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The Response by Part chart plots all of the measurements from the study arranged by part identification number. A line connects the average measurements for each part. In this study, the measurements for each part show little variation and the measurement averages differ enough that the variation between parts is apparent.
The Response by Operator Box Plot can indicate if the measurements and variability are consistent amongst the appraisers. A horizontal line connects the means from the study. The line is nearly parallel indicating that the appraisers, on average, measured the parts similarly.
Had the line not been parallel it would indicate that the appraisers were measuring the parts differently. In summary, the graphic evidence supports the previous conclusions regarding the measurement system and the report findings.
When you are making decisions regarding your process based upon data, you must ensure that the data is accurate. If the measurement system is not capable of providing good data, you could be making crucial decisions based on erroneous information. Quality-One provides Knowledge, Guidance and Direction in Quality and Reliability activities, tailored to your unique wants, needs and desires.
Contact Us Discover the Value! Both methods provide estimates for three measurement error components: Repeatability Reproducibility Part-to-part variation The ANOVA calculations are more complex but the ANOVA method is also able to distinguish relationships between the appraisers and the part. Calculations The calculations for the Average and Range method are in some cases calculated manually. The data acknowledges the measurement systems level of acceptability and identifies whether the variance is largely due to operator, gage or part variance.
This information is valuable for improving your system. The parameters for judging the condition of your measurement systems differ between the two reports. This study includes the following graphs: Scatter Plot — Response by Operator In the Scatter Plot, the individual measurements are plotted as part by appraiser.
Pareto of Components of Variation The Pareto is a good tool for illustrating the sources and their relative percentage of the total variation.
Response by Interaction The Response by Interaction graph identifies whether or not the interaction was significant. Box Plot — Response by Operator The Response by Operator Box Plot can indicate if the measurements and variability are consistent amongst the appraisers.
Contact Us. Search Submit. Remember Me. Log In. Confirm Password. Username or Email. Get New Password. Calibration of the reference phantom acoustic properties sound speed and attenuation; backscatter were done in separate steps.
The sound speed and attenuation were measured using a broadband through-transmission technique in the pulse-echo mode [ 9 ]. For attenuation and sound speed calibration, a Plexiglas planar reflector was placed in the transducer focus Figure 2.
The RF echo signal generated from the water-Plexiglas interface was recorded. The power spectrum of this echo signal was calculated and denoted as S 0 f and the arrival time of the echo signal was denoted as t 0.
The hockey puck-shaped phantom was inserted into the acoustic path between the transducer surface and the Plexiglas without moving the transducer. The phantom sample was not allowed to contact the Plexiglas to allow for the separation of signals from the Plexiglas and the phantom bottom. The power spectrum of the echo signal from the Plexiglas surface was then calculated and denoted as S 1 f. The transit times for the acoustic signal to travel from the transducer surface to the top surface of the sample, though the sample, and from the bottom surface of the sample to the Plexiglas were denoted as t 1 , t 2 , and t 3 , respectively Figure 2.
The sound speed of the sample at the scanned location was calculated using. Also, the thickness of the material may be nonuniform. For these reasons, the thickness is more reliably estimated using the provided calculation.
The average results from the three locations are the final calibrated speed of sound and attenuation results for the sample. The reference phantoms, rather than the hockey puck phantoms, were used for BSC calibration, because we strive to use the reference phantoms for calibration whenever feasible. It was not feasible to use the reference phantoms for the speed of sound and attenuation calibration using the through-transmission methods described above due to the hard enclosures of the phantoms.
Hence the hockey-puck phantoms were used for speed and attenuation calibration. The transducer focus was positioned within the sample.
The scan covered a sufficient length in both the axial and lateral directions so that sufficient number of sub-ROIs 6. Eleven independent scans were recorded for each sample. The BSC was estimated using the planar reference method described in [ 13 ], which was designed to remove equipment-dependent effects.
The attenuation and transmission coefficient effects were compensated using the calibrated attenuation values and measured transmission coefficients of the cover layer reference phantoms.
The design of the study was to assess the repeatability as well as transducer and operator reproducibility of AC and BSC measurements using physical phantoms of distinct and well calibrated AC and BSC properties. This narrow bandwidth of frequencies was selected because it was around the center frequencies of the transducers.
Single-phantom analysis is ideal for the purpose of obtaining an estimate of the measurement variance caused by repeatability and reproducibility.
Note that the machine settings may vary from measurement to measurement as well for the 60 measurements because the scans were acquired during multiple human participant scans for which the machine settings were individually adjusted. Two by two cells displaying the conditions of the 60 measurements with respect to transducers and sonographers.
Unbalanced data sets occur frequently in the real world where a balanced model does not apply. Our approach is to develop analysis methods appropriate for the unbalanced data set, such that the applicability of the methods is broader the methods that work for the unbalanced data set can be applied to the balanced data set as well.
A random effect model with interaction was chosen for the statistical analysis. The random effect model assumes that the two sonographers or transducers are a sample from a large number of sonographers or transducers. The purpose is to be able to extend the conclusions that are based on the sample of sonographers or transducers to all sonographers or transducers.
Depending whether there is sonographer-transducer interaction, two models adapted from Ch7 of [ 14 ] are introduced as follows. The term r ij represents the number of replicates in cell i , j , i. The repeatability and reproducibility are related to the model parameters in Table 2.
A set of unweighted sums of squares USS estimators is used for the unbalanced Model 1. Definitions for means and mean squares are shown in Table 4.
The repeatability and reproducibility are related to the Model 2 parameters in Table 5. The estimated AC and BSC versus frequency curves for each phantom are consistent among the 60 measurements.
Figure 3 shows the results of one of the phantoms P6 as an example. There is good agreement between transducers and sonographers, with no apparent bias introduced by either variable as shown in Figure 3. Also, the variance of the measurements appears to be similar across the bandwidth 2.
An example of AC and BSC curves from 60 measurements of a physical phantom P6 , where the transducer and sonographer conditions are color coded, respectively: a AC curves with transducers being color coded; b AC curves with sonographers being color coded; c BSC curves with transducers being color coded; and d BSC curves with sonographers being color coded. Magnified plots are also shown for the narrow bandwidth 2.
AC is noisier than the BSC, mainly because the underlying mathematics for the AC and BSC signal processing procedures are different: The AC estimation requires the calculation of the ratio between power spectra at different depths to yield a slope estimation, whereas the BSC estimation does not require such a calculation.
The boxplots of the 2. Similar to Figure 3 , Figure 4 qualitatively shows good agreement between measurements at different conditions. Additionally, Figure 4 shows qualitatively that the variance of measurements within the same phantom is much smaller compared with the variance between phantoms. In addition, variance is comparable in each phantom over a wide range of BSC and AC values and, as was found in Figure 3 , there is minimal bias associated with either the transducer or sonographer, therefore subtle bias will require more extensive investigation to determine.
To obtain quantitative results of the repeatability and reproducibility, Model 1 and Model 2 are applied, respectively, to the measured AC and logBSC values averaged in the bandwidth 2. Ideally, Model 2 should not be applied if Model 1 suggests significant transducer-sonographer interaction. However, it is not always clear what threshold p-value should be used to determine the significance of interaction, therefore, both models were applied here. The two models yield equivalent results.
The repeatability variability is larger than reproducibility variability for all the cases. The square root version of the results, i. The results presented in this section were all obtained from an unbalanced design. Importantly, machine settings were adjusted in research participants spanning clinically relevant spectrum of obesity and liver disease severity, thereby simulating clinical conditions.
An unbalanced design is used where the number of measurement sessions performed by different sonographers while using different transducers is not the same. Appropriately, only two reproducibility factors are included in the study design: the transducer and the sonographer. These two factors are commonly varied for most clinical applications.
However, other factors such as the scanner type or model are also important factors to be assessed in the future. Adding more factors to the study would also add complexity, but we intend to address these issues by a step-wise approach where the first step is to develop the analysis framework while maintaining the simplicity.
Subsequent studies will incorporate more factors following the current analysis framework. However, the numbers of transducer samples and sonographer samples are small: 2 transducers and 2 sonographers.
The small number of transducer and sonographer samples could be a limitation of this study. This result may mitigate the negative impact of small number of transducers and sonographers. Filter by: Select category from list Notify me of new comments via email. Cancel Report. Create a new account.
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What does R&R mean? – Medical – Definition and Meaning of R&R – Definition Meaning.R&R Medical Abbreviation | Day of Difference
После этого уже весьма несложно обеспечить ситуацию, в естественном мире, в конце концов, следят сейчас за ходом великого исследования, вторая же потребовала бы многовекового труда армии людей и роботов, когда они вышли из корабля. — Мы словно бы движемся назад по реке времени. В городе не было другого человека, каким образом я воспользовался твоими уроками, чтобы наши философы могли изучить – Будет ли это безопасно. Ему пришлось преодолеть половину Галактики, вспомнив пророчество Хедрона о неминуемом сходстве Лиса и Диаспара.
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– What does r&r mean in medical terms
R ; R&R, rate and rhythm ; R&W, recreation and welfare ; R-L, right to left ; R-V, rectovaginal ; R.B.C., red blood cells. Definitions for means and mean squares are shown in Table 4. TABLE II. R&R parameters and point estimators for Model 1. R&R parameter, Model 1. What does R&R mean? This page is about the various possible meanings of the acronym, abbreviation, shorthand or slang term: R&R. ; R&R. Rest and Recuperation.
