Nicole Martinez

The HML's new voxel phantoms: two human males, one human female, and two male canines.

Abstract The Human Monitoring Laboratory (HML) has created five new voxel phantoms that can be used for Monte Carlo simulations. Three phantoms were created from computer tomography image sets that were obtained from facilities in Italy and the USA: a human male and the male canines. Two other phantoms were constructed from commercially available software that is used to demonstrate human anatomical features: a human male and a human female. All the voxel phantoms created by the HML that are described in this note are available at no cost to interested researchers.

Contributions from Women to the Radiation Sciences: A Brief History

Contributions from men to radiation science are well known, particularly the early contributions from such luminaries as William Roentgen, James Chadwick, Niels Bohr, Robert Oppenheimer, and the like. Although not ignored per se, beyond Marie Curie and Lise Meitner, the contributions of female nuclear scientists are not as widely recognized. This paper provides a concise historical summary of contributions to radiation science from the discovery of radiation through the current status of international leadership within the radiation protection community. Beyond lead scientists and academics, this paper also considers support personnel as well as the role women have played in the advancement of radiation epidemiology.

Review of Gender and Racial Diversity in Radiation Protection

Abstract The rapidly changing demographics of the United States workforce include a large number of women and members of minority groups that are currently underrepresented in science and engineering-related education and careers. Recent research indicates that while singular incidents of sexism do exist, gender bias more often affects women in various subtle ways. The effects of stereotype threat and the lack of appropriate mentoring and female role models are samples of the possible factors contributing to performance and longevity for women in math-intensive fields. To address how this issue affects those in radiation protection, the current status of women in the field is reviewed as a progression through the scientific pipeline, from education and employment to positions in scientific bodies and professional recognition, with primary focus on American women and institutions. Racial diversity demographics are reviewed where available. Findings indicate women and minority racial groups are underrepresented in multiple aspects of education, research, and leadership. While gender diversity across the field has not yet reached gender parity, trending indicates that the percentage of women earning degrees in radiation protection has consistently increased over the last four decades. Diversity of racial groups, however, has remained fairly consistent and is well below national averages. Diverse perspectives have been documented in collective problem-solving to lead to more innovative solutions.

Reflectance-Based Vegetation Index Assessment of Four Plant Species Exposed to Lithium Chloride

This study considers whether a relationship exists between response to lithium (Li) exposure and select vegetation indices (VI) determined from reflectance spectra in each of four plant species: Arabidopsis thaliana, Helianthus annuus (sunflower), Brassica napus (rape), and Zea mays (corn). Reflectance spectra were collected every week for three weeks using an ASD FieldSpec Pro spectroradiometer with both a contact probe (CP) and a field of view probe (FOV) for plants treated twice weekly in a laboratory setting with 0 mM (control) or 15 mM of lithium chloride (LiCl) solution. Plants were harvested each week after spectra collection for determination of relevant physical endpoints such as relative water content and chlorophyll content. Mixed effects analyses were conducted on selected endpoints and vegetation indices (VI) to determine the significance of the effects of treatment level and length of treatment as well as to determine which VI would be appropriate predictors of treatment-dependent endpoints. Of the species considered, A. thaliana exhibited the most significant effects and corresponding shifts in reflectance spectra. Depending on the species and endpoint, the most relevant VIs in this study were NDVI, PSND, YI, R1676/R1933, R750/R550, and R950/R750.

Phosphorus Stress-Induced Changes in Plant Root Exudation Could Potentially Facilitate Uranium Mobilization from Stable Mineral Forms

Apparent deficiency of soil mineral nutrients often triggers specific physio-morphological changes in plants, and some of these changes could also inadvertently increase the ability of plants to mobilize radionuclides from stable mineral forms. This work, through a series of sand-culture, hydroponics, and batch-equilibration experiments, investigated the differential ability of root exudates of Andropogon virginicus grown under conditions with variable phosphorus (P) availability (KH2PO4, FePO4, Ca3(PO4)2, and no P) to solubilize uranium (U) from the uranyl phosphate mineral Chernikovite. The mineral form of P, and hence the bioavailability of P, affected the overall composition of the root exudates. The lower bioavailable forms of P (FePO4 and Ca3(PO4)2), but not the complete absence of P, resulted in a higher abundance of root metabolites with chelating capacity at 72 hrs after treatment application. In treatments with lower P-bioavailability, the physiological amino acid concentration inside of the roots increased, whereas the concentration of organic acids in the roots decreased due to the active exudation. In batch dissolution experiments, the organic acids, but not amino acids, increase the dissolution U from Chernikovite. The root exudate matrix of plants exposed to low available forms of P induced a >60% increase in U dissolution from Chernikovite due to 5-16 times greater abundance of organic acids in these treatments. However, this was ca. 70% of the theoretical dissolution achievable by this exudate matrix. These results highlight the potential of using active management of soil P as an effective tool to alter the plant-mediated mobilization of U in contaminated soil.

ICRP Publication 138: Ethical Foundations of the System of Radiological Protection:

Abstract – Despite a longstanding recognition that radiological protection is not only a matter of science, but also ethics, ICRP publications have rarely addressed the ethical foundations of the system of radiological protection explicitly. The purpose of this publication is to describe how the Commission has relied on ethical values, either intentionally or indirectly, in developing the system of radiological protection with the objective of presenting a coherent view of how ethics is part of this system. In so doing, it helps to clarify the inherent value judgements made in achieving the aim of the radiological protection system as underlined by the Commission in Publication 103. Although primarily addressed to the radiological protection community, this publication is also intended to address authorities, operators, workers, medical professionals, patients, the public, and its representatives (e.g. NGOs) acting in the interest of the protection of people and the environment. This publication provides the key steps concerning the scientific, ethical, and practical evolutions of the system of radiological protection since the first ICRP publication in 1928. It then describes the four core ethical values underpinning the present system: beneficence/ non-maleficence, prudence, justice, and dignity. It also discusses how these core ethical values relate to the principles of radiological protection, namely justification, optimisation, and limitation. The publication finally addresses key procedural values that are required for the practical implementation of the system, focusing on accountability, transparency, and inclusiveness. The Commission sees this publication as a founding document to be elaborated further in different situations and circumstances.

A proposed simple model for estimating occupational radiation dose to staff from veterinary 18F-FDG pet procedures.

AbstractSeveral studies have been conducted concerning the radiation dose to hospital personnel from positron emission tomography (PET) radiopharmaceuticals, but to date only one parallel study has been conducted for veterinary staff. Veterinary patients present challenges not encountered with human patients, as they require anesthesia and therefore more intensive monitoring than human patients. This paper presents a simple model for estimating the effective radiation dose to veterinary staff using occupational dose data from PET studies at Colorado State University’s (CSU) James L. Voss Veterinary Teaching Hospital. The model consists of three point sources within a soft tissue cylinder, and sample calculations are provided for estimating dose to nuclear medicine technologists and an anesthesia technologist based on four different sized dogs. The estimated doses are within the range of actual occupational doses published previously. There are different protocols for the sequence of events in veterinary PET, specifically the order of anesthesia induction and radiopharmaceutical injection. When 18F-FDG injection is performed prior to anesthesia induction, the estimated dose is between 1.5 and 3.6 times higher than the doses received if injection is done after anesthesia induction, although expected doses for both protocols are below occupational dose limits based on a case load of 100 veterinary patients per year. The model is based on the techniques used at CSU, but it can be modified for different hospitals as well as differently sized animals.