Ford, Eric C.

Abstract Purpose With cancer ranking as the third leading cause of death in the Philippines and a disparity in healthcare resources across regions, this research aimed to assess the state of radiotherapy medical physics in the country. Methodology The study utilized a comprehensive online survey with 94 structured questions answered by 19 clinics. Results Most of the participants were within 1–3 years of training (41%), with a slight majority working in private hospitals (55%). linear accelerators (LINACs) were universally used with one Co‐60 unit available, and High Dose Rate (HDR) brachytherapy was common. Intensity‐Modulated Radiotherapy (IMRT) and 3D‐Conformal Radiotherapy (3D‐CRT) are practiced in all 19 clinics, with advanced techniques like Stereotactic Body Radiotherapy (SBRT), Stereotactic Radiosurgery (SRS), and Intraoperative Radiotherapy (IORT) limited to NCR, while modalities such as Volumetric Modulated Arc Therapy (VMAT) (21%) and 2D RT (68%) are more widely practiced. Imaging modalities included the wide adoption of Computed Tomography (CT), though only 64% of respondents had dedicated CT simulators in their clinics. Gynecologic and breast cancers were frequently treated, while bone marrow transplants (total body irradiation) were rare. For quality assurance (QA) devices, Solid Water Phantoms and Scanning Water Tanks (86%) were the most common devices for dosimetry and measurement. 82% reported performing patient‐specific QA (PSQA), with EPID dosimetry being the most common (55%) PSQA device used. Quality management practices varied between Qualified Medical Physicists and Medical Physics Trainees, with most Qualified Medical Physicists performing routine checks. Treatment interruptions were mainly due to staffing and machine downtime, rather than power outages or natural disasters. Most clinics had their own systems (86%) to document safety incidents, but only a few reported incidents (32%) to the IAEA SAFRON program. Lastly, participants expressed a willingness to collaborate in research despite limited time. Conclusion This study provides an understanding of the current landscape of radiation therapy physics in the Philippines, highlighting the need to address workforce disparities, ensure equitable cancer treatment access, optimize dosimetric tools and QA devices, and prioritize resource allocation and research collaboration to advance radiation oncology practices.

Background: Lower-dose cone-beam computed tomography protocols for image-guided radiotherapy may permit target localization while minimizing radiation exposure. We prospectively evaluated a lower-dose cone-beam protocol for central nervous system image-guided radiotherapy across a multinational pediatrics consortium. Methods: Seven institutions prospectively employed a lower-dose cone-beam computed tomography central nervous system protocol (weighted average dose 0.7 mGy) for patients ≤21 years. Treatment table shifts between setup with surface lasers versus cone-beam computed tomography were used to approximate setup accuracy, and vector magnitudes for these shifts were calculated. Setup group mean, interpatient, interinstitution, and random error were estimated, and clinical factors were compared by mixed linear modeling. Results: Among 96 patients, with 2179 pretreatment cone-beam computed tomography acquisitions, median age was 9 years (1-20). Setup parameters were 3.13, 3.02, 1.64, and 1.48 mm for vector magnitude group mean, interpatient, interinstitution, and random error, respectively. On multivariable analysis, there were no significant differences in mean vector magnitude by age, gender, performance status, target location, extent of resection, chemotherapy, or steroid or anesthesia use. Providers rated >99% of images as adequate or better for target localization. Conclusions: A lower-dose cone-beam computed tomography protocol demonstrated table shift vector magnitude that approximate clinical target volume/planning target volume expansions used in central nervous system radiotherapy. There were no significant clinical predictors of setup accuracy identified, supporting use of this lower-dose cone-beam computed tomography protocol across a diverse pediatric population with brain tumors.