Cutaneous and local radiation injuries

The threat of a large-scale radiological or nuclear (R/N) incident looms in the present-day climate, as noted most recently in an editorial in Scientific American (March 2021). These large-scale incidents are infrequent but affect large numbers of people. Smaller-scale R/N incidents occur more often, affecting smaller numbers of people. There is more awareness of acute radiation syndrome (ARS) in the medical community; however, ionising radiation-induced injuries to the skin are much less understood. This article will provide an overview of radiation-induced injuries to the skin, deeper tissues, and organs. The history and nomenclature; types and causes of injuries; pathophysiology; evaluation and diagnosis; current medical management; and current research of the evaluation and management are presented. Cutaneous radiation injuries (CRI) or local radiation injuries (LRI) may lead to cutaneous radiation syndrome, a sub-syndrome of ARS. These injuries may occur from exposure to radioactive particles suspended in the environment (air, soil, water) after a nuclear detonation or an improvised nuclear detonation (IND), a nuclear power plant incident, or an encounter with a radioactive dispersal or exposure device. These incidents may also result in a radiation-combined injury; a chemical, thermal, or traumatic injury, with radiation exposure. Skin injuries from medical diagnostic and therapeutic imaging, medical misadministration of nuclear medicine or radiotherapy, occupational exposures (including research) to radioactive sources are more common but are not the focus of this manuscript. Diagnosis and evaluation of injuries are based on the scenario, clinical picture, and dosimetry, and may be assisted through advanced imaging techniques. Research-based multidisciplinary therapies, both in the laboratory and clinical trial environments, hold promise for future medical management. Great progress is being made in recognising the extent of injuries, understanding their pathophysiology, as well as diagnosis and management; however, research gaps still exist.

Cytogenetic follow-up studies on humans with internal and external exposure to ionizing radiation

Cells exposed to ionizing radiation have a wide spectrum of DNA lesions that include DNA single-strand breaks, DNA double-strand breaks (DSBs), oxidative base damage and DNA-protein crosslinks. Among them, DSB is the most critical lesion, which when mis-repaired leads to unstable and stable chromosome aberrations. Currently, chromosome aberration analysis is the preferred method for biological monitoring of radiation-exposed humans. Stable chromosome aberrations, such as inversions and balanced translocations, persist in the peripheral blood lymphocytes of radiation-exposed humans for several years and, therefore, are potentially useful tools to prognosticate the health risks of radiation exposure, particularly in the hematopoietic system. In this review, we summarize the cytogenetic follow-up studies performed by REAC/TS (Radiation Emergency Assistance Center/Training site, Oak Ridge, USA) on humans exposed to internal and external radiation. In the light of our observations as well as the data existing in the literature, this review attempts to highlight the importance of follow-up studies for predicting the extent of genomic instability and its impact on delayed health risks in radiation-exposed victims.

Radium dial workers: back to the future

PURPOSE

This paper reviews the history of the radium dial workers in the United States, summarizes the scientific progress made since the last evaluation in the early 1990s, and discusses current progress in updating the epidemiologic cohort and applying new dosimetric models for radiation risk assessment.

BACKGROUND

The discoveries of radiation and radioactivity led quickly to medical and commercial applications at the turn of the 20th century, including the development of radioluminescent paint, made by combining radium with phosphorescent material and adhesive. Workers involved with the painting of dials and instruments included painters, handlers, ancillary workers, and chemists who fabricated the paint. Dial painters were primarily women and, prior to the mid to late 1920s, would use their lips to give the brush a fine point, resulting in high intakes of radium. The tragic experience of the dial painters had a significant impact on industrial safety standards, including protection measures taken during the Manhattan Project. The dial workers study has formed the basis for radiation protection standards for intakes of radionuclides by workers and the public.

EPIDEMIOLOGIC APPROACH

The mortality experience of 3,276 radium dial painters and handlers employed between 1913 and 1949 is being determined through 2019. The last epidemiologic follow-up was 30 years ago when most of these workers were still alive. Nearly 65% were born before 1920, 37.5% were teenagers when first hired, and nearly 50% were hired before 1930 when the habit of placing brushes in mouths essentially stopped. Comprehensive dose reconstruction techniques are being applied to estimate organ doses for each worker related to the intake of 226Ra, 228Ra, and associated photon exposures. Time dependent dose-response analyses will estimate lifetime risks for specific causes of death.

DISCUSSION

The study of radium dial workers is part of the Million Person Study of low-dose health effects that is designed to evaluate radiation risks among healthy American workers and veterans. Despite being one of the most important and influential radiation effects studies ever conducted, shifting programmatic responsibilities and declining funding led to the termination of the radium program of studies in the early 1990s. Renewed interest and opportunity have arisen. With scientific progress made in dosimetric methodology and models, the ability to perform a study over the entire life span, and the potential applicability to other scenarios such as medicine, environmental contamination and space exploration, the radium dial workers have once again come to the forefront.

The Neutrophil to Lymphocyte Ratio as a Triage Tool in Criticality Accidents

ABSTRACT

During triage of possibly irradiated individuals after a criticality accident or nuclear weapon event, it is necessary to decide whether a patient has experienced a clinically significant dose (> 2 Gy) that would require referral for additional evaluation and medical treatment. This is a binary decision: yes or no. The neutrophil-to-lymphocyte ratio (NLR) is an appropriate decision parameter, is simple to obtain in field operations, and is recognized in clinical medicine as an independent marker of systemic inflammation. NLR is evaluated for usefulness in triage using data from the Radiation Accident Registry at the Radiation Emergency Assistance Center/Training Site (REAC/TS). A criticality accident data set has been prepared using historic complete blood counts from 12 criticality events with 33 patients. In addition, a cohort of 125 normal controls has been assembled for comparison with the radiation accident data. In the control set, NLR is found to be 2.1 ± 0.06 (mean ± SEM) and distributed consistent with a Gaussian distribution. A patient from the 1958 Y-12 criticality accident is presented as an example of the time dependence of NLR after an event. In this case, NLR is statistically elevated above controls from <4 h until ~20 d post-event, and for times >20 d post-event, NLR is less than the control value, returning to baseline > ~40 d. The latter result has been confirmed using late hematological data taken from patients at Hiroshima and Nagasaki, and this appears to be a general finding. Since triage is a binary decision, analyzing NLR with receiver operating characteristic (ROC) statistics is appropriate. Maximizing the Youden J statistic (sensitivity + specificity -1) determines an appropriate decision point. For this data set, the decision point for NLR is found to be 3.33, with area under the curve (AUC) 0.865, sensitivity 0.67, specificity 0.97, positive predictive value (PPV) 0.85, and negative predictive value (NPV) 0.92. Therefore, when a known criticality accident or nuclear weapon event has occurred and if the patient's NLR is greater than 3.33 early post-event, then that person should be referred for further health physics and medical evaluation.

Power Function Retention of Radionuclides in a Wound

NCRP Report 156 describes soluble radionuclide retention kinetics in a wound, segregated into four retention categories: weak (W), moderate (M), strong (S), and avid (A). An alternate single-parameter model, the negative power function, t, is presented in this paper to describe the time behavior of radionuclide retention. With this mathematical description, γ is a single parameter that can be used to assign the wound retention category rapidly. Using the power function description of wound retention, the various wound categories present as straight lines on log scales with different slopes corresponding to the various retention categories. Regression analysis of average retention values in NCRP 156 shows γ = 0.735 ± 0.132, 0.514 ± 0.015, 0.242 ± 0.016, and 0.053 ± 0.023 for the weak, moderate, strong, and avid categories, respectively. A case study is presented (REAC/TS Registry case 1284) where a power function is shown to fit retention data in a Pu/Am hand wound up to 2,000 d (5.4 y) post-accident.

The Pseudo-Pelger huët Cell as a Retrospective Dosimeter: Analysis of a Radium Dial Painter Cohort

Recently, the pseudo-Pelger Huët anomaly in peripheral blood neutrophils has been described as a new radiation-induced, stable biomarker. In this study, pseudo-Pelger Huët anomaly was examined in peripheral blood slides from a cohort of 166 former radium dial painters and ancillary personnel in the radium dial industry, 35 of whom had a marrow dose of zero above background. Members of the radium dial painter cohort ingested Ra and Ra at an early age (average age 20.6 ± 5.4 y; range 13-40 y) during the years 1914-1955. Exposure duration ranged from 1-1,820 wk with marrow dose 1.5-6,750 mGy. Pseudo-Pelger Huët anomaly expressed as a percentage of total neutrophils in this cohort rises in a sigmoidal fashion over five decades of red marrow dose. Six subjects in this cohort eventually developed malignancies: five osteosarcomas and one mastoid cell neoplasm. The pseudo-Pelger Huët anomaly percentage in these cases of neoplasm increases with marrow dose and is best fit with a sigmoid function, suggestive of a threshold effect. No sarcomas are seen for a marrow dose under 2 Gy. These results indicate that pseudo-Pelger Huët anomaly in peripheral blood is a reasonable surrogate for the estimation of alpha dose to bone marrow in historic radiation cases. Hypotheses are discussed to explain late (months to years), early (hours to days), and intermediate (weeks to months) effects of ionizing radiation, respectively, on the expression of genes encoding inner nuclear membrane proteins and their receptors, on the structure and function of nuclear membrane proteins and lipids, and on cytokinesis through chromatin bridge formation.

The Pseudo-Pelger HuËt Cell-A New Permanent Radiation Biomarker

Using archival peripheral blood slides obtained from patients in the 1958 Y-12 criticality accident, the authors have recently described the pseudo-Pelger Huët anomaly (PHA) in neutrophils as a new radiation-induced biomarker. The current work provides additional evidence that PHA is also a permanent biomarker, potentially useful in retrospective dosimetry. In the Y-12 cohort, the high dose group (n = 5, 2.98-4.61 Gy-Eq) exhibited 13.0 ± 0.85 % Pelger Huët cells (mean ± SEM) in the neutrophil population compared to 6.8 ± 1.6 % in the low dose group (n = 3, 0.29-0.86 Gy-Eq; p = 0.008). An age and gender-matched control group (n = 8) exhibited 3.6 ± 0.9 % PH cells. Results of a one-way ANOVA show that the high dose group is statistically different from both the low dose group and the control group (p = 0.002). In the Y-12 cohort, PHA appears <12 h post-accident and is permanent for more than 16 y. Similar long-term persistence of the PHA mutation has been obtained from examination of peripheral blood slides from the 1971 Co accident at the Variable Dose Rate Irradiation Facility (VDRIF) in Oak Ridge, TN. In order to investigate the pseudo-PH cell as a biomarker in animal studies under well controlled dosimetry, peripheral blood slides were obtained from animals in a nonhuman primate (NHP) (Macaca mulatta) total-body irradiation (TBI) model (Co γ rays at 0.6 Gy min; dose range 1-8.5 Gy, LD50/60 6.44 Gy). In the NHP studies, the first measurement of PHA is taken at 5 h post-irradiation, then daily for days 1-5 and every 5-10 d thereafter. In the TBI model, the PH cell appears quickly (<5 h) post-irradiation, and the dose-dependent PH percentage is constant from 1 d over the 60-d monitoring period of the experiments. Using the average of data from 1-60 d, a linear dose response (PHA % slope = 0.49 ± 0.07 % Gy, r = 0.92) is obtained over the dose range 0-8.5 Gy. The authors conclude that ionizing radiation induces dose-dependent internuclear bridges in circulating neutrophils, and this morphological change can be used both as an acute phase biomarker and as a tool for retrospective dosimetry.

Management of ionizing radiation injuries and illnesses, part 4: acute radiation syndrome

To provide proper medical care for patients after a radiation incident, it is necessary to make the correct diagnosis in a timely manner and to ascertain the relative magnitude of the incident. The present article addresses the clinical diagnosis and management of high-dose radiation injuries and illnesses in the first 24 to 72 hours after a radiologic or nuclear incident. To evaluate the magnitude of a high-dose incident, it is important for the health physicist, physician, and radiobiologist to work together and to assess many variables, including medical history and physical examination results; the timing of prodromal signs and symptoms (eg, nausea, vomiting, diarrhea, transient incapacitation, hypotension, and other signs and symptoms suggestive of high-level exposure); and the incident history, including system geometry, source-patient distance, and the suspected radiation dose distribution.

Case Report: Industrial X-Ray Injury Treated With Non-Cultured Autologous Adipose-Derived Stromal Vascular Fraction (SVF)

Local cutaneous injuries induced by ionizing radiation (IR) are difficult to treat. Many have reported local injection of adipose-derived stromal vascular fraction (SVF), often with additional therapies, as an effective treatment of IR-induced injury even after other local therapies have failed. The authors report a case of a locally recurrent, IR-induced wound that was treated with autologous, non-cultured SVF without other concurrent therapy. A nondestructive testing technician was exposed to 130 kVp x rays to his non-dominant right thumb on 5 October 2011. The wound healed 4 mo after initial conservative therapy with oral/topical α-tocopherol, oral pentoxifylline, naproxen sodium, low-dose oral steroids, topical steroids, hyperbaric oxygen therapy (HBOT), oral antihistamines, and topical aloe vera. Remission lasted approximately 17 mo with one minor relapse in July 2012 after minimal trauma and subsequent healing. Aggressive wound breakdown during June 2013 required additional therapy with HBOT. An erythematous, annular papule developed over the following 12 mo (during which time the patient was not undergoing prescribed treatment). Electron paramagnetic resonance (EPR) done more than 2 mo after exposure to IR revealed dose estimates of 14 ± 3 Gy and 19 ± 6 Gy from two centers using different EPR techniques. The patient underwent debridement of the 0.5 cm papular area, followed by SVF injection into and around the wound bed and throughout the thumb without complication. Eleven months post SVF injection, the patient has been essentially asymptomatic with an intact integument. These results raise the possibility of prolonged benefit from SVF therapy without the use of cytokines. Since there is currently no consensus on the use of isolated SVF therapy in chronic, local IR-induced injury, assessment of this approach in an appropriately powered, controlled trial in experimental animals with local radiation injury appears to be indicated.

Appearance of pseudo-Pelger Huet anomaly after accidental exposure to ionizing radiation in vivo

To evaluate the morphology of formed elements of human blood after exposure to ionizing radiation in vivo, archival smears of peripheral blood from eight individuals involved in the 1958 Y-12 criticality accident at Oak Ridge, Tennessee, were examined manually by light microscopy. For each case, increased interlobar bridging was observed in nuclei of the myeloid cells, many of which were bilobed and morphologically similar to Pelger Huet (PH) cells. The high-dose group (n = 5, 2.98-4.61 Gy-Eq) exhibited 13.0 ± 0.85% PH cells (mean ± SEM) in the neutrophil population compared to 6.8 ± 1.6% in the low-dose group (n = 3, 0.29-0.86 Gy-Eq; p = 0.008). An age- and gender-matched control group (n = 8) exhibited 3.6 ± 0.9% PH cells. Results of a one-way ANOVA show that the high-dose group is statistically different from both the low-dose group and the control group (p = 0.002). However, the low-dose group is not statistically different from the control group (p = 0.122). The mean number of nuclear lobes in blood neutrophils was also enumerated as a function of time after exposure and was found to be diminished, consistent with incomplete nuclear segmentation that is characteristic of the Pelger Huet anomaly (PHA). In contrast to these changes in myeloid cells, the morphology of erythrocytes and platelets appeared to be normal. The authors conclude that ionizing radiation induces abnormal morphology of circulating neutrophils, which is similar to the pseudo-PHA that is acquired in disorders such as myelodysplastic syndrome, acute myeloid leukemia, and leukemoid reactions. Potential molecular mechanisms by which radiation induces this morphological change are discussed. From this cohort, the biomarker appears to be present early post-accident (<9 h) and stable at least up to 16 y post-accident. Assessment of circulating pseudo-Pelger Huet cells is being investigated as a potential biodosimetric tool.

Management of Ionizing Radiation Injuries and Illnesses, Part 5: Local Radiation Injury

This final article in the series on the medical management of ionizing radiation injuries and illnesses focuses on the effects of acute ionizing radiation exposure to one of the largest organ systems of the body—the skin. These injuries may extend beyond the skin into deeper tissues and cause local radiation injury. There are numerous causes of these injuries, ranging from industrial incidents to medical procedures. In the present article, the authors characterize the clinical course, pathophysiologic process, sources of injury, diagnosis, and management of local radiation injury and describe a clinical scenario. This information is important for primary care physicians, to whom patients are likely to initially present with such injuries. J Am Osteopath Assoc. 2014;114(11):840-848 doi: 10.7556/jaoa.2014.170

Clinical application of the AFRRI BAT computer program

The Biodosimetry Assessment Tool (BAT) is a computer program developed by the Armed Forces Radiobiology Research Institute (AFRRI) as an aid to provide early diagnostic information (clinical signs and symptoms, physical dosimetry, etc.) to health care providers responsible for the initial management of radiation casualties after a major radiation incident. It is designed primarily to permit collection, integration, and archiving of data obtained from patients accidentally exposed to ionizing radiation. BAT also provides an early estimate of radiation dose using the timing of prodromal symptoms, clinical data, and various aspects of the time-dependent hematology profile. Collection of relevant data is facilitated by use of structured templates and user-friendly software. The BAT software is illustrated here using five historical cases from the U.S. Radiation Accident Registry maintained by the Radiation Emergency Assistance Center/Training Site (REAC/TS) for the U.S. Department of Energy.

Synopsis of partial-body radiation diagnostic biomarkers and medical management of radiation injury workshop

Radiation exposures from accidents, nuclear detonations or terrorist incidents are unlikely to be homogeneous; however, current biodosimetric approaches are developed and validated primarily in whole-body irradiation models. A workshop was held at the Armed Forces Radiobiology Research Institute in May 2008 to draw attention to the need for partial-body biodosimetry, to discuss current knowledge, and to identify the gaps to be filled. A panel of international experts and the workshop attendees discussed the requirements and concepts for a path forward. This report addresses eight key areas identified by the Workshop Program Committee for future focus: (1) improved cytogenetics, (2) clinical signs and symptoms, (3) cutaneous bioindicators, (4) organ-specific biomarkers, (5) biophysical markers of dose, (6) integrated diagnostic approaches, (7) confounding factors, and (8) requirements for post-event medical follow-up. For each area, the status, advantages and limitations of existing approaches and suggestions for new directions are presented.

Diagnosis and treatment of polonium poisoning

OBJECTIVES

Interest in the clinical toxicology of (210)polonium ((210)Po) has been stimulated by the poisoning of Alexander Litvinenko in 2006. This article reviews the clinical features, diagnosis, and treatment of acute radiation syndrome (ARS) resulting from the ingestion of (210)Po. PHYSICAL CHARACTERISTICS: (210)Po is a high-energy alpha-emitter (radioactive half-life 138 days) that presents a radiation hazard only if taken into the body, for example, by ingestion, because of the low range of alpha particles in biological tissues. As a result, external contamination does not cause radiation sickness.

TOXICOKINETICS

Ingested (210)Po is concentrated initially in red blood cells and then the liver, kidneys, spleen, bone marrow, gastrointestinal (GI) tract, and gonads. (210)Po is excreted in urine, bile, sweat, and (possibly) breath and is also deposited in hair. After ingestion, unabsorbed (210)Po is present in the faeces. The elimination half-life in man is approximately 30-50 days. In the absence of medical treatment, the fatal oral amount is probably in the order of 10-30 microg.

CLINICAL PRESENTATION

If the absorbed dose is sufficiently large (e.g., >0.7 Gy), (210)Po can cause ARS. This is characterized by a prodromal phase, in which nausea, vomiting, anorexia, lymphopenia, and sometimes diarrhea develop after exposure. Higher radiation doses cause a more rapid onset of symptoms and a more rapid reduction in lymphocyte count. The prodromal phase may be followed by a latent phase during which there is some clinical improvement. Subsequently, the characteristic bone marrow (0.7-10 Gy), GI (8-10 Gy), or cardiovascular/central nervous system syndromes (>20 Gy) develop, with the timing and pattern of features dependent on the systemic dose. The triad of early emesis followed by hair loss and bone marrow failure is typical of ARS. Those patients who do not recover die within weeks to months, whereas in those who survive, full recovery can take many months.

INVESTIGATION AND DIAGNOSIS

Serial blood counts are important for assessing the rate of reduction in lymphocyte counts. Chromosome analysis, especially the dicentric count, may establish radiation effects and provides an estimation of dose. The diagnosis of (210)Po poisoning is established by the presence of (210)Po in urine and faeces and the exclusion of other possible causes. In the absence of a history of exposure, diagnosis is very difficult as clinical features are similar to those of much more common conditions, such as GI infections and bone marrow failure caused, for example, by drugs, other toxins, or infections.

MANAGEMENT

Good supportive care is essential and should be directed at controlling symptoms, preventing infections but treating those that do arise, and transfusion of blood and platelets as appropriate. Gastric aspiration or lavage may be useful if performed soon after ingestion. Chelation therapy is also likely to be beneficial, with research in animals suggesting reduced retention in the body and improvements in survival, although increased activity in some radiosensitive organs has also been reported with some chelating agents. Dimercaprol (British Anti-Lewisite) (with penicillamine as an alternative) is currently recommended for (210)Po poisoning, but animal models also indicate efficacy for 2,3,-dimercapto-1-propanesulfonic acid, meso-dimercaptosuccinic acid, or N,N -dihydroxyethylethelene-diamine-N,N -bis-dithiocarbamate.

CONCLUSIONS

Internal contamination with (210)Po can cause ARS, which should be considered in patients presenting initially with unexplained emesis, followed later by bone marrow failure and hair loss.

A note on the number of survey stations required in a mass casualty radiation event

Guidance on the minimum number of radiation triage stations required in a radiation-related mass casualty event is presented using the mathematical discipline of queueing theory. These conclusions are valid under very general statistical assumptions regarding the average rate of victims seeking assistance and the average rate of persons who can be processed at a single survey station per unit time.

Nuclear terrorism: triage and medical management of radiation and combined-injury casualties

This article addresses the medical effects of nuclear explosions and other forms of radiation exposure, assessment of radiation dose, triage of victims, definitive treatment of radiation and combined-injury casualties, and planning for emergency services after a terrorist attack involving a nuclear device. It reviews historical events of mass radiation-induced casualties and fatalities at Hiroshima, Chernobyl, and Goiania, and discusses various scenarios for nuclear terrorism.

Medical treatment of radiological casualties: current concepts

The threat of radiologic or nuclear terrorism is increasing, yet many physicians are unfamiliar with basic treatment principles for radiologic casualties. Patients may present for care after a covert radiation exposure, requiring an elevated level of suspicion by the physician. Traditional medical and surgical triage criteria should always take precedence over radiation exposure management or decontamination. External contamination from a radioactive cloud is easily evaluated using a simple Geiger-Muller counter and decontamination accomplished by prompt removal of clothing and traditional showering. Management of surgical conditions in the presence of persistent radioactive contamination should be dealt with in a conventional manner with health physics guidance. To be most effective in the medical management of a terrorist event involving high-level radiation, physicians should understand basic manifestations of the acute radiation syndrome, the available medical countermeasures, and the psychosocial implications of radiation incidents. Health policy considerations include stockpiling strategies, effective use of risk communications, and decisionmaking for shelter-in-place versus evacuation after a radiologic incident.

Medical management of radiological casualties

Victims of radiological terrorism events require prompt diagnosis and treatment of medical and surgical conditions as well as conditions related to radiation exposure. Hospital emergency personnel should triage victims using traditional medical and trauma criteria. Radiation dose can be estimated early post-event using rapid-sort, automated biodosimetry and clinical parameters such as the clinical history, the time to emesis (TE), and lymphocyte depletion kinetics. For TE < 2 h, the effective whole-body dose is at least 3 Gy. If TE < 1 h, the whole-body dose most probably exceeds 4 Gy. Lymphocyte depletion follows dose-dependent, first order kinetics after high-level gamma and criticality incidents. Patient radiation dose can be estimated very effectively from the medical history, serial lymphocyte counts, and TE, and subsequently confirmed with chromosome-aberration bioassay, the current gold standard. These data are effectively analyzed using the Armed Forces Radiobiology Research Institute Biodosimetry Assessment Tool. The medical management of patients with acute, moderate to severe radiation exposure (effective whole-body dose >3 Gy) should emphasize the rapid administration of colony stimulating factors. All of these compounds decrease the duration of radiation-induced neutropenia and stimulate neutrophil recovery, albeit with some variability, in patients who have received myelotoxic chemotherapy, and all have demonstrated benefit in irradiated animals. For those patients developing febrile radiation-induced neutropenia, adherence to the current Infectious Diseases Society of America guidelines for high-risk neutropenia is recommended.

Biodosimety Assessment Tool: a post-exposure software application for management of radiation accidents

The Biodosimetry Assessment Tool software application under development will equip health care providers with diagnostic information (clinical signs and symptoms, physical dosimetry, etc.) germane to the management of human radiation casualties. Designed primarily for prompt use after a radiation incident, the user-friendly program facilitates collection, integration, and archiving of data obtained from exposed persons. Data collected in templates are compared with established radiation dose responses obtained from the literature to provide multiparameter dose assessments. The program archives clinical information (e.g., extent of contamination, wounds, infection, etc.) useful for casualty management, displays relevant diagnostic information in a concise format, and can be used to manage both military and civilian radiation accidents. In addition, monitoring of diagnostic information of individuals using this program could potentially minimize the severity of psychological casualties by making a marked impact on the way that both radiation casualties and the worried well view their exposure, dose, and future risk for the development of disease.

Early dose assessment in criticality accidents

Early estimation of dose is useful in the medical evaluation of severe radiation accidents. In a prior publication, lymphocyte depletion kinetics were shown to follow an exponential decline for gamma accidents in which the average whole-body dose was in the range 50 cGy < D < 8-10 Gy. In that study, the depletion rate constant was linearly related to dose, within the statistical variation of the historical hematological data. This simple technique has now been extended to include analysis of various types of criticality accidents (liquid process; water moderated systems; metallic systems). Lymphocyte depletion in high-level mixed gamma/neutron accidents is found to be approximately equal, at a given effective dose, to that for gamma accidents. This universality would indicate a neutron RBE for human lymphocytes close to unity. Furthermore, the technique appears to be insensitive to the shape of gamma and neutron spectra, therefore making it especially robust for initial, approximate dose estimation.

Calcium kinetics in children with osteogenesis imperfecta type III and IV: pre- and post-growth hormone therapy

Children with osteogenesis imperfecta (OI) type III and type IV were studied using a (42)Ca stable isotope technique. Serum dilution kinetics of (42)Ca were studied pre- and post-growth hormone (GH) treatment in 9 OI III (age range 5-9 years) and 8 OI IV patients (age range 5-12 years). Each subject was studied twice: at baseline and following GH therapy (range 1-1.5 years). Isotopic enrichments of (42)Ca were followed over 7 days using thermal ionization mass spectrometry. A binding site model, which describes reversible and irreversible binding of calcium (Ca) ions to postulated short- and long-term binding sites in bone, was used to analyze the kinetic data. In type III patients, GH treatment (1) increased the fraction of short-term binding sites, theta (0.777 +/- 0.112 versus 0.877 +/- 0.05, respectively; P = 0.034); (2) increased the apparent half-life of a Ca ion attached to the long-term binding site by 76% (P = 0. 009); (3) although not statistically significant (P = 0.098), a trend toward an increased growth rate was observed with increasing change in theta (Deltatheta); (4) patients experienced a 75% increase in growth rate during the first 6 months of treatment. In type IV patients, GH treatment increased the apparent half-life of a Ca ion attached to the long-term binding site by 83% (P = 0.048), however, no trend toward an increased growth rate was observed with increasing Deltatheta in these patients. These significant changes in Ca binding to bone may influence growth in type III patients.

Early dose assessment following severe radiation accidents

Early treatment of victims of high level acute whole-body x-ray or gamma exposure has been shown to improve their likelihood of survival. However, in such cases, both the magnitude of the exposure and the dosimetry profile(s) of the victim(s) are often not known in detail for days to weeks. A simple dose-prediction algorithm based on lymphocyte kinetics as documented in prior radiation accidents is presented here. This algorithm provides an estimate of dose within the first 8 h following an acute whole-body exposure. Early lymphocyte depletion kinetics after a severe radiation accident follow a single exponential, L(t) = L(o)e(-k(D¿t), where k(D) is a rate constant, dependent primarily on the average dose, D. Within the first 8 h post-accident, K(D) may be calculated utilizing serial lymphocyte counts. Data from the REAC/TS Radiation Accident Registry were used to develop a dose-prediction algorithm from 43 gamma exposure cases where both lymphocyte kinetics and dose reconstruction were felt to be reasonably reliable. The inverse relationship D(K) may be modeled by a simple two parameter curve of the form D = a/(1 + b/K) in the range 0 < or = D < or = 15 Gy, with fitting parameters (mean +/- SD): a = 13.6 +/- 1.7 Gy, and b = 1.0 +/- 0.20 d(-1). Dose estimated in this manner is intended to serve only as a first approximation to guide initial medical management.

Calcium kinetics in glycogen storage disease type 1a

Glycogen storage disease type 1a (Von Gierke's disease) is one of the more common glycogen storage diseases (GSD). GSD 1a patients can have severe idiopathic osteopenia, often beginning at a young age. Since calcium tracer studies offer a sensitive probe of the bone microenvironment and of calcium deposition, kinetics might be disturbed in patients with GSD 1a. Plasma dilution kinetics obtained using the stable isotope 42Ca are shown in this paper to be quite different between GSD 1a patients and age-matched controls. Comparison of kinetic parameters in these two populations is made using a new binding site model for describing calcium dynamics at the plasma-bone interface. This model describes reversible binding of calcium ions to postulated short-term and long-term sites by a retention probability density function psi (t). Using this analysis, adult GSD subjects exhibited a significant decrease (P = 0.023) in the apparent half-life of a calcium ion on the longer-term site compared with controls. The general theory of calcium tracer dilution kinetics is then discussed in terms of a new model of short-term calcium homeostasis recently proposed by Bronner and Stein [5].

Calcium tracer kinetics show decreased irreversible flow to bone in glucocorticoid treated patients

Osteopenia resulting from pharmacologic doses of glucocorticoids is well known. Previously, there has been no satisfactory quantitative model describing the kinetics of calcium flow in subjects on chronic steroid use. A mathematical model of calcium isotope interaction with bone is described and applied to determine an estimate of kinetic parameters characterizing these changes. Calcium tracer dilution kinetics after a bolus injection of 42Ca were measured in 14 subjects with juvenile dermatomyositis, 6 on prednisone regimens and 8 on treatment regimens without prednisone. Irreversible tracer loss from plasma bone is found to be significantly reduced (P = 0.043) in the glucocorticoid-treated patients compared with patients on nonsteroid regimens. Reversible flow to bone is noted to be similar in the two groups. These results suggest a direct effect of glucocorticoids on osteoblast function.

A three-hour measurement to evaluate bone calcium turnover

It is well established that short-term clearance of an intravenous calcium load in vivo reflects bone uptake. Using results from isotope-dilution experiments with 42Ca, a 3-h test has been developed to measure a quantity, gamma, related to bone accretion. This test is proposed as a useful, clinically applicable measure of bone status. For early times, t, after a bolus of 42Ca, plasma tracer dilution was well approximated by t-gamma, where gamma is related to the fractional rate of loss of tracer, q, from blood into bone (1/q)(dq/dt) = -gamma/t). Gamma was evaluated from kinetic measurements on 91 normal female children, adolescents, and adult women in the age range 4-50 years. For t < or = 3 h, all clearance curves were well fit by a power function. Gamma was found to vary from 0.244 +/- 0.031 for adult premenopausal women (N = 22) to 0.392 +/- 0.056 for prepubertal children (N = 29). Using the Spearman rank-order correlation test, gamma was correlated with bone accretion measured from classic calcium kinetic studies with a correlation coefficient of 0.721, significant at p < 0.005. In those cases in which accretion and resorption remain tightly linked, gamma also provides information on the state of calcium loss from bone. Gamma was evaluated in 14 subjects with bone disease characterised by increased resorption (osteoporosis, Paget's disease) and in 27 subjects with decreased accretion (osteogenesis imperfecta, types I, III, IV; steroid-treated juvenile dermatomyositis). All subjects with Paget's disease and with osteoporosis showed increased gamma, consistent with high bone turnover. The osteoporotic patients furthermore exhibited gamma increasing monotonically by approximately 1% per year after age 55.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of stable isotopic tracers in studies of whole body calcium metabolism

Stable isotopic tracers of calcium have been used to characterize the absorption of dietary calcium and the subsequent distribution of this element through the body. For a group of 7 healthy children, ages 4-14, and 7 children with osteogenesis imperfecta (OI), types I, III and IV, ages 6-17, there were no detectable differences in the fractional absorption of dietary calcium, 0.29+/-0.11 and 0.28+/-0.16, respectively. The total exchangeable pool of calcium was found to be 161+/-52 mg/kg for the healthy children and 95+/-29 mg/kg for the 3 children with Type I OI, 250+/-75 mg/kg for the 3 children with Type III OI and 216 mg/kg for the child with Type IV OI.

A non-Markovian model for calcium kinetics in the body

We present a new generalized compartmental model for calcium kinetics as measured by tracer concentration in blood plasma. The parameter measuring incorporation of calcium in bone discriminates between different levels of physical development in female teenagers and between teenagers and adults.

Ultrasonic pulse-echo determination of thermal injury in deep dermal burns

Burns of all kinds represent a serious class of traumatic injury, affecting over two million people annually in the United States alone. Of this number, over 70000 are serious enough to require extended hospitalization. Currently, there is no sensitive, quantitative technique for measuring the depth of thermal damage in such injuries. An ultrasonic pulse-echo technique is described here whereby such information can be obtained within a few minutes postburn. Results from model porcine experiments are given to illustrate the usefullness of the method, and implication for the clinical care of human burn victims are discussed.