Page 423 - 2014 Printable Abstract Book
P. 423
administered questionnaires. Descriptive statistical analyses were used to characterize the radioisotope
procedures performed and radiation safety practices employed by the RTs, and ANOVA and Chi-square
methods were used to test for changes in these procedures and practices over time. Results: 6,289 (67%)
of the 9,398 RTs completed the detailed radioisotope procedures work history module. Results of analyses
characterizing this subgroup of radiologic technologists will be presented. Conclusions: Results from this
analysis will be helpful in guiding future studies on cancer and other disease risks, as well as the
effectiveness of occupational radiation protection and safety practices in the USRT cohort.
(PS7-77) Prevalence of thyroid nodules and absorbed dose from Iodine-131 in a Ukrainian cohort
2
1;2
following the Chernobyl accident. Eric Grimm ; Alina Brenner, MD, PhD, M.P.H. ; and The Ukrainian-
3;4
American Study Risk Analysis Group . , University of Colorado-Denver Anschutz Medical Campus, Aurora,
2
1
CO ; NIH NCI DCEG Radiation Epidemiology Branch, Rockville, MD ; Multiple Institutions, Multiple
4
3
Locations, Ukraine ; and Multiple Institutions, Multiple Locations, MD
Internal exposure to Iodine-131 has been associated with an increased risk of both malignant and
benign thyroid nodules in previous studies. However, data concerning the precise dose-response
relationship and how it is modified by factors such as age or iodine deficiency remain limited. Because
thyroid nodules are considered an early marker of thyroid cancer and are more common, dose-response
studies of nodules according to size and ultrasound characteristics could provide insights into mechanisms
of thyroid carcinogenesis. We examined the relationship between Iodine-131 dose and the prevalence of
thyroid nodules detected in a Ukrainian-American cohort (n=13,008) at baseline screening approximately
12 years after exposure from the 1986 Chernobyl nuclear accident. Cohort participants were < 18 years
of age at the time of the accident and had individual radioactivity measurements taken within two
months. The mean Iodine-131 dose was 0.64 Gy with a maximum of 41.56 Gy. We estimated odds ratios
(OR) and computed 95% confidence intervals using logistic regression. Likelihood ratio tests were used to
evaluate the significance of model parameters and test for interactions. After accounting for sex, oblast
of residence (Zhitomir, Kiev, and Chernihiv), presence of diffuse goiter, and age a significant log-linear
quadratic trend was found (p value: 0.0018) between thyroid nodule prevalence (n=263) and absorbed
Iodine-131 dose; the OR at 1 Gy was 2.08 (95% CI: 1.60-2.75). Furthermore, there were significant
interactions between dose and oblast of residence in 1986 and between dose and age at exposure with
higher thyroid nodule risks observed for Chernihiv residents compared to residents of other oblasts and
for younger children at the time of the accident compared to older ones. A further challenge involves
performing dose-response analyses according to ultrasound characteristics of thyroid nodules.
Preliminary analyses of thyroid nodule prevalence suggest that while the magnitude of Iodine-131 dose-
response is lower than that for thyroid cancer, its modification pattern by oblast of residence and age at
exposure are similar. Because the background rate of thyroid nodules increases with age, analyzing
incidence data from subsequent screenings should improve characterization of Iodine-131 risk with age
and time.
procedures performed and radiation safety practices employed by the RTs, and ANOVA and Chi-square
methods were used to test for changes in these procedures and practices over time. Results: 6,289 (67%)
of the 9,398 RTs completed the detailed radioisotope procedures work history module. Results of analyses
characterizing this subgroup of radiologic technologists will be presented. Conclusions: Results from this
analysis will be helpful in guiding future studies on cancer and other disease risks, as well as the
effectiveness of occupational radiation protection and safety practices in the USRT cohort.
(PS7-77) Prevalence of thyroid nodules and absorbed dose from Iodine-131 in a Ukrainian cohort
2
1;2
following the Chernobyl accident. Eric Grimm ; Alina Brenner, MD, PhD, M.P.H. ; and The Ukrainian-
3;4
American Study Risk Analysis Group . , University of Colorado-Denver Anschutz Medical Campus, Aurora,
2
1
CO ; NIH NCI DCEG Radiation Epidemiology Branch, Rockville, MD ; Multiple Institutions, Multiple
4
3
Locations, Ukraine ; and Multiple Institutions, Multiple Locations, MD
Internal exposure to Iodine-131 has been associated with an increased risk of both malignant and
benign thyroid nodules in previous studies. However, data concerning the precise dose-response
relationship and how it is modified by factors such as age or iodine deficiency remain limited. Because
thyroid nodules are considered an early marker of thyroid cancer and are more common, dose-response
studies of nodules according to size and ultrasound characteristics could provide insights into mechanisms
of thyroid carcinogenesis. We examined the relationship between Iodine-131 dose and the prevalence of
thyroid nodules detected in a Ukrainian-American cohort (n=13,008) at baseline screening approximately
12 years after exposure from the 1986 Chernobyl nuclear accident. Cohort participants were < 18 years
of age at the time of the accident and had individual radioactivity measurements taken within two
months. The mean Iodine-131 dose was 0.64 Gy with a maximum of 41.56 Gy. We estimated odds ratios
(OR) and computed 95% confidence intervals using logistic regression. Likelihood ratio tests were used to
evaluate the significance of model parameters and test for interactions. After accounting for sex, oblast
of residence (Zhitomir, Kiev, and Chernihiv), presence of diffuse goiter, and age a significant log-linear
quadratic trend was found (p value: 0.0018) between thyroid nodule prevalence (n=263) and absorbed
Iodine-131 dose; the OR at 1 Gy was 2.08 (95% CI: 1.60-2.75). Furthermore, there were significant
interactions between dose and oblast of residence in 1986 and between dose and age at exposure with
higher thyroid nodule risks observed for Chernihiv residents compared to residents of other oblasts and
for younger children at the time of the accident compared to older ones. A further challenge involves
performing dose-response analyses according to ultrasound characteristics of thyroid nodules.
Preliminary analyses of thyroid nodule prevalence suggest that while the magnitude of Iodine-131 dose-
response is lower than that for thyroid cancer, its modification pattern by oblast of residence and age at
exposure are similar. Because the background rate of thyroid nodules increases with age, analyzing
incidence data from subsequent screenings should improve characterization of Iodine-131 risk with age
and time.
