[Evaluation of Transmitted X-ray Spectrum, Lead Equivalent, and Uniformity of Radiation Protective Clothing Made of Lead-containing and Lead-free Materials].

PURPOSE: The purpose of this study was to evaluate the protective performance of several new radiation-protective clothing and to clarify issues of quality control. METHODS: The composition of the shielding elements was analyzed using X-ray fluorescence analysis, and the energy spectrum of transmitted X-rays was measured. Furthermore, the lead equivalent and uniformity were measured from the transmitted X-ray doses according to Japanese industrial standards (JIS). Uniformity was evaluated by transmitting X-ray images of each radiation protective clothing in addition to the conventional method. RESULTS: The energy spectrum showed K-absorption edges of lead, bismuth, tin, etc., which were detected in the composition analysis. The multi-layered protective material maintained higher shielding ability at high tube voltages. In addition, X-ray images of the radiation-protective clothing showed uneven density and dots, and the differences in uniformity measurement methods and points that didn't meet the required shielding capacity were seen. CONCLUSION: The current JIS does not allow accurate evaluation of the lead equivalent and uniformity, so visual evaluation of X-ray images is important. It is necessary to establish standardized standards for quality control performed by each facility.

Optimal assessment for anterior talofibular ligament injury utilizing stress ultrasound entails internal rotation during plantarflexion.

OBJECTIVES: An optimal load and ankle position for stress ultrasound of the injured anterior talofibular ligament (ATFL) are unknown. The objectives of this study were to compare stress ultrasound and ankle kinematics from a 6 degree-of-freedom (6-DOF) robotic testing system as a reference standard for the evaluation of injured ATFL and suggest cut-off values for ultrasound diagnosis. METHODS: Ten fresh-frozen human cadaveric ankles were used. Loads and ankle positions examined by the 6-DOF robotic testing system were: 40 N anterior load, 1.7 Nm inversion, and 1.7 Nm internal rotation torques at 30° plantarflexion, 15° plantarflexion, and 0° plantarflexion. Bony translations were measured by ultrasound and a robotic testing system under the above conditions. After measuring the intact ankle, ATFL was transected at its fibular attachment under arthroscopy. Correlations between ultrasound and robotic testing systems were calculated with Pearson correlation coefficients. Paired t-tests were performed for comparison of ultrasound measurements of translation between intact and transected ATFL and unloaded and loaded conditions in transected ATFL. RESULTS: Good agreement between ultrasound measurement and that of the robotic testing system was found only in internal rotation at 30° plantarflexion (ICC â€‹= â€‹0.77; 95% confidence interval 0.27-0.94). At 30° plantarflexion, significant differences in ultrasound measurements of translation between intact and transected ATFL (p â€‹< â€‹0.01) were found in response to 1.7 Nm internal rotation torque and nonstress and stress with internal rotation (p â€‹< â€‹0.01) with mean differences of 2.4 â€‹mm and 1.9 â€‹mm, respectively. CONCLUSION: Based on the data of this study, moderate internal rotation and plantarflexion are optimal to evaluate the effects of ATFL injury when clinicians utilize stress ultrasound in patients. LEVEL OF EVIDENCE: III.

Ultrasound-Guided Anterior Talofibular Ligament Repair With Augmentation Can Restore Ankle Kinematics: A Cadaveric Biomechanical Study.

Background: Anterior talofibular ligament (ATFL) repair of the ankle is a common surgical procedure. Ultrasound (US)-guided anchor placement for ATFL repair can be performed anatomically and accurately. However, to our knowledge, no study has investigated ankle kinematics after US-guided ATFL repair. Hypothesis: US-guided ATFL repair with and without inferior extensor retinaculum (IER) augmentation will restore ankle kinematics. Study Design: Controlled laboratory study; Level of evidence, 4. Methods: A 6 degrees of freedom robotic testing system was used to apply multidirectional loads to fresh-frozen cadaveric ankles (N = 9). The following ankle states were evaluated: ATFL intact, ATFL deficient, combined ATFL repair and IER augmentation, and isolated US-guided ATFL repair. Three loading conditions (internal-external rotation torque, anterior-posterior load, and inversion-eversion torque) were applied at 4 ankle positions: 30° of plantarflexion, 15° of plantarflexion, 0° of plantarflexion, and 15° of dorsiflexion. The resulting kinematics were recorded and compared using a 1-way repeated-measures analysis of variance with the Benjamini-Hochberg test. Results: Anterior translation in response to an internal rotation torque significantly increased in the ATFL-deficient state compared with the ATFL-intact state at 30° and 15° of plantarflexion (P = .022 and .03, respectively). After the combined US-guided ATFL repair and augmentation, anterior translation was reduced significantly compared with the ATFL-deficient state at 30° and 15° of plantarflexion (P = .0012 and .005, respectively). Anterior translation was not significantly different for the isolated ATFL-repair state compared with the ATFL-deficient or ATFL-intact states at 30° and 15° of plantarflexion. Conclusion: Combined US-guided ATFL repair with augmentation of the IER reduced lateral ankle laxity due to ATFL deficiency. Isolated US-guided ATFL repair did not reduce laxity due to ATFL deficiency, nor did it increase instability compared with the intact ankle. Clinical Relevance: US-guided ATFL repair with IER augmentation is a minimally-invasive technique to reduce lateral ankle laxity due to ATFL deficiency. Isolated US-guided ATFL repair may be a viable option if accompanied by a period of immobilization.

An improved quantitative ultrasonographic technique could assess anterior translation of the glenohumeral joint accurately and reliably.

PURPOSE: Since poor repeatability of the load and shift test using a grading scale has been reported, an objective and quantitative method to assess anterior translation should be established to assess glenohumeral joint function. The purpose of this study was to assess the accuracy and repeatability of the ultrasonographic techniques to quantify anterior translation of the glenohumeral joint. METHODS: Eight fresh-frozen cadaveric shoulders were used. For the standard technique, the ultrasound transducer was positioned on the anterolateral aspect of the shoulder viewing the coracoid process, glenoid, and humeral head. For the revised technique, the transducer was positioned on the anterior aspect of the shoulder, perpendicular to the scapular plane, viewing the conjoint tendon, glenoid, and humeral head. During the load and shift test, the distance between anterior edges of the glenoid and the humeral head was measured. The difference between distances before and after applying an anterior load was calculated as an anterior translation and compared with the anterior translation assessed using a motion tracking system. The repeatability and accuracy of both techniques were analyzed statistically. RESULTS: Intra- and inter-observer repeatability was good-excellent for both ultrasonographic techniques (ICC, 0.889-0.998). The revised technique achieved a stronger correlation to the anterior translations obtained using the motion tracking system (R = 0.810-0.913, p < 0.001) than the standard technique (R = 0.619-0.806, p < 0.001). CONCLUSION: Better accuracy and repeatability was found in the revised technique than the standard technique. The revised technique will be useful to determine the individual laxity and modify the treatment plan and return-to-sports protocol. LEVEL OF EVIDENCE: III.

Sonographically Guided Anchor Placement in Anterior Talofibular Ligament Repair Is Anatomic and Accurate.

BACKGROUND: Arthroscopic repair is a widely accepted surgical treatment for chronic ankle instability; however, recent studies have shown that arthroscopic repair is nonanatomic in its anchor placement and resultant biomechanics. Ultrasound may improve the accuracy of the anchor placement. HYPOTHESIS: Our hypothesis was that the accuracy of anchor placement in sonographically guided anterior talofibular ligament (ATFL) repair will be comparable with that in open ATFL repair. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: The study included 26 patients who received surgical treatment between April 2012 and October 2019 for chronic ankle instability. Fifteen patients underwent open modified Broström repair and 11 underwent sonographically guided ATFL repair. The distance between the anchor hole and the fibular obscure tubercle was measured using 3-dimensional computed tomography and was compared between the operative procedures. For comparison, a noninferiority trial was employed, with open modified Broström repair as the reference surgery. The noninferiority margin was defined as 5 mm. RESULTS: The mean ± SD distance between the anchor and fibular obscure tubercle was 6.0 ± 2.7 mm in open repair and 5.6 ± 3.3 mm in sonographically guided repair. The mean difference in distance between the techniques (open repair - sonographically guided repair) was 0.37 mm (95% CI, -2.1 to 2.9 mm). The lower margin of the confidence interval was within the noninferiority margin (-5 to 5 mm). CONCLUSION: Anchor placement under sonographically guided ATFL repair was equivalent to that of open ATFL repair and can be considered anatomic and accurate.

Low-Noise Photoplethysmography Sensor Using Correlated Double Sampling for Heartbeat Interval Acquisition.

This study designs a low-power photoplethysmography (PPG) sensor based on the error compensation method for heartbeat interval acquisition. To perform heartbeat monitoring in daily life, it is necessary to obtain long-term and accurate heartbeat interval data with low power consumption, because of the limited size and battery capacity of the PPG sensor. Effective reduction in the power consumption of the sensor requires the duty-cycled LEDs and lowering pulse repetition frequency (PRF), i.e., decreasing the sampling rate. However, these methods reduce the accuracy of the heartbeat interval measurement because of signal-to-noise ratio (SNR) degradation and sampling errors. We propose an algorithm for heartbeat interval error compensation and incorporate a low-noise readout circuit to improve SNR. The readout circuit uses current integration to achieve low duty-cycle LED driving. A correlated double sampling (CDS) is introduced to minimize the random noise arising from the switching operation of the integration circuit. An error compensation method based on the PPG waveform similarity is also introduced using the autocorrelation and linear interpolation. The measurement results obtained from nine subjects show that a total current consumption of 28.2 µA is achieved with a 20-Hz PRF and 0.3% LED duty cycle. The proposed design effectively reduces the mean absolute error (MAE) of the heartbeat interval to an average of 6.2 ms.

A 5-ms Error, 22-µA Photoplethysmography Sensor using Current Integration Circuit and Correlated Double Sampling.

This paper presents a low-power Photoplethysmography (PPG) sensing method. The PPG is commonly used in recent wearable devices to detect cardiovascular information including heartbeat. The heartbeat is useful for physical activity and stress monitoring. However, the PPG circuit consumes large power because it consists of LED and photodiode. To reduce its power consumption without accuracy degradation, a cooperative design of circuits and algorithms is proposed in this work. A straightforward way to reduce the power is intermittent driving of LED, but there is a disadvantage that the signal is contaminated by a noise while circuit switching. To overcome this problem, we introduce correlated double sampling (CDS) method, which samples an integration circuit output twice with short intervals after the LED turns on and uses the difference of these voltage. Furthermore, an up-conversion method using linear interpolation, and an error correction using autocorrelation are introduced. The proposed PPG sensor, which consists of the LED, the photodiode, the current integration circuit, a CMOS switch, an A/D converter, and an MCU, is prototyped. It is evaluated by actual measurement with 22-year-old subject. The measurement results show that 22-µA total current consumption is achieved with 5-ms mean absolute error.