Arsen i jego związki nieorganiczne. Metoda oznaczania w powietrzu na stanowiskach pracy

Arsenic is a chemical element classified as metalloids (semi-metals). Some arsenic compounds have been classified (according to CLP) as carcinogens, causing cancers of skin, respiratory system, liver and leukemia. In the industry, workers are exposed to arsenic and its compounds in its extraction, in metallurgy of non-ferrous metal ores, in metal refining processes, in the production of alloys, semiconductors, pigments and insecticides. In Poland, binding value of the hygienic standard (NDS) at workplace air, for the inhalable fraction of arsenic aerosol and its inorganic compounds, converted into As is 0.01 mg/m3 . A determination method has been developed that enables the determination of this substance in the air of 0.1 − 2 values of the hygiene standard, in accordance with the requirements of Standard PN-EN 482. Arsenic is determined with the atomic absorption spectrometry with electrothermal atomization (ET-AAS), in the concentration range of 5.00 − 100.0 μg/l which allows the determination of arsenic and its compounds in workplace air in the range of 0.0010 − 0.021 mg/m3 (for 480-L air sample). The presented procedure enables the determination of this substance with the use of individual dosimetry. This article discusses the problems of occupational safety and health, which are covered by health sciences and environmental engineering.

Individual dosimetry system for targeted alpha therapy based on PHITS coupled with microdosimetric kinetic model

Background An individual dosimetry system is essential for the evaluation of precise doses in nuclear medicine. The purpose of this study was to develop a system for calculating not only absorbed doses but also EQDX(α/β) from the PET-CT images of patients for targeted alpha therapy (TAT), considering the dose dependence of the relative biological effectiveness, the dose-rate effect, and the dose heterogeneity. Methods A general-purpose Monte Carlo particle transport code PHITS was employed as the dose calculation engine in the system, while the microdosimetric kinetic model was used for converting the absorbed dose to EQDX(α/β). PHITS input files for describing the geometry and source distribution of a patient are automatically created from PET-CT images, using newly developed modules of the radiotherapy package based on PHITS (RT-PHITS). We examined the performance of the system by calculating several organ doses using the PET-CT images of four healthy volunteers after injecting 18F-NKO-035. Results The deposition energy map obtained from our system seems to be a blurred image of the corresponding PET data because annihilation γ-rays deposit their energies rather far from the source location. The calculated organ doses agree with the corresponding data obtained from OLINDA 2.0 within 20%, indicating the reliability of our developed system. Test calculations by replacing the labeled radionuclide from 18F to 211At suggest that large dose heterogeneity in a target volume is expected in TAT, resulting in a significant decrease of EQDX(α/β) for higher-activity injection. Conclusions As an extension of RT-PHITS, an individual dosimetry system for nuclear medicine was developed based on PHITS coupled with the microdosimetric kinetic model. It enables us to predict the therapeutic and side effects of TAT based on the clinical data largely available from conventional external radiotherapy.

Individual Dosimetry System for Targeted Alpha Therapy Based on PHITS Coupled with Microdosimetric Kinetic Model

Background: An individual dosimetry system is essential for the evaluation of precise doses in nuclear medicine. The purpose of this study was to develop a system for calculating not only absorbed doses but also EQDX(α/β) from the PET-CT images of patient for targeted alpha therapy (TAT), considering the dose dependence of the relative biological effectiveness, the dose-rate effect, and the dose heterogeneity. Methods: A general-purpose Monte Carlo particle transport code PHITS was employed as the dose calculation engine in the system, while the microdosimetric kinetic model was used for converting the absorbed dose to EQDX(α/β). PHITS input files for describing the geometry and source distribution of a patient are automatically created from PET-CT images, using newly developed modules of DICOM2PHITS. We examined the performance of the system by calculating several organ doses using the PET-CT images of four healthy volunteers after injecting 18F-NKO-035. Results: The deposition energy map obtained from our system seems to be a blurred image of the corresponding PET data because annihilation γ-rays deposit their energies rather far from the source location. The calculated organ doses agree with the corresponding data obtained from OLINDA 2.0 within 20%, indicating the reliability of our developed system. Test calculations by replacing the labeled radionuclide from 18F to 211At suggest that large dose heterogeneity in a target volume is expected in TAT, resulting in a significant decrease of EQDX(α/β) for higher-activity injection. Conclusions: An individual dosimetry system including the function for calculating EQDX(α/β) was developed based on PHITS coupled with the microdosimetric kinetic model. It enables us to predict the therapeutic and side effects of TAT based on the clinical data largely available from conventional external radiotherapy.

Role of individual dosimetry for affected residents in postaccident recovery: the Fukushima experience

The accident at Fukushima Daiichi nuclear power plant on 11 March 2011 released radioactive material into the atmosphere, and contaminated land in Fukushima and several neighbouring prefectures. During rehabilitation, it is important to accurately understand and determine individual external doses to allow individuals to make informed decisions about whether or not to return to the affected areas. Personal dosimeters (D-Shuttle), used together with a global positioning system and geographic information system device, can provide realistic individual external doses and associated individual external doses, ambient doses, and activity patterns of individuals in the affected areas of Fukushima. This study involved more than 250 affected residents. The results help to determine realistic individual external doses, and corresponding time–activity patterns and airborne monitoring ambient dose rates, which can be used to predict future cumulative external doses after residents return to their homes in evacuation areas. In addition, insights gained by the study can help to explain the role of individual external dose measurements for affected residents in postaccident recovery, based mainly upon the experience gained in measuring, assessing, and communicating individual external doses.

Using and Explaining Individual Dosimetry Data

Measurement of individual radiation dose is crucial for planning protective measures after nuclear accidents. The purpose of this article is to explain the various initiatives taken after the TEPCO Fukushima Daiichi Nuclear Power Plant accident, including the D-shuttle project wherein residents from affected areas wore a personal dosimeter to measure their own external exposure. The experience in Fukushima revealed several issues such as gaining residents’ trust and ensuring appropriate communication of the measured data. The D-shuttle project also revealed that obtaining individual dose measurement data had 2 purposes, as the information obtained was to be utilized by the residents for self-protection and by the authorities for deriving the dose distribution of the population to aid in designing large-scale protection measures. The lessons learned are that both the residents and the authorities need to understand and share the meaning of individual dose measurements and the measurement results must be used with due respect for the residents’ privacy and other concerns.

Patients with recurrent glioblastoma multiforme

Summary Aim: The objective of this study was to assess the feasibility, dosimetry, tolerability and efficacy of systemically administrated p-[131I] - iodo-L-phenylalanine (131IPA) combined with hypo-fractionated external beam radiation therapy (EBRT) in patients with recurrent glioblastoma multiforme (GBM). Patients, methods: Five patients (2 women, 3 men, aged 27-69) with recurrent GBM and exhaustion of regular therapy options were included. All had a positive O-(2-[18F]Fluoroethyl)- L-tyrosine positron emission tomography (FET-PET) and pretherapeutic dosimetry was performed. Tumour targeting was verified by 131IPA-SPECT up to six days after radiotracer administration. After 131IPA therapy, patients were treated with hypo-fractionated EBRT in six fractions of 5 Gy (n = 4) or in eleven fractions of 2 Gy in one case. Results: Based on the individual dosimetry, the patients received a single intravenous administration of 2 to 7 GBq of 131IPA, resulting in radiation absorbed doses to the blood of 0.80–1.47 Gy. The treatment was well tolerated; only minor complaints of nausea and vomiting that responded to ondansetron and pantoprazol were noticed in the first two patients. After preventive medication, the last three patients had no complaints during therapy. In none of the patients a decrease of leukocyte or thrombocyte counts below the baseline level or the lower normal limit was observed. Tumour doses from 131IPA were low (≤ 1 Gy) and all patients died three to eight (median 5.5) months after therapy. Conclusion: In this initial experience, treatment of GBM with 131IPA in combination with EBRT was demonstrated to be safe and well tolerated, but less effective than suggested by the animal studies.