Cassandra Stambaugh - Academia.edu (original) (raw)
Papers by Cassandra Stambaugh
Radiotherapy and Oncology, Aug 31, 2023
Cureus, Mar 2, 2023
To investigate time efficiency, applicability, and accuracy of using a web-based, independent qua... more To investigate time efficiency, applicability, and accuracy of using a web-based, independent quality assurance (QA) platform and vendor-dependent based system check for daily linear accelerator (LINAC) QA. Time needed to perform daily QA on a single (n=1) LINAC was collected for three months. Task Group report 142 (TG-142) compliant daily QA included dosimetry checks (four photon, four electron beams); imaging checks (planar kilovolt (kV) & megavolt (MV), kV cone-beam computed tomography (CBCT)); and mechanical and safety checks using SunCHECK Machine (SCM) (Sun Nuclear Inc., Melbourne, FL, USA). Additionally, Machine Performance Check (MPC) (Varian Medical Systems, Inc., Palo Alto, CA, USA) was performed for all energies. Four trained radiation therapists performed daily QA on both platforms. Data were collected to identify the time required to complete both SCM and MPC. Additionally, the two platforms were evaluated on usability and features. Output results were compared to our monthly standard to assess accuracy. On average, SCM took 22 minutes with a standard deviation of six minutes and MPC took 15 minutes with a standard deviation of three minutes. MPC output results were impacted due to the beam output being coupled to the beam profile changes. As a result, the two systems on average disagreed by -1.41% after three months despite being baselined at the same time point and output agreeing well initially (average difference of -0.1% across all energies). While there was overlap in the tests performed, SCM tests were more relevant to TG-142 while MPC tests were beneficial to machine service and, with a clear understanding of the limitations of the system, found suitable as a secondary backup to SCM for daily output verification. This work demonstrates that a comprehensive TG-142 daily QA can be designed using SCM and MPC can be added as a beneficial tool and backup for output verification while still maintaining an efficient daily QA process.
International Journal of Radiation Oncology Biology Physics, Nov 1, 2020
Purpose/Objective(s): Cancer is the leading cause of death in Canada -yet research has demonstrat... more Purpose/Objective(s): Cancer is the leading cause of death in Canada -yet research has demonstrated that medical education in oncology is perceived as inadequate by learners, educators and generalist physicians. The Medical Council of Canada (MCC) conducts two examinations as Canada's national standard of assessment of medical graduates. This study aimed to determine the representation of topics in the Medical Council of Canada Qualifying Examination e Part 1 (MCCQE-1) objectives with respect to leading public health priorities, including cancer. Based on current literature, our hypothesis is that cancer will be underrepresented as an objective topic in the MCCQE-1 compared to other leading disease priorities. Materials/Methods: The MCCQE-1 lists roles in which medical graduates should be competent. The focus of this study was the "Medical Expert" role and its associated testable objectives. A deductive coding method, using NVivo 11 software, was used to map these objectives for the representation of leading Canadian health priorities e specifically oncology, cardiology, cerebrovascular disease and chronic lower respiratory disease. Using the International Statistical Classification of Diseases and Related Health problems, 10 th edition (ICD-10, WHO, 2016), in conjunction with reports on the leading causes of death in Canada, key terms for the abovementioned health priorities were determined. Two coders analyzed the data to increase objectivity and reduce bias. Results: Mapping of the MCCQE-1 objectives found 190 discreet topics listed under the Medical Expert objectives section. Of those 190, oncology content was found in 57 (30%), cardiovascular diseases in 56 (29.5%), cerebrovascular diseases in 21 (11%) and chronic lower respiratory diseases in 7 (3.7%) respectively. Within the 57 objectives containing oncology content, the three most frequently mentioned cancer sites were gastrointestinal (16/57, 23%), followed by generalized/nonspecific indicators of cancer (7/57, 12%) and genitourinary/musculoskeletal cancers (6/57 each, or 10.5%). The mapping of each disease content by two coders had inter rater agreement greater than 99%, with Kappa values ranging from 0.73 e 1.00, indicating substantial agreement. Conclusion: Findings suggest that top public health concerns in Canada are highly represented in the MCCQE-1 examination. Further work is needed to understand the mismatch between content representation on the MCCQE-1 and perceptions of learners, educators and generalist physicians regarding inadequate education in cancer.
Journal of Applied Clinical Medical Physics
This work of fiction is part of a case study series developed by the Medical Physics Leadership A... more This work of fiction is part of a case study series developed by the Medical Physics Leadership Academy (MPLA). It is intended to facilitate the discussion of the managerial and leadership challenges faced by a clinical medical physicist. In this case, a physicist David used to work in a clinic where he thrived and felt like a leader, despite not having the title. After a job change, he is now officially the “Lead Physicist” at a hospital newly affiliated with a large academic healthcare system. He believes he will be equally successful. Yet he struggles to bring about changes and get buy‐in from coworkers. In the end, he feels like giving up and considers changing his job. This case is in the scenario of Problem Diagnosis.i The intended use of this case, through group discussion or self‐study, is to encourage readers to perform a comprehensive analysis that identifies the root cause of the problem. This case study falls under the scope of and is supported by the MPLA, a committee i...
Cureus
To investigate time efficiency, applicability, and accuracy of using a web-based, independent qua... more To investigate time efficiency, applicability, and accuracy of using a web-based, independent quality assurance (QA) platform and vendor-dependent based system check for daily linear accelerator (LINAC) QA. Time needed to perform daily QA on a single (n=1) LINAC was collected for three months. Task Group report 142 (TG-142) compliant daily QA included dosimetry checks (four photon, four electron beams); imaging checks (planar kilovolt (kV) & megavolt (MV), kV cone-beam computed tomography (CBCT)); and mechanical and safety checks using SunCHECK Machine (SCM) (Sun Nuclear Inc., Melbourne, FL, USA). Additionally, Machine Performance Check (MPC) (Varian Medical Systems, Inc., Palo Alto, CA, USA) was performed for all energies. Four trained radiation therapists performed daily QA on both platforms. Data were collected to identify the time required to complete both SCM and MPC. Additionally, the two platforms were evaluated on usability and features. Output results were compared to our monthly standard to assess accuracy. On average, SCM took 22 minutes with a standard deviation of six minutes and MPC took 15 minutes with a standard deviation of three minutes. MPC output results were impacted due to the beam output being coupled to the beam profile changes. As a result, the two systems on average disagreed by -1.41% after three months despite being baselined at the same time point and output agreeing well initially (average difference of -0.1% across all energies). While there was overlap in the tests performed, SCM tests were more relevant to TG-142 while MPC tests were beneficial to machine service and, with a clear understanding of the limitations of the system, found suitable as a secondary backup to SCM for daily output verification. This work demonstrates that a comprehensive TG-142 daily QA can be designed using SCM and MPC can be added as a beneficial tool and backup for output verification while still maintaining an efficient daily QA process.
International Journal of Radiation Oncology Biology Physics, 2020
Purpose/Objective(s): Cancer is the leading cause of death in Canada -yet research has demonstrat... more Purpose/Objective(s): Cancer is the leading cause of death in Canada -yet research has demonstrated that medical education in oncology is perceived as inadequate by learners, educators and generalist physicians. The Medical Council of Canada (MCC) conducts two examinations as Canada's national standard of assessment of medical graduates. This study aimed to determine the representation of topics in the Medical Council of Canada Qualifying Examination e Part 1 (MCCQE-1) objectives with respect to leading public health priorities, including cancer. Based on current literature, our hypothesis is that cancer will be underrepresented as an objective topic in the MCCQE-1 compared to other leading disease priorities. Materials/Methods: The MCCQE-1 lists roles in which medical graduates should be competent. The focus of this study was the "Medical Expert" role and its associated testable objectives. A deductive coding method, using NVivo 11 software, was used to map these objectives for the representation of leading Canadian health priorities e specifically oncology, cardiology, cerebrovascular disease and chronic lower respiratory disease. Using the International Statistical Classification of Diseases and Related Health problems, 10 th edition (ICD-10, WHO, 2016), in conjunction with reports on the leading causes of death in Canada, key terms for the abovementioned health priorities were determined. Two coders analyzed the data to increase objectivity and reduce bias. Results: Mapping of the MCCQE-1 objectives found 190 discreet topics listed under the Medical Expert objectives section. Of those 190, oncology content was found in 57 (30%), cardiovascular diseases in 56 (29.5%), cerebrovascular diseases in 21 (11%) and chronic lower respiratory diseases in 7 (3.7%) respectively. Within the 57 objectives containing oncology content, the three most frequently mentioned cancer sites were gastrointestinal (16/57, 23%), followed by generalized/nonspecific indicators of cancer (7/57, 12%) and genitourinary/musculoskeletal cancers (6/57 each, or 10.5%). The mapping of each disease content by two coders had inter rater agreement greater than 99%, with Kappa values ranging from 0.73 e 1.00, indicating substantial agreement. Conclusion: Findings suggest that top public health concerns in Canada are highly represented in the MCCQE-1 examination. Further work is needed to understand the mismatch between content representation on the MCCQE-1 and perceptions of learners, educators and generalist physicians regarding inadequate education in cancer.
Journal of Applied Clinical Medical Physics, 2021
Abstract This work of fiction re‐enacts a scenario in which a medical physics resident was not ab... more Abstract This work of fiction re‐enacts a scenario in which a medical physics resident was not able to address a physics call during patient simulation and was criticized by the supervising faculty physicist in front of the team and the patient. The resident and the faculty agreed to meet afterwards to debrief the situation, in the hope of establishing a better working relationship. The intended use of this case, through group discussion, self‐study, or role‐play, is to encourage readers to discuss the situation at hand, inspire professionalism and leadership thinking, and allow the practice of conflict management. Facilitator's notes are available upon request to the MPLA Cases Subcommittee. This case study falls under the scope of and is supported by the Medical Physics Leadership Academy (MPLA), a committee in the American Association of Physicists in Medicine (AAPM).
Journal of Applied Clinical Medical Physics, 2021
This fictional case describes a managerial situation of implementing cone‐beam computed tomograph... more This fictional case describes a managerial situation of implementing cone‐beam computed tomography faced by a solo medical physicist in a rural community hospital. The intended use of the case study, in either a facilitated learning session or self‐study, is to inspire the readers to discuss the situation, analyze the institutional and personal factors, apply relevant leadership skills, and propose action plans. This case study falls under the scope of, and is supported by, the Medical Physics Leadership Academy (MPLA). A sample facilitator’s guide or self‐study guide is included in the manuscript for reference by users of this case study.
Journal of Applied Clinical Medical Physics, 2021
This guide provides a framework and general steps for writing a case study for the Medical Physic... more This guide provides a framework and general steps for writing a case study for the Medical Physics Leadership Academy (MPLA). 1,2 This guide may be used as part of the Request for Proposal (RFP) for case studies in AAPM leadership-themed sessions. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
International Journal of Radiation Oncology*Biology*Physics, 2021
PURPOSE/OBJECTIVE(S) To examine current practice patterns in non-English speaking breast cancer p... more PURPOSE/OBJECTIVE(S) To examine current practice patterns in non-English speaking breast cancer patients undergoing Deep Inspiratory Breath Hold (DIBH). We hypothesize that disparities in DIBH utilization exist between English and non-English speaking patients. MATERIALS/METHODS An anonymous, voluntary online survey was distributed to residency program coordinators of U.S. radiation oncology departments to survey their faculty and recent graduates. Eligibility was limited to board-certified radiation oncologists who have treated breast cancer within the prior 6 months. RESULTS There were 66 respondents, 50 of whom were eligible. 70% (n = 35) of eligible respondents were from academic sites. Slightly over half (52%) of respondents reported that at least 10% of their patients were non-English speaking. Most offered DIBH at their institution (92%) and of those, 82% of responding radiation oncologists used DIBH for at least a quarter or more of their breast cancer patients. Nearly all of those who use DIBH (98%) used coaching at the time of simulation, with about a third (37%) answering they would be "less likely" to utilize DIBH for non-English speaking patients. If DIBH is used for non-English speaking patients, 86% would take into consideration potential language barriers for proper execution of DIBH. However, slightly over one-half of respondents had an interpreter present 76-100% of the time at CT simulation. At the first DIBH treatment, 31% used an interpreter 76-100% of the time. And at each subsequent treatment, 11% used an interpreter 76-100% of the time. CONCLUSION Disparities in the application of DIBH exist despite its established utility in reducing cardiac dose. This study provides evidence that language barriers may impact physician treatment practices from initial consideration of DIBH to subsequent delivery. Even within a limited sampling of self-reported responses, this data suggests that breast cancer treatment considerations and subsequent execution are negatively affected in non-English speaking patients.
Journal of Applied Clinical Medical Physics, 2018
Implementing tighter intensity modulated radiation therapy (IMRT) quality assurance (QA) toleranc... more Implementing tighter intensity modulated radiation therapy (IMRT) quality assurance (QA) tolerances initially resulted in high numbers of marginal or failing QA results and motivated a number of improvements to our calculational processes. This work details those improvements and their effect on results. One hundred eighty IMRT plans analyzed previously were collected and new gamma criteria were applied and compared to the original results. The results were used to obtain an estimate for the number of plans that would require additional dose volume histogram (DVH)-based analysis and therefore predicted workload increase. For 2 months and 133 plans, the established criteria were continued while the new criteria were applied and tracked in parallel. Because the number of marginal or failing plans far exceeded the predicted levels, a number of calculational elements were investigated: IMRT modeling parameters, calculation grid size, and couch top modeling. After improvements to these elements, the new criteria were clinically implemented and the frequency of passing, questionable, and failing plans measured for the subsequent 15 months and 674 plans. The retrospective analysis of selected IMRT QA results demonstrated that 75% of plans should pass, while 19% of IMRT QA plans would need DVH-based analysis and an additional 6% would fail. However, after applying the tighter criteria for 2 months, the distribution of plans was significantly different from prediction with questionable or failing plans reaching 47%. After investigating and improving several elements of the IMRT calculation processes, the frequency of questionable plans was reduced to 11% and that of failing plans to less than 1%. Tighter IMRT QA tolerances revealed the need to improve several elements of our plan calculations. As a consequence, the accuracy of our plans have improved, and the frequency of finding marginal or failing IMRT QA results, remains within our practical ability to respond.
Medical Physics, 2018
Purpose: To determine clinically relevant pass/question/fail criteria for gamma analysis of inten... more Purpose: To determine clinically relevant pass/question/fail criteria for gamma analysis of intensity modulated radiation therapy quality assurance (IMRT QA) plans, identify which plans should be further analyzed with dose-volume histogram (DVH) metrics, and create a workflow for performing that DVH-based analysis. Methods: Eleven plans, five prostate and six head/neck, were selected to represent known good plans based on their high passing rate using conventional IMRT QA criteria. These were modified by moving the programmed MLC positions to underdose the target or overdose important structures by varying amounts. Commercially available hardware/software was used to measure and analyze all plans (76 total) using 4%/3mm, 3%/3mm, 3%/2mm and 2%/2mm gamma criteria. Two receiver operator characteristic (ROC) curves per criterion were created to assess effective passing rates. One ROC curve was to find a higher threshold that determined a clear pass and the second to find a lower threshold to determine a clear failure. Plans between these two thresholds need DVH-based analysis to assess the clinical consequence of the dose difference. The modified plans were analyzed in the planning system and reconstructed in commercially available DVH-based analysis software to access the accuracy and usefulness of the software. Results: Analysis of the ROC curves showed optimal pass and fail thresholds for plan error detection per criterion to achieve clinically relevant sensitivity and specificity. Based on measurement Accepted Article This article is protected by copyright. All rights reserved. uncertainty and pass/fail ranges, 3%/2mm gamma criteria with a pass threshold of 95% and a fail threshold of 90% were most optimal. DVH analysis showed good agreement with all reconstructed plans except where the changes to the MLC patterns caused the periphery of the target to be underdosed. For questionable plans, comparing the organ-specific DVHs to the physician-provided planning constraints proved to be an efficient and effective workflow since plans for which the target dose was slightly high or where organs at risk was underdosed could be released for treatment without consulting the physician for a clinical decision. Conclusion: This work indicates the potential for appreciable improvement in error detection for IMRT QA. Using effective pass/fail thresholds to determine plans that need DVH-based analysis minimizes the need for excessive, time-consuming, analysis, and making use of the dosimetric constraints of the plan minimizes the burden on physicians. Overall, DVH-based analysis is a powerful tool that can provide substantial insight over the traditional approach that does not provide structure-specific data.
Medical Physics, 2015
Previous studies show that dose to a moving target can be estimated using 4D measurementguided do... more Previous studies show that dose to a moving target can be estimated using 4D measurementguided dose reconstruction based on a process called virtual motion simulation, or VMS. A potential extension of VMS is to estimate dose during dynamic multileaf collimator (MLC)-tracking treatments. The authors introduce a modified VMS method and quantify its performance as proof-ofconcept for tracking applications. Methods: Direct measurements with a moving biplanar diode array were used to verify accuracy of the VMS dose estimates. A tracking environment for variably sized circular MLC apertures was simulated by sending preprogrammed control points to the MLC while simultaneously moving the accelerator treatment table. Sensitivity of the method to simulated tracking latency (0-700 ms) was also studied. Potential applicability of VMS to fast changing beam apertures was evaluated by modeling, based on the demonstrated dependence of the cumulative dose on the temporal dose gradient. Results: When physical and virtual latencies were matched, the agreement rates (2% global/2 mm gamma) between the VMS and the biplanar dosimeter were above 96%. When compared to their own reference dose (0 induced latency), the agreement rates for VMS and biplanar array track closely up to 200 ms of induced latency with 10% low-dose cutoff threshold and 300 ms with 50% cutoff. Time-resolved measurements suggest that even in the modulated beams, the error in the cumulative dose introduced by the 200 ms VMS time resolution is not likely to exceed 0.5%. Conclusions: Based on current results and prior benchmarks of VMS accuracy, the authors postulate that this approach should be applicable to any MLC-tracking treatments where leaf speeds do not exceed those of the current Varian accelerators.
Medical Physics, 2015
The authors designed data, methods, and metrics that can serve as a standard, independent of any ... more The authors designed data, methods, and metrics that can serve as a standard, independent of any software package, to evaluate dose-volume histogram (DVH) calculation accuracy and detect limitations. The authors use simple geometrical objects at different orientations combined with dose grids of varying spatial resolution with linear 1D dose gradients; when combined, ground truth DVH curves can be calculated analytically in closed form to serve as the absolute standards. Methods: RT structure sets containing a small sphere, cylinder, and cone were created programmatically with axial plane spacing varying from 0.2 to 3 mm. Cylinders and cones were modeled in two different orientations with respect to the IEC 1217 Y axis. The contours were designed to stringently but methodically test voxelation methods required for DVH. Synthetic RT dose files were generated with 1D linear dose gradient and with grid resolution varying from 0.4 to 3 mm. Two commercial DVH algorithms- (Philips Radiation Oncology Systems) and PlanIQ (Sun Nuclear Corp.)-were tested against analytical values using custom, noncommercial analysis software. In Test 1, axial contour spacing was constant at 0.2 mm while dose grid resolution varied. In Tests 2 and 3, the dose grid resolution was matched to varying subsampled axial contours with spacing of 1, 2, and 3 mm, and difference analysis and metrics were employed: (1) histograms of the accuracy of various DVH parameters (total volume, D max , D min , and doses to % volume: D99, D95, D5, D1, D0.03 cm 3) and (2) volume errors extracted along the DVH curves were generated and summarized in tabular and graphical forms. Results: In Test 1, produced 52 deviations (15%) while PlanIQ produced 5 (1.5%). In Test 2, and PlanIQ differed from analytical by >3% in 93 (36%) and 18 (7%) times, respectively. Excluding D min and D max as least clinically relevant would result in 32 (15%) vs 5 (2%) scored deviations for vs PlanIQ in Test 1, while Test 2 would yield 53 (25%) vs 17 (8%). In Test 3, statistical analyses of volume errors extracted continuously along the curves show to have more errors and higher variability (relative to PlanIQ), primarily due to 's lack of sufficient 3D grid supersampling. Another major driver for errors is an inconsistency in implementation of the "end-capping"; the additional volume resulting from expanding superior and inferior contours halfway to the next slice is included in the total volume calculation, but dose voxels in this expanded volume are excluded from the DVH. PlanIQ had fewer deviations, and most were associated with a rotated cylinder modeled by rectangular axial contours; for coarser axial spacing, the limited number of cross-sectional rectangles hinders the ability to render the true structure volume. Conclusions: The method is applicable to any DVH-calculating software capable of importing RT structure set and dose objects (the authors' examples are available for download). It includes a collection of tests that probe the design of the DVH algorithm, measure its accuracy, and identify failure modes. Merits and applicability of each test are discussed.
Journal of applied clinical medical physics / American College of Medical Physics, Jan 8, 2015
It was previously demonstrated that dose delivered by a conventional linear accelerator using IMR... more It was previously demonstrated that dose delivered by a conventional linear accelerator using IMRT or VMAT can be reconstructed - on patient or phantom datasets - using helical diode array measurements and a technique called planned dose perturbation (PDP). This allows meaningful and intuitive analysis of the agreement between the planned and delivered dose, including direct comparison of the dose-volume histograms. While conceptually similar to modulated arc techniques, helical tomotherapy introduces significant challenges to the PDP formalism, arising primarily from TomoTherapy delivery dynamics. The temporal characteristics of the delivery are of the same order or shorter than the dosimeter's update interval (50 ms). Additionally, the prevalence of often small and complex segments, particularly with the 1 cm Y jaw setting, lead to challenges related to detector spacing. Here, we present and test a novel method of tomotherapy-PDP (TPDP) designed to meet these challenges. One o...
Radiotherapy and Oncology, Aug 31, 2023
Cureus, Mar 2, 2023
To investigate time efficiency, applicability, and accuracy of using a web-based, independent qua... more To investigate time efficiency, applicability, and accuracy of using a web-based, independent quality assurance (QA) platform and vendor-dependent based system check for daily linear accelerator (LINAC) QA. Time needed to perform daily QA on a single (n=1) LINAC was collected for three months. Task Group report 142 (TG-142) compliant daily QA included dosimetry checks (four photon, four electron beams); imaging checks (planar kilovolt (kV) & megavolt (MV), kV cone-beam computed tomography (CBCT)); and mechanical and safety checks using SunCHECK Machine (SCM) (Sun Nuclear Inc., Melbourne, FL, USA). Additionally, Machine Performance Check (MPC) (Varian Medical Systems, Inc., Palo Alto, CA, USA) was performed for all energies. Four trained radiation therapists performed daily QA on both platforms. Data were collected to identify the time required to complete both SCM and MPC. Additionally, the two platforms were evaluated on usability and features. Output results were compared to our monthly standard to assess accuracy. On average, SCM took 22 minutes with a standard deviation of six minutes and MPC took 15 minutes with a standard deviation of three minutes. MPC output results were impacted due to the beam output being coupled to the beam profile changes. As a result, the two systems on average disagreed by -1.41% after three months despite being baselined at the same time point and output agreeing well initially (average difference of -0.1% across all energies). While there was overlap in the tests performed, SCM tests were more relevant to TG-142 while MPC tests were beneficial to machine service and, with a clear understanding of the limitations of the system, found suitable as a secondary backup to SCM for daily output verification. This work demonstrates that a comprehensive TG-142 daily QA can be designed using SCM and MPC can be added as a beneficial tool and backup for output verification while still maintaining an efficient daily QA process.
International Journal of Radiation Oncology Biology Physics, Nov 1, 2020
Purpose/Objective(s): Cancer is the leading cause of death in Canada -yet research has demonstrat... more Purpose/Objective(s): Cancer is the leading cause of death in Canada -yet research has demonstrated that medical education in oncology is perceived as inadequate by learners, educators and generalist physicians. The Medical Council of Canada (MCC) conducts two examinations as Canada's national standard of assessment of medical graduates. This study aimed to determine the representation of topics in the Medical Council of Canada Qualifying Examination e Part 1 (MCCQE-1) objectives with respect to leading public health priorities, including cancer. Based on current literature, our hypothesis is that cancer will be underrepresented as an objective topic in the MCCQE-1 compared to other leading disease priorities. Materials/Methods: The MCCQE-1 lists roles in which medical graduates should be competent. The focus of this study was the "Medical Expert" role and its associated testable objectives. A deductive coding method, using NVivo 11 software, was used to map these objectives for the representation of leading Canadian health priorities e specifically oncology, cardiology, cerebrovascular disease and chronic lower respiratory disease. Using the International Statistical Classification of Diseases and Related Health problems, 10 th edition (ICD-10, WHO, 2016), in conjunction with reports on the leading causes of death in Canada, key terms for the abovementioned health priorities were determined. Two coders analyzed the data to increase objectivity and reduce bias. Results: Mapping of the MCCQE-1 objectives found 190 discreet topics listed under the Medical Expert objectives section. Of those 190, oncology content was found in 57 (30%), cardiovascular diseases in 56 (29.5%), cerebrovascular diseases in 21 (11%) and chronic lower respiratory diseases in 7 (3.7%) respectively. Within the 57 objectives containing oncology content, the three most frequently mentioned cancer sites were gastrointestinal (16/57, 23%), followed by generalized/nonspecific indicators of cancer (7/57, 12%) and genitourinary/musculoskeletal cancers (6/57 each, or 10.5%). The mapping of each disease content by two coders had inter rater agreement greater than 99%, with Kappa values ranging from 0.73 e 1.00, indicating substantial agreement. Conclusion: Findings suggest that top public health concerns in Canada are highly represented in the MCCQE-1 examination. Further work is needed to understand the mismatch between content representation on the MCCQE-1 and perceptions of learners, educators and generalist physicians regarding inadequate education in cancer.
Journal of Applied Clinical Medical Physics
This work of fiction is part of a case study series developed by the Medical Physics Leadership A... more This work of fiction is part of a case study series developed by the Medical Physics Leadership Academy (MPLA). It is intended to facilitate the discussion of the managerial and leadership challenges faced by a clinical medical physicist. In this case, a physicist David used to work in a clinic where he thrived and felt like a leader, despite not having the title. After a job change, he is now officially the “Lead Physicist” at a hospital newly affiliated with a large academic healthcare system. He believes he will be equally successful. Yet he struggles to bring about changes and get buy‐in from coworkers. In the end, he feels like giving up and considers changing his job. This case is in the scenario of Problem Diagnosis.i The intended use of this case, through group discussion or self‐study, is to encourage readers to perform a comprehensive analysis that identifies the root cause of the problem. This case study falls under the scope of and is supported by the MPLA, a committee i...
Cureus
To investigate time efficiency, applicability, and accuracy of using a web-based, independent qua... more To investigate time efficiency, applicability, and accuracy of using a web-based, independent quality assurance (QA) platform and vendor-dependent based system check for daily linear accelerator (LINAC) QA. Time needed to perform daily QA on a single (n=1) LINAC was collected for three months. Task Group report 142 (TG-142) compliant daily QA included dosimetry checks (four photon, four electron beams); imaging checks (planar kilovolt (kV) & megavolt (MV), kV cone-beam computed tomography (CBCT)); and mechanical and safety checks using SunCHECK Machine (SCM) (Sun Nuclear Inc., Melbourne, FL, USA). Additionally, Machine Performance Check (MPC) (Varian Medical Systems, Inc., Palo Alto, CA, USA) was performed for all energies. Four trained radiation therapists performed daily QA on both platforms. Data were collected to identify the time required to complete both SCM and MPC. Additionally, the two platforms were evaluated on usability and features. Output results were compared to our monthly standard to assess accuracy. On average, SCM took 22 minutes with a standard deviation of six minutes and MPC took 15 minutes with a standard deviation of three minutes. MPC output results were impacted due to the beam output being coupled to the beam profile changes. As a result, the two systems on average disagreed by -1.41% after three months despite being baselined at the same time point and output agreeing well initially (average difference of -0.1% across all energies). While there was overlap in the tests performed, SCM tests were more relevant to TG-142 while MPC tests were beneficial to machine service and, with a clear understanding of the limitations of the system, found suitable as a secondary backup to SCM for daily output verification. This work demonstrates that a comprehensive TG-142 daily QA can be designed using SCM and MPC can be added as a beneficial tool and backup for output verification while still maintaining an efficient daily QA process.
International Journal of Radiation Oncology Biology Physics, 2020
Purpose/Objective(s): Cancer is the leading cause of death in Canada -yet research has demonstrat... more Purpose/Objective(s): Cancer is the leading cause of death in Canada -yet research has demonstrated that medical education in oncology is perceived as inadequate by learners, educators and generalist physicians. The Medical Council of Canada (MCC) conducts two examinations as Canada's national standard of assessment of medical graduates. This study aimed to determine the representation of topics in the Medical Council of Canada Qualifying Examination e Part 1 (MCCQE-1) objectives with respect to leading public health priorities, including cancer. Based on current literature, our hypothesis is that cancer will be underrepresented as an objective topic in the MCCQE-1 compared to other leading disease priorities. Materials/Methods: The MCCQE-1 lists roles in which medical graduates should be competent. The focus of this study was the "Medical Expert" role and its associated testable objectives. A deductive coding method, using NVivo 11 software, was used to map these objectives for the representation of leading Canadian health priorities e specifically oncology, cardiology, cerebrovascular disease and chronic lower respiratory disease. Using the International Statistical Classification of Diseases and Related Health problems, 10 th edition (ICD-10, WHO, 2016), in conjunction with reports on the leading causes of death in Canada, key terms for the abovementioned health priorities were determined. Two coders analyzed the data to increase objectivity and reduce bias. Results: Mapping of the MCCQE-1 objectives found 190 discreet topics listed under the Medical Expert objectives section. Of those 190, oncology content was found in 57 (30%), cardiovascular diseases in 56 (29.5%), cerebrovascular diseases in 21 (11%) and chronic lower respiratory diseases in 7 (3.7%) respectively. Within the 57 objectives containing oncology content, the three most frequently mentioned cancer sites were gastrointestinal (16/57, 23%), followed by generalized/nonspecific indicators of cancer (7/57, 12%) and genitourinary/musculoskeletal cancers (6/57 each, or 10.5%). The mapping of each disease content by two coders had inter rater agreement greater than 99%, with Kappa values ranging from 0.73 e 1.00, indicating substantial agreement. Conclusion: Findings suggest that top public health concerns in Canada are highly represented in the MCCQE-1 examination. Further work is needed to understand the mismatch between content representation on the MCCQE-1 and perceptions of learners, educators and generalist physicians regarding inadequate education in cancer.
Journal of Applied Clinical Medical Physics, 2021
Abstract This work of fiction re‐enacts a scenario in which a medical physics resident was not ab... more Abstract This work of fiction re‐enacts a scenario in which a medical physics resident was not able to address a physics call during patient simulation and was criticized by the supervising faculty physicist in front of the team and the patient. The resident and the faculty agreed to meet afterwards to debrief the situation, in the hope of establishing a better working relationship. The intended use of this case, through group discussion, self‐study, or role‐play, is to encourage readers to discuss the situation at hand, inspire professionalism and leadership thinking, and allow the practice of conflict management. Facilitator's notes are available upon request to the MPLA Cases Subcommittee. This case study falls under the scope of and is supported by the Medical Physics Leadership Academy (MPLA), a committee in the American Association of Physicists in Medicine (AAPM).
Journal of Applied Clinical Medical Physics, 2021
This fictional case describes a managerial situation of implementing cone‐beam computed tomograph... more This fictional case describes a managerial situation of implementing cone‐beam computed tomography faced by a solo medical physicist in a rural community hospital. The intended use of the case study, in either a facilitated learning session or self‐study, is to inspire the readers to discuss the situation, analyze the institutional and personal factors, apply relevant leadership skills, and propose action plans. This case study falls under the scope of, and is supported by, the Medical Physics Leadership Academy (MPLA). A sample facilitator’s guide or self‐study guide is included in the manuscript for reference by users of this case study.
Journal of Applied Clinical Medical Physics, 2021
This guide provides a framework and general steps for writing a case study for the Medical Physic... more This guide provides a framework and general steps for writing a case study for the Medical Physics Leadership Academy (MPLA). 1,2 This guide may be used as part of the Request for Proposal (RFP) for case studies in AAPM leadership-themed sessions. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
International Journal of Radiation Oncology*Biology*Physics, 2021
PURPOSE/OBJECTIVE(S) To examine current practice patterns in non-English speaking breast cancer p... more PURPOSE/OBJECTIVE(S) To examine current practice patterns in non-English speaking breast cancer patients undergoing Deep Inspiratory Breath Hold (DIBH). We hypothesize that disparities in DIBH utilization exist between English and non-English speaking patients. MATERIALS/METHODS An anonymous, voluntary online survey was distributed to residency program coordinators of U.S. radiation oncology departments to survey their faculty and recent graduates. Eligibility was limited to board-certified radiation oncologists who have treated breast cancer within the prior 6 months. RESULTS There were 66 respondents, 50 of whom were eligible. 70% (n = 35) of eligible respondents were from academic sites. Slightly over half (52%) of respondents reported that at least 10% of their patients were non-English speaking. Most offered DIBH at their institution (92%) and of those, 82% of responding radiation oncologists used DIBH for at least a quarter or more of their breast cancer patients. Nearly all of those who use DIBH (98%) used coaching at the time of simulation, with about a third (37%) answering they would be "less likely" to utilize DIBH for non-English speaking patients. If DIBH is used for non-English speaking patients, 86% would take into consideration potential language barriers for proper execution of DIBH. However, slightly over one-half of respondents had an interpreter present 76-100% of the time at CT simulation. At the first DIBH treatment, 31% used an interpreter 76-100% of the time. And at each subsequent treatment, 11% used an interpreter 76-100% of the time. CONCLUSION Disparities in the application of DIBH exist despite its established utility in reducing cardiac dose. This study provides evidence that language barriers may impact physician treatment practices from initial consideration of DIBH to subsequent delivery. Even within a limited sampling of self-reported responses, this data suggests that breast cancer treatment considerations and subsequent execution are negatively affected in non-English speaking patients.
Journal of Applied Clinical Medical Physics, 2018
Implementing tighter intensity modulated radiation therapy (IMRT) quality assurance (QA) toleranc... more Implementing tighter intensity modulated radiation therapy (IMRT) quality assurance (QA) tolerances initially resulted in high numbers of marginal or failing QA results and motivated a number of improvements to our calculational processes. This work details those improvements and their effect on results. One hundred eighty IMRT plans analyzed previously were collected and new gamma criteria were applied and compared to the original results. The results were used to obtain an estimate for the number of plans that would require additional dose volume histogram (DVH)-based analysis and therefore predicted workload increase. For 2 months and 133 plans, the established criteria were continued while the new criteria were applied and tracked in parallel. Because the number of marginal or failing plans far exceeded the predicted levels, a number of calculational elements were investigated: IMRT modeling parameters, calculation grid size, and couch top modeling. After improvements to these elements, the new criteria were clinically implemented and the frequency of passing, questionable, and failing plans measured for the subsequent 15 months and 674 plans. The retrospective analysis of selected IMRT QA results demonstrated that 75% of plans should pass, while 19% of IMRT QA plans would need DVH-based analysis and an additional 6% would fail. However, after applying the tighter criteria for 2 months, the distribution of plans was significantly different from prediction with questionable or failing plans reaching 47%. After investigating and improving several elements of the IMRT calculation processes, the frequency of questionable plans was reduced to 11% and that of failing plans to less than 1%. Tighter IMRT QA tolerances revealed the need to improve several elements of our plan calculations. As a consequence, the accuracy of our plans have improved, and the frequency of finding marginal or failing IMRT QA results, remains within our practical ability to respond.
Medical Physics, 2018
Purpose: To determine clinically relevant pass/question/fail criteria for gamma analysis of inten... more Purpose: To determine clinically relevant pass/question/fail criteria for gamma analysis of intensity modulated radiation therapy quality assurance (IMRT QA) plans, identify which plans should be further analyzed with dose-volume histogram (DVH) metrics, and create a workflow for performing that DVH-based analysis. Methods: Eleven plans, five prostate and six head/neck, were selected to represent known good plans based on their high passing rate using conventional IMRT QA criteria. These were modified by moving the programmed MLC positions to underdose the target or overdose important structures by varying amounts. Commercially available hardware/software was used to measure and analyze all plans (76 total) using 4%/3mm, 3%/3mm, 3%/2mm and 2%/2mm gamma criteria. Two receiver operator characteristic (ROC) curves per criterion were created to assess effective passing rates. One ROC curve was to find a higher threshold that determined a clear pass and the second to find a lower threshold to determine a clear failure. Plans between these two thresholds need DVH-based analysis to assess the clinical consequence of the dose difference. The modified plans were analyzed in the planning system and reconstructed in commercially available DVH-based analysis software to access the accuracy and usefulness of the software. Results: Analysis of the ROC curves showed optimal pass and fail thresholds for plan error detection per criterion to achieve clinically relevant sensitivity and specificity. Based on measurement Accepted Article This article is protected by copyright. All rights reserved. uncertainty and pass/fail ranges, 3%/2mm gamma criteria with a pass threshold of 95% and a fail threshold of 90% were most optimal. DVH analysis showed good agreement with all reconstructed plans except where the changes to the MLC patterns caused the periphery of the target to be underdosed. For questionable plans, comparing the organ-specific DVHs to the physician-provided planning constraints proved to be an efficient and effective workflow since plans for which the target dose was slightly high or where organs at risk was underdosed could be released for treatment without consulting the physician for a clinical decision. Conclusion: This work indicates the potential for appreciable improvement in error detection for IMRT QA. Using effective pass/fail thresholds to determine plans that need DVH-based analysis minimizes the need for excessive, time-consuming, analysis, and making use of the dosimetric constraints of the plan minimizes the burden on physicians. Overall, DVH-based analysis is a powerful tool that can provide substantial insight over the traditional approach that does not provide structure-specific data.
Medical Physics, 2015
Previous studies show that dose to a moving target can be estimated using 4D measurementguided do... more Previous studies show that dose to a moving target can be estimated using 4D measurementguided dose reconstruction based on a process called virtual motion simulation, or VMS. A potential extension of VMS is to estimate dose during dynamic multileaf collimator (MLC)-tracking treatments. The authors introduce a modified VMS method and quantify its performance as proof-ofconcept for tracking applications. Methods: Direct measurements with a moving biplanar diode array were used to verify accuracy of the VMS dose estimates. A tracking environment for variably sized circular MLC apertures was simulated by sending preprogrammed control points to the MLC while simultaneously moving the accelerator treatment table. Sensitivity of the method to simulated tracking latency (0-700 ms) was also studied. Potential applicability of VMS to fast changing beam apertures was evaluated by modeling, based on the demonstrated dependence of the cumulative dose on the temporal dose gradient. Results: When physical and virtual latencies were matched, the agreement rates (2% global/2 mm gamma) between the VMS and the biplanar dosimeter were above 96%. When compared to their own reference dose (0 induced latency), the agreement rates for VMS and biplanar array track closely up to 200 ms of induced latency with 10% low-dose cutoff threshold and 300 ms with 50% cutoff. Time-resolved measurements suggest that even in the modulated beams, the error in the cumulative dose introduced by the 200 ms VMS time resolution is not likely to exceed 0.5%. Conclusions: Based on current results and prior benchmarks of VMS accuracy, the authors postulate that this approach should be applicable to any MLC-tracking treatments where leaf speeds do not exceed those of the current Varian accelerators.
Medical Physics, 2015
The authors designed data, methods, and metrics that can serve as a standard, independent of any ... more The authors designed data, methods, and metrics that can serve as a standard, independent of any software package, to evaluate dose-volume histogram (DVH) calculation accuracy and detect limitations. The authors use simple geometrical objects at different orientations combined with dose grids of varying spatial resolution with linear 1D dose gradients; when combined, ground truth DVH curves can be calculated analytically in closed form to serve as the absolute standards. Methods: RT structure sets containing a small sphere, cylinder, and cone were created programmatically with axial plane spacing varying from 0.2 to 3 mm. Cylinders and cones were modeled in two different orientations with respect to the IEC 1217 Y axis. The contours were designed to stringently but methodically test voxelation methods required for DVH. Synthetic RT dose files were generated with 1D linear dose gradient and with grid resolution varying from 0.4 to 3 mm. Two commercial DVH algorithms- (Philips Radiation Oncology Systems) and PlanIQ (Sun Nuclear Corp.)-were tested against analytical values using custom, noncommercial analysis software. In Test 1, axial contour spacing was constant at 0.2 mm while dose grid resolution varied. In Tests 2 and 3, the dose grid resolution was matched to varying subsampled axial contours with spacing of 1, 2, and 3 mm, and difference analysis and metrics were employed: (1) histograms of the accuracy of various DVH parameters (total volume, D max , D min , and doses to % volume: D99, D95, D5, D1, D0.03 cm 3) and (2) volume errors extracted along the DVH curves were generated and summarized in tabular and graphical forms. Results: In Test 1, produced 52 deviations (15%) while PlanIQ produced 5 (1.5%). In Test 2, and PlanIQ differed from analytical by >3% in 93 (36%) and 18 (7%) times, respectively. Excluding D min and D max as least clinically relevant would result in 32 (15%) vs 5 (2%) scored deviations for vs PlanIQ in Test 1, while Test 2 would yield 53 (25%) vs 17 (8%). In Test 3, statistical analyses of volume errors extracted continuously along the curves show to have more errors and higher variability (relative to PlanIQ), primarily due to 's lack of sufficient 3D grid supersampling. Another major driver for errors is an inconsistency in implementation of the "end-capping"; the additional volume resulting from expanding superior and inferior contours halfway to the next slice is included in the total volume calculation, but dose voxels in this expanded volume are excluded from the DVH. PlanIQ had fewer deviations, and most were associated with a rotated cylinder modeled by rectangular axial contours; for coarser axial spacing, the limited number of cross-sectional rectangles hinders the ability to render the true structure volume. Conclusions: The method is applicable to any DVH-calculating software capable of importing RT structure set and dose objects (the authors' examples are available for download). It includes a collection of tests that probe the design of the DVH algorithm, measure its accuracy, and identify failure modes. Merits and applicability of each test are discussed.
Journal of applied clinical medical physics / American College of Medical Physics, Jan 8, 2015
It was previously demonstrated that dose delivered by a conventional linear accelerator using IMR... more It was previously demonstrated that dose delivered by a conventional linear accelerator using IMRT or VMAT can be reconstructed - on patient or phantom datasets - using helical diode array measurements and a technique called planned dose perturbation (PDP). This allows meaningful and intuitive analysis of the agreement between the planned and delivered dose, including direct comparison of the dose-volume histograms. While conceptually similar to modulated arc techniques, helical tomotherapy introduces significant challenges to the PDP formalism, arising primarily from TomoTherapy delivery dynamics. The temporal characteristics of the delivery are of the same order or shorter than the dosimeter's update interval (50 ms). Additionally, the prevalence of often small and complex segments, particularly with the 1 cm Y jaw setting, lead to challenges related to detector spacing. Here, we present and test a novel method of tomotherapy-PDP (TPDP) designed to meet these challenges. One o...