2024 Program with Abstracts

Session 4: Quality and Safety - Lombardy/Umbria

le 8 juin 2024 from 8h30 CDT to 9h30 CDT

Scientific Session 4 – Quality and Safety
Saturday, June 8, 2024, 8:30-9:30

Scientific Session 4: Quality and Safety – Presentation 1

A Radiation Therapy Emergency Treatment Preparedness System for Disastrous Situations.

Lixin Zhan, Leah Wolfe, Ernest Osei, Sara Kaune
Grand River Regional Cancer

Purpose: Ransomware has become a big threat to healthcare IT systems including radiotherapy. When under attack, we lose access to both OIS and RT image servers. To minimize treatment interruption, we have implemented an emergency rescue system for our RT environment.

Methods: This system relies on the file based DICOM RT mode for treatment. We have built an isolated Linux environment. Patients under treatment and ready for treatment are obtained by SQL query of Aria. Necessary information for contacting and uniquely identifying those patients, together with treatment schedules and other notes are retrieved at the same time. We used DCMTK for retrieving DICOM files required which include DICOM RP/RS/CT/RI. There are document based files are helpful in determining the correct treatment information which cannot be obtained by SQL query. There are also treatment records saved on the image servers in DICOM format already. We set up a data helper server for obtaining those files without introducing further attack vectors to the critical clinical servers. The rescue system will copy those files from the data helper. All above are script based and scheduled to run automatically. Once done, it disables the network interface and put itself offline.

Results and Conclusion: The emergency treatment solution has been established and is able to successfully retrieve all necessary information in preparation for disastrous situations. Together with the development of proper department emergency policy, it is expected to help minimize the unfavorable effects for patients under treatment even if the clinical RT system is not available for a prolonged time.


Scientific Session 4: Quality and Safety – Presentation 2

The hierarchy of hazard controls in MR safety guidance.

Ives R. Levesque, Evan McNabb, Véronique Fortie
McGill University

Purpose: To critically assess safety guidance and practices in clinical magnetic resonance using the hierarchy of hazard controls.

Methods: Publicly available, widely used guidance documents for MR safety practice were gathered. A 5-point scale was assigned to the various levels in the hierarchy of hazard controls, from Elimination (score=5) to Personal Protective Equipment (score=1). MR safety practices recommended in the guidance documents were surveyed and scored using the 5-point scale. The safety practices were grouped by category of risk addressed (e.g. main field, RF field, gradient field), and considered separately according to their applicability for MR personnel, patients, and non-MR personnel.

Results: On the proposed scale, hazard controls for MR personnel, patients, and research participants achieve moderate median scores with a range spanning the scale. Hazard controls for these individuals relies most commonly on Engineering Controls (score=3). Hazard controls for non-MR personnel achieve a higher score, largely because these individuals can be protected through Elimination. Controls within categories of risk feature a range of safety measures and corresponding scores.

Conclusion: The analysis presented in this work could serve as a tool to analyse choices made in the deployment of safety measures, to motivate decision- or policy-making, as a tool for assessment of MR safety programs, or as an approach for future design of safety measures.


Scientific Session 4: Quality and Safety– Presentation 3

Investigating Angular Couch Acceleration During Dynamic Trajectory-based Radiotherapy Treatment: Patient Comfort Guidelines for Future Plan Optimization.

Eva Lee, Alasdair Syme, Chris Thomas, Lee MacDonald
Dalhousie University, Nova Scotia Health

Purpose: Dynamic trajectory-based radiotherapy improves plan quality by introducing additional degrees of freedom. However, the impact of patient comfort due to dynamic couch motions remains a major concern. This preliminary study investigates couch kinematics to offer potential guidelines for treatment plan optimization.

Methods: Seven multi-metastase plans were studied, each consisting of a full gantry arc and two 180o couch arcs. A transition window (TW) delivery technique was used to deliver all plans with dynamic motions on a Varian TrueBeam accelerator. TW is defined as the fraction of CP during which the requested MLC motion must be completed for the CP transition. The width of TWs can vary from 0% to 100%, allowing for variable couch speed between CP. Couch motion was rotational only. Angular velocity was measured with an accelerometer placed on the couch’s inferior end, and angular acceleration was calculated from the measured data. A motion prediction tool was developed to estimate couch position, velocity, and acceleration during dynamic treatments.

Results: The preliminary result showed that the average couch angular velocity increases as the control point transition window widens, whereas angular acceleration decreases. Plans achieved an average angular acceleration of 2.1 deg/s2, 1.9 deg/s2, and 1.1 deg/s2 when delivered at TW widths of 20%, 40%, and 60%. Compared to real-world examples, Ferris wheel and marry-go-round typically operate at 0.1 deg/s2 and 4.5 deg/s2, respectively.

Conclusions: The study’s results contribute to defining the acceptable limits of dynamic motions during radiotherapy. Future work aims to correlate the acceleration and patient comfort.

Scientific Session 4: Quality and Safety – Presentation 4

Severity driven FMEA approach to Radiation Therapy.

Alejandra Rangel, Ahmar Abbas, Ady Abdellatif, Jean-Pierre Bissonnette, Leigh Conroy, Jenna King, Humza Nusrat, Mike Oliver, Ryan Studinski, Mark Weston, Ilma Xhaferllari
Carlo Fidani Regional Cancer Centre (CFRCC), Stronach Regional Cancer Centre, R. S. McLaughlin Durham Regional Cancer Centre, Princess Margaret Cancer Centre, Royal Victoria Regional Health Centre, Odette Cancer Centre, Northeast Cancer Centre, Juravinski Cancer Centre, University of Iowa, Windsor Regional Cancer Centre

Purpose: To introduce a new Failure Modes and Effects Analysis (FMEA) approach from the automotive industry within medical physics, to apply this updated FMEA to radiation therapy (RT) and to discuss the robustness of a severity-driven 3-tiered risk profile approach.

Methods: A list of Failure Modes (FMs) were identified from a generic RT process starting at plan generation and ending with treatment start (excluding PSQA). Eight physicists, all from different cancer centres in Ontario, scored the FMs according to TG-100 but generated two different risk profiles: the traditional Risk Priority Number (RPN) and the Action priority (AP) from the automotive industry.

Results: The identified FMs ranged from 6-128 RPN using average scores, and 54-360 RPN using worst-case scores. The score agreement among physicists had the lowest standard deviation for Occurrence and Severity (S) and the largest for Detectability. The traditional prioritization method (RPN top 25% plus those with S>8) selected 13 FMs including 1 with S=2 while the AP approach selected 5 FMs as Medium level including 1 with S=4. The RPN approach reprioritizes FMs depending whether average or worst-case scores are considered while the AP approach is consistent by increasing the priority to High level and adding more Medium level FMs.

Conclusion: The new approach to FMEA allows for some variation in the scores without changing the order of the risk profile. Particularly, the selection of risky FMs is driven by severity and error prevention. The AP approach in contrast quickly identifies risky FMs in a time efficient manner.


Scientific Session 4: Quality and Safety – Presentation 5

Custom carved foam and surface-guided setup for VMAT TBI

Andrew Robertson, Cassidy Northway, Bradford Gill, Marita L. Rodriguez, Aissa Keulen, Isaac Tai, Conrad Yuen, Cheryl Duzenli, Ingrid Spadinger
BC Cancer Vancouver

Purpose: To facilitate a singular comfortable and expedient setup for VMAT TBI treatments, we have developed a patient-customized couch-indexed upper-body-moulded setup device and a tattoo-less surface-guided radiation therapy (SGRT) positioning verification procedure.

Methods: Following CT simulation, the patient’s body contour is exported to RhinoTM CAD software and a VorumTM robotic carver then carves the shape of their upper body (head-pelvis) into 15-cm-thick cross-linked polyethylene foam. The foam is indexed to a rotating TBI board that enables efficient transition of the patient between head-to-gantry and feet-to-gantry treatment positions. Lower body positioning is provided by adjustable knee and foot supports that are also indexed to the TBI board. The foam cradle readily reproduces the patient position, particularly on their posterior surface. SGRT imaging (AlignRT) is used to verify the anterior surface position at each isocentre during initial setup on a TrueBeam linac at pre-planned couch coordinates. A final CBCT-based image match to the priority organ at risk (typically lungs) is done before delivery of the first VMAT arc.

Results: Initial experience found that the indexed foam support positioned the upper body within a 5 mm margin for all head-pelvis isocentres when using planned couch coordinates, as verified by SGRT. The exception to this was a uniform 5 mm vertical shift to adjust for foam material that was not present posteriorly during CT. Lateral and longitudinal shifts were less than 3 mm.

Conclusion: Custom-carved indexed foam supports can efficiently and accurately replicate the positioning of the upper body during VMAT TBI treatments.



Scientific Session 4: Quality and Safety – Presentation 6

FMEA Based Comparison of Measurement and Software Based Patient Specific Quality Assurance

Ryan Studinski, Ahmar Abbas, Ady Abdellatif, Jean-Pierre Bissonnette, Leigh Conroy, Jenna King, Humza Nusra, Mike Oliver, Alejandra Rangel, Ilma Xhaferllari, Mark Weston
Juravinski Cancer Centre, Stronach Regional Cancer Centre, R. S. McLaughlin Durham Regional Cancer Centre, Princess Margaret Cancer Centre, Royal Victoria Regional Health Centre, Odette Cancer Centre, Northeast Cancer Centre, Carlo Fidani Regional Cancer Centre, Windsor Regional Cancer Centre, University of Iowa

Purpose: To assess the effectiveness of different patient-specific quality assurance (PSQA) techniques (measurement vs. software) using FMEA analysis with the goal of developing recommendations on appropriate PSQA for the Province of Ontario.

Methods: The working group listed possible failure modes leading up to radiation therapy delivery. Each mode was scored using standard FMEA scoring for occurrence and severity. Detectability was scored for three scenarios; detection based solely on PSQA measurement, software-based PSQA, and traditional methods of checking for errors (chart checks, machine QC, etc.). For the traditional checks, the working group also classified what type of check would likely catch the error.

Results: Comparison of the two sets of PSQA scores indicated that only 8 of the 37 failure modes would be better caught by PSQA than traditional techniques, and measurements would flag more of them and more effectively. A direct comparison of RPN scores between the two PSQA techniques also indicated that measurement would catch a similar number but more severe errors than software. It was also noted that software-based PSQA detected a higher percentage of random errors vs. systematic ones.

Conclusions: While requiring additional investigation, there are indications that there is value in doing some sort of PSQA. In particular Software-based PSQA techniques compliment a strong linear accelerator and treatment planning system quality assurance program for catching a wide range of failure modes.