Quality Assurance Tests Research Articles

SyncMRT: a solution to image-guided synchrotron radiotherapy for quality assurance and pre-clinical trials.

In this work, a new image guidance system and protocols for delivering image-guided radiotherapy (IGRT) on the Imaging and Medical Beamline (IMBL) at the ANSTO Australian Synchrotron are introduced. The image guidance methods used and the resulting accuracy of tumour alignment in in vivo experiments are often under-reported. Image guidance tasks are often complex, time-consuming and prone to errors. If unchecked, they may result in potential mis-treatments. We introduce SyncMRT, a software package that provides a simple, image guidance tool-kit for aligning samples to the synchrotron beam. We have demonstrated sub-millimetre alignment using SyncMRT and the small-animal irradiation platform (the DynamicMRT system) on the IMBL. SyncMRT has become the standard for carrying out IGRT treatments on the IMBL and has been used in all pre-clinical radiotherapy experiments since 2017. Further, we introduce two quality assurance (QA) protocols to synchrotron radiotherapy on the IMBL: the Winston-Lutz test and hidden target test. It is shown that the presented QA tests are appropriate for picking up geometrical setup errors and assessing the end-to-end accuracy of the image guidance process. Together, these tools make image guidance easier and provide a mechanism for reporting the geometric accuracy of synchrotron-based IGRT treatments. Importantly, this work is scalable to other delivery systems, and is in continual development to support the upcoming veterinary radiotherapy trials on the IMBL.

A RADIATION SAFETY ASSESSMENT OF X-RAY DIAGNOSTIC UNITS IN S.M.S HOSPITAL JAIPUR: AN INSTITUTIONAL STUDY

The aim of a quality assurance (QA) program is to assist a radio-diagnostic facility in consistently obtaining adequate radiological information with a minimum of dose and a minimum of cost. An integrated part of a quality assurance program is quality control (QC) in which a series of examinations and checks on equipment performance are undertaken, so that any changes can be objectively monitored and remedies made. The main objective of the present work was to carry out an independent audit of the important features of QA tests and radiation safety parameters in medical X-ray installations, which would reflect the safety status and to assess the regulatory requirements of the safety code. We conducted a radiological safety and quality assurance audit of 32 medical X-ray diagnostic machines installed in SMS hospital, Jaipur. A QA kit consisting of a kVp test meter, ionization chamber-based radiation survey meter and other standard accessories were used for the required measurements. The study mainly covered eight quality control checks that is accuracy check of accelerating potential (kVp), linearity of tube current (mA station)and timer, congruence of radiation and optical field, and total filtration, beam alignment, focal spot size, leakage radiation survey, and beam out. The status test is carried out in order to establish the functional status of the equipments. They operated and functioned correctly and prevented movement when activated. All measured values were well within the tolerance limit.

Five-year evaluation of a low-cost quality assurance protocol for clinical ultrasound transducers.

To implement, execute and evaluate a quality assurance test protocol for clinical ultrasound transducers that is software-based, user-independent, inexpensive, easily repeatable, and does not require tissue phantoms. The test protocol is based on in-air reverberation images. The software test tool generates uniformity- and reverberation profiles to monitor system sensitivities and signal uniformities that provide a sensitive analysis of transducer status. Whenever a transducer was suspected to be damaged validating tests were conducted using the Sonora FirstCall test system. A total of 21 transducers from five ultrasound scanner systems were included in the study. Tests were performed every other month for a total of 5 years. Each transducer was tested on average 11.7 times. Testing a transducer required a total of 2.75 hours annually. The ultrasound quality assurance test protocol detected an average annual fail rate of 10.7%. The test protocol provides a reliable approach for monitoring transducer lens status of clinically used ultrasound transducers. The ultrasound quality assurance test protocol may potentially find deviations in diagnostic quality before being noticed by the clinicians. Thus, the ultrasound quality assurance test protocol holds the ability to reduce the risk of undiscovered image quality degradation hereby minimizing the danger of diagnostic errors.

Feasibility of postoperative spine stereotactic body radiation therapy in proximity of carbon and titanium hybrid implants using a robotic radiotherapy device

Background and purposeTo assess the feasibility of postoperative stereotactic body radiation therapy (SBRT) for patients with hybrid implants consisting of carbon fiber reinforced polyetheretherketone and titanium (CFP-T) using CyberKnife.Materials and methodsAll essential steps within a radiation therapy (RT) workflow were evaluated. First, the contouring process of target volumes and organs at risk (OAR) was done for patients with CFP-T implants. Second, after RT-planning, the accuracy of the calculated dose distributions was tested in a slab phantom and an anthropomorphic phantom using film dosimetry. As a third step, the accuracy of the mandatory image guided radiation therapy (IGRT) including automatic matching was assessed using the anthropomorphic phantom. For this goal, a standard quality assurance (QA) test was modified to carry out its IGRT part in presence of CFP-T implants.ResultsUsing CFP-T implants, target volumes could precisely delineated. There was no need for compromising the contours to overcome artifact obstacles. Differences between measured and calculated dose values were below 11% for the slab phantom, and at least 95% of the voxels were within 5% dose difference. The comparisons for the anthropomorphic phantom showed a gamma-passing rate (5%, 1 mm) of at least 97%. Additionally the test results with and without CFP-T implants were comparable. No issues concerning the IGRT were detected. The modified machine QA test resulted in a targeting error of 0.71 mm, which corresponds to the results of the unmodified standard tests.ConclusionDose calculation and delivery of postoperative spine SBRT is feasible in proximity of CFP-T implants using a CyberKnife system.

Techno-Economic Feasibility Analysis of a Fully Mobile Radiation Oncology System Using Monte Carlo Simulation.

PURPOSEDisparities in radiation oncology (RO) can be attributed to geographic location, socioeconomic status, race, sex, and other societal factors. One potential solution is to implement a fully mobile (FM) RO system to bring radiotherapy to rural areas and reduce barriers to access. We use Monte Carlo simulation to quantify techno-economic feasibility with uncertainty, using two rural Missouri scenarios.METHODSRecently, a semimobile RO system has been developed by building an o-ring linear accelerator (linac) into a mobile coach that is used for temporary care, months at a time. Transitioning to a more FM-RO system, which changes location within a given day, presents technical challenges including logistics and quality assurance. This simulation includes cancer census in both northern and southeastern Missouri, multiple treatment locations within a given day, and associated expenditures and revenues. A subset of patients with lung, breast, and rectal diseases, treated with five fractions, was simulated in the FM-RO system.RESULTSThe FM-RO can perform all necessary quality assurance tests as suggested in national medical physics guidelines within 1.5 hours, thus demonstrating technological feasibility. In northern and southeastern Missouri, five-fraction simulations' net incomes were, in US dollars (USD), $1.55 ± 0.17 million (approximately 74 patients/year) and $3.65 USD ± 0.25 million (approximately 98 patients/year), respectively. The number of patients seen had the highest correlation with net income as well as the ability to break-even within the simulation. The model does not account for disruptions in care or other commonly used treatment paradigms, which may lead to differences in estimated economic return. Overall, the mobile system achieved a net benefit, even for the most negative simulation scenarios.CONCLUSIONOur simulations suggest technologic success and economic viability for a FM-RO system within rural Missouri and present an interesting solution to address other geographic disparities in access to radiotherapy.

Impact of a Centralized Database System on Radiation Therapy Quality Assurance Management at a Large Health Care Network: 5 Years’ Experience

PurposeThis study reports the impact of using a centralized database system for major equipment quality assurance (QA) at a large institution. Methods and MaterialsA centralized database system has been implemented for radiation therapy machine QA in our institution at 6 campuses with 11 computed tomographies and 22 linear accelerators (LINACs). The database system was customized to manage monthly and annual computed tomography and LINAC QA. This includes providing the same set of QA procedures across the enterprise, digitally storing all measurement records, and generating trend analyses. Compared with conventional methods (ie, paper forms), the effectiveness of the database system was quantified by changes in the compliance of QA tests and perceptions of staff to the efficiency of data retrieval and analyses. An anonymized questionnaire was provided to physicists enterprise-wide to assess workflow changes. ResultsWith the implementation of the database system, the compliance of QA test completion improved from 80% to >99% for the entire institution. This resonates with the 56% of physicists who found the database system helpful in guiding them through QA, and 25% of physicists found the contrary, and 19% reported no difference (n = 16). Meanwhile, 40% of physicists reported longer times needed to record data using the database system compared with conventional methods, and another 40% suggested otherwise. In addition, 87% and 80% found the database more efficient to analyze and retrieve previous data, respectively. This was also reflected by the shorter time taken to generate year-end QA statistics using the software (5 vs 30 min per LINAC). Overall, 94% of physicists preferred the centralized database system over conventional methods and endorsed continued use of the system. ConclusionsA centralized database system is useful and can improve the effectiveness and efficiency of QA management in a large institution. With consistent data collection and proper data storage using a database, high-quality data can be obtained for failure modes and effects analyses as per TG 100.

Developing quality assurance tests for simultaneous Positron Emission Tomography - Magnetic Resonance imaging for radiotherapy planning.

Background and purpose Simultaneous Positron Emission Tomography – Magnetic Resonance (PET-MR) imaging can potentially improve radiotherapy by enabling more accurate tumour delineation and dose painting. The use of PET-MR imaging for radiotherapy planning requires a comprehensive Quality Assurance (QA) programme to be developed. This study aimed to develop the QA tests required and assess their repeatability and stability. Materials and methods QA tests were developed for: MR image quality, MR geometric accuracy, electromechanical accuracy, PET-MR alignment accuracy, Diffusion Weighted (DW)-MR Apparent Diffusion Coefficient (ADC) accuracy and PET Standard Uptake Value (SUV) accuracy. Each test used a dedicated phantom and was analysed automatically or semi-automatically, with in–house software. Repeatability was evaluated by three same-day measurements with independent phantom positions. Stability was assessed through 12 monthly measurements. Results The repeatability Standard Deviations (SDs) of distortion for the MR geometric accuracy test were . The repeatability SDs in ADC difference from reference were for the DW-MR accuracy test. The PET SUV difference from reference repeatability SD was . The stability SDs agreed within , 1 percentage point and 1.4 percentage points of the repeatability SDs for the geometric, ADC and SUV accuracy tests respectively. There were no monthly trends apparent. These results were representative of the other tests. Conclusions QA Tests for radiotherapy planning PET-MR have been developed. The tests appeared repeatable and stable over a 12-month period. The developed QA tests could form the basis of a QA programme that enables high-quality, robust PET-MR imaging for radiotherapy planning.

Longitudinal assessment of quality assurance measurements in a 1.5T MR-linac: Part II-Magnetic resonance imaging.

PurposeTo describe and report longitudinal quality assurance (QA) measurements for the magnetic resonance imaging (MRI) component of the Elekta Unity MR‐linac during the first year of clinical use in our institution.Materials and methodsThe performance of the MRI component of Unity was evaluated with daily, weekly, monthly, and annual QA testing. The measurements monitor image uniformity, signal‐to‐noise ratio (SNR), resolution/detectability, slice position/thickness, linearity, central frequency, and geometric accuracy. In anticipation of routine use of quantitative imaging (qMRI), we characterize B0/B1 uniformity and the bias/reproducibility of longitudinal/transverse relaxation times (T1/T2) and apparent diffusion coefficient (ADC). Tolerance levels for QA measurements of qMRI biomarkers are derived from weekly monitoring of T1, T2, and ADC.ResultsThe 1‐year assessment of QA measurements shows that daily variations in each MR quality metric are well below the threshold for failure. Routine testing procedures can reproducibly identify machine issues. The longitudinal three‐dimensional (3D) geometric analysis reveals that the maximum distortion in a diameter of spherical volume (DSV) of 20, 30, 40, and 50 cm is 0.4, 0.6, 1.0, and 3.1 mm, respectively. The main source of distortion is gradient nonlinearity. Maximum peak‐to‐peak B0 inhomogeneity is 3.05 ppm, with gantry induced B0 inhomogeneities an order of magnitude smaller. The average deviation from the nominal B1 is within 2%, with minimal dependence on gantry angle. Mean ADC, T1, and T2 values are measured with high reproducibility. The median coefficient of variation for ADC, T1, and T2 is 1.3%, 1.1%, and 0.5%, respectively. The median bias for ADC, T1, and T2 is −0.8%, −0.1%, and 3.9%, respectively.ConclusionThe MRI component of Unity operates within the guidelines and recommendations for scanner performance and stability. Our findings support the recently published guidance in establishing clinically acceptable tolerance levels for image quality. Highly reproducible qMRI measurements are feasible in Unity.

End to end comparison of surface-guided imaging versus stereoscopic X-rays for the SRS treatment of multiple metastases with a single isocenter using 3D anthropomorphic gel phantoms.

IntroductionTwo end‐to‐end tests evaluate the accuracy of a surface‐guided radiation therapy (SGRT) system (CRAD Catalyst HD) for position verification in comparison to a stereoscopic x‐ray imaging system (Brainlab Exactrac ) for single‐isocenter, multiple metastases stereotactic radiosurgery (SRS) using 3D polymer gel inserts.Materials and methodsA 3D‐printed phantom (Prime phantom, RTsafe PC, Athens, Greece) with two separate cylindrical polymer gel inserts were immobilized in open‐face masks and treated with a single isocentric, multitarget SRS plan. Planning was done in Brainlab (Elements) to treat five metastatic lesions in one fraction, and initial setup was done using cone beam computed tomography. Positional verification was done using orthogonal X‐ray imaging (Brainlab Exactrac) and/or a surface imaging system (CRAD Catalyst HD, Uppsala, Sweden), and shift discrepancies were recorded for each couch angle. Forty‐two hours after irradiation, the gel phantom was scanned in a 1.5 Tesla MRI, and images were fused with the patient computed tomography data/structure set for further analysis of spatial dose distribution.ResultsDiscrepancies between the CRAD Catalyst HD system and Brainlab Exactrac were <1 mm in the translational direction and <0.5° in the angular direction at noncoplanar couch angles. Dose parameters (D Mean% , D 95%) and 3D gamma index passing rates were evaluated for both setup modalities for each planned target volume (PTV) at a variety of thresholds: 3%/2 mm (Exactrac≥93.1% and CRAD ≥87.2%), 5%/2 mm (Exactrac≥95.6% and CRAD ≥94.6%), and 5%/1 mm (Exactrac≥81.8% and CRAD ≥83.7%).ConclusionDose metrics for a setup with surface imaging was found to be consistent with setup using x‐ray imaging, demonstrating high accuracy and reproducibility for treatment delivery. Results indicate the feasibility of using surface imaging for position verification at noncoplanar couch angles for single‐isocenter, multiple‐target SRS using end‐to‐end quality assurance (QA) testing with 3D polymer gel dosimetry.

Building of Anti-Bacterial Smart Sterilization Room Based on Internet of Things Using PIR Sensor and Its Quality Assurances

The dangers of bacteria can cause health problems or infections of the respiratory tract. This research is related to the design of an anti-bacterial smart room sterilization system based on the Internet of Things (IoT) using a Passive Infrared Receiver (PIR). This study aims to sterilize with a monitoring and security system with PIR sensors and Blynk platform. Tool testing is carried out by taking 7 data from 1 object with 3 scanario which are sterilization without an object, sterilization by detecting objects, sterilization by detecting objects which is back to the room. In this system each condition is monitored on the Blynk platform. The advantage of this system is managed and monitored safety sterilization process remotely by Blynk. This tool has also gone through measurement quality assurance testing by adopting ISO 17025 including sensitivity, selectivity, precision, working range , tool toughness, and measurement uncertainty. The quality of service (QoS) test in this system gets an average delay of 122 milliseconds, throughput of 1045 bit/s and packet loss of 0.06%. This sterilizer can be monitored and operated remotely and is equipped with a security system.

Clinical Implementation and Initial Experience With a 1.5 Tesla MR-Linac for MR-Guided Radiation Therapy for Gynecologic Cancer: An R-IDEAL Stage 1 and 2a First in Humans Feasibility Study of New Technology Implementation

PurposeMagnetic resonance imaging–guided linear accelerator systems (MR-linacs) can facilitate the daily adaptation of radiation therapy plans. Here, we report our early clinical experience using a MR-linac for adaptive radiation therapy of gynecologic malignancies. Methods and MaterialsTreatments were planned with an Elekta Monaco v5.4.01 and delivered by a 1.5 Tesla Elekta Unity MR-linac. The system offers a choice of daily adaptation based on either position (ATP) or shape (ATS) of the tumor and surrounding normal structures. The ATS approach has the option of manually editing the contours of tumors and surrounding normal structures before the plan is adapted. Here, we documented the duration of each treatment fraction; set-up variability (assessed by isocenter shifts in each plan) between fractions; and, for quality assurance, calculated the percentage of plans meeting the γ-criterion of 3%/3-mm distance to agreement. Deformable accumulated dose calculations were used to compare accumulated versus planned dose for patient treated with exclusively ATP fractions. ResultsOf the 10 patients treated with 90 fractions on the MR-linac, most received boost doses to recurrence in nodes or isolated tumors. Each treatment fraction lasted a median 32 minutes; fractions were shorter with ATP than with ATS (30 min vs 42 min, P < .0001). The γ criterion for all fraction plans exceeded >90% (median, 99.9%; range, 92.4%-100%; ie, all plans passed quality assurance testing). The average extent of isocenter shift was <0.5 cm in each axis. The accumulated dose to the gross tumor volume was within 5% of the reference plan for all ATP cases. Accumulated doses for lesions in the pelvic periphery were within <1% of the reference plan as opposed to –1.6% to –4.4% for central pelvic tumors. ConclusionsThe MR-linac is a reliable and clinically feasible tool for treating patients with gynecologic cancer.

I Don’t “Recall”: The Decision to Delay Innovation Launch to Avoid Costly Product Failure

Innovations embody novel features or cutting-edge components aimed at delivering desired customer benefits. Oftentimes, however, we observe the need to recall new products shortly after their introduction. Indeed, a firm may rush an innovation to market in an attempt to pre-empt rivals and capture early demand, yet in so doing forgo rigorous testing, thus subjecting itself to the risk of a product recall. To shed light on this phenomenon, we construct a dynamic game-theoretic model in which firms plan to launch their innovations. Each firm must decide whether to conduct time-consuming quality assurance testing, which ensures no defects or safety problems but delays the launch. If the innovation is released without such testing and a recall occurs, the firm incurs pecuniary costs and faces future reputation damage in marketing the recalled innovation. We investigate the strategic forces behind firms’ testing and launch-timing decisions in this context. The analysis uncovers a novel mechanism, linked to the possibility of a rival going bankrupt, that causes firms to become more inclined to rush to market and take on the risk of product failure even as the negative consequences of a recall increase. The results further demonstrate how firms’ desire to forgo testing exhibits an inverse-U pattern as consumers become more heterogeneous and how competitive forces may induce both firms to forgo testing, although the resulting profits are lower than had they both committed to conduct testing. The framework is extended to examine how product recall considerations affect firms’ research and development (R&amp;D) investments. Although, in general, post-innovation product failure discourages R&amp;D effort, we identify conditions under which an increase in the recall probability stimulates firms to innovate. Several model extensions are presented, and managerial implications are discussed. This paper was accepted by Dmitri Kuksov, marketing. Supplemental Material: The online appendix is available at https://doi.org/10.1287/mnsc.2022.4303 .

GITAD 2020: quality assurance test through 20\xa0years of experience

GITAD (Grupo Iberoamericano de Trabajo en Análisis de DNA) was founded in 1998 as the first operational group of AICEF (Academia Iberoamericana de Criminalística y Estudios Forenses), formally created in 1999. The mission and the vision of GITAD are to promote the development of forensic genetics in Ibero-American countries and to achieve the maximum level of innovation and quality in each country, and with that aim, a proficiency test was developed. Since 1999, the member laboratories receive four reference samples with the objective of obtaining the genetic profile with their routine protocols, a theoretical exercise since 2003, and since 2007, it was incorporated a forensic sample, which changes every year. The consensus results and the different discrepancies are discussed in an annual meeting. This article illustrates the evolution of the proficiency test through 20 years from different points of view: the increase of participant laboratories, the evolution of the different DNA typing techniques reported by the Ibero-American participant laboratories, the challenges that the proficiency test have met, and future perspectives for a continuous improvement of the proficiency test, especially regarding its accreditation under ISO 17043.

The impact of silo storage on the fatigue and cracking resistance of asphalt mixes

During production, hot mix asphalt plants can store mixes in silos for a few hours before they get transported to the job site. Additional aging and possible blending between RAP and virgin binders take place inside the silo which affect mix properties. This study addresses the impact of silo storage on mix fatigue and cracking performance. The flexural beam test has been widely established as a representative fatigue test, however due to its complexity, it is difficult to implement as a quality control test. The semi-circular bending test (SCB) and the indirect tensile asphalt cracking test (IDEAL-CT) are simple and quick tests that are currently being used by some state agencies to assess the cracking resistance of asphalt mixes. The ability of SCB and IDEAL-CT to predict fatigue-related cracking as compared to flexural beam testing is also investigated in this study. Four plant-produced mixes were collected before and after silo storage, and tested using flexural beam, SCB, and IDEAL-CT. It was noted that the SCB and IDEAL-CT are highly influenced by the mix stiffness, and the cracking resistance was reduced considerably with silo storage. This finding has important implications when using either of these tests for construction quality control and assurance. It was concluded that the flexibility index (FI) from the SCB and the cracking tensile index (CTindex) from the IDEAL-CT did not provide a direct measure of the fatigue performance as compared to the flexural beam test.

Commissioning and routine quality assurance of the Radixact Synchrony system

The Radixact Synchrony system allows for target motion correction when tracking either fiducials in/around the target or a dense lesion in the lung. As such evaluation testing and quality assurance (QA) tests are required. To allow for QA procedures to be performed with a range of available phantoms evaluation of the dosimetric delivery accuracy was performed for a range of motions, phantoms, and motion platforms. A Computerized Imaging Reference Systems, Incorporated (CIRS) 1D motion platform and Accuray Tomotherapy "Cheese" phantom was utilized to perform absolute dose and GafChromic EBT3 film measurements. A HexaMotion platform and Delta4 phantom were utilized to quantify the effects of 1D and 3D motions. Inter-device comparison was performed with the ArcCHECK and Delta4 phantoms and GafChromic EBT3 film, five patient plans were delivered to each phantom when static and with two different motion types both with and without Synchrony motion correction. A range of QA tests are described. A phantom was designed to allow for daily verification of system functionality. This test allows for the detection of either fiducials or a dense silicone target with a stationary phantom. Monthly testing procedures are described that allow the user to verify the dosimetric improvement when utilizing synchrony delivery motion compensation versus uncorrected motions. These can be performed utilizing a 1D motion stage with an ion-chamber and GafChromic EBT3 film to allow for a 2D dosimetric validation. Alternatively, a 3D motion platform can be utilized where available. Monthly and annual imaging tests are described. Finally, annual test procedures designed to verify the coincidence of the imaging system and treatment isocenter are described. The evaluation of the Synchrony system using a range of QA devices shows consistently high dosimetric accuracy with similar trends in passing criteria found with GafChromic EBT3 film, ArcCHECK, and Delta4 phantoms for density-based respiratory model compensation. These results highlight the large improvements in the dose distribution when motion is accounted for with the Synchrony system as measured with a range of phantoms and motion platforms that the majority of users will have available. The testing methods and QA procedures described provide guidance for new users of the Radixact Synchrony system as they implement their own QA programs for this system, until such time as an AAPM task group report is made available. QA procedures including Kilovolts (kV) imaging quality metrics and imaging dose parameters, dose deposition accuracy, target detection coincidence, and target position detection accuracy are described.

Development, construction and tests of the Mu2e electromagnetic calorimeter mechanical structures

The “muon-to-electron conversion” (Mu2e) experiment at Fermilab will search for the charged lepton flavour violating neutrino-less coherent conversion of a muon into an electron in the field of an aluminum nucleus. The observation of this process would be the unambiguous evidence of the existence of physics beyond the standard model. Mu2e detectors comprise a straw-tracker, an electromagnetic calorimeter and an external veto for cosmic rays. In particular, the calorimeter provides excellent electron identification, a fast calorimetric online trigger, and complementary information to aid pattern recognition and track reconstruction. The detector has been designed as a state-of-the-art crystal calorimeter and employs 1348 pure Cesium Iodide (CsI) crystals readout by UV-extended silicon photosensors and fast front-end and digitization electronics. A design consisting of two identical annular matrices (named “disks”) positioned at the relative distance of 70 cm downstream the aluminum target along the muon beamline satisfies the Mu2e physics requirements. The hostile Mu2e operational conditions, in terms of radiation levels (total expected ionizing dose of 12 krad and a neutron fluence of 5 × 1010 n/cm2 @ 1 MeVeq (Si)/y), magnetic field intensity (1 T) and vacuum level (10−4 Torr) have posed tight constraints on scintillating materials, sensors, electronics and on the design of the detector mechanical structures and material choice. The support structure of each 674 crystal matrix is composed of an aluminum hollow ring and parts made of open-cell vacuum-compatible carbon fiber. The photosensors and front-end electronics for the readout of each crystal are inserted in a machined copper holder and make a unique mechanical unit. The resulting 674 mechanical units are supported by a machined plate of vacuum-compatible plastic material. The plate also integrates the cooling system made of a network of copper lines flowing a low temperature radiation-hard fluid and placed in thermal contact with the copper holders to constitute a low resistance thermal bridge. The data acquisition electronics are hosted in aluminum custom crates positioned on the external lateral surface of the disks. The crates also integrate the electronics cooling system as lines running in parallel to the front-end system. In this paper we report on the calorimeter mechanical structure design, the mechanical and thermal simulations that have determined the design technological choices, and the status of component production, quality assurance tests and plans for assembly at Fermilab.

Diagnostic test accuracy using digital retinal imaging in the detection of any diabetic retinopathy by graders in Vietnam, against a reference standard from the UK

AbstractPurposeTo compare the diagnostic test accuracy (DTA) of trained nurses, mid‐level and senior ophthalmologists in Vietnam against a reference standard from the UK, and assess the impact of further training on graders.MethodsFundus photographs were taken and graded at two different time points by trained nurses, mid‐level ophthalmologists and senior ophthalmologists in Vietnam using the UK National Screening Committee classification system. A reference standard from the UK regraded all images in masked fashion and DTA was calculated using sensitivity and specificity (with 95% CIs), and positive and negative predictive values.ResultsBetween September and November 2018, 431 people with diabetes attended diabetic retinopathy (DR) screening in Southern Vietnam. The sensitivity for detecting any DR for all grader groups in Vietnam was low (&lt;43%) against the reference standard in the UK. The sensitivity for detecting referable DR and referrable diabetic macular oedema was particularly low (&lt;20%) for all grader groups. Subsequently, an additional subset of images from 138 consecutive patients screened from March to April 2021 was regraded in the UK to evaluate graders’ performance after additional training was delivered. A significant improvement in DTA among all grader groups in Vietnam was identified, with sensitivity for detecting any DR exceeding 85%. Nurses achieved the highest sensitivity for grading referable DR (76.9%, 60.3–88.3%) and mid‐level ophthalmologists attained the highest sensitivity for detecting referable maculopathy (77.5%, 61.2–88.6).ConclusionsGrading accuracy was low in Vietnam in the first six months of implementing a training programme. Many factors may have contributed to poor grader performance, including inadequate training and feedback, insufficient time to participate in quality assurance testing and competing work responsibilities. After further training was delivered, DTA among all graders in Vietnam increased. Findings from this study are particularly important for DR programme planners in low‐ and middle‐income countries.

End-to-End Quality Assurance of Stereotactic Radiation Therapy Using an Anthropomorphic Head Phantom

In the clinic, routine quality assurance tests ensure the proper functioning of each individual aspect of a radiation therapy treatment delivery. However, these tests may not guarantee an accurate treatment delivery. In this work, we present the design and application of a head phantom (using 3D printing technology) developed for end-to-end quality assurance of a stereotactic radiation therapy treatment for brain metastases, coupled with inserts for ion chamber, and film and gel dosimeters. The head phantom was subjected to the entire clinical workflow, with each stage of the process being performed by the appropriate clinical personnel to ensure that this quality assurance test mimics the clinical scenario.

Pulsed Wave Doppler Measurements of Maximum Velocity: Dependence on Sample Volume Size.

Pulsed wave (PW) Doppler ultrasound is routinely used in the clinic to assess blood flow. Our annual Doppler quality assurance tests revealed unexpectedly large errors in measurement of maximum velocity, exceeding our tolerance (error >20%), when using certain scanners with small Doppler sample volume dimensions. The aim of this study was to assess the dependence of maximum velocity estimates on PW Doppler sample volume size. A flow phantom with known steady flow was used to acquire maximum velocity estimates (maximum velocities of 24, 39 and 85 cm/s and sample volume range of 0.3-20 mm) with a variety of transducers and scanners in clinical use (51 probes from 4 manufacturers). Selected acoustic outputs were characterized using free-field hydrophone measurements. All maximum velocity estimates were within our tolerance for sample volume sizes ≥1.5 mm, although maximum velocity estimates typically increased with decreasing sample volume size. Errors exceeding our tolerance were commonly found for one manufacturer when using smaller sample volumes, resulting in up to 75% overestimation. Although intrinsic spectral broadening based on transit time considerations may help explain our findings, the sample volume dependence raises potential clinical concerns that users should be aware of and which manufacturers should consider addressing.

Review and comparison of acceptance criteria for Senna and its preparations according to BP (2015 and 2020) and USP-NF (39-34 and 43-38)

Background: Quality and quantity assurance of herbs are global concerns. This study aimed to classify and compare the monographs and test procedures of Senna parts and preparations according to two editions of BP and USP-NF. The monographs and specifications were compared to suggest an applicable approach to extract relevant data. Methods: BP 2015 and 2020, USP-NF 39-34 and 43-38, as well as scientific databases were used for literature review. Results: the results of this study were classified in 3 tables; table 1 classified specifications of herbal monographs in pharmacopeias. Table 2 classified various identification tests, measurement methods, and standard phytochemicals for quantitative assays. Table 3 outlined and categorized related physicochemical and contamination tests for quality assurance according to two editions of BP and USP-NF. In both editions of USP-NF, only sennosides powder and tablets were required to be analyzed for heavy metals. Hence, microbial contamination tests were merely included for leaves and pods of Senna. In both editions of BP, assessment of microbial contamination was merely included in the monograph of dry extract of Senna, not for the rest of monographs. Comparing two editions of BP indicated that in BP 2020, LC and HPTLC methods were added to assure the quality of pods and leaflets of Senna species. Conclusion: preparation of tabular data will assist analysts to extract desired information and guidelines to prepare licensed herbal products. This approach could be applicable to select relevant tests according to the facilities and equipment of laboratories.