Quality management system to enhance radiotherapy accuracy and safety at the Uganda Cancer Institute

Abstract

Radiotherapy is a cornerstone of cancer management, yet its complexity and reliance on advanced technology make it prone to errors, particularly in low to middle-income countries (LMICs). At the Uganda Cancer Institute (UCI), radiotherapy services historically relied on two-dimensional radiotherapy (2DRT) using cobalt 60 units. Between 2021 and 2023, three advanced treatment equipment (linear accelerators: Varian Medical System International) and three dimensional treatment planning systems (TPS) were commissioned, enabling the introduction of advanced radiotherapy treatment modalities such as three dimensional conformal radiotherapy (3DCRT), intensity modulated radiotherapy (IMRT), and volumetric modulated arc therapy (VMAT). While these technologies have the potential to increase treatment ac curacy, they also amplify the risk of errors due to inadequate quality management systems, limited training, and equipment challenges. The study aimed to enhance the quality and safety of radiotherapy services at UCI by developing and implementing a comprehensive Quality Management System (QMS) to optimize resource utilization, improve treatment accuracy, and ensure patient safety. A mixed Physics based quality assurance methods were applied (monitor unit recalculations, independent treatment planning system (TPS) verification, in-vivo dosimetry (IVD), clinical target volume (CTV) to planning target volume (PTV) margin, and end to end dosimetry audits), analyzing treatment data from 2,244 (1,164 for manual recalculations, 423 for independent TPS verification, 493 for in IVD, and 164 for CTV to PTV margin evaluation) patients treated between 2018 and 2025 and data from experimental measurements performed on the linacs (end-to-end dosimetry audit). Specific interventions included the development of an Incident Reporting and Learning System (IRLS) to capture and analyze treatment errors; in IVDfor 2DRTand3DCRTusingcalibrated diodes to verify dose delivery accuracy; independent verification of TPS calculations for 3DCRT, IMRT, and VMAT using secondary software and manual monitor unit checks; end to end dosimetry audits with anthropomorphic phantoms to assess work ow integrity; and determination of CTV to PTV margins for prostate and cervical cancer using portal imaging and cone beam computed tomography (CBCT). Risk assessment was guided by Failure Mode and Effects Analysis (FMEA), while dosimetric verification adhered to IAEA TRS 398 and ICRU dose accuracy standards. Results: With a current daily patient throughput of 210 280, the increased workload has placed significant demands on pretreatment patient-specific QA, treatment quality, equipment performance, and routine machine QA protocols. Treatment time calculation accuracy for cobalt-60-based treatments improved from 82.8 % to 93.2 % within ±5 % tolerance between 2018 and 2020. Approximately 85% of IVD measurements were within accepted limits, and end-to-end dosimetry audits showed dose agreement within 2.1% of TPS calculations. However, phantom setup errors and linac output calibration inconsistencies led to deviations of up to 6.1% in some cases. A high patient volume (210280 patients per day) has significantly impacted machine parameters, resulting in outputs that deviate from tolerance limits and adversely af fecting the quality of patient treatments. Optimized CTV-to-PTV margins were established for prostate and cervical cancer, improving geometric accuracy. Out of a total of 984 measurements of systematic and random setup errors, 70.4 % of the errors were within 5 mm, while 86.1% were within 10 mm. The IRLS enabled systematic documentation and analysis of incidents fostering a culture of safety and continuous learning at Uganda's only radiotherapy center. Conclusion: The study successfully developed and implemented a comprehensive QMS that improved treatment accuracy, strengthened patient safety, and optimized resource use at UCI. By integrating incident learning, dosimetric verification, and systematic audits, the framework provides a replicable model for LMICs transitioning to advanced radiotherapy technologies. The findings align with SDG 3 (Good Health and Well-being) and SDG 4 (Quality Education), contributing to national health priorities under Uganda Vision 2040 and the National Development Plan IV.