3 ◽  
Operator Reproducibility

Abstract Background 99mTc-PYP scintigraphy provides differential diagnosis of ATTR cardiomyopathy (ATTR-CM) from light chain cardiac amyloidosis and other myocardial disorders without biopsy. This study was aimed to assess the diagnostic feasibility and the operator reproducibility of 99mTc-PYP quantitative SPECT. Method Thirty-seven consecutive patients who underwent a 99mTc-PYP thorax planar scan followed by SPECT and CT scans to diagnose suspected ATTR-CM were enrolled. For the quantitative SPECT, phantom studies were initially performed to determine the image conversion factor (ICF) and partial volume correction (PVC) factor to recover 99mTc-PYP activity concentration in the myocardium for calculating the standardized uptake value (SUV) (unit: g/ml). SUVmax was compared among groups of ATTR-CM, AL cardiac amyloidosis, and other pathogens (others) and among categories of Perugini visual scores (grades 0–3). The intra- and inter-operator reproducibility of quantitative SPECT was verified, and the corresponded repeatability coefficient (RPC) was calculated. Results The ICF was 79,327 Bq/ml to convert count rate in pixel to 99mTc activity concentration. PVC factor as a function of the measured activity concentration ratio in the myocardium and blood-pool was [y = 1.424 × (1 − exp(− 0.759 × x)) + 0.104]. SUVmax of ATTR-CM (7.50 ± 2.68) was significantly higher than those of AL (1.96 ± 0.35) and others (2.00 ± 0.74) (all p < 0.05). SUVmax of grade 3 (8.95 ± 1.89) and grade 2 (4.71 ± 0.23) were also significantly higher than those of grade 1 (1.92 ± 0.31) and grade 0 (1.59 ± 0.39) (all p < 0.05). Correlation coefficient (R2) of SUVmax reached 0.966 to 0.978 with only small systematic difference (intra = − 0.14; inter = − 0.23) between two repeated measurements. Intra- and inter-operator RPCs were 0.688 and 0.877. Conclusions 99mTc-PYP quantitative SPECT integrated with adjustable PVC factors is feasible to quantitatively and objectively assess the burden of cardiac amyloidosis for diagnosis of ATTR-CM.

scholarly journals Radioecological situation on the territory of the Volga Region Department of Hydrometeorology and Environmental Monitoring in 2016

2018 ◽  
Vol 7 (2) ◽  
pp. 40-44
Author(s):  
Yuliya Nikolaevna Zalybina ◽  
Vasily Semenovich Grigoriev ◽  
Valeriy Vitalyevich Sklyuev
Keyword(s):  
Surface Layer ◽  
Environmental Monitoring ◽  
Activity Concentration ◽  
Total Activity ◽  
Volga Region ◽  
Contamination Assessment ◽  
Environment Quality ◽  
Local Agriculture ◽  
Normal Limits ◽  
Radioecological Monitoring

The environment quality is an extremely relevant question, including taking into account radio-ecological situation. The development of local agriculture should take into account various radiation parameters that determine the current radiation situation. In particular, it is necessary to do regular radioecological monitoring of environmental pollution of the Samara Region and adjacent territories on the main types of radiometric observations. The paper focuses on the reliable and rapid detection of radioactive contamination, assessment of the radiation situation with the help of radio-ecological control of natural environment components. In the paper on the basis of the Volga Region Department of Hydrometeorology and Environmental Monitoring data the authors assess the radiation situation in the settlements of Samara, Saratov, Orenburg, Penza and Ulyanovsk Regions. The paper contains values of aerosols -activity concentration in the surface layer of the atmosphere as well as the data of the average annual values in Samara and adjacent regions. According to the data of radioecological monitoring the level of total -activity of radioactive fallout from the atmosphere is shown. The maximum values of the total -activity concentration of the atmospheric surface layer aerosols were recorded in summer, which is due to the secondary wind dust rise from the contaminated areas. It was shown that the average annual value of the total -activity of aerosols according to the results of studies is within the normal limits. The paper also contains conclusions about the degree of danger of the atmosphere surface layer contamination by technogenic radionuclides.

Multi-contrast CT imaging using a high energy resolution CdTe detector and a CZT photon-counting detector

2022 ◽  
Vol 17 (01) ◽  
pp. P01004
Author(s):  
N. Clements ◽  
D. Richtsmeier ◽  
A. Hart ◽  
M. Bazalova-Carter
Keyword(s):  
Contrast Agent ◽  
Energy Resolution ◽  
Photon Counting ◽  
High Energy ◽  
Ct Imaging ◽  
High Energy Resolution ◽  
Great Promise ◽  
Contrast Imaging ◽  
Low Contrast ◽  
Reconstruction Methods

Abstract Computed tomography (CT) imaging with high energy resolution detectors shows great promise in material decomposition and multi-contrast imaging. Multi-contrast imaging was studied by imaging a phantom with iodine (I), gadolinium (Gd), and gold (Au) solutions, and mixtures of the three using a cadmium telluride (CdTe) spectrometer with an energy resolution of 1% as well as with a cadmium zinc telluride (CZT) detector with an energy resolution of 13%. The phantom was imaged at 120 kVp and 1.1 mA with 7 mm of aluminum filtration. For the CdTe data collection, the phantom was imaged using a 0.2 mm diameter x-ray beam with 96 ten-second data acquisitions across the phantom at 45 rotation angles. For the CZT detector, we had 720 projections using a cone beam, and the six detector energy thresholds were set to 23, 33, 50, 64, 81, and 120 keV so that three thresholds corresponded to the K-edges of the contrast agents. Contrast agent isolation methods were then examined. K-edge subtraction and novel spectrometric algebraic image reconstruction (SAIR) were used for the CdTe data. K-edge subtraction alone was used for the CZT data. Linearity plots produced similar R 2 values and slopes for all three reconstruction methods. Comparing CdTe methods, SAIR offered less noise than CdTe K-edge subtraction and better geometric accuracy at low contrast concentrations. CdTe contrast agent images of I, Gd, and Au offered less noise and greater contrast than the CZT images, highlighting the benefits of high energy resolution CdTe detectors for possible use in pre-clinical or clinical CT imaging.

360° CZT gamma cameras for nuclear medicine and molecular imaging

2021 ◽  
Author(s):  
Laetitia Imbert ◽  
Achraf Bahloul ◽  
Antoine Verger ◽  
Pierre-Yves Marie
Keyword(s):  
Nuclear Medicine ◽  
Molecular Imaging ◽  
Gamma Cameras

scholarly journals Changes in the Activity and Concentration of Superoxide Dismutase Isoenzymes (Cu/Zn SOD, MnSOD) in the Blood of Healthy Subjects and Patients with Acute Pancreatitis

Antioxidants ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 948
Author(s):  
Milena Ściskalska ◽  
Monika Ołdakowska ◽  
Grzegorz Marek ◽  
Halina Milnerowicz
Keyword(s):  
Oxidative Stress ◽  
Acute Pancreatitis ◽  
Superoxide Dismutase ◽  
Healthy Subjects ◽  
Activity Concentration ◽  
Total Activity ◽  
Sod1 Gene ◽  
Markers Of Inflammation ◽  
Total Antioxidant ◽  
The Impact

This study was aimed at evaluating the changes in the concentration and activity of all superoxide dismutase isoenzymes (SOD1, SOD2, SOD3) in the blood of patients with acute pancreatitis (AP) and healthy subjects, taking into account the extracellular (plasma) and intracellular (erythrocyte lysate) compartment. The relationships between the activity/concentration of SODs, metal concentration and the markers of inflammation were evaluated. To assess the pro/antioxidative imbalance, the malonyldialdehyde (MDA) concentration and the value of total antioxidant capacity (TAC) were measured. The impact of single-nucleotide polymorphism (SNP) in the SOD1 gene (rs2070424) on the activity/concentration of SOD1 as the main isoenzyme of the SOD family was also analyzed in this study. The SOD2 activity in erythrocytes was increased compared to plasma: 10-fold in the AP patient group and 5-fold in healthy subjects. The plasma of AP patients showed an increased SOD1 concentration and decreased SOD2 and SOD3 concentrations compared to healthy subjects. The Cu/Zn SOD (SOD1 + SOD3) concentration in plasma of AP patients was elevated compared to healthy subjects, but changes in plasma Cu/Zn SOD (SOD1 + SOD3) activity in the examined groups were not observed. An influence of SNP rs2070424 in the SOD1 gene on the total activity of SOD in AP patients (with AG genotype), accompanied by an increased IL-6 concentration, was observed. In oxidative stress conditions induced by inflammation, the participation of individual forms of plasma SOD isoenzymes in total antioxidative activity of SOD changed. A significant increase in the intracellular SOD1 concentration in plasma of AP patients proves the important role of this isoenzyme in the neutralization of oxidative stress induced by impaired Cu and Zn homeostasis. The presence of increased concentration of SOD2 in erythrocytes of healthy subjects and AP patients confirms the important function of this isoenzyme in the antioxidative defense.

DEVELOPMENT AND EVALUATION OF RECONSTRUCTION METHODS FOR AN IN-HOUSE DESIGNED CONE-BEAM MICRO-CT IMAGING SYSTEM

2006 ◽  
Vol 18 (05) ◽  
pp. 270-275 ◽  
Author(s):  
HSIAO-MEI FU ◽  
HO-SHIANG CHUEH ◽  
WEN-KAI TSAI ◽  
JYH-CHENG CHEN
Keyword(s):  
Imaging System ◽  
Cone Beam Ct ◽  
Ct Imaging ◽  
Bone Sample ◽  
Cone Beam ◽  
Human Tooth ◽  
Micro Ct ◽  
Reconstruction Methods ◽  
Pixel Value ◽  
Tooth Sample

Purpose: Cone-beam micro computed tomography CT (micro-CT) can offer comprehensive 3D information and high-resolution images. This technology can be used with other imaging modalities in the preclinical application of molecular imaging research. Image reconstruction algorithm affects final image spatial resolution, which is the primary topic of this study. We use two types of reconstruction methods, which are analytical (tent-FDK) and statistical iterative (convex algorithm) algorithms, to reconstruct the micro-CT images for evaluation. Materials and Methods: In this study, projection data of the Defrise phantom and HA (Hydroxy-Apatite) phantom were obtained using an in-house designed micro-CT imaging system and images were reconstructed with the tent-FDK and convex algorithms. We develop a new way to calculate the system matrix of our micro-CT. Human tooth sample and mouse bone sample data were reconstructed with the analytic and iterative algorithms. Results: The Defrise phantom results show coronal view of the images reconstructed by the tent-FDK and convex algorithms. From the profile of the results, image reconstructed by the convex algorithm has higher pixel value in the high-density layer. Comparison of the results of human tooth sample and mouse bone sample reconstructed by the two kinds of algorithms, the image reconstructed by the convex algorithm has fewer artifacts and more correct pixel value representing for the attenuation coefficients. Conclusion: Tent-FDK algorithm is a kind of useful analytic method to reconstruct cone-beam CT data. We also develop the convex iterative method to reconstruct images for low dose X-ray cone-beam CT, which performs better than the analytical one in general.

scholarly journals Estimation of the Contribution of Dust Storm on April 16, 2020 to Radioactive Contamination of the Atmosphere During Forest Fires in the Exclusion Zone

2021 ◽  
Vol 20 ◽  
pp. 81-95
Author(s):  
M. M. Таlerko ◽  
◽  
Т. D. Lev ◽  
V. O. Кashpur ◽  
◽  
...  
Keyword(s):  
Forest Fires ◽  
Dust Storm ◽  
Nuclear Power ◽  
Activity Concentration ◽  
Total Activity ◽  
137Cs Activity ◽  
Wildland Fires ◽  
Exclusion Zone ◽  
137Cs Activity Concentration ◽  
Burned Areas

On April 16, 2020, a strong dust storm was observed in the northern regions of Ukraine, which coincided with the period of intense wildland fires in the Chornobyl exclusion zone. The activity of 137Cs in aerosol particles released into the atmosphere as a result of resuspension from burned areas in the meadow biocenoses in the exclusion zone is evaluated in the article. Resuspension of radioactively contaminated particles from burned areas formed after fires in meadow biocenoses of the exclusion zone can be a powerful source of air contamination in the zone itself, as well as increase of the radionuclides transport outside it. The total 137Cs activity that entered the atmosphere during the dust storm was estimated to be about 162 GBq, i. e. up to 20% of the total activity emitted in the air during the entire period of forest fires on April 3–20, 2020. The 137Cs emission from burned areas during the dust storm on April 16 and 17 amounted to 0.24% of the total stock of 137Cs activity in this territory. According to the results of modeling, the relative contribution of wildland fires and resuspension due to the dust storm on April 16 and 17 significantly depends on the distance to the emission sources. It was found that the resuspension of radioactive particles from burned areas during the dust storm determined 80–95% of the 137Cs activity concentration in the surface air near Chornobyl nuclear power plant and in Chornobyl city and the rest was due to the continuing forest fires in neighboring territories. The maximum 3-hour averaged value of the 137Cs activity concentration in the air due to resuspension from the burned areas was obtained for the location of the monitoring post VRP-750 of SSE “Ecocenter” to be about 28 mBq/m3 for the period 9–12 hours on April 16. In Kyiv, the 3-hour averaged 137Cs activity concentration due to the dust storm in the Exclusion Zone was calculated as 44 μBq/m3 in the period from 9 to 12 hours on April 17, 2020. This value was only about 4% of the total 137Cs activity in the air in this period.

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