Quality Assurance Plan Research Articles

First Retrospective QA of FAST-01 Clinical Treatment Fields Using High-Speed Quantitative Scintillation Imaging.

To retrospectively validate the dose and dose rates delivered in XXX clinical trial fields via sub-millimeter spatial and <0.25 ms temporal resolution scintillation imaging. An ultra-fast intensified CMOS camera (4.5-12 kHz sampling rate) imaged the light response of a scintillator sheet at treatment isocenter and irradiated by pencil beam scanning proton fields, including XXX clinical fields. Dose and dose rate linearity studies were performed, followed by camera calibration, via EBT3 film. An EDGE diode detector was placed directly under the scintillator at the surface and at 5cm depth, for comparison with the imaging data and log files. Frame-by-frame analysis of image stacks yielded dose and dose-rate maps for each delivery at the surface. Using the percent depth dose curves and 3D spot profiles, the surface images were projected to 5 cm depth for comparison with a secondary diode and log file recordings. Camera response was linear with dose (R2 =0.9998) and beam current (R2=0.9883) from 2-12Gy and 20-210nA, respectively. Gamma analysis of the cumulative dose maps at 3%/2mm indicated a mean passing rate of 100% compared with film. Total irradiation time agreed with the log file recordings with an average deviation of 0.20±0.07ms. At the surface, the average imaged dose rate across the seven fields was 114±1Gy/s, agreeing with the diode within 1±1%. The dose at 5cm depth from the projected images (mean 8.4 Gy) agreed with the reported dose (log files) within 0.13±0.03 Gy (2±1%). The average dose rate from projected images at 5 cm depth was 62±1 Gy/s which agreed with the reported and diode values within 2±3%. This study provides the first independent validation of dose and dose rate for clinical proton XXX fields at unprecedented spatiotemporal resolution. Owing to the non-trivial dose rate distributions in PBS fields, such direct 2D dose rate mapping will be important in future pre-treatment plan quality assurance.

First clinical implementation of a highly efficient daily online adapted proton therapy (DAPT) workflow

Objective.This study presents the first clinical implementation of an efficient online daily adaptive proton therapy workflow (DAPT).Approach.The DAPT workflow includes apre-treatment phase,where atemplateand afallback planare optimized on the planning computed tomography (CT). In theonline phase, theadapted planis re-optimized on daily images from an in-room CT. Daily structures are rigidly propagated from the planning CT. Automated Quality Assurance (QA) involves geometric, sanity checks and an independent dose calculation from the machine files. Differences from the template plan are analyzed field-by-field, and clinical plan is assessed by reviewing the achieved clinical goals using a traffic light protocol. If the daily adapted plan fails any QA or clinical goals, the fallback plan is used. In theoffline phasethe delivered dose is recalculated from log-files onto the daily CT, and a gamma analysis is performed (3%/3 mm). The DAPT workflow has been applied to selected adult patients treated in rigid anatomy for the last serie of the treatment between October 2023 and April 2024.Main Results.DAPT treatment sessions averaged around 23 min [range: 15-30 min] and did not exceed the typical 30 minute time slot. Treatment adaptation, including QA and clinical plan assessment, averaged just under 7 min [range: 3:30-16 min] per fraction. All plans passed the online QAs steps. In the offline phase a good agreement with the log-files reconstructed dose was achieved (minimum gamma pass rate of 97.5%). The online adapted plan was delivered for >85% of the fractions. In 92% of total fractions, adapted plans exhibited improved individual dose metrics to the targets and/or organs at risk.Significance.This study demonstrates the successful implementation of an online daily DAPT workflow. Notably, the duration of a DAPT session did not exceed the time slot typically allocated for non-DAPT treatment. As far as we are aware, this is a first clinical implementation of daily online adaptive proton therapy.

Review of Quality Audit in a Radiation Oncology Department in a Tertiary Care Hospital- 2 Year-Results.

This study aimed to report the findings of comprehensive weekly quality audit of radiotherapy procedures conducted at our institute, assessing various domains including clinical notes, contour delineation, treatment planning, prescription accuracy, patient-specific quality assurance, and treatment set-up checks. The audit protocol, based on the Peer Review Audit Tool (PRAT) from the Royal Australian and New Zealand College of Radiologists, evaluated six critical parameters: clinical decisions, contours, treatment prescriptions, plan evaluation, plan quality assurance, and daily treatment set-ups. Patients were assessed for changes categorized as no change, minor change, or major change. The audit panel comprised radiation oncologists, medical physicists, and therapists. The audit is conducted on a weekly basis, including patients who initiated treatment within the preceding week. Between December 2020 to October 2023, 1831 cases were treated with radiotherapy in our institution and all of them were included in the quality audit. Overall, majority of patients exhibited no changes across various domains, with minor adjustments noted in a small percentage of cases. Notably, the clinical note check domain showed 99% adherence to standards, while contour delineation and treatment planning domains displayed minor adjustments in 2.7% and 1.7% of cases, respectively. Prescription accuracy and patient-specific quality assurance demonstrated high compliance, with minimal changes observed. Treatment set-up checks revealed minor variations in 0.3% and major changes in 0.2% of cases. This study underscores the importance of comprehensive quality audits in radiation oncology to ensure precision and consistency in treatment delivery. By identifying potential areas for improvement and maintaining high standards across all stages of the radiotherapy process, such audits play a crucial role in optimizing treatment outcomes and enhancing patient safety.

Characterizing devices for validation of dose, dose rate, and LET in ultra high dose rate proton irradiations.

Ultra high dose rate (UHDR) radiotherapy using ridge filter is a new treatment modality known as conformal FLASH that, when optimized for dose, dose rate (DR), and linear energy transfer (LET), has the potential to reduce damage to healthy tissue without sacrificing tumor killing efficacy via the FLASH effect. Clinical implementation of conformal FLASH proton therapy has been limited by quality assurance (QA) challenges, which include direct measurement of UHDR and LET. Voxel DR distributions and LET spectra at planning target margins are paramount to the DR/LET-related sparing of organs at risk. We hereby present a methodology to achieve experimental validation of these parameters. Dose, DR, and LET were measured for a conformal FLASH treatment plan involving a 250-MeV proton beam and a 3D-printed ridge filter designed to uniformly irradiate a spherical target. We measured dose and DR simultaneously using a 4D multi-layer strip ionization chamber (MLSIC) under UHDR conditions. Additionally, we developed an "under-sample and recover (USRe)" technique for a high-resolution pixelated semiconductor detector, Timepix3, to avoid event pile-up and to correct measured LET at high-proton-flux locations without undesirable beam modifications. Confirmation of these measurements was done using a MatriXX PT detector and by Monte Carlo (MC) simulations. MC conformal FLASH computed doses had gamma passing rates of>95% (3mm/3% criteria) when compared to MatriXX PT and MLSIC data. At the lateral margin, DR showed average agreement values within 0.3% of simulation at 100Gy/s and fluctuations ∼10% at 15Gy/s. LET spectra in the proximal, lateral, and distal margins had Bhattacharyya distances of<1.3%. Our measurements with the MLSIC and Timepix3 detectors shown that the DR distributions for UHDR scenarios and LET spectra using USRe are in agreement with simulations. These results demonstrate that the methodology presented here can be used effectively for the experimental validation and QA of FLASH treatment plans.

The Oncology QCARD Initiative: Fostering efficient evaluation of initial real-world data proposals.

The oncology quality, characterization, and assessment of real-world data (Oncology QCARD) Initiative was formed to develop a set of minimum study design and data elements needed to evaluate the fitness of the real-world data (RWD) source(s) proposed in an initial study concept as part of early interaction with scientific reviewers. A multidisciplinary executive committee (EC) was established to guide the Oncology QCARD Initiative. The EC conducted a landscape review of published literature, guidances, and guidelines to evaluate relevant dimensions of data quality measurement. Guided by the review and informed by expert feedback, the Oncology QCARD Initial Protocol Characterization (IPC) provides a summary of minimum elements needed to adequately describe an initial clinical study concept that involves RWD and is intended to support decision-making. Fit-for-use data and fit-for-purpose design emerged as themes from the landscape analysis. Data that are fit-for-use are both relevant (sufficiently capturing exposure, outcomes, and covariates) and reliable (understanding data accrual and quality control and whether the data represent the underlying concepts they are intended to represent) to answer a specific research question. A fit-for-purpose design takes appropriate steps to ensure internal and external validity and allows for transparency in reporting. The QCARD-IPC focuses on high-level characteristics of RWD sources and study design domains including data temporality, population, medical product exposure, comparators, and covariates, endpoints, statistical analysis, and data quality assurance plans. Evaluation of studies including RWD requires understanding the data source, study design, and potential biases to preliminarily evaluate whether selected RWD are fit-for-use for the research question. The Oncology QCARD-IPC provides a structured, transparent approach to facilitate early review and enhanced communication between study sponsors and scientific reviewers of initial study proposals including RWD.

Framing the Multi-Centre Qualitative Research Design as a Novel Methodology for Nursing and Healthcare Research: Reflections and A Methodological Discussion.

To discuss the multi-centre qualitative methodology as a unique design, articulate its guiding paradigm/theoretical perspectives, and highlight its methodological and methodical issues. A secondary objective is to generate further scholarly discourse regarding the multi-centre approach within the broader qualitative research tradition. Methodological discussion. Rather than an emphasis on only experiences, the multi-centre approach is presented as a unique design which also focuses on uncovering why a phenomenon or problem exists and perceptions regarding the phenomenon/problem. With its focus on capturing multiple subjective realities, the multi-centre qualitative design is arguably underpinned by pragmatist constructivism which offers a robust framework for researching phenomenon in a way that is both theoretically informed and practically relevant. Methodologically, the multi-centre qualitative research design emphasises a problem-centred enquiry, collaborative approach and rigorous study protocols, systematic site selection, contextual immersion and sensitivity and methodical flexibility. With the rapidly evolving nursing and global health landscape, the multi-centre design lends itself to exploring and capturing perceptions on a larger scale compared to single site studies. Careful planning, availability of adequate resources, rigorous protocols and quality assurance plans are critical to ensuring its success. The multi-centre approach offers the possibility of undertaking the same study across multiple settings/locations which has the potential to improve representation and strengthen transferability. This methodological discussion offers clarity regarding the use of the multi-centre approach and offering strategies for its subsequent uptake in nursing and healthcare research. Not applicable. No patient or public contribution.

Study path analyses for quality assurance and support of study planning

AbstractUtilizing student lifecycle data provided by campus management systems yields the opportunity to conduct study path analyses. Methods of artificial intelligence (AI) and data science can be used to analyze study paths, identify indicators for success, and gain insights into problems and issues of student cohorts following different study paths. Meanwhile, AI can also be used to support students through informed study planning. This article presents the project AIStudyBuddy with its focus on utilizing rule-based AI and process mining to support study planning and cohort monitoring. The concept of a reference architecture and data model for study path analytics as well as details on the development of the two user applications, StudyBuddy for students and BuddyAnalytics for study program designers, are presented. By exploring how AI and process mining can be applied in the scope of the two applications, the article addresses the question of how AI can be used for quality assurance in study planning and student cohort monitoring.

MR-OCTAVIUS 4D with 1500 MR and 1600 MR arrays is suitable for plan QA in a 1.5 T MRI-linac

To ensure the accuracy of radiation delivery to patients in a 1.5 T MRI-linac, the implementation of quality assurance (QA) devices compatible with MR technology is essential. The OCTAVIUS 4D MR, made by PTW (Freiburg, Germany) is designed to ensure consistent and ideal alignment of its detectors with the direction of each beam segment. This study focuses on investigating the fundamental characteristics of the detector response for the OCTAVIUS Detector (OD) 1500 MR and OCTAVIUS 1600 MR when used in the MR-compatible OCTAVIUS 4D. Characteristics examined included short-term reproducibility, dose linearity, field size dependency, monitor unit (MU) rate dependency, dose-per-pulse dependency, and angular dependency. The evaluation of OD 1500 MR also involved measuring 25 clinical treatment plans across diverse target sizes and anatomical sites, including the liver/pancreas, rectum, prostate, lungs, and lymph nodes. One plan was measured with the standard setup and with a 5 cm left offset. The OD 1600 MR was not available for these measurements. The capability of the OD 1500 MR to identify potential errors was assessed by introducing a MU and positional shift within the software. The results demonstrated no significant differences in short-term reproducibility ( <0.2% ), dose linearity ( <1% ), field size dependency ( <0.7% for field sizes larger than 5 cm × 5 cm), MU rate dependency ( <0.8% ), dose-per-pulse dependency ( <0.4% ) and angular dependency (standard deviation <0.5% ). All tests of clinical plans were successfully completed. The OD 1500 MR demonstrated compatibility with the standard 95% pass rate when employing a global 3%/3 mm gamma criterion, and a 90% pass rate using a global 2%/2 mm gamma criterion. The detector demonstrated the capacity to measure treatment plans with a 5 cm left offset. With the standard parameters, the gamma test was sensitive to position errors but required an addition tests of mean/median dose or point dose in order to detect small dose difference.

Impact of on-trial IGRT quality assurance in an international adaptive radiotherapy trial for participants with bladder cancer

Background and purposeRadiotherapy trial quality assurance (RT QA) is crucial for ensuring the safe and reliable delivery of radiotherapy trials, and minimizing inter-institutional variations. While previous studies focused on outlining and planning quality assurance (QA), this work explores the process of Image-Guided Radiotherapy (IGRT), and adaptive radiotherapy.This study presents findings from during-accrual QA in the RAIDER trial, evaluating concordance between online and offline plan selections for bladder cancer participants undergoing adaptive radiotherapy. RAIDER had two seamless stages; stage 1 assessed adherence to dose constraints of dose escalated radiotherapy (DART) and stage 2 assessed safety. The RT QA programme was updated from stage 1 to stage 2. Materials and methodsData from all participants in the adaptive arms (standard dose adaptive radiotherapy (SART) and DART) of the trial was requested (33 centres across the UK, Australia and New Zealand). Data collection spanned September 2015 to December 2022 and included the plans selected online, on Cone-Beam Computed Tomography (CBCT) data. Concordance with the plans selected offline by the independent RT QA central reviewer was evaluated. ResultsAnalysable data was received for 72 participants, giving a total of 884 CBCTs. The overall concordance rate was 83% (723/884). From stage 1 to stage 2 the concordance in the plans selected improved from 75% (369/495) to 91% (354/389). ConclusionDuring-accrual IGRT QA positively influenced plan selection concordance, highlighting the need for ongoing support when introducing a new technique. Overall, it contributes to advancing the understanding and implementation of QA measures in adaptive radiotherapy trials.

Patient-specific quality assurance of dynamically-collimated proton therapy treatment plans.

The dynamic collimation system (DCS) provides energy layer-specific collimation for pencil beam scanning (PBS) proton therapy using two pairs of orthogonal nickel trimmer blades. While excellent measurement-to-calculation agreement has been demonstrated for simple cube-shaped DCS-trimmed dose distributions, no comparison of measurement and dose calculation has been made for patient-specific treatment plans. To validate a patient-specific quality assurance (PSQA) process for DCS-trimmed PBS treatment plans and evaluate the agreement between measured and calculated dose distributions. Three intracranial patient cases were considered. Standard uncollimated PBS and DCS-collimated treatment plans were generated for each patient using the Astroid treatment planning system (TPS). Plans were recalculated in a water phantom and delivered at the Miami Cancer Institute (MCI) using an Ion Beam Applications (IBA) dedicated nozzle system and prototype DCS. Planar dose measurements were acquired at two depths within low-gradient regions of the target volume using an IBA MatriXX ion chamber array. Measured and calculated dose distributions were compared using 2D gamma analysis with 3%/3mm criteria and low dose threshold of 10% of the maximum dose. Median gamma pass rates across all plans and measurement depths were 99.0% (PBS) and 98.3% (DCS), with a minimum gamma pass rate of 88.5% (PBS) and 91.2% (DCS). The PSQA process has been validated and experimentally verified for DCS-collimated PBS. Dosimetric agreement between the measured and calculated doses was demonstrated to be similar for DCS-collimated PBS to that achievable with noncollimated PBS.

Machine learning and lean six sigma for targeted patient-specific quality assurance of volumetric modulated arc therapy plans

Background and purposeRadiotherapy plans with excessive complexity exhibit higher uncertainties and worse patient-specific quality assurance (PSQA) results, while the workload of measurement-based PSQA can impact the efficiency of the radiotherapy workflow. Machine Learning (ML) and Lean Six Sigma, a process optimization method, were implemented to adopt a targeted PSQA approach, aiming to reduce workload, risk of failures, and monitor complexity. Materials and methodsLean Six Sigma was applied using DMAIC (define, measure, analyze, improve, and control) steps. Ten complexity metrics were computed for 69,811 volumetric modulated arc therapy (VMAT) arcs from 28,612 plans delivered in our Institute (2013–2021). Outlier complexities were defined as >95th-percentile of the historical distributions, stratified by treatment. An ML model was trained to predict the gamma passing rate (GPR-3 %/1mm) of an arc given its complexity. A decision support system was developed to monitor the complexity and expected GPR. Plans at risk of PSQA failure, either extremely complex or with average GPR <90 %, were identified. The tool’s impact was assessed after nine months of clinical use. ResultsAmong 1722 VMAT plans monitored prospectively, 29 (1.7 %) were found at risk of failure. Planners reacted by performing PSQA measurement and re-optimizing the plan. Occurrences of outlier complexities remained stable within 5 %. The expected GPR increased from a median of 97.4 % to 98.2 % (Mann-Whitney p < 0.05) due to plan re-optimization. ConclusionsML and Lean Six Sigma have been implemented in clinical practice enabling a targeted measurement-based PSQA approach for plans at risk of failure to improve overall quality and patient safety.

The Impact of Virtual Teaching and Learning on Skill and Knowledge Acquisition in the Training of Health Professionals

This paper aims to examine how virtual teaching and learning affect the acquisition of skills and knowledge among healthcare professionals in Ghana using the SWOT framework and socio ecological model. The findings indicate that virtual teaching offers benefits such as improved accessibility, flexibility, cost effectiveness and opportunities for expanding training using technologies. However challenges were noted in skill development and digital disparities. Threats included declines in competency and sustainability issues. The socio ecological perspective emphasized how factors across levels are interconnected. In conclusion the combined analysis using SWOT and socio ecological models provides an understanding of how virtual teaching impacts healthcare education in Ghana. Recommendations include investing in infrastructure training faculty members and supporting learners better; promoting collaboration among healthcare professionals; well as establishing quality assurance measures and plans, for long term sustainability. The study provides guidance on how to enhance the execution and impact of virtual education programs, in training health professionals. The results guide the development of policies based on evidence, allocation of resources and collaboration across sectors to establish an enduring policy framework for virtual healthcare professional education in Ghana.

The Impact of Virtual Teaching and Learning on Skill and Knowledge Acquisition in the Training of Health Professionals

This paper aims to examine how virtual teaching and learning affect the acquisition of skills and knowledge among healthcare professionals in Ghana using the SWOT framework and socio ecological model. The findings indicate that virtual teaching offers benefits such as improved accessibility, flexibility, cost effectiveness and opportunities for expanding training using technologies. However challenges were noted in skill development and digital disparities. Threats included declines in competency and sustainability issues. The socio ecological perspective emphasized how factors across levels are interconnected. In conclusion the combined analysis using SWOT and socio ecological models provides an understanding of how virtual teaching impacts healthcare education in Ghana. Recommendations include investing in infrastructure training faculty members and supporting learners better; promoting collaboration among healthcare professionals; well as establishing quality assurance measures and plans, for long term sustainability. The study provides guidance on how to enhance the execution and impact of virtual education programs, in training health professionals. The results guide the development of policies based on evidence, allocation of resources and collaboration across sectors to establish an enduring policy framework for virtual healthcare professional education in Ghana.

Radiotherapy Plan Quality Assurance in NRG Oncology Trials for Brain and Head/Neck Cancers: An AI-Enhanced Knowledge-Based Approach.

The quality of radiation therapy (RT) treatment plans directly affects the outcomes of clinical trials. KBP solutions have been utilized in RT plan quality assurance (QA). In this study, we evaluated the quality of RT plans for brain and head/neck cancers enrolled in multi-institutional clinical trials utilizing a KBP approach. The evaluation was conducted on 203 glioblastoma (GBM) patients enrolled in NRG-BN001 and 70 nasopharyngeal carcinoma (NPC) patients enrolled in NRG-HN001. For each trial, fifty high-quality photon plans were utilized to build a KBP photon model. A KBP proton model was generated using intensity-modulated proton therapy (IMPT) plans generated on 50 patients originally treated with photon RT. These models were then applied to generate KBP plans for the remaining patients, which were compared against the submitted plans for quality evaluation, including in terms of protocol compliance, target coverage, and organ-at-risk (OAR) doses. RT plans generated by the KBP models were demonstrated to have superior quality compared to the submitted plans. KBP IMPT plans can decrease the variation of proton plan quality and could possibly be used as a tool for developing improved plans in the future. Additionally, the KBP tool proved to be an effective instrument for RT plan QA in multi-center clinical trials.

Error detection for radiotherapy planning validation based on deep learning networks.

Quality assurance (QA) of patient-specific treatment plans for intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) necessitates prior validation. However, the standard methodology exhibits deficiencies and lacks sensitivity in the analysis of positional dose distribution data, leading to difficulties in accurately identifying reasons for plan verification failure. This issue complicates and impedes the efficiency of QA tasks. The primary aim of this research is to utilize deep learning algorithms for the extraction of 3D dose distribution maps and the creation of a predictive model for error classification across multiple machine models, treatment methodologies, and tumor locations. We devised five categories of validation plans (normal, gantry error, collimator error, couch error, and dose error), conforming to tolerance limits of different accuracy levels and employing 3D dose distribution data from a sample of 94 tumor patients. A CNN model was then constructed to predict the diverse error types, with predictions compared against the gamma pass rate (GPR) standard employing distinct thresholds (3%, 3mm; 3%, 2mm; 2%, 2mm) to evaluate the model's performance. Furthermore, we appraised the model's robustness by assessing its functionality across diverse accelerators. The accuracy, precision, recall, and F1 scores of CNN model performance were 0.907, 0.925, 0.907, and 0.908, respectively. Meanwhile, the performance on another device is 0.900, 0.918, 0.900, and 0.898. In addition, compared to the GPR method, the CNN model achieved better results in predicting different types of errors. When juxtaposed with the GPR methodology, the CNN model exhibits superior predictive capability for classification in the validation of the radiation therapy plan on different devices. By using this model, the plan validation failures can be detected more rapidly and efficiently, minimizing the time required for QA tasks and serving as a valuable adjunct to overcome the constraints of the GPR method.

Stereotactic body radiation therapy (SBRT) for prostate cancer: Improving treatment delivery efficiency and accuracy

PurposeIn stereotactic body radiation therapy (SBRT) for prostate cancer, intrafraction motion is an important source of treatment uncertainty as it could not be completely smoothed through fractionation. Herein, we compared different arrangements and beam qualities for extreme hypofractionated treatments to minimize beam delivery time and so intrafractional errors. MethodsA retrospective dataset of 11 patients was used. Three volumetric modulated arc therapy (VMAT) beam arrangements were compared for a prescription dose of 40 Gy/5 fractions: two full arcs, 6 MV flattening filter free (FFF); one full arc, 6 MV FFF; one full arc, 10 MV FFF. A plan quality index was defined to compare achievement of the planning goals. Plan complexity was evaluated with the modulation factor. Dose delivery accuracy and efficiency were measured with patient-specific quality assurance plans. ResultsAll treatment plans fulfilled all dose objectives. No statistical differences were found both in plan quality and complexity. Very accurate dose delivery was achieved with the three arrangements, with mean γ passing rates >96.5 % (2 %/2 mm criteria). Slightly but significantly higher γ passing rates were observed with single-arc 6 MV FFF. Contrariwise, statistically significant reductions of the delivery time were obtained with single-arc geometries: the average delivery times were 1.6 min (−46.1 %) and 1.3 min (−56.2 %) for 6 and 10 MV FFF respectively. ConclusionsThe high-quality, very fast and accurate dose delivery of single-arc plans confirmed the suitability of this arrangement for prostate SBRT. In particular, the significant reduction of delivery time would improve treatment robustness against intrafraction prostate motion.

Efficient EPID-based quality assurance of beam time delay for respiratory-gated radiotherapy with validation on Catalyst™ and AlignRT™ systems.

To propose a straightforward and time-efficient quality assurance (QA) approach of beam time delay for respiratory-gated radiotherapy and validate the proposed method on typical respiratory gating systems, Catalyst™ and AlignRT™. The QA apparatus was composed of a motion platform and a Winston-Lutz cube phantom (WL3) embedded with metal balls. The apparatus was first scanned in CT-Sim and two types of QA plans specific for beam on and beam off time delay, respectively, were designed. Static reference images and motion testing images of the WL3 cube were acquired with EPID. By comparing the position differences of the embedded metal balls in the motion and reference images, beam time delays were determined. The proposed approach was validated on three linacs with either Catalyst™ or AlignRT™ respiratory gating systems. To investigate the impact of energy and dose rate on beam time delay, a range of QA plans with Eclipse (V15.7) were devised with varying energy and dose rates. For all energies, the beam on time delays in AlignRT™ V6.3.226, AlignRT™ V7.1.1, and Catalyst™ were 92.13 5.79ms, 123.11 6.44ms, and 303.44 4.28ms, respectively. The beam off time delays in AlignRT™ V6.3.226, AlignRT™ V7.1.1, and Catalyst™ were 121.87 1.34ms, 119.33 0.75ms, and 97.69 2.02ms, respectively. Furthermore, the beam on delays decreased slightly as dose rates increased for all gating systems, whereas the beam off delays remained unaffected. The validation results demonstrate the proposed QA approach of beam time delay for respiratory-gated radiotherapy was both reproducible and time-efficient to practice for institutions to customize accordingly.

Flexible pavement longitudinal joint quality evaluation using non-destructive testing

Longitudinal joint construction quality is critical to the life of flexible pavements. Maintaining deteriorated longitudinal joints has become a challenge for many highway agencies. Improving the joint's quality through better compaction during construction can help achieve flexible pavements with longer service lives and less maintenance. Current quality control (QC) and quality assurance (QA) plans provide limited coverage. Consequently, the risk of missing areas with poor joint compaction is significant. A density profiling system (DPS) is a non-destructive alternative to conventional destructive evaluation methods. It can provide quick and continuous real-time coverage of the compaction during construction in dielectrics. The paper presents several case studies comparing various types of longitudinal joints and demonstrating the use of DPS to evaluate the joint's compaction quality. The paper shows that dielectric measurements can provide valuable insight into the ability of various construction techniques to achieve adequate levels of compaction at the longitudinal joint. The paper proposes a dielectric-based longitudinal joint quality index (LJQI) to evaluate the relative compaction of the joint during construction. It also shows that adopting DPS for assessing the compaction of longitudinal joints can minimize the risk of agencies accepting poorly constructed joints, identify locations of poor quality during construction, and achieve better-performing flexible pavements.

Patterns of quality assurance and treatment planning for stereotactic body radiation therapy in India - A survey.

The use of stereotactic body radiation therapy (SBRT) is an increasing trend in the country. The aim of this study is to gain knowledge on patterns of quality assurance (QA) and treatment planning (TP) aspects with respect to SBRT. A questionnaire with multiple choice was designed to determine practices of SBRT covering areas such as years of experience, type of linear accelerator, tumor-motion strategies, calculation algorithm used in the TP system (TPS), the protocol used for small field dosimetry, the detector used for small field dosimetry and QA, respiratory management during delivery. The survey was sent to all radiotherapy institutes in the country having a minimum of one linear accelerator, and responses were analyzed. From June 2022 to December 2022, 265 responses to the SBRT survey were received with response rate as 60.4%. The most common reason for not adopting SBRT was reported as a lack of capability of treatment machines to deliver SBRT (61.6%). Lung (81.1%) was the most practiced site. The most common delivery unit was a conventional linear accelerator (83%); 6 MV FFF (85.7%) was mostly used energy; volumetric-modulated arc radiotherapy (VMAT) (91.5%) was mostly used delivery technique; most of the equipment (more than 91.5%) used multileaf collimator (MLC) leaf width ≤5 mm. The most popular methods used for motion strategies during computed tomography (CT) were motion-encompassing and breath-hold techniques used by 65 (62.5%) and 62 (59.6%) respondents, respectively. The most popular method used for respiratory management during delivery was breath-hold by 55 (52.4%) respondents. Most TPS are equipped with either Type-C or Type-B algorithms. Heterogeneity was observed in the QA protocol and acceptance criteria for analysis of patient-specific QA. The survey resulted in heterogeneity in QA and TP aspects among users of SBRT and demands for harmonizing the dosimetric aspects of SBRT in the country.

Treatment planning evaluation and experimental validation of the magnetic resonance-based intrafraction drift correction

Background and purposeMRI-guided online adaptive treatments can account for interfractional variations, however intrafraction motion reduces treatment accuracy. Intrafraction plan adaptation methods, such as the Intrafraction Drift Correction (IDC) or sub-fractionation, are needed. IDC uses real-time automatic monitoring of the tumor position to initiate plan adaptations by repositioning segments. IDC is a fast adaptation method that occurs only when necessary and this method could enable margin reduction. This research provides a treatment planning evaluation and experimental validation of the IDC. Materials and methodsAn in silico treatment planning evaluation was performed for 13 prostate patients mid-treatment without and with intrafraction plan adaptation (IDC and sub-fractionation). The adaptation methods were evaluated using dose volume histogram (DVH) metrics. To experimentally verify IDC a treatment was mimicked whereby a motion phantom containing an EBT3 film moved mid-treatment, followed by repositioning of segments. In addition, the delivered treatment was irradiated on a diode array phantom for plan quality assurance purposes. ResultsThe planning study showed benefits for using intrafraction adaptation methods relative to no adaptation, where the IDC and sub-fractionation showed consistently improved target coverage with median target coverages of 100.0%. The experimental results verified the IDC with high minimum gamma passing rates of 99.1% and small mean dose deviations of maximum 0.3%. ConclusionThe straightforward and fast IDC technique showed DVH metrics consistent with the sub-fractionation method using segment weight re-optimization for prostate patients. The dosimetric and geometric accuracy was shown for a full IDC workflow using film and diode array dosimetry.