Beam flatness modulation for a flattening filter free photon beam utilizing a novel direct leaf trajectory optimization model.

Flattening filter free (FFF) linear accelerators produce a fluence distribution that is forward peaked. Various dosimetric benefits, such as increased dose rate, reduced leakage and out of field dose has led to the growth of FFF technology in the clinic. The literature has suggested the idea of vendors offering dedicated FFF units where the flattening filter (FF) is removed completely and manipulating the beam to deliver conventional flat radiotherapy treatments. This work aims to develop an effective way to deliver modulated flat beam treatments, rather than utilizing a physical FF. This novel optimization model is an extension of the direct leaf trajectory optimization (DLTO) previously developed for volumetric modulated radiation therapy (VMAT) and is capable of accounting for all machine and multileaf collimator (MLC) dynamic delivery constraints, using a combination of linear constraints and a convex objective function. Furthermore, the tongue and groove (T&G) effect was also incorporated directly into our model without introducing nonlinearity to the constraints, nor nonconvexity to the objective function. The overall beam flatness, machine deliverability, and treatment time efficiency were assessed. Regular square fields, including field sizes of 10 × 10 cm2 to 40 × 40 cm2 were analyzed, as well as three clinical fields, and three arbitrary contours with "concave" features. Quantitative flatness was measured for all modulated FFF fields, and the results were comparable or better than their open FF counterparts, with the majority having a quantitative flatness of less than 3.0%. The modulated FFF beams, due to the included efficiency constraint, were able to achieve acceptable delivery time compared to their open FF counterpart. The results indicated that the dose uniformity and flatness for the modulated FFF beams optimized with the DLTO model can successfully match the uniformity and flatness of their conventional FF counterparts, and may even provide further benefit by taking advantage of the unique FFF beam characteristics.

Navigating Challenges in Teleradiology Implementation: A Case Study from Saudi Arabia's Healthcare System.

Background and Aims: Teleradiology is the practice of interpreting medical images acquired in an off-site location. Teleradiology has been utilized widely around the world to address the needs for subspecialty coverage, workload balancing, and as a solution for understaffing. This study aims to assess the perceptions of teleradiology among radiologists in Saudi Arabia, investigate any challenges they might face, and explore strategies that would help mitigate those challenges. Methods: A cross-sectional study using a self-administered electronic questionnaire was conducted to collect responses from radiologists practicing or having practiced teleradiology in Saudi Arabia. The questionnaire was conducted from January to June 2023, and 105 responses were included in the analysis. The responses were analyzed using chi-squared testing to investigate factors affecting the radiologists' perceptions. Results: The most common challenges for teleradiology were access to patients' health records, access to prior imaging exams, and concerns about image quality assurance. Around 74% of participants perceived teleradiology to be beneficial for geographic, after-hour, and subspecialties coverage. Teleradiology was also perceived to help reduce the turn-around time of radiology interpretations. Better communication with referring physicians and technologists was seen as a way to help improve teleradiology services. Conclusion: The findings suggest that the perception of teleradiology's challenges and benefits may not be influenced by experience, workplace, or subspecialty. Emphasis should be placed on the importance of quality assurance of images acquired remotely. Addressing the concerns and challenges related to access to patients' health records is also crucial to ensuring the successful implementation of teleradiology in the country.

Exploring Barriers in Self-Reporting of Errors and Near Misses: A Cross-Sectional Study on Radiation Oncology in Saudi Arabia.

Background: Radiation therapy utilizes complex technologies to target tumors. Radiation therapy is not immune to human errors. Reporting medical errors and near misses is crucial to improving patient outcomes and ensuring the safety of future patients. Objective: This study aimed to measure the attitudes of radiotherapy staff members in Saudi Arabia regarding reporting errors and near misses in radiation therapy practice. It also examined the participants' reporting patterns and behaviors and explored the potential barriers to reporting errors and near misses as perceived by the participants. Methods: A cross-sectional study utilizing an online questionnaire was implemented. A sample of 70 health professionals working in radiation oncology departments in Saudi Arabia, including radiation oncologists, medical physicists, and radiotherapists, were recruited to participate in this study from January to June 2023. The data was analyzed using chi-squared testing to compare different groups, and the Kruskal-Wallis was used to find any statistically significant differences between different groups. Results: The study included 70 radiotherapy staff members. Professional roles did not significantly impact participants' decisions to report minor or major errors, with most consistently reporting errors to their supervisors regardless of role. The study revealed that fear of professional sanctions and the potential negative impact on a department's reputation are significant barriers to reporting errors or near misses. However, Only 17% of radiation oncologists did consider departmental sanctions as a barrier. Participants identified communication failure as the most significant source of errors in radiation oncology departments. The study also found a high level of agreement among the participants regarding the responsibility of reporting errors and near misses. Conclusion: The study investigated reporting errors and near misses in radiotherapy and considered the factors influencing them. The findings highlight the importance of effective communication and the implementation of an electronic reporting system.

A sliding-window approach for improved VMAT dose calculation accuracy.

The continuous delivery of volumetric modulated arc therapy (VMAT) plans is usually approximated by discrete apertures at evenly-spaced gantry angles for dose calculation purposes. This approximation can potentially lead to large dose calculation errors if the gantry angle spacings are large and/or there are large changes in the MLC apertures from one control point (CP) to the next. In this work, we developed a sliding-window (SW) method to improve VMAT dose calculation accuracy. For any 2 adjacent VMAT CPs ni and ni + 1, the dose distribution was approximated by a 2-CP SW IMRT beam with the starting MLC positions at CP ni and ending MLC positions at CP ni + 1, with the gantry angle fixed in the middle of the 2 VMAT CPs. Therefore, a VMAT beam with N CPs was approximated by a SW plan with N-1 SW beams. To validate the method, VMAT plans were generated for 10 patients in Pinnacle using 4° gantry spacing. Each plan was converted to a SW plan and dose was recalculated. Another VMAT plan, with 1° gantry spacing, was created by interpolating the original VMAT beam. The original plans were delivered on an Elekta Versa HD and measured with ArcCHECK. For both the isodose distribution and DVH, there were significant differences between the original VMAT plan and either the SW or the interpolated plan. However, they were indistinguishable between the SW and the interpolated plans. When compared with measurement, the average passing rates of the original VMAT plans were 87.3 ± 2.8% and 93.1 ± 1.0% for the 5 HN and 5 spine SBRT cases, respectively. On the other hand, the passing rates for both the VMAT1 and SW plans were above 95% for all the 10 cases studied. The dose calculation times of the original VMAT plans and the SW plans were very similar. We conclude that the proposed SW approach improves VMAT dose calculation accuracy without increase in dose calculation time.