Medical use of ionizing radiation has been a major contributor to the population dose from man-made sources of radiation for many years. Current issues in radiation protection of patients include not only the rapidly increasing collective dose to the population, but also that a substantial percentage of diagnostic imaging examinations are unnecessary, and the cumulative dose to individuals from medical exposure is growing. Therefore, a number of new challenges have emerged in recent years with regard to a various issues related to use of ionizing radiation in medicine. Inevitably, major issues of protection pertain to high dose procedures, as interventional procedures, computed tomography and hybrid imaging and sensitive population groups as children and females of reproductive capacity. The challenges have been brought to different professionals groups and stakeholders as dosimetrists, radiation biologists, patients, referring physicians, radiologists, radiographers, medical physicists and manufacturers. This talk explores these issues with special emphasis on the appropriates of medical exposures, dose tracking and optimization of practice, impact on new technologies and accident prevention. Activities of relevant international organization is also discussed.

Soon after their formation, radioactive nuclides are attached to atmospheric aerosol particles and participate in the formation and growth of the accumulation mode of aerosol particles (from 0.1 to 2 μm). In this talk, the basic features and definitions of radioactive aerosols together with the appropriate instrumentation that is used for studying radioactive aerosol particles and their behavior in the atmosphere will be presented. The behavior of naturally occurring radioactive aerosol particles (especially ²¹⁰Pb and ⁷Be) and their behavior in various environments, including the Arctic, will be discussed. Specifically, ⁷Be with the advantage of relatively easy determination and a life-time long enough to allow for long-distance transport and short enough to prevent long-term accumulation of the isotope in large reservoirs and has been widely used as a tracer in atmospheric science. The consequences of nuclear tests and nuclear accidents due to the dispersion of aerosol particles in short and long distances as well as the size distribution of radioactive aerosol particles in many European countries immediately after the Chernobyl and Fukushima accident will be also presented.

Enhancing immune responses in metastatic cancers remains a challenge. We present results obtained from studies in immune competent mice that aimed to determine whether magnetic iron oxide nanoparticle (MION) hyperthermia (HT) can enhance abscopal effects with radiotherapy (RT) and immune checkpoint inhibitors (IT) in models of disseminated disease. Models described include metastatic breast (4T1 in BALB/c mice), prostate (Myc-CaP in FVB/N mice), and colorectal (CT26 in FVB/N mice) cancers. Methods involved focal treatment of primary tumor with a combination of single-fraction MION HT +/- fractionated RT (e.g. 3 x 8 Gy) +/- systemic IT with anti-PD-1 and anti-CTLA-4 antibodies (both 4 x 10 mg/kg, weekly i.p.). Endpoints included measures of primary tumor growth, disease burden (growth of distant or metastatic tumors), survival, and immunologic correlates from tumor tissues using histopathology, cytokine array, or flow cytometry analysis. Results generally demonstrated that compared to untreated controls, all treatment groups demonstrated a decreased primary tumour volume; however, when compared against surgical resection, only combination therapies that included RT provided the best local and distant tumor control. These cohorts showed more infiltration of CD3+ T-lymphocytes into the primary tumour. Combinations that proved most effective for primary tumours generated modest reductions in numbers of lung metastases in the 4T1 model. We conclude from these studies that single-fraction MION HT added to RT+IT improved local tumour control and recruitment of CD3+ T-lymphocytes, with a modest effect to reduce lung metastases.

One of the very first papers describing radioactivity in oil extraction appeared in 1906 just a scant eight years after its discovery by Henri Bequerel in Paris 1896. The world currently consumes about100 million barrels of oil daily and is produced in countries throughout the globe through onshore drilling which refers to drilling deep holes under the earth's surface and offshore drilling which relates to drilling underneath the seabed. It was only in the late 1970’s and early 1980’s where a significant amount of research was done in characterizing the radioactivity in extraction processes which included, scale, produced water, sludge, etc. What is more surprising than the unexpected amounts of radioactivity in the oil extraction sector is the orders of magnitude differences of radiation from different onshore fields. Thus, handling of these radioactive by products including transportation, clean-up procedures, and burial requires stringent training and monitoring procedures. A detailed overview of radioactivity measurements and radiation protection guidelines for the oil exploration sector of the waste products will be presented.

Once solid tumors reach a diameter of a few mm, further growth becomes limited due to lack of oxygen and nutrients and the accumulation of toxic metabolites. Therefore, the capacity to attract surrounding blood vessels, called the “angiogenic switch” or “tumor angiogenesis”, is essential for further tumor growth as well as for the spread of tumor cells to distant organs (metastasis). The stimulation of blood vessels toward the tumor is principally mediated by secretion of the vascular endothelial cell growth factor (VEGF) either by the tumor cells or by other cells in the tumor environment like tumor-associated fibroblasts and tumor-associated adipocytes. Different anti-angiogenic compounds have been approved for treatment of solid tumors including monoclonal antibodies (such as cetuximab), fusion proteins (aflibercept) or small molecule kinase inhibitors (dasatinib, sunitinib, nintedanib). More recent findings suggest that a subset of solid tumors is able to form blood vessel-like structures that can support blood flow. This process is called “vasculogenic/vascular mimicry” and represents an attractive therapeutic target for treatment of solid tumors with a high invasive potential and bad prognosis.

Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident contamination is dominated by the fission products like (I, Te, Be, Cs, Sr isotopes, etc.). Typically, the fission products are neutron rich isotopes therefore beta particles will be released from the nucleus to reach stable isotope configuration. This decay process is commonly accomplished with gamma ray emission therefore gamma-ray spectroscopy is applied primary for fission products determination in samples affected by nuclear accident. However, some fission products such as ⁹⁰Sr, ⁸⁹Sr; are pure beta emitters. ⁹⁰Sr (t_1/2 = 28.8 y) is one of the most common and hazardous fission products released by a nuclear reactor accident. Due to its chemical similarity to calcium, accumulates in bones and irradiates bone marrow, causing high radio-toxicity. Therefore, to assess ⁹⁰Sr is important in case of a nuclear disaster. Measurement of ⁹⁰Sr using radiometric methods is a time‑consuming process since it involves a complex sample preparation and analytical separation required to produce reliable data.

Soil samples contaminated with radiocaesium due to Fukushima accident were collected from exclusion zone in Fukushima Prefecture. Soil samples were digested using conc. HNO₃, HF and HClO₄. The contamination of ⁹⁰Sr is significantly lower, by four or five magnitudes than radiocaesium isotopes. A resin called DGA (N,N,N_N_ tetraoctyl-1,5-diglycolamide) and Sr spec resin were used for efficient chemical separation prior to mass spectrometry method.

Thermal ionization mass spectrometry (TIMS) is the technique of choice because of its inherent high precision and accurate measurement of isotopic ratio. Typical abundance sensitivity for strontium isotope ratio measurement with conventional TIMS is about 10^-7. By the use of a special lens like the WARP filter for TIMS, an upper limit of 1.0 x 10^-10 was achieved. A new ⁹⁰Sr analysis method was developed using the Isotopx Ltd., Phoenix X62 TIMS. The abundance sensitivity for the ⁹⁰Sr/⁸⁸Sr ratio was 2.1×10^‑10 and this could ensure detection limit of 100 Bq·kg^‑1 (19 fg·g^‑1) ⁹⁰Sr in Fukushima soil samples. The method has been validated using two certified reference materials e.g. wild berry (IRMM-426) and freshwater lake sediment (NIST-4354). This mass spectrometry method is faster than conventional radiometric techniques.