IOMP SCHOOL WEBINARS 2022

Doses over 100 cGy have consistent biological effects that radiation protection limits are based on. However, low dose effects remain misunderstood. DNA mechanistic simulations are a tool to perform in silico experiments at low doses to evaluate their effects on cell survival (SF) curves and to distinguish the probability and specific damage repair mechanisms through damage location — comparable to biochemical in vitro assays.

Renewed interest in ultra-high dose rates (UHDR) in radiation therapy has been prompted by a growing body of literature supporting UHDR irradiation (“FLASH”) as a means to reduce normal-tissue toxicity compared to conventional dose-rates, while maintaining isoeffective tumour control and the ability to freeze target motion. This session provides a general overview of FLASH radiobiological concepts, the competing mechanistic explanations, and delivery techniques for this exciting frontier.

Raymond Wu was instrumental in setting up the International Medical Physics Certification Board more than 10 years ago. As CEO he guided IMPCB through its rapid growth phase, including mature processes for accreditation of Medical Physics Certification Boards and certification of medical physicists in countries where no certification board exists. This mini-symposium celebrates his contributions to IMPCB and medical physics as he retires at the end of 2022.

The International Day of Medical Physics (IDMP) is celebrated annually on 7 November, the birthday of Marie Skłodowska-Curie. This special webinar brings together regional leaders from all six IOMP regional organizations plus North America to share perspectives on the role and advancement of the medical physics profession globally.

A joint IOMP-IFMBE webinar celebrating Clinical Engineering Day 2022, exploring the management and maintenance of medical technologies from both medical physics and biomedical engineering perspectives. Topics include the intersection of clinical engineering and medical physics, technological advancements as a driving factor of contemporary healthcare, and the collaborative roles of IOMP and IFMBE.

Medical physicists are essential healthcare professionals working in hospitals, industry, academia, research institutions, and radiation protection authorities. This presentation summarises the key categories of patient safety issues and provides information about what medical physicists can do to promote patient radiation safety, covering justified radiation use, dose optimization, and quality assurance.

Patient safety is now recognized as a large and growing global public health challenge. The theme of World Patient Safety Day 2022 is "Medication Safety." In the context of radiation safety, this presentation addresses the importance of quality and safety in the use of radiopharmaceuticals in both manufacturing and administration, within the WHO’s framework of organized activities to lower risks and reduce avoidable harm.

The guiding principle is always "do not harm." Radiation in medical applications is used in imaging, treatment, or as a guiding tool for interventions. The discussion of what constitutes a harmful dose depends on the purpose of the application and must always be discussed with the patient. This talk presents the patient’s perspective on radiation risk communication, benefit-harm balance, and shared decision-making in screening and treatment.

Malignant tumours have decreased oxygenation due to malformed blood vessels, which decreases the effectiveness of radiotherapy. This study quantified alterations of the tumour microenvironment achievable with varying RT fractionation. Imaging showed the most significant increase in vascularisation and oxygen saturation for 2 Gy × 5 fractions. This optimal fractionation was then combined with anti-PD1 and anti-CTLA-4 immune checkpoint inhibitors, with concurrent administration resulting in the most tumours cured and leading to rechallenge resistance.

Current proton radiotherapy planning assumes a constant RBE of 1.1 as recommended by ICRU report 78. However, increasing evidence points to variable proton RBE that depends on the endpoint, dose per fraction, beam quality (LET), and tissue type. This presentation gives a brief overview of the clinical evidence for variable proton RBE, introduces mathematical models for variable RBE based on in vitro cell survival data, and critically discusses the implications of moving from a constant 1.1 to a variable proton RBE.

Quality requirements in breast imaging are high, especially in breast cancer screening. The large parameter space for optimization, the many new techniques being introduced, and the time required for clinical trials have driven the development of virtual clinical trial (VCT) frameworks. This presentation covers the typical components of VCT studies, their validation and limitations, and unique results achievable only with virtual imaging trials — including synthetic data for AI training and optimization of contrast-enhanced mammography.

Geant4 is a Monte Carlo toolkit widely used in medical physics for radiotherapy treatment plan verification, equipment design for radiotherapy and nuclear medicine, medical imaging dosimetry, and radiation protection. This seminar covers the capabilities of Geant4 11.0, the G4-Med international benchmarking project for systematic testing of Geant4 physics models, and how to get started with Geant4 for medical applications.

Geant4-DNA is an extension of the Geant4 Monte Carlo simulation toolkit, initially proposed by the European Space Agency. It aims at simulating in a mechanistic way the biological effects of ionizing radiation on living organisms at the sub-cellular level — including the physical, physico-chemical and chemical stages after irradiation — allowing prediction of early DNA damage from biological targets. Geant4-DNA is freely available and contains examples of various applications in physics, chemistry and radiobiology.

Diagnostic medical radiation sources have substantial contributions to effective dose worldwide. The NCI is developing tools including NCICT (CT), NCINM (nuclear medicine), and NCIRF (radiography/fluoroscopy) to estimate individualized organ doses. These tools are actively used for epidemiological and clinical research. The presentation covers major research outcomes and remaining challenges in organ dose estimation.

Targeted and selective internal radiotherapy have boosted the development of clinical internal dosimetry. Recent developments include better appraisal of activity uptake in different compartments, more accurate pharmacokinetics, and improved absorbed dose determination. The presentation addresses the growing awareness of real methodological and technological challenges in therapeutic nuclear medicine dosimetry, and the increasing dissemination of commercial treatment planning software.

There is accumulating evidence from epidemiological studies for increased risk of some non-cancer effects following low to moderate doses of ionizing radiation, particularly for circulatory diseases, lens opacities, and neurological effects, which may take decades to manifest. This webinar provides an overview of recent epidemiological results and ongoing research on non-cancer diseases related to ionizing radiation exposure, with special emphasis on medical application of radiation.

Recent studies suggest that every year worldwide about a million patients might be exposed to doses of the order of 100 mGy due to recurrent radioimaging procedures. This webinar provides a synthesis of recent epidemiological evidence on radiation-related cancer risks at this dose range: evidence from atomic bomb survivors (Rühm), low dose-rate exposures during adulthood (Laurier), and in utero and childhood exposures (Wakeford). Conclusion: doses of ~100 mGy from recurrent medical imaging are of concern from the viewpoint of radiological protection.

Intra-tumoral heterogeneity is largely ignored in radiation therapy treatment planning. Imaging biomarkers derived from quantitative MRI (qMRI) enable voxel-wise mapping of biological characteristics, providing an opportunity to optimise RT dose distributions based on spatially defined intra-tumoral biology. Mapping changes in qMRI post-treatment offers the opportunity for early identification of those at risk of recurrence. This presentation showcases work demonstrating how quantitative imaging can produce 3D maps of tumour heterogeneity for precision-based biologically targeted RT.

While much of medical physics is vested with imaging and therapy technologies, those technologies are effective only to the extent they are used for the care of patients. This presentation offers a holistic perspective anchored to the principles of Medical Physics 3.0, integrating the rigor of the science of medical physics with the relevance of clinical practice — towards patient-centered care through clinically-relevant metrologies, effectual translational research, and evidence-based clinical processes.

Medical physics has led to many achievements in modern medical practice — from high-resolution diagnostics to high-precision treatment. However, the rapid pace of personalized therapeutic approaches poses unique challenges while providing new opportunities for physics in medicine beyond traditional roles. This lecture reviews current trends in personalized medicine, strategic initiatives by medical physics societies, additional skills required, and examples of physics involvement in medicine beyond traditional medical physics — particularly state-of-the-art quantitative imaging biomarkers.