Specific Quality Assurance Research Articles

Management Framework for Quality Assurance to Strengthen Technology and TVET Pre-service Teacher Education

This study developed a management framework for quality assurance to enhance Technical-Vocational Education and Training (TVET) and technology pre-service teacher education programs in CALABARZON (Cavite, Laguna, Batangas, Rizal, and Quezon). Using the three-round Delphi consensus-building technique, the research assessed quality assurance practices and challenges in managing Bachelor of Technology and Livelihood Education (BTLEd) and Bachelor of Technical Vocational Teacher Education (BTVTEd) programs. The study also examined key factors affecting student performance in licensure examinations, career decision influences, and strategies to improve program appeal. Thirteen Delphi experts, including College Deans and program chairs, and 117 BTLEd and BTVTEd graduates participated. Thematic and statistical analyses, including the Mann-Whitney U test, compared assessment differences between graduates concerning licensure exam performance, career decisions, and program appeal strategies. The findings highlight that Teacher Education Institutions (TEIs) in the region prioritize quality assurance through curriculum reviews, faculty engagement, accreditation, facility maintenance, and continuous improvement. However, they face challenges such as resource limitations, curriculum misalignment, faculty development issues, and lack of specific quality assurance standards for TVET programs. Graduates noted factors influencing their licensure exam performance and career decisions, emphasizing the importance of review preparation, teaching strategies, and professional development. To enhance program appeal, there is a need for sustained career guidance, institutional initiatives, and program awareness efforts. The study recommends strengthening collaboration with stakeholders and implementing the proposed management framework to align with national and international standards.

Validation of MLC leaf open time calculation methods for PSQA in adaptive radiotherapy with tomotherapy units.

Treatment delivery safety and accuracy are essential to control the disease and protect healthy tissues in radiation therapy. For usual treatment, a phantom-based patient specific quality assurance (PSQA) is performed to verify the delivery prior to the treatment. The emergence of adaptive radiation therapy (ART) adds new complexities to PSQA. In fact, organ at risks and target volume re-contouring as well as plan re-optimization and treatment delivery are performed with the patient immobilized on the treatment couch, making phantom-based pretreatment PSQA impractical. In this case, phantomless PSQA tools based on multileaf collimator (MLC) leaf open times (LOTs) verifications provide alternative approaches for the Radixact® treatment units. However, their validity is compromised by the lack of independent and reliable methods for calculating the LOT performed by the MLC during deliveries. To provide independent and reliable methods of LOT calculation for the Radixact® treatment units. Two methods for calculating the LOTs performed by the MLC during deliveries have been implemented. The first method uses the signal recorded by the build-in detector and the second method uses the signal recorded by optical sensors mounted on the MLC. To calibrate the methods to the ground truth, in-phantom ionization chamber LOT measurements have been conducted on a Radixact® treatment unit. The methods were validated by comparing LOT calculations with in-phantom ionization chamber LOT measurements performed on two Radixact® treatment units. The study shows a good agreement between the two LOT calculation methods and the in-phantom ionization chamber measurements. There are no notable differences between the two methods and the same results were observed on the different treatment units. The two implemented methods have the potential to be part of a PSQA solution for ART in tomotherapy.

Impact of Reference Selection on Gamma Analysis in Patient-Specific Quality Assurance for Monte Carlo-Based Treatment Planning Systems.

Our study aimed to establish a standardized methodology for selecting "reference" and "evaluated" distributions in gamma analysis for Monte Carlo (MC) based intensity modulated treatment plans. Evaluation of importance of reference selection in MC based and non MC based treatment planning systems were analysed using a study classification. Three categories were utilized to analyzed gamma passing rates across using different treatment planning systems (TPS) and detectors for thirty five patients. Category 1 utilized MC-based Monaco TPS plans and a 2 dimensional(2D) I'mRTMatriXX detector. Category 2 employed non-MC-based Eclipse TPS plans, assessed with a 2D I'mRTMatriXX detector. In Category 3, MC-based Monaco TPS plans were validated using a Dolphin detector. All plans were subjected to analysis using gamma criteria, which considered a dose difference of 3% and a distance to agreement of 3mm. Additionally, another set of gamma criteria was employed, with a dose difference of 3% and a distance to agreement of 2mm. An introduced Asymmetric factors in both 2D and 3D analysis will quantify the asymmetric nature of gamma based on the choice of "reference" distribution. For 2D Gamma analysis, MC-based Monaco TPS and I'mRTMatriXX showed a consistent positive Zk2D trend for all patients, with significant p-values below 0.01 for both gamma passing criteria. In contrast, non-MC based Eclipse TPS exhibited varied Zk2D results, with non-significant p-values. In 3D Gamma analysis, all patients exhibited positive Zk3D values with significant p-values below 0.01 when "references" were swapped. The Pearson correlation between asymmetricity and isodose volumes was notably high at 0.99 for both gamma criteria. Our study highlights the imperative of using MC-based TPS as the definitive "reference" in gamma analysis for patient specific quality assurance of intensity modulated radiation therapy, emphasizing that variations can mislead results, especially given gamma analysis's sensitivity to MC calculation noise.

Machine learning and deep learning prediction of patient specific quality assurance in breast IMRT radiotherapy plans using Halcyon specific complexity indices

IntroductionNew radiotherapy machines such as Halcyon are capable of delivering dose-rate of 600 monitor-units per minute, allowing large numbers of patients treated per day. However, patient-specific quality assurance (QA) is still required, which dramatically decrease machine availability. Innovative artificial intelligence (AI) algorithms could predict QA result based on complexity metrics. However, no AI solution exists for Halcyon machines and the complexity metrics to be used have not been definitively determined. The aim of this study was to develop an AI solution capable of firstly determining the complexity indices to be obtained and secondly predicting patient-specific QA in a routine clinical setting. MethodsThree hundred and eighteen beams from 56 patients with breast cancer were used. The seven complexity indices named Modulation-Complexity-Score (MCS), Small-Aperture-Score (SAS10), Beam-Area (BA), Beam-Irregularity (BI), Beam-Modulation (BM), Gantry and Collimator angles were used as input to the AI model. Machine learning (ML) and deep learning (DL) models using tensorflow were set up to predict DreamDose QA conformance. ResultsMCS, BI, gantry and collimator angle are not correlated with QA compliance. Therefore, ML and DL models were trained using SAS10, BA and BM complexity indices. ROC analyses enabled to find best predicted probability threshold to increase specificity and sensitivity. ML models did not show satisfactory performance with an area under-the-curve (AUC) of 0.75 and specificity and sensitivity of 0.88 and 0.86. However, optimised DL model showed better performance with an AUC of 0.95 and specificity and sensitivity of 0.98 and 0.97. ConclusionThe DL model demonstrated a high degree of accuracy in its predictions of the quality assurance (QA) results. Our online predictive QA-platform offers significant time savings in terms of accelerator occupancy and working time.

Development and validation of 3D printed anthropomorphic head phantom with eccentric holes for medical LINAC quality assurance testing in stereotactic radiosurgery

Stereotactic Radiosurgery (SRS) for brain tumors using Medical Linear Accelerator (LINAC) demands high precision and accuracy. A specific Quality Assurance (QA) is essential for every patient undergoing SRS to protect nearby non-cancerous cells by ensuring that the X-ray beams are targeted according to tumor position. In this work, a water-filled generic anthropomorphic head phantom consisting of two removable parts with eccentric holes was developed using Additive Manufacturing (AM) process for performing QA in SRS. In the patient specific QA, the planned radiation dose using Treatment Planning System (TPS) was compared with the dose measured in the phantom. Also, the energy consistency of radiation beams was tested at 200 MU for different energy beams at the central and eccentric holes of the phantom using an ionization chamber. Experimentally examined results show that planned doses in TPS are reaching the target within a 5% deviation. The ratio of the dose delivered in the eccentric hole to the dose delivered to the central hole shows variations of less than 2% for the energy consistency test. The designed, low-cost water-filled anthropomorphic phantom is observed to improve positioning verification and accurate dosimetry of patient-specific QA in SRS treatment.

The Comparison of Surface Dose in Vivo Dosimetry Using 3D-CRT and IMRT Technique on Breast Cancer Case

The aim of this study is to verify the adequacy of the surface radiation dose calculated by the Treatment Planning System (TPS) using 3DCRT and IMRT technique with the dose measured by the TLD-100, referring to the report of the American Association of Physicists in Medicine Task Group No.219 (AAPM-TG No.219). This research process began with annealing the TLD-100 at the Research Center for Safety Technology Metrology and Nuclear Quality of the National Innovation Research Agency (PRTKMMR-BRIN), followed by scanning the TLD-100 on the surface of the phantom plate using a CT simulator. In addition, the TLD-100 was calibrated with different radiation doses (0; 20; 50; 80; 100; 150; 200; 250; 370) cGy. Verification of the surface radiation dose was performed by calculating the TPS surface dose by Patient Specific Quality Assurance (PSQA) and comparing it with the dose measured by the TLD-100. The result is Radiation techniques such as IMRT are more conformal than 3D-CRT because they precisely control dose intensity, making the TLD dose in IMRT closer to TPS. Differences in detector types such as TLD also affect the results of radiation dose measurements. Continuous assessment of patient dose is important for the safety of radiation therapy.

A joint ESTRO and AAPM guideline for development, clinical validation and reporting of artificial intelligence models in radiation therapy

Background and purposeArtificial Intelligence (AI) models in radiation therapy are being developed with increasing pace. Despite this, the radiation therapy community has not widely adopted these models in clinical practice. A cohesive guideline on how to develop, report and clinically validate AI algorithms might help bridge this gap. Methods and materialsA Delphi process with all co-authors was followed to determine which topics should be addressed in this comprehensive guideline. Separate sections of the guideline, including Statements, were written by subgroups of the authors and discussed with the whole group at several meetings. Statements were formulated and scored as highly recommended or recommended. ResultsThe following topics were found most relevant: Decision making, image analysis, volume segmentation, treatment planning, patient specific quality assurance of treatment delivery, adaptive treatment, outcome prediction, training, validation and testing of AI model parameters, model availability for others to verify, model quality assurance/updates and upgrades, ethics. Key references were given together with an outlook on current hurdles and possibilities to overcome these. 19 Statements were formulated. ConclusionA cohesive guideline has been written which addresses main topics regarding AI in radiation therapy. It will help to guide development, as well as transparent and consistent reporting and validation of new AI tools and facilitate adoption.

Feasibility of patient-specific quality assurance (PSQA) for real-time robotic stereotactic body radiotherapy (SBRT) based on tumor motion traces.

To design a patient specific quality assurance (PSQA) process for the CyberKnife Synchrony system and quantify its dosimetric accuracy using a motion platform driven by patient tumor traces with rotation. The CyberKnife Synchrony system was evaluated using a motion platform (MODUSQA) and a SRS MapCHECK phantom. The platform was programed to move in the superior-inferior (SI) direction based on tumor traces. The detector array housed by the StereoPhan was placed on the platform. Extra rotational angles in pitch (head down, 4.0°±0.15° or 1.2°±0.1°) were added to the moving phantom to examine robot capability of angle correction during delivery. A total of 15 Synchrony patients were performed SBRT PSQA on the moving phantom. All the results were benchmarked by the PSQA results based on static phantom. For smaller pitch angles, the mean gamma passing rates were 99.75%±0.87%, 98.63%±2.05%, and 93.11%±5.52%, for 3%/1mm, 2%/1mm, and 1%/1mm, respectively. Large discrepancy in the passing rates was observed for different pitch angles due to limited angle correction by the robot. For larger pitch angles, the corresponding mean passing rates were dropped to 93.00%±10.91%, 88.05%±14.93%, and 80.38%±17.40%. When comparing with the static phantom, no significant statistic difference was observed for smaller pitch angles (p=0.1 for 3%/1mm), whereas a larger statistic difference was observed for larger pitch angles (p<0.02 for all criteria). All the gamma passing rates were improved, if applying shift and rotation correction. The significance of this work is that it is the first study to benchmark PSQA for the CyberKnife Synchrony system using realistically moving phantoms with rotation. With reasonable delivery time, we found it may be feasible to perform PSQA for Synchrony patients with a realistic breathing pattern.

Characterization of an enhanced formulation N-(3-methoxypropyl) acrylamide polymer gel dosimeter by the addition of an organic sensitizer for clinical practice

Polymer gel dosimeters are being developed and improved to perform measurements of radiation dose distributions in 3-dimensions (3-D) for the purpose of patient specific quality assurance for cancer patients and the configuration of treatment planning systems. The effect of organic glucose sensitizer (GL) material on N-(3-methoxypropyl) acrylamide polymer gel dosimeter (NMPAGAT) was presented in this study and evaluated after irradiation using nuclear magnetic resonance (NMR) read-out technique in terms of spin–spin relaxation rate (R2) of hydrogen protons within the water molecule. The improved tissue equivalent polymers of GL-NMPAGAT were irradiated using a medical linear accelerator with photon beams with doses up to 20 Gy, energies range 6–15 MV, dose rates range 50–500 cGy/min, and irradiation temperatures range 15–25 °C. The R2 dose sensitivity of GL-NMPAGT polymer with a concentration of 25 % wt GL was improved significantly and found to be two times higher than the same gel without GL in the linear dose response of 0.07–8 Gy. The 0.07 Gy represents the minimum detectable dose in the improved dosimeters. The dosimeter was found stable within a period of up to two weeks after irradiation, which is significant. No significant dose rate, energy dependence, and irradiation temperature for the dosimeter was observed over the range studied. There is decrease in R2 values with increasing scanning temperature. The gel is water equivalent and has theoretical energy-independent response from 0.1 to 20 MeV with density of 1.023 ± 0.003 g/cm3 and Zeff of 7.53. The results of the improved dosimeter in this study (i.e., 100 %, 0.32 s−1 Gy−1, and 8 Gy linearity) are toward the upper limit compared to other polymer gel dosimeters even with sensitizer additives.

Commissioning and dosimetric verification of volumetric modulated arc therapy for multiple modalities using electronic portal imaging device-based 3D dosimetry system: a novel approach.

The purpose of this study was to validate an electronic portal imaging device (EPID) based 3-dimensional (3D) dosimetry system for the commissioning of volumetric modulated arc therapy (VMAT) delivery for flattening filter (FF) and flattening filter free (FFF) modalities based on test suites developed according to American Association of Physicists in Medicine Task Group 119 (AAPM TG 119) and pre-treatment patient specific quality assurance (PSQA).With ionisation chamber, multiple-point measurement in various planes becomes extremely difficult and time-consuming, necessitating repeated exposure of the plan. The average agreement between measured and planned doses for TG plans is recommended to be within 3%, and both the ionisation chamber and PerFRACTION™ measurement were well within this prescribed limit. Both point dose differences with the planned dose and gamma passing rates are comparable with TG reported multi-institution results. From our study, we found that no significant differences were found between FF and FFF beams for measurements using PerFRACTION™ and ion chamber. Overall, PerFRACTION™ produces acceptable results to be used for commissioning and validating VMAT and for performing PSQA. The findings support the feasibility of integrating PerFRACTION™ into routine quality assurance procedures for VMAT delivery. Further multi-institutional studies are recommended to establish global baseline values and enhance the understanding of PerFRACTION™'s capabilities in diverse clinical settings.

Strategic endowment fund management: Elevating quality assurance in higher education - insights from case studies and best practices

This research explores the pivotal role of strategic endowment fund management in elevating the quality assurance standards within higher education institutions. Quality assurance in higher education is of paramount importance, especially in a global context where educational excellence is a driving force for socioeconomic development. Drawing from an extensive analysis of case studies across diverse geographical regions and institutional types, this research identifies key strategies and best practices that have yielded tangible improvements in educational quality. It explores the innovative ways in which endowment funds are established, managed, and leveraged to address specific quality assurance challenges faced by higher education institutions. Furthermore, it examines the ethical considerations inherent in fund allocation and distribution, ensuring equitable access to resources for quality enhancement. In doing so, this research paper not only underscores the critical association between endowment fund management and higher education quality assurance but also provides a repository of practical insights and best practices that can guide policymakers, educational leaders, and philanthropic organizations in their efforts to sustain and elevate the quality of higher education worldwide. As higher education institutions grapple with the challenges of the 21st century, strategic endowment fund management emerges as a powerful tool in ensuring that educational quality remains at the forefront.

P 21 - Patient specific quality assurance of small field PBS proton beam

P 21 - Patient specific quality assurance of small field PBS proton beam

Towards Quality Assurance in MOOCs: A Comprehensive Review and Micro-Level Framework

MOOCs (massive open online courses), because of their scale and accessibility, have become a major area of interest in contemporary education. However, despite their growing popularity, the question of their quality remains a central concern, partly due to the lack of consensus on the criteria establishing such quality. This study set out to fill this gap by carrying out a systematic review of the existing literature on MOOC quality and proposing a specific quality assurance framework at a micro level. The methodology employed in this research consisted of a careful analysis of MOOC success factor’s using Biggs’ classification scheme, conducted over a four-year period from 2018 to 2022. The results highlighted the compelling need to consider various indicators across presage, process, and product variables when designing and evaluating MOOCs. This implied paying particular attention to pedagogical quality, both from the learner’s and the teacher’s point of view. The quality framework thus developed is of significant importance. It offers valuable guidance to MOOC designers, learners, and researchers, providing them with an in-depth understanding of the key elements contributing to MOOC quality and facilitating their continuous improvement. In addition, this study highlighted the need to address aspects for future research, including large-scale automated evaluation of MOOCs. By focusing on pedagogical quality, MOOCs can play a vital role in providing meaningful learning experiences, maximizing learner satisfaction, and ensuring their success as innovative educational systems adapted to the changing needs of contemporary education.

ACPSEM position paper: pre-treatment patient specific plan checks and quality assurance in radiation oncology.

The Australasian College of Physical Scientists and Engineers in Medicine (ACPSEM) has not previously made recommendations outlining the requirements for physics plan checks in Australia and New Zealand. A recent workforce modelling exercise, undertaken by the ACPSEM, revealed that the workload of a clinical radiation oncology medical physicist can comprise of up to 50% patient specific quality assurance activities. Therefore, in 2022 the ACPSEM Radiation Oncology Specialty Group (ROSG) set up a working group to address this issue. This position paper authored by ROSG endorses the recommendations of the American Association of Physicists in Medicine (AAPM) Task Group 218, 219 and 275 reports with some contextualisation for the Australia and New Zealand settings. A few recommendations from other sources are also endorsed to complete the position.

Reduction of Patient Specific Quality Assurance (PSQA) using complexity metrics

Reduction of Patient Specific Quality Assurance (PSQA) using complexity metrics

Development of a 3D printed phantom for commissioning and quality assurance of multiple brain targets stereotactic radiosurgery

Single plan techniques for multiple brain targets (MBT) stereotactic radiosurgery (SRS) are now routine. Patient specific quality assurance (QA) for MBT poses challenges due to the limited capabilities of existing QA tools which necessitates several plan redeliveries. This study sought to develop an SRS QA phantom that enables flexible MBT patient specific QA in a single delivery, along with complex SRS commissioning. PLA marble and PLA StoneFil materials were selected based on the literature and previous research conducted in our department. The HU numbers were investigated to determine the appropriate percentage infill for skull and soft-tissue equivalence. A Prusa MK3S printer in conjunction with the above-mentioned filaments were used to print the SRS QA phantom. Quality control (QC) was performed on the printed skull, film inserts and plugs for point dose measurements. EBT3 film and point dose measurements were performed using a CC04 ionisation chamber. QC demonstrated that the SRS QA phantom transverse, coronal and sagittal film planes were orthogonal within 0.5°. HU numbers for the skull, film inserts and plugs were 858 ± 20 and 35 ± 12 respectively. Point and EBT3 film dose measurements were within 2.5% and 3%/2 mm 95% gamma pass rate, respectively except one Gross Tumour Volume (GTV) that had a slightly lower gamma pass rate. Dose distributions to five GTVs were measured with EBT3 film in a single plan delivery on CyberKnife. In conclusion, an SRS QA phantom was designed, and 3D printed and its use for performing complex MBT patient specific QA in a single delivery was demonstrated.

Evaluation of a novel patient-specific quality assurance phantom for robotic single-isocentre, multiple-target stereotactic radiosurgery, and stereotactic radiotherapy.

To evaluate patient-specific quality assurance (PSQA) of 3 targets in a single delivery using a novel film-based phantom. The phantom was designed to rotate freely as a sphere and could measure 3 targets with film in a single delivery. After identifying the coordinates of 3 targets in the skull, the rotation angles about the equator and meridian were computed for optimal phantom setup, ensuring the film plane intersected the 3 targets. The plans were delivered on the CyberKnife system using fiducial tracking. The irradiated films were scanned and processed. All films were analysed using 3 gamma criteria. Fifteen CyberKnife test plans with 3 different modalities were delivered on the phantom. Both automatic and marker-based registration methods were applied when registering the irradiated film and dose plane. Gamma analysis was performed using a 3%/1 mm, 2%/1 mm, and 1%/1 mm criteria with a 10% threshold. For the automatic registration method, the passing rates were 98.2% ± 1.9%, 94.2% ± 3.7%, and 80.9% ± 6.3%, respectively. For the marker-based registration approach, the passing rates were 96.4% ± 2.7%, 91.7% ± 4.3%, and 78.4% ± 6.2%, respectively. A novel spherical phantom was evaluated for the CyberKnife system and achieved acceptable PSQA passing rates using TG218 recommendations. The phantom can measure true-composite dose and offers high-resolution results for PSQA, making it a valuable device for robotic radiosurgery. This is the first study on PSQA of 3 targets concurrently on the CyberKnife system.

Stereotactic radiosurgery in India: A nationwide survey of technology and quality assurance practices.

India is rapidly adopting advanced treatments like Stereotactic Radiosurgery (SRS). However, there is a paucity of data on SRS practice. The aim of study is to assess the current status of technology and practices of machine quality assurance (QA) and patient specific quality assurance for SRS in India. A survey questionnaire was designed using Google Forms and sent to chief/senior medical physicists across 220 radiotherapy centers in India on July 15, 2022. It contained questions on infrastructure availability, treatment planning, and QA. SRS was found to be extensively used for the treatment of brain metastases (99.3%), followed by meningioma (50.3%), acoustic neuroma (45.5%), and pituitary tumours (33.1%). The most commonly used photon energy and treatment technique were 6MV FFF and VMAT, respectively. A prescription isodose line ranging from 70% to 100% was selected by linac users. Most linac institutes verify pretreatment doses. There was a lack of uniformity in the analysis metrics such as Low Dose Threshold, Dose Difference, and Distance to Agreement. A survey revealed that the variety of SRS QA programs being followed at Indian radiotherapy centers. This is the first study to report the physics practice of SRS in India. The survey shows a need to carry out a postal dose audit for small static photon fields in India.

Comprehensive characterisation of the IBA myQA SRS for SRS and SBRT patient specific quality assurance.

The myQA SRS (IBA) is a new to market 2D complementary metal oxide semiconductor detector array with an active area 140 × 120mm2 and 0.4mm resolution, making it a potential real-time dosimetry alternative to radiochromic film for stereotactic plan verification. Characterisation of the device was completed to assess performance. The dosimetric properties of the device were assessed for 6FF and 6FFF beams from a Varian TrueBeam STx with high definition multileaf collimator. Clinical suitability of the device for Patient Specific Quality Assurance was verified using ten SRS/SBRT plans, compared against other detectors, as well as multi leaf collimator (MLC) tests including picket fence and chair. Gamma analysis was performed using myQA software with criteria of 4%/1mm. The device demonstrated compliance with recommended specifications for basic tests. After the required warm-up period, the maximum deviation in detector signal from initial readings was 0.2%. Short-term and long-term reproducibility was 0.1% (6FF) and 1.0% (6FFF), respectively. Dose linearity was within 0.3% (6FF) and 0.7% (6FFF) and dose-rate dependence within 1.7% (6FF) and 2.9% (6FFF) and were verified with a Farmer type ionization chamber (PTW 30013). Angular dependence was quantified for coplanar and non-coplanar situations. Output factors and beam profiles measured on the device showed agreement within 1% of baseline RAZOR diode (IBA) and CC04 ionisation chamber (IBA) measurements for field sizes 1 × 1 to 10 × 10cm2. The minimum gamma (4%/1mm) pass rates for MLC-pattern tests were 96.5% and 98.1% for the myQA SRS and film, respectively. The average gamma (4%/1mm) pass rates for SBRT and SRS plans were 98.8% and 99.8% respectively. This work represents one of the first studies performed on the commissioning and performance characterisation of this novel device, demonstrating its accuracy and reliability, making it highly useful as a film alternative in stereotactic treatment plan verification.

Evaluation of 2D ion chamber arrays for patient specific quality assurance using a static phantom at a 0.35 T MR-Linac

IntroductionPatient specific quality assurance (QA) in MR-Linacs can be performed with MR-compatible ion chamber arrays. However, the presence of a static magnetic field can alter the angular response of such arrays substantially. This works investigates the suitability of two ion chamber arrays, an air-filled and a liquid-filled array, for patient specific QA at a 0.35 T MR-Linac using a static phantom. MethodsIn order to study the angular response, the two arrays were placed in a static, solid phantom and irradiated with 9.96 × 9.96 cm2 fields every 10° beam angle at a 0.35 T MR-Linac. Measurements were compared to the TPS calculated dose in terms of gamma passing rate and relative dose to the central chamber. 20 patient specific quality assurance plans were measured using the liquid-filled array. ResultsThe air-filled array showed asymmetric angular response changes of central chamber dose of up to 18% and down to local 3 mm / 3% gamma rates of 20%, while only minor differences within 3% (excluding parallel irradiation and beams through the couch edges) were found for the liquid-filled ion chamber array without rotating the phantom. Patient plan QA using the liquid-filled array yielded a median local 3 mm / 3% 3D gamma passing rate of 99.8% (range 96.9%–100%) ConclusionA liquid-filled ionization chamber array in combination with a static phantom can be used for efficient patient specific plan QA in a single measurement set-up in a 0.35 T MR-Linac, while the air-filled ion chamber array phantom shows large angular response changes and has its limitations regarding patient specific QA measurements