99mTc internal contaminations measurements among nuclear medicine medical personnel during ventilation - perfusion SPECT lung scans.

This paper presents results of measurements of 99mTc activity concentration in air and nuclear medical personnel blood during ventilation-perfusion SPECT lung scans. 99mTc activity measurements were conducted at the Nuclear Medicine Department, John Paul II Hospital, Krakow. Technicians and nurses who perform examinations were equipped with personal aspirators enabling air sampling to determine the radiation exposure at their workplaces. Measurements allowed to evaluate the concentration of 99mTc in 14 air samples and it ranged from 7800 ± 600 to 10,000 ± 1000 Bq m-3 for air samples collected by technicians and from 390 ± 30 to 600 ± 40 Bq m-3 for air samples collected by nurses. In addition 99mTc concentrations in blood of medical personnel were determined in 24 samples. For technicians the maximum 99mTc blood concentration levels reached 920 ± 70 Bq L-1 and 1300 ± 100 Bq L-1. In the case of nurses, the maximum estimated activity concentrations were about ten times lower, namely 71 ± 7 Bq L-1 and 39 ± 3 Bq L-1. Although the intakes appear to be relatively high, the resulting annual effective doses are about 34 µSv for technicians and only 2 µSv for nurses.

131I thyroid activity and committed dose assessment among family members of patients treated with radioactive iodine.

The main goal of the present study was estimation of an internal contamination of 131I among family members of patients treated with radioactive iodine. Thyroid activity measurements of 131I in examined volunteers were performed using a whole-body spectrometer at the institute of nuclear physics, Polish academy of sciences. During this research, 20 relatives of patients treated with 131I were examined: eight women and 12 men with an age in the range from 3 to 72 years. In the case of nine individuals, the activity of 131I in the thyroid was below the detection limit, but among the remaining 11 individuals, the activity varied from (9 ± 3) Bq up to (1140 ± 295) Bq. Subsequently, based on the measurements of thyroid 131I activities, the corresponding doses were assessed. The highest estimated effective dose reached 218 µSv, while the thyroid equivalent dose was 2.4 mSv. In addition, the experimental data obtained were statistically analysed together with the results of surveys of the individuals participating in the study by means of correspondence analysis and nonparametric tests: Mann-Whitney, gamma, χ2 and Yule Phi coefficient. These analyses revealed relationships between 131I activities in the thyroids of the examined individuals and their housing conditions as well as consumption of meals prepared by the patients.

99mTc activity concentrations in room air and resulting internal contamination of medical personnel during ventilation-perfusion lung scans.

This paper presents the results of measurements of 99mTc activity concentrations in indoor air in a nuclear medicine department and resulting estimated 99mTc intake by medical personnel. 99mTc air activity measurements were conducted at the Nuclear Medicine Department, John Paul II Hospital, Krakow, Poland, during ventilation-perfusion SPECT lung scans. Technetium from the air was collected by means of a mobile aerosol sampler with a Petryanov filter operating at an average flow rate of 10 dm3 min-1. Measured activities ranged from 99 ± 11 to 6.1 ± 0.5 kBq m-3. The resulting daily average intake of 99mTc by medical staff was estimated to be 5.4 kBq, 4.4 kBq, 3.0 kBq and 2.5 kBq, respectively, for male technicians, female technicians, male nurses and female nurses. Corresponding annual effective doses were 1.6 µSv for technicians and 1 µSv for nurses. The highest equivalent dose values were determined for extrathoracic (ET) airways: 5 µSv and 10 µSv for nurses and technicians, respectively. It is concluded that estimated annual absorbed doses are over three orders of magnitude lower than the dose limit established in the Polish Atomic Law Act and in recommendations of the International Commission on Radiological Protection for medical staff.

Measurement of 131I activity in air indoor Polish nuclear medical hospital as a tool for an internal dose assessment.

This paper presents results of 131I air activity measurements performed within nuclear medical hospitals as a tool for internal dose assessment. The study was conducted at a place of preparation and administration of 131I ("hot room") and at a nurse station. 131I activity measurements were performed for 5 and 4 consecutive working days, at the "hot room" and nurse station, respectively. Iodine from the air was collected by a mobile HVS-30 aerosol sampler combined with a gas sampler. Both the gaseous and aerosol fractions were measurement. The activities in the gaseous fraction ranged from (28 ± 1 Bq m-3) to (492 ± 4) Bq m-3. At both sampling sites, the activity of the gaseous iodine fraction trapped on activated charcoal was significantly higher than that of the aerosol fraction captured on Petrianov filter cloth. Based on these results, an attempt has been made to estimate annual inhalation effective doses, which were found to range from 0.47 mSv (nurse female) to 1.3 mSv (technician male). The highest annual inhalation equivalent doses have been found for thyroid as 32, 27, 13, and 11 mSv, respectively, for technician male, technical female, nurse male, and nurse female. The method presented here allows to fill the gaps in internal doses measurements. Moreover, because method has been successful used for many years in radioactive contamination monitoring of air in cases of serious nuclear accidents, it should also be used in nuclear medicine.

131I INTERNAL CONTAMINATION AND COMMITTED DOSE ASSESSMENT AMONG NUCLEAR MEDICINE MEDICAL PERSONNEL.

This study presents 131I thyroid activity measurements of 56 employees of the Department of Nuclear Medicine and Endocrine Oncology, Centre for Oncology in Gliwice. The research instrument was a whole-body spectrometer. In 44 out of 56 examined staff members, the determined 131I activity was found to be above the detection limit. The measured activities ranged from 6 ± 2 to 457 ± 118 Bq. The maximum estimated committed effective dose reached was 1.5 mSv/y. The results were compared with previous measurements conducted in another Polish nuclear medical unit. From this comparison, we can see that radiological safety among nuclear medicine personnel can be improved by appropriate work organisation. Reducing exposure of workers can be achieved by properly organised turnovers concerning the most vulnerable worksites. In addition, to lower the radiation risk, it is essential to comply strictly with the isolation regime for the patients.

Measurement of 131I activity in thyroid of nuclear medical staff and internal dose assessment in a Polish nuclear medical hospital.

This paper presents results of 131I thyroid activity measurements in 30 members of the nuclear medicine personnel of the Department of Endocrinology and Nuclear Medicine Holy Cross Cancer Centre in Kielce, Poland. A whole-body spectrometer equipped with two semiconductor gamma radiation detectors served as the basic research instrument. In ten out of 30 examined staff members, the determined 131I activity was found to be above the detection limit (DL = 5 Bq of 131I in the thyroid). The measured activities ranged from (5 ± 2) Bq to (217 ± 56) Bq. The highest activities in thyroids were detected for technical and cleaning personnel, whereas the lowest values were recorded for medical doctors. Having measured the activities, an attempt has been made to estimate the corresponding annual effective doses, which were found to range from 0.02 to 0.8 mSv. The highest annual equivalent doses have been found for thyroid, ranging from 0.4 to 15.4 mSv, detected for a cleaner and a technician, respectively. The maximum estimated effective dose corresponds to 32% of the annual background dose in Poland, and to circa 4% of the annual limit for the effective dose due to occupational exposure of 20 mSv per year, which is in compliance with the value recommended by the International Commission on Radiological Protection.

Stereotactic radiosurgery for metastatic spine tumors.

Spinal metastases invariably affect the majority of patients with cancer. Many will develop symptoms related to pain and disability from epidural spinal cord compression as well as pathologic fracture of the vertebrae. With the emergence of targeted systemic therapies and a better understanding of cancer biology, patients are living longer with bony metastases. This poses particular challenges, as palliation of pain and maintenance of local tumor control are paramount to quality of life and overall functional independence for these patients. Stereotactic radiosurgery (SRS) has emerged as a potent primary standalone and adjuvant treatment option for spinal metastases. To date, the primary indications for SRS include 1) upfront standalone treatment for painful bony metastases in the oligometastatic patient, 2) standalone or post-operative treatment following progression or recurrence of local disease despite previous conventional external beam radiation therapy (cEBRT), and 3) following surgery during which epidural disease is decompressed and the spine stabilized when indicated. SRS has demonstrated a significant advantage over cEBRT for tumors traditionally regarded as relatively radioresistant such as sarcoma, melanoma, renal cell carcinoma, non-small cell lung cancer and colon carcinoma.9 The radiobiological advantage of increased tumoricidal dose delivery and spinal cord dose sparing in SRS have made this a powerful treatment alternative to cEBRT particularly within the context of re-irradiation. Given the limitations of spinal cord dose constraints, surgery is still the first-line therapy in patients with high-grade epidural spinal cord compression (ESCC). Epidural compression can be treated with SRS, however this risks radiation-induced myelopathy and challenges the safety of effective dose delivery at the dural margin.11 With increasing dose, radiation-induced vertebral fracture is the most serious and prevalent side effect of SRS.53 An overview of SRS, including the most common indications, complications, and outcomes for spinal metastases are presented here.

Food price policy can favorably alter macronutrient intake in China.

The rapid change in diets, physical activity and body composition in low income countries has led to the coexistence of large pockets of undernutrition and overnutrition. Public health strategies for addressing this situation may be necessary, and price policy options are examined for China. Longitudinal dietary data collected in China in 1989-1993 on a sample of 5625 adults aged 20-45 y were examined. Three-day averages of food group consumption and nutrient intake were used in longitudinal statistical models to examine separately the effects of food prices on the decision to consume each food group and then the amount consumed. The effects of changes in six food prices on the consumption of each of six food groups, not just the food group whose price had changed, and on three macronutrients were estimated. The effects show large and significant price effects. If the joint effects of the nutrition transition are to be considered, then there are clear tradeoffs among which foods to tax and which to subsidize. Most important is the effect of prices in reducing fat intake of the rich but not adversely affecting protein intake for the poor. Increases in the prices of pork, eggs and edible oils are predicted to lower fat intake. Only increases in pork prices led to reduced protein intakes. This raises questions about earlier policy changes being implemented in China and provides insight into an important and controversial area for public health policy.

The effects of maternal-child health service utilization on subsequent contraceptive use in Morocco.

There are a number of reasons for anticipating that contact by women in developing country settings with modern maternal-child health (MCH) services will lead to increased use of family planning services. Indeed, the expectation of such a relationship underlies the integrated service delivery strategy that has been adopted on a more or less global basis. However, the available empirical evidence in support of this proposition is inconclusive. This study re-examines this issue in Morocco. Household survey data and data on the supply environment for health and family planning services gathered in 1992 are analysed in the study. A full-information maximum likelihood estimator is used to control for the possible endogeneity of health care and contraceptive choices. The findings indicate a substantial and apparently causal relationship between the intensity of MCH service use and subsequent contraceptive use. Policy simulations indicate that sizeable increases in contraceptive prevalence might be realized by increasing the coverage and intensity of use of MCH services.

PIP: This study examined the association between frequency of use of maternal and child health (MCH) services and subsequent contraceptive use (CU) in Morocco. Data were obtained from a 1992 Moroccan Health Survey among 3267 married women with at least 1 live birth and the 1992 Service Availability Module. Analysis was based on full information maximum likelihood estimates and nonparametric, discrete factor strategies. The analysis ignored the possibility that CU can lead to increase MCH use, because few women use contraception before a first birth. Findings indicate that intensity of MCH service use was a statistically significant determinant of subsequent CU. The magnitude of the effect was large. For example, an increase in MCH service use from 2 to 4 would result in an increase of over 71% in contraceptive prevalence, from 32% to 55%. Modern CU would increase from 55% to 65%. Traditional CU would increase from 7% to 19%. Increases were more likely despite controls for individual and household characteristics. Findings do not explain the role of integrated services. Since there are numerous sources of supply, it is likely that counseling and promotion by health facility staff were significant factors. Evidence supports the need to include community-level factors in the analysis, but key community factors remain unmeasured.

Quality, accessibility, and contraceptive use in rural Tanzania.

We examine how informants' reports on community perceptions of the quality and accessibility of family planning facilities relate to the use of modern contraceptives by individuals in rural Tanzania. Using information on individual-level contraceptive use in conjunction with community-level information on the accessibility and quality of family planning facilities, we employ two distinct statistical procedures to illustrate the impacts of accessibility and quality on contraceptive use. Both procedures treat the community-level variables as imperfect indicators of characteristics of the facilities, and they yield nearly identical implications. We find that a community-level, subjective perception of a family planning facility's quality has a significant impact on community members' contraceptive use whereas other community measures such as time, distance, and subjective perception of accessibility have trivial and insignificant direct impacts, net of the control variables. Future research that uncovers the determinants of perceptions of both community-level and individual-level quality could provide key insights for developing effective and efficient family planning programs.

Discrete factor approximations in simultaneous equation models: estimating the impact of a dummy endogenous variable on a continuous outcome.

This paper contains a Monte Carlo evaluation of estimators used to control for endogeneity of dummy explanatory variables in continuous outcome regression models. When the true model has bivariate normal disturbances, estimators using discrete factor approximations compare favorably to efficient estimators in terms of precision and bias; these approximation estimators dominate all the other estimators examined when the disturbances are non-normal. The experiments also indicate that one should liberally add points of support to the discrete factor distribution. The paper concludes with an application of the discrete factor approximation to the estimation of the impact of marriage on wages.

Alcohol use and wages: new results from the National Household Survey on Drug Abuse.

A recent study published in the Journal of Health Economics by French and Zarkin [French, M.T., Zarkin, G.A., 1995. Is moderate alcohol use related to wages? Evidence from four worksites, Journal of Health Economics 14, 319-344] found evidence of a positive, inverse-U-shaped relationship between wages and alcohol consumption for individuals at four worksites. In this paper, we attempted to replicate French and Zarkin's findings using a combined sample of prime-age workers from the 1991 and 1992 National Household Surveys on Drug Abuse (NHSDA). Whereas French and Zarkin found that individuals who consume approximately 1.5 to 2.5 drinks per day have higher wages than non-drinkers and heavy drinkers, we found no evidence of a turning point at this consumption level for either men or women. Our results do suggest that men who use alcohol have approximately 7% higher wages than men who do not drink, and this apparent wage premium is approximately the same over a wide range of alcohol consumption. For women, the estimated alcohol use premium is approximately half as large as for men and is statistically insignificant.

Binary outcomes and endogenous explanatory variables: tests and solutions with an application to the demand for contraceptive use in Tunisia.

Many demographic studies examine discrete outcomes, and researchers often suspect that some of the explanatory variables may be influenced by the same unobserved factors that determine the discrete outcome under examination. In linear models, the standard solution to this potential endogeneity bias is an estimator such as two-stage least squares. These methods have been extended to models with limited dependent variables, but there is little information on the performance of the methods in the types of data sets typically used in demographic research. This paper helps to fill this gap. It describes a simple analytic framework for estimating the effects of explanatory variables on discrete outcomes, which controls for the potential endogeneity of explanatory variables. It also discusses tests for exogeneity and joint determination of the outcomes and the explanatory variables. It summarizes the results of a Monte Carlo study of the performance of these techniques and uses these results to suggest how researchers should approach these problems in practice. We apply these methods to the examination of the impact of fertility intentions on contraceptive use, based on data from the 1988 Tunisia Demographic and Health Survey.

Premium increases and disenrollment from state risk pools.

State risk pools exist primarily for persons who want to buy health insurance, but are either medically uninsurable or are only able to find a policy at considerably higher cost than the rate for a standard insured person. While some people enroll in state risk pools for extended periods, many enroll only for a limited time. This study analyzes duration of enrollment in eight state risk pools using data from 1988 through 1991. A discrete time hazard model provides estimates of the relationship between voluntary disenrollment and enrollee and plan characteristics. Among other findings, the regressions provide evidence of substantial increases in disenrollment in most states in response to premium increases that either were implemented by the plan or occurred as enrollees aged into higher risk categories.

Family structure and physicians' hours in large, multispecialty groups.

There is a consensus that male physicians work more hours than female physicians, but no consensus on how or why female physicians limit hours. Drawing on a new national survey of physicians in large, multispecialty groups, we conclude that much of the hours differential is due to differences in nonpractice incomes and is likely to be permanent. However, due to reductions in family responsibilities for women and increases in nonpractice incomes for men, the differential should narrow somewhat as the current cohort of physicians ages. We also infer that the link between hours and practice choices may well account for much of the diversity of the literature.

Evidence of fertility regulation among rural French villagers, 1749-1789: a sequential econometric model of birth-spacing behavior (Part 2).

This is the second part of a two-part paper in which the authors examine statistical models of marital fertility regulation in rural France from 1749 to 1789. They create a case against the "natural fertility" characterization of the period by presenting "clear indications that marital fertility was being regulated in congruence with the differential valuations placed upon children, according to their gender and age. A complex pattern is found in the non-biological responses of couples' fertility to both non-familial and familial experience of infant deaths, which take the form of 'hoarding' and 'replacement effects', respectively. Evidence is present bearing upon the suspected endogeneity of infant deaths, and its relationship to the adoption of preventive methods of limiting family size." (SUMMARY IN FRE)

Evidence of fertility regulation among rural French villagers, 1749-1789: a sequential econometric model of birth-spacing behavior (Part 1).

PIP: The fertility histories of married couples in rural parishes in northern France in 1749-89--a period in which this population was assumed to have demonstrated natural fertility--were used to develop an econometric model of the sequence of live births. The shape and level of the parity-specific hazard rate is presumed, in natural fertility scenarios, to be unresponsive to differences in the number of surviving children. The log-logistic distribution was used to model the micro-level stochastic process governing the waiting time to next birth, while a multiple-branch specification of the likelihood function allowed for variations in inherent fecundability and behavioral heterogeneities that are independent of exogenous observable characteristics. The most striking finding was the emergence in the 3-branch model of a significant positive coefficient between the "girls alive" (but not "boys alive") variable and the birth spacing interval. Also observed was an inhibiting effect on fertility of increases in maternal age when the 3-branch model was used. Overall, comparison of log-likelihood values indicates that the fit of the model is substantially improved by introduction of a 3rd branch that includes additional data on covariates related to couples' previous experiences with child mortality. In addition, the results refute the assumption of natural fertility in this pre-Revolutionary rural French population and suggest, instead, that both fertility regulation and son preference were practiced.^ieng

Cohort parity analysis: statistical estimates of the extent of fertility control.

Cohort parity analysis (CPA) is a method for indirect measurement of the extent and timing of the adoption of fertility control within marriage. It uses information on the parity distribution of a cohort of women of specified marriage ages and durations. A multinomial model of parity provides a convenient framework for the computation of distributional parameters describing the extent to which marital fertility control has been accepted and characterizing the way control has been used within specific durations of marriage. This leads to a pair of easily implemented formulas for upper- and lower-bound estimates of the expected proportion of the population ever controlling and the distribution of controllers by parity. The power of CPA is illustrated, using census data for currently married couples in Dublin, Belfast, and other county boroughs of Ireland in 1911.