scholarly journals An international multi-center investigation on the accuracy of radionuclide calibrators in nuclear medicine theragnostics

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Clarita Saldarriaga Vargas ◽  
Matthias Bauwens ◽  
Ivo N. A. Pooters ◽  
Stefaan Pommé ◽  
Steffie M. B. Peters ◽  
...  
Keyword(s):  
Measurement Accuracy ◽  
Reference Value ◽  
Sample Container ◽  
Large Variability ◽  
Radionuclide Calibrator ◽  
Activity Measurements ◽  
Measured Activity ◽  
Patient Doses ◽  
Multi Center Study ◽  
Accurate Quantification

Abstract Background Personalized molecular radiotherapy based on theragnostics requires accurate quantification of the amount of radiopharmaceutical activity administered to patients both in diagnostic and therapeutic applications. This international multi-center study aims to investigate the clinical measurement accuracy of radionuclide calibrators for 7 radionuclides used in theragnostics: 99mTc, 111In, 123I, 124I, 131I, 177Lu, and 90Y. Methods In total, 32 radionuclide calibrators from 8 hospitals located in the Netherlands, Belgium, and Germany were tested. For each radionuclide, a set of four samples comprising two clinical containers (10-mL glass vial and 3-mL syringe) with two filling volumes were measured. The reference value of each sample was determined by two certified radioactivity calibration centers (SCK CEN and JRC) using two secondary standard ionization chambers. The deviation in measured activity with respect to the reference value was determined for each radionuclide and each measurement geometry. In addition, the combined systematic deviation of activity measurements in a theragnostic setting was evaluated for 5 clinically relevant theragnostic pairs: 131I/123I, 131I/124I, 177Lu/111In, 90Y/99mTc, and 90Y/111In. Results For 99mTc, 131I, and 177Lu, a small minority of measurements were not within ± 5% range from the reference activity (percentage of measurements not within range: 99mTc, 6%; 131I, 14%; 177Lu, 24%) and almost none were outside ± 10% range. However, for 111In, 123I, 124I, and 90Y, more than half of all measurements were not accurate within ± 5% range (111In, 51%; 123I, 83%; 124I, 63%; 90Y, 61%) and not all were within ± 10% margin (111In, 22%; 123I, 35%; 124I, 15%; 90Y, 25%). A large variability in measurement accuracy was observed between radionuclide calibrator systems, type of sample container (vial vs syringe), and source-geometry calibration/correction settings used. Consequently, we observed large combined deviations (percentage deviation > ± 10%) for the investigated theragnostic pairs, in particular for 90Y/111In, 131I/123I, and 90Y/99mTc. Conclusions Our study shows that substantial over- or underestimation of therapeutic patient doses is likely to occur in a theragnostic setting due to errors in the assessment of radioactivity with radionuclide calibrators. These findings underline the importance of thorough validation of radionuclide calibrator systems for each clinically relevant radionuclide and sample geometry.

scholarly journals An international multi-center investigation on the accuracy of radionuclide calibrators in nuclear medicine theranostics

2020 ◽  
Author(s):  
Clarita Saldarriaga Vargas ◽  
Matthias Bauwens ◽  
Ivo NA Pooters ◽  
Stefaan Pommé ◽  
Steffie MB Peters ◽  
...  
Keyword(s):  
Measurement Accuracy ◽  
Reference Value ◽  
Sample Container ◽  
Large Variability ◽  
Radionuclide Calibrator ◽  
Activity Measurements ◽  
Measured Activity ◽  
Patient Doses ◽  
Multi Center Study ◽  
Accurate Quantification

Abstract Background: Personalized molecular radiotherapy based on theragnostics requires accurate quantification of the amount of radiopharmaceutical activity administered to patients both in diagnostic and therapeutic applications. This international multi-center study aims to investigate the clinical measurement accuracy of radionuclide calibrators for 7 radionuclides used in theragnostics: 99mTc, 111In, 123I, 124I, 131I, 177Lu and 90Y.Methods: In total, 32 radionuclide calibrators from 8 hospitals located in the Netherlands, Belgium and Germany were tested. For each radionuclide, a set of four samples comprising two clinical containers (10-mL glass vial and 3-mL syringe) with two filling volumes were measured. The reference value of each sample was determined by two certified radioactivity calibration centers (SCK CEN and JRC) using two secondary standard ionization chambers. The deviation in measured activity with respect to the reference value was determined for each radionuclide and each measurement geometry. In addition, the combined systematic deviation of activity measurements in a theragnostic setting was evaluated for 5 clinically-relevant theragnostic pairs: 131I/123I, 131I/124I, 177Lu/111In, 90Y/99mTc and 90Y/111In.Results: For 99mTc, 131I, and 177Lu, a small minority of measurements were not within ±5% range from the reference activity (percentage of measurements not within range: 99mTc: 6%, 131I: 14%, 177Lu: 24%) and almost none were outside ±10% range. However, for 111In, 123I, 124I and 90Y more than half of all measurements were not accurate within ±5% range (111In: 51%, 123I: 83%, 124I: 63%, 90Y: 61%) and not all were within ±10% margin (111In: 22%, 123I: 35%, 124I: 15%, 90Y: 25%). A large variability in measurement accuracy was observed between radionuclide calibrator systems, type of sample container (vial vs syringe), and source-geometry calibration/correction settings used. Consequently, we observed large combined deviations (percentage deviation > ±10%) for the investigated theragnostic pairs, in particular for 90Y/111In, 131I/123I and 90Y/99mTc.Conclusions: Our study shows that substantial over- or under-estimation of therapeutic patient doses are likely to occur in a theragnostic setting due to errors in the assessment of radioactivity with radionuclide calibrators. These findings underline the importance of thorough validation of radionuclide calibrator systems for each clinically-relevant radionuclide and sample geometry.

scholarly journals An international multi-center investigation on the accuracy of radionuclide calibrators in nuclear medicine theranostics

2020 ◽  
Author(s):  
Clarita Saldarriaga Vargas ◽  
Matthias Bauwens ◽  
Ivo NA Pooters ◽  
Stefaan Pommé ◽  
Steffie MB Peters ◽  
...  
Keyword(s):  
Measurement Accuracy ◽  
Reference Value ◽  
Sample Container ◽  
Large Variability ◽  
Radionuclide Calibrator ◽  
Activity Measurements ◽  
Measured Activity ◽  
Patient Doses ◽  
Multi Center Study ◽  
Accurate Quantification

Abstract Background: Personalized molecular radiotherapy based on theranostics requires accurate quantification of the amount of radiopharmaceutical activity administered to patients both in diagnostic and therapeutic applications. This international multi-center study aims to investigate the clinical measurement accuracy of radionuclide calibrators for 7 radionuclides used in theranostics: 99mTc, 111In, 123I, 124I, 131I, 177Lu and 90Y.Methods: In total, 32 radionuclide calibrators from 8 hospitals located in the Netherlands, Belgium and Germany were tested. For each radionuclide, a set of four samples comprising two clinical containers (10-mL glass vial and 3-mL syringe) with two filling volumes were measured. The reference value of each sample was determined by two certified radioactivity calibration centers (SCK CEN and JRC) using two secondary standard ionization chambers. The deviation in measured activity with respect to the reference value was determined for each radionuclide and each measurement geometry. In addition, the combined systematic deviation of activity measurements in a theranostic setting was evaluated for 5 clinically-relevant theranostic pairs: 131I/123I, 131I/124I, 177Lu/111In, 90Y/99mTc and 90Y/111In.Results: For 99mTc, 131I, and 177Lu, a small minority of measurements were not within ±5% range from the reference activity (percentage of measurements not within range: 99mTc: 6%, 131I: 14%, 177Lu: 24%) and almost none were outside ±10% range. However, for 111In, 123I, 124I and 90Y more than half of all measurements were not accurate within ±5% range (111In: 51%, 123I: 83%, 124I: 63%, 90Y: 61%) and not all were within ±10% margin (111In: 22%, 123I: 35%, 124I: 15%, 90Y: 25%). A large variability in measurement accuracy was observed between radionuclide calibrator systems, type of sample container (vial vs syringe), and source-geometry calibration/correction settings used. Consequently, we observed large combined deviations (percentage deviation > ±10%) for the investigated theranostic pairs, in particular for 90Y/111In, 131I/123I and 90Y/99mTc.Conclusions: Our study shows that substantial over- or under-estimation of therapeutic patient doses are likely to occur in a theranostic setting due to errors in the assessment of radioactivity with radionuclide calibrators. These findings underline the importance of thorough validation of radionuclide calibrator systems for each clinically-relevant radionuclide and sample geometry.

scholarly journals Effects of Loading and Boundary Conditions on the Performance of Ultrasound Compressional Viscoelastography: A Computational Simulation Study to Guide Experimental Design

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2590
Author(s):  
Che-Yu Lin ◽  
Ke-Vin Chang
Keyword(s):  
Boundary Conditions ◽  
Simulation Study ◽  
Viscoelastic Properties ◽  
Measurement Accuracy ◽  
Computational Simulation ◽  
Vertical Direction ◽  
Fixation Method ◽  
Element Analysis ◽  
Sample Container

Most biomaterials and tissues are viscoelastic; thus, evaluating viscoelastic properties is important for numerous biomedical applications. Compressional viscoelastography is an ultrasound imaging technique used for measuring the viscoelastic properties of biomaterials and tissues. It analyzes the creep behavior of a material under an external mechanical compression. The aim of this study is to use finite element analysis to investigate how loading conditions (the distribution of the applied compressional pressure on the surface of the sample) and boundary conditions (the fixation method used to stabilize the sample) can affect the measurement accuracy of compressional viscoelastography. The results show that loading and boundary conditions in computational simulations of compressional viscoelastography can severely affect the measurement accuracy of the viscoelastic properties of materials. The measurement can only be accurate if the compressional pressure is exerted on the entire top surface of the sample, as well as if the bottom of the sample is fixed only along the vertical direction. These findings imply that, in an experimental validation study, the phantom design should take into account that the surface area of the pressure plate must be equal to or larger than that of the top surface of the sample, and the sample should be placed directly on the testing platform without any fixation (such as a sample container). The findings indicate that when applying compressional viscoelastography to real tissues in vivo, consideration should be given to the representative loading and boundary conditions. The findings of the present simulation study will provide a reference for experimental phantom designs regarding loading and boundary conditions, as well as guidance towards validating the experimental results of compressional viscoelastography.

scholarly journals The IG- file use to Gauge the Apical Diameter in Endodontics: An In Vitro Study

2018 ◽  
Vol 12 (1) ◽  
pp. 638-646 ◽  
Author(s):  
Massimo Amato ◽  
Alfredo Iandolo ◽  
Giuseppe Pantaleo ◽  
Dina Abtellatif ◽  
Michele Simeone ◽  
...  
Keyword(s):  
Measurement Accuracy ◽  
Reference Value ◽  
In Vitro Study ◽  
Vitro Study ◽  
Root Canals ◽  
New Instrument ◽  
Clinician Experience ◽  
Incorrect Measurement ◽  
The Difference

Aim: The aim of this study was to evaluate the efficacy of the IG-file, a new instrument designed for apical diameter gauging. Materials and Methods: After shaping with F1 Universal Protaper, 60 roots were randomly divided into two groups and assigned to two operators, One Expert in Endodontics (EO) and One Unexpert (UO). In each sample, after canal curvatures have been detected, the apical diameters were measured with the IG-file and the K-NiTi. The results were compared with the reference value obtained by retrograde apical gauging. The data were statistically analyzed. Results: Among 60 samples, 10% of errors were recorded when the IG-files were used; in the K-NiTi group the incorrect measurements were 70%. In both groups (expert and unexpert) the IG-file measurements were more accurate than the K-NiTi (90 vs 33 and 90 vs 26,7). The differences were statistically significant. In curved canals, the difference between measurement rates performed with both instruments was statistically significant (85,7% IG-file vs 28,6% K-NiTi) as well as for the samples without curvatures (92,3% IG file vs 30,8% NiTi file). In root canals without curvatures overestimation errors in K-NiTi file group are more frequent than underestimation errors. This difference was statistically significant. Conclusion: A proper gauging of the apical diameter has a key role in endodontic therapy; an incorrect measurement can lead to clinical failures. This “in vitro” study highlights that IG-file improves measurement accuracy independently from clinician experience. Furthermore, in curved canals, the IG-file is more accurate than K-NiTi.

scholarly journals Metrological Assurance for Radioactive Waste Monitors Based on HPGe Detectors

2018 ◽  
pp. 47-53
Author(s):  
F. V. Finkel ◽  
А. J. Kail ◽  
А. D. Sokolov ◽  
V. V. Gostilo
Keyword(s):  
Radioactive Waste ◽  
Simulation Method ◽  
Accounting System ◽  
Position Change ◽  
Bar Code ◽  
Russian Research Institute ◽  
Activity Measurements ◽  
Hpge Detectors ◽  
Measured Activity

The methods of calibration and parameters measurements of radioactive waste monitors with the purpose to provide the unity and required precision of the characterization of waste activity measurements are reviewed. The monitors based on HPGe detectors are intended for small, medium and large volumes of radioactive waste and are equipped with rotation mechanisms for the barrel with strain-gauge balance and actuator for horizontal shifting, dosimeters for dose rate measurement, software and accounting system by bar code. The required range of the measured activity which is necessary for the operation of the spectrometric section without overloadings is ensured by removal or approaching of the barrel to the detector and position change of the vertical lead shields of the collimator. The rotation of the barrel with RAW ensures decreasing the measurement error at the presence of the heterogeneities by density of the filler and inequalities of activity distribution by the barrel volume. The monitors have different mechanisms and accessories for the measurements in various modes. The calibration of the monitors by the registration efficiency is performed using standard sources in point geometry as well as by the complex calculation of the efficiencies curves by Monte Carlo simulation method. For calibration of the monitors by the method of direct comparison the volumetric activities sources in real 200, 400 and 700 l barrels with matrix-fillers placed inside were manufactured and certified. The manufactured volumetric measures of activity have been certificated at the All-Russian Research Institute of Metrology named after D. I. Mendeleev. An integral part of the metrological support of all developed RAWmonitors is their software, features of which are being considered.

scholarly journals Comparison of G-guide and Image-free Navigation System in Accuracy of Stem Anteversion Assessment During Total Hip Arthroplasty

2019 ◽  
Vol 13 (1) ◽  
pp. 109-116 ◽  
Author(s):  
Yuki Fujihara ◽  
Shigeo Fukunishi ◽  
Tomokazu Fukui ◽  
Shoji Nishio ◽  
Yu Takeda ◽  
...  
Keyword(s):  
Image Analysis ◽  
Navigation System ◽  
Measurement Accuracy ◽  
Femoral Stem ◽  
Reference Value ◽  
Image Analysis System ◽  
Measurement Systems ◽  
Comparative Accuracy ◽  
Ct Image Analysis ◽  
Analysis System

Introduction: We have developed and utilized the Gravity-guide (G-guide) as a simple manual instrument for intraoperative assessment and adjustment of stem anteversion (AV). Since 2013, we simultaneously measured stem AV using the G-guide and image-free navigation during THA procedure. The purpose of this study was to compare the measurement accuracy of the G-guide and navigation system using the postoperative CT results as a reference. Methods: In total, 59 hips in 56 patients who underwent primary THA using both the G-guide and image-free navigation system were included in the study. All patients underwent postoperative CT examination, and the femoral stem AV was assessed using a 3D image analysis system (Zed hip, LEXI, Japan). The AV angle derived from the postoperative CT image analysis was used as the reference value to assess the accuracy of the two intraoperative measurement systems. Results: The discrepancy between the G-guide and the postoperative CT-measured values averaged 5.0° ± 3.9°, while the corresponding value for the navigation system was 5.2° ± 4.1°. Acceptable accuracy with a measurement error of less than 10° was achieved in 86% and 90% of the cases for the G-guide and navigation measurements respectively. Conclusion: Consequently, it was shown that both navigation and G-guide measurements can achieve comparative accuracy and are clinically useful.

Does a food intervention makes abiraterone treatment affordable?

2019 ◽  
Vol 37 (15_suppl) ◽  
pp. e16523-e16523
Author(s):  
Nielka P. Van Erp ◽  
Guillemette Emma Benoist ◽  
Winald R. Gerritsen ◽  
Niven Mehra ◽  
David Burger ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Metastatic Prostate Cancer ◽  
Fold Increase ◽  
Plasma Exposure ◽  
Time Curve ◽  
Large Variability ◽  
Fasted State ◽  
Effect Of Food ◽  
Multi Center Study ◽  
Clinical Trial Information

e16523 Background: Abiraterone is registered for metastatic prostate cancer. It is used in a fixed oral dose of 1000mg OD in a fasted state in combination with 10mg prednisone daily. Although large differences in the effect of food on abiraterone exposure are reported (ranging from 1-10 fold increase in area under the concentration time curve (AUC)) it is generally accepted that abiraterone is much better absorbed in the presence of food. By administering abiraterone with food a reduced dose can be given while maintaining equivalent abiraterone exposure. Moreover aadministering abiraterone with food is more patient friendly and it could significantly reduce the treatment costs of abiraterone.The aim of this study was to establish the bio-equivalent lower dose of abiraterone when taken with a continental breakfast compared to the standard intake of 1000mg OD in fasted state. Methods: In this phase I cross-over multi-center study abiraterone pharmacokinetics (PK) were evaluated in patients with metastatic prostate cancer who were treated with 1000 mg abiraterone in a fasted state, followed by 500 mg taken with a continental breakfast. After both periods of 14 days, abiraterone plasma exposure was measured. Bioequivalence was assumed when the GMR (fed/fasted) of the AUC0-24h and Cmax and their 90% confidence interval (CI) were within the range of 0.8 and 1.7. Results: 14 patients were enrolled into the study, of whom 12 were eligible for PK analysis. GMR (fed/fasted) AUC0-24h was 0.88 (90% CI 0.73-1.07), GMR Cmax was 1.03 (CI 0.79-1.34) and the GMR of Ctrough was 0.81 (90% CI 0.60-1.10). Conclusions: Ingesting 500mg abiraterone with a continental breakfast was not considered bio-equivalence when compared to 1000mg taken fasted. The criteria for bio-equivalence could not be met due to the large variability in pharmacokinetics of abiraterone within and between patients. Due to this large variability in abiraterone exposure, we believe that dose optimization by food intake is not a feasible strategy for abiraterone. The intake of abiraterone with food could not be advised based on the results presented in our study. Clinical trial information: NCT02883166. [Table: see text]

scholarly journals Improving pupil diameter measurement accuracy in a remote eye tracking system

2019 ◽  
Vol 63 (1) ◽  
pp. 49-53
Author(s):  
Joseph T Coyne ◽  
Noelle Brown ◽  
Cyrus K. Foroughi ◽  
Ciara M Sibley
Keyword(s):  
Eye Tracking ◽  
Measurement Accuracy ◽  
Pupil Diameter ◽  
Tracking System ◽  
Reference Value ◽  
Cognitive Tasks ◽  
Diameter Measurement ◽  
Average Difference ◽  
Fixed Size ◽  
System Data

Pupil diameter (PD) has been used to track changes in mental effort across a broad range of cognitive tasks for over 60 years. PD is often measured from remote eye tracking systems, which all have the same limitation: the lack of a known reference value to convert the pixels captured within the systems to millimeters. Researchers frequently normalize their data within an individual to overcome this issue, however recent studies have found individual differences in resting PDs. This paper investigated the use of a fiduciary marker of a fixed size and an individual’s interpupillary distance, as known reference values. Both techniques substantially improved the accuracy of PD data compared to the unadjusted system data. Further, the average difference between both techniques and the uncorrected pupil diameter was just under .4mm, which is approximately the equivalent of most studies finding differences in cognitive load.

P4381Improvement of the PISA method in the setting of mitral regurgitation of complex geometry

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
C Papolla ◽  
J Adda ◽  
G Habib ◽  
R Rieu
Keyword(s):  
Mitral Regurgitation ◽  
Measurement Accuracy ◽  
Complex Geometry ◽  
Electromagnetic Flowmeter ◽  
Reference Value ◽  
Proximal Isovelocity Surface Area ◽  
Multiple Jets ◽  
Circular Orifice ◽  
Double Activation

Abstract Background Doppler echocardiographic methods, such as proximal isovelocity surface area (PISA) are used to quantify mitral regurgitations. However, their accuracy and reproducibility are still discussed, especially in case of mitral regurgitations of complex geometry. Purpose The aim of this study was to test in-vitro the accuracy of the PISA method depending on the shape and number of regurgitant flows. Methods Several regurgitant volumes (RV) were produced through various regurgitation severities and shapes in a left heart double activation simulator. Circular mitral regurgitation (MR) was performed with a circular orifice in a rigid plate. Triangular and oblong MR were performed by suturing the extremity of a bioprosthesis leaflet to the annulus. Multiple jets regurgitation was performed by suturing centrally the two leaflets of an anatomically shaped mitral valve made of hydrogel. A transesophageal echocardiography probe was used to acquire the data. The RV was calculated with the classical PISA method (hemispheric assumption), or by considering the PISA as a hemicylinder or a double hemisphere. It was then compared to a reference value obtained from an electromagnetic flowmeter measurement (accuracy ± 2 ml/min). Results A central and circular orifice was correctly quantified, as expected, with the hemispheric assumption (bias 0.2±1.9 ml, p=0.46). For a triangular central jet, the hemispheric assumption best estimated the RV (−3.5±14.8 ml, p=0.10). An oblong MR was underestimated with the hemispheric assumption (−18.3±14.9 ml, p<0.01) whereas the hemicylindrical assumption was more accurate (−0.2±5.8 ml, p=0.85). In case of 2 regurgitant jets, considering only the largest jet led to an important underestimation (−10.9±5.6 ml, p<0.01), whereas adding the two RV was more accurate (−1.2±8.2 ml, p=0.50). Conclusions In case of a single central orifice, the hemispheric assumption correctly quantified the MR. In case of an oblong orifice, the hemicylindrical assumption provided a good quantification with simple measurements. In case of multiple jets of different sizes, it was more accurate to consider both jets for RV calculation. Acknowledgement/Funding Képhalios part of Affluent Medical

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