Sources, Effects and Risks of Ionizing Radiation

This report describes recommended techniques for radiopharmaceutical biodistribution data acquisition and analysis in human subjects to estimate radiation absorbed dose using the Medical Internal Radiation Dose (MIRD) schema. The document has been prepared in a format to address two audiences: individuals with a primary interest in designing clinical trials who are not experts in dosimetry and individuals with extensive experience with dosimetry-based protocols and calculational methodology. For the first group, the general concepts involved in biodistribution data acquisition are presented, with guidance provided for the number of measurements (data points) required. For those with expertise in dosimetry, highlighted sections, examples and appendices have been included to provide calculational details, as well as references, for the techniques involved. This document is intended also to serve as a guide for the investigator in choosing the appropriate methodologies when acquiring and preparing product data for review by national regulatory agencies. The emphasis is on planar imaging techniques commonly available in most nuclear medicine departments and laboratories. The measurement of the biodistribution of radiopharmaceuticals is an important aspect in calculating absorbed dose from internally deposited radionuclides. Three phases are presented: data collection, data analysis and data processing. In the first phase, data collection, the identification of source regions, the determination of their appropriate temporal sampling and the acquisition of data are discussed. In the second phase, quantitative measurement techniques involving imaging by planar scintillation camera, SPECT and PET for the calculation of activity in source regions as a function of time are discussed. In addition, nonimaging measurement techniques, including external radiation monitoring, tissue-sample counting (blood and biopsy) and excreta counting are also considered. The third phase, data processing, involves curve-fitting techniques to integrate the source time-activity curves (determining the area under these curves). For some applications, compartmental modeling procedures may be used. Last, appendices are included that provide a table of symbols and definitions, a checklist for study protocol design, example formats for quantitative imaging protocols, temporal sampling error analysis techniques and selected calculational examples. The utilization of the presented approach should aid in the standardization of protocol design for collecting kinetic data and in the calculation of absorbed dose estimates.

https://jnm.snmjournals.org/content/jnumed/40/2/37S.full.pdf

MIRD pamphlet no. 16: Techniques for quantitative radiopharmaceutical biodistribution data acquisition and analysis for use in human radiation dose estimates.

Recent epidemiological studies of the association between lung cancer and exposure to radon and its decay products are reviewed. Particular emphasis is given to pooled case-control studies of residential exposures, and to cohorts of underground miners exposed to relatively low levels of radon. The residential and miner epidemiological studies provide consistent estimates of the risk of lung cancer, with significant associations observed at average annual concentrations of approximately 200 Bq/m³ and cumulative occupational levels of approximately 50 working level months (WLM), respectively. Based on recent results from combined analyses of epidemiological studies of miners, a lifetime excess absolute risk of 5 × 10⁻⁴ per WLM [14 × 10⁻⁵ per (mJh/m³)] should now be used as the nominal probability coefficient for radon- and radon-progeny-induced lung cancer, replacing the previous Publication 65 (ICRP, 1993) value of 2.8 × 10⁻⁴ per WLM [8 × 10⁻⁵ per (mJh/m³)]. Current knowledge of radon-associated risks for organs other than the lungs does not justify the selection of a detriment coefficient different from the fatality coefficient for radon-induced lung cancer. Publication 65 (ICRP, 2003) recommended that doses from radon and its progeny should be calculated using a dose conversion convention based on epidemiological data. It is now concluded that radon and its progeny should be treated in the same way as other radionuclides within the ICRP system of protection; that is, doses from radon and its progeny should be calculated using ICRP biokinetic and dosimetric models. ICRP will provide dose coefficients per unit exposure to radon and its progeny for different reference conditions of domestic and occupational exposure, with specified equilibrium factors and aerosol characteristics.

https://journals.sagepub.com/doi/pdf/10.1016/j.icrp.2011.08.011

Lung Cancer Risk from Radon and Progeny and Statement on Radon

This paper discusses the doses from radon and from its short-lived decay products to a number of organs and tissues and to the foetus. The aim is to put all these doses into context rather than concentrating only on the largest contributions. There is also a brief discussion of the evidence from epidemiology on the risks of exposure to radon and its decay products. As is well known, under normal circumstances the greatest hazard is to the respiratory tract from inhalation of radon decay products. Radon decay products may also give substantial doses to skin. Under some circumstances it seems likely that ingested radon could give significant doses to the stomach. Other risks appear to be smaller; the results given here allow them to be compared.

https://iopscience.iop.org/article/10.1088/0952-4746/22/4/304/pdf

Doses to organs and tissues from radon and its decay products.

Introduction
The level of administered activity in radionuclide therapy is often limited by haematological toxicity resulting from the absorbed dose delivered to the bone marrow. The purpose of these EANM guidelines is to provide advice to scientists and clinicians on data acquisition and data analysis related to bone-marrow and whole-body dosimetry.

EANM Dosimetry Committee guidelines for bone marrow and whole-body dosimetry

Limits for Intakes of Radionuclides by Workers. ICRP Publication 30, Part 3

THE presence of free radicals in tobacco smoke has been reported already. During the course of a programme concerned with free radicals and alkylating agents in tobacco smoke it was observed that the concentration of free radicals in tobacco smoke condensate varied considerably as a function of methods used for collecting and subsequent treatment with solvents. To determine the biological effects of free radicals it became apparent that a method was needed whereby smoke could be directly applied to lung tissue without first collecting and processing the condensate. The method reported here enabled lung tissue to be directly exposed to cigarette smoke in a manner similar to normal smoking and resulted in the observation of distinct changes in the lung tissue as measured by electron spin resonance (ESR).

Effects of Tobacco Smoke on Lung Tissue as measured by Electron Spin Resonance

Kinetics and Oxygen Requirements of a Light-Induced Electron Spin Resonance Signal from Whole Spinach Chloroplasts

Electron spin resonance measurements of single crystals of α-aminoisobutyric acid, which are both irradiated and measured at 77 °K, give rise to a strong central absorption line at the center of tw...

Initial damage centers in γ-irradiated α-aminoisobutyric acid

The paper reports Charpy impact test measurements of the fracture toughness of nuclear pressure vessel material subjected to various neutron fluences The results indicate that the weld material is the weakest part of this vessel, but it should maintain adequate strength to permit operation to the end of the design life.

David G. Cadena

Papers

Limits for Intakes of Radionuclides by Workers. ICRP Publication 30, Part 3

Effects of Tobacco Smoke on Lung Tissue as measured by Electron Spin Resonance

Kinetics and Oxygen Requirements of a Light-Induced Electron Spin Resonance Signal from Whole Spinach Chloroplasts

Initial damage centers in γ-irradiated α-aminoisobutyric acid

Neutron-embrittlement of steels in nuclear pressure vessels