Thyroid Exposure Research Articles

Dental Cone-Beam Computed Tomography: Are the Eye Lens and Thyroid at Risk?

Background: The purpose of this study was to assess radiation dose to the eye lens (EL) and thyroid gland (TG) from 22 protocols used in maxillofacial imaging with cone-beam computed tomography (CBCT).Methods and Results: NanoDot optically stimulated luminescence dosimeters were used to assess scattered radiation to the EL and TG using a phantom. The dosimeters were secured at four sites around areas of interest. Mean eye radiation dose was significantly associated with field of view (FOV) size (r=0.830, P<0.001). Meanwhile, the mean thyroid radiation dose was found to be significantly associated only with exposure time (r=0.464, P=0.030). Mandible centralization was observed to be the most significant predictor for a greater effective thyroid dose; mandible FOV centralization had 0.236 odds of a higher thyroid dose than maxilla FOV centralization.Conclusion: FOV size significantly impacted EL dose. Thyroid exposure was affected by FOV centralization and exposure time. Centering the FOV on the mandible resulted in a greater effective dose due to the proximity of the TG to the primary beam.

Подход к оценке мониторинговых уровней оперативного вмешательства после аварии на АЭС с использованием системы RODOS

The paper presents a comprehensive analysis of the IAEA's methodology for calculating the operational intervention levels (OILs) to protect the public in the aftermath of a radiation disaster based on monitoring data. Developing the OILs assessment approach involves outlining specific indicators based on accident scenario characteristics, geographical location of nuclear power plants, timing after releases, and dose criteria established by the Russian regulatory documents. The paper highlights the feasibility of using a unified computation tool to solve interconnected tasks, such as "prediction of radiological consequences" and "development of monitoring OILs". A methodological approach to assessing monitoring OILs using RODOS models, designed for predicting the consequences of a radiation accident, has been developed. This approach includes three stages: assessing the radiological significance of a scenario, evaluating monitoring OILs for different generic criteria, and justifying the recommended values of OILs. Calculations were performed to show how the new methodology can be used based on the data for the most severe possible accidents at VVER-440, VVER-1000, VVER-1200, and BN-800 reactors. The results showed that the maximum radiation doses for the prospective BN-800 and VVER-1200 reactors do not exceed the dose criteria for evacuation of the public. The dynamics of OILs were computed for the most severe accident scenario at the VVER-440 reactor, using the "ambient dose rate" metric and "evacuation" dose criteria for effective and thyroid exposure, which are justified in the Russian NRB-99/2009. The OILs obtained through the presented methodology have been compared to the aggregated values of the same indicator calculated using the IAEA methodology in a "ground scenario". Further research is needed to validate monitoring techniques for potential accidents at Russian nuclear power plants. The research should consider regional conditions and the Russian regulatory framework.

Influence of short-lived radioiodines other than 131I on screening direct thyroid measurements with TCS-172 NAI(TL) survey meters.

In a nuclear emergency, one of the actions taken for the sake of public is to monitor thyroid exposure to radioiodines. Japan's Nuclear Regulation Authority recently published a report on such monitoring and proposed direct thyroid measurements with conventional NaI(Tl) survey meters (e.g. Hitachi model TCS-172) as a primary screening method. A previous study proposed screening levels (SLs) used in these simplified measurements as the net reading values of the TCS-172 device. Age-specific SLs were derived from a thyroid equivalent dose of 100mSv due to the inhalation intake of 131I. This study addressed the possible influence of short-lived iodine isotopes other than 131I on the simplified measurements. In preparation for such measurements, the responses of the device for 132I as an ingrowth component from 132Te, 133I, 134I and 135I in the thyroid were evaluated by numerical simulations using age-specific stylized phantoms in addition to those obtained for 131I in the previous study. The radioactivity ratios of the relevant isotopes were taken from the inventory data of the Fukushima Daiichi Nuclear Power Plant. The results were used to predict the net readings of the device when 132Te-132I and 133I as well as 131I were inhaled at 24 or 72h after the shutdown of a nuclear power plant. In these cases, the signals from 132Te-132I and 133I become undetectable a couple of days after intake, which could lead to underestimations of the thyroid dose. To estimate the thyroid dose accurately from the simplified measurements, it is necessary to identify the exact time of intake after the shutdown and the actual physiochemical property of 132Te that affects the thyroid uptake of 132I.

An organ-effective modulation for non-contrast chest computed tomography imaging: effect on image quality and thyroid exposure reduction.

We investigate the efficacy of organ-effective modulation (OEM) technique for thyroid dose reduction among various body habitus and its impact on image quality in chest non-contrast computed tomography (CT). We prospectively enrolled 64 patients who underwent non-contrast chest CT from January to May 2022. The skin-absorbed radiation dose over the thyroid (Dthyroid) was obtained using a thermoluminescence dosemeter. Signal-to-noise ratio and image noise was also quantitatively assessed. In subjective analyses, two radiologists independently evaluated images based on a 5-point scale. The OEM group showed a markedly decrease in Dthyroid when compared with the non-OEM group (p<0.05). No significant difference was observed regarding the image noise (p<0.05), except for the ventral air space. The subjective scores of two radiologists showed no significant differences between the non-OEM and OEM groups. OEM can effectively reduce the radiation exposure of thyroid without compromising on image quality in non-contrast chest CT.

Screening levels of TCS-172 NaI(Tl) survey meters used for direct thyroid measurements in nuclear disasters.

It is a challenging task to establish a feasible and robust method for the population monitoring of individuals' thyroid exposure following an accidental intake of radioiodines in a nuclear emergency, because of the time restriction. The authors previously proposed a method for such monitoring to obtain as many reliable human data as possible and one of the components is simplified measurements by conventional NaI(Tl) survey meters that are intended to be used for the initial triage to identify significantly exposed individuals and get an overall picture of the exposure levels in a target population in a timely manner. This study determined screening levels (SLs) for a conventional NaI(Tl) survey meter (model TCS-172, Hitachi, Japan) using the conversion factor (131I kBq in the thyroid per μSv h-1) that were obtained from experiments and simulations with age-specific phantoms. The results demonstrated that the derived SLs for 100mSv thyroid equivalent dose were as follows: 0.2μSvh-1 (SL1) for the age group≤5-y-olds, 0.5μSvh-1 (SL2) for the 10- and 15-y-old age groups and 1.0μSvh-1 (SL3) for adults. These SLs would be reasonably available within 1week after the intake of 131I on the safe side.

Dose Dependence of Morbidity in Persons with Thyroid Exposure Due to Radioactive Iodine Intake During Fetal Development

Dose Dependence of Morbidity in Persons with Thyroid Exposure Due to Radioactive Iodine Intake During Fetal Development

Reduction of thyroid radioactive iodine exposure by oral administration of cyclic oligosaccharides

Alpha-cyclodextrin, a six d-glucose cyclic oligosaccharide, has several applications in food and pharmaceuticals, but has also been reported to retain iodine in a stable manner for 16 months. Radioactive iodine, which may cause thyroid cancer and hypofunction, must be properly managed. If the absorption of radioactive iodine is suppressed, it can be expected to lead to a reduction in thyroid exposure. This study clarified the inhibition of radioactive iodine absorption by the oral administration of α-cyclodextrin in a murine model using direct measurement of single photon emission computed tomography. The uptake of radioactive iodine into the thyroid gland in mice administered with radioactive iodine and an α-cyclodextrin solution was approximately 40% lower after 24 h. The finding that oral uptake of α-cyclodextrin has an inhibitory effect on the transfer of radioactive iodine to the thyroid gland has potential for application in many fields such as food, pharmaceuticals, nuclear emergency preparedness, and medicine.

Thyroid dose reduction shield with the generation of less artifacts used for fast chest CT examination

Fast chest CT scans with high-pitch factors are effective to reduce motion artifacts, but the over-ranging effect may increase harmful radiation exposure to organs which are located near the outside of the imaging area. This becomes a particular problem during chest CT imaging when managing the radiation dose to the radio-sensitive thyroid, which is located around the upper end of the imaging area. The use of an X-ray shielding material can reduce the exposure dose to the thyroid. However, when the shielding is performed using metal foil, metal artifacts definitely appear, and they interfere with the CT image. To solve this problem, we developed a novel less-artifact thyroid shield in which fine bismuth oxide particles are embedded in low-density polyurethane (PU) foam. This study aims to present the usefulness of our X-ray shield through experimentation using a human body phantom. Three kinds of thyroid shields were used: a commercially-available lead foil as a reference, investigational clay products to evaluate the proper amount of the fine bismuth oxide particles, and bismuth PU shields which are proposed in this study. Furthermore, a bismuth PU shield with an added PU spacer was fabricated for the further suppression of the artifacts. Under clinical conditions, shielding ability and image quality were evaluated. Thyroid doses were measured using small-type OSL dosimeters, and the dose reduction rates were determined. In addition, the image qualities of the thyroid and lung regions were evaluated using a contrast-to-noise ratio (CNR) and an artifact index (AI). When the thyroid is outside the scanning region, thyroid exposure without the shield was caused by over-ranging X-rays and showed 11 mGy. When applying bismuth with an effective mass thickness of 0.12 g/cm2 to the bismuth PU shield, the thyroid exposure dose was reduced by half. In addition, we confirmed that if this shield enters the scanning region through accident, the AI would be less than 10. Also, when using our thyroid shield, the occurrence of metal artifacts was drastically suppressed. In conclusion, our thyroid shield can reduce the radiation exposure dose in half while maintaining acceptable image quality. This is a valuable tool in solving the issue of radiation exposure when performing fast chest CT scans. The shield has breathability and flexibility, and patients can apply the shield to their necks by themselves.

Exposure to the Thyroid from Intake of Radioiodine Isotopes after the Chornobyl Accident. Report I: Revised Doses and Associated Uncertainties for the Ukrainian-American Cohort.

Thyroid doses from intake of radioiodine isotopes (131I, 132Te+132I, and 133I) and associated uncertainties were revised for the 13,204 Ukrainian-American cohort members exposed in childhood and adolescence to fallout from the Chornobyl nuclear power plant accident. The main changes related to the revision of the 131I thyroid activity measured in cohort members, the use of thyroid-mass values specific to the Ukrainian population, and the revision of the 131I ground deposition densities in Ukraine. Uncertainties in doses were assessed considering shared and unshared errors in the parameters of the dosimetry model. Using a Monte-Carlo simulation procedure, 1,000 individual stochastic thyroid doses were calculated for each cohort member. The arithmetic mean of thyroid doses from intake of 131I, 132Te+132I, and 133I for the entire cohort was 0.60 Gy (median = 0.22 Gy). For 9,474 subjects (71.6% of the total), the thyroid doses were less than 0.5 Gy. Thyroid doses for 42 cohort members (0.3% of the total) exceeded 10 Gy while the highest dose was 35 Gy. Intake of 131I contributed around 95% to internal thyroid exposure from radioiodine isotopes. The geometric standard deviation of individual stochastic thyroid doses varied among cohort members from 1.4 to 4.3 with an arithmetic mean of 1.6 and a median of 1.4. It was shown that the contribution of shared errors to the dose uncertainty was small. The revised thyroid doses resulted, in average, in around 40% decrease for cohort members from Zhytomyr Oblast and an increase of around 24% and 35% for the cohort members from Kyiv and Chernihiv Oblast, respectively. Arithmetic mean of TD20 doses for the cohort was around 8% less than that estimated in TD10, 0.60 Gy vs. 0.65 Gy, respectively; however, global median of TD20 doses somewhat increased compared to TD10: 0.22 Gy vs. 0.19 Gy, respectively. The difference between TD10 and TD20 was mainly due to a revision of the individual 131I thyroid activity measured in the cohort members.

Assessment of internal exposure to 131I and short-lived radioiodine isotopes and associated uncertainties in the Ukrainian cohort of persons exposed in utero.

This study revised the thyroid doses for 2582 Ukrainian in utero cohort members exposed to Chornobyl fallout (the Ukrainian in utero cohort) based on revision of: (i) 131I thyroid activity measured in the Ukrainian population, (ii) thyroid dosimetry system for entire Ukraine, and (iii) 131I ground deposition densities in Ukraine. Other major improvements included: (i) assessment of uncertainties in the thyroid doses considering shared and unshared error, and (ii) accounting for intake of short-lived radioisotopes of tellurium and iodine (132Te+132I and 133I). Intake of 131I was the major pathway for thyroid exposure, its median contribution to the thyroid dose was 97.4%. The mean prenatal and postnatal thyroid dose from 131I was 87mGy (median = 17mGy), higher than previous deterministic dose of 72mGy (median = 12mGy). For 39 individuals (1.5%) the dose exceeded 1.0Gy, while the highest dose among the cohort members was 2.7Gy. The geometric standard deviation (GSD) of 1000 individual stochastic doses varied from 1.9 to 5.2 with a mean of 3.1 and a median of 3.2. The lowest uncertainty (mean GSD = 2.3, median GSD = 2.2) was found for the subjects whose mothers were measured for 131I thyroid activity, while for individuals, whose mothers were not measured, the mean and median GSDs were 3.4. Uncertainties in thyroid doses were driven by shared errors associated with the parameters of the ecological model.

Restoration of Homeostasis in the Tracheal Mucosa After Thyroid Surgery in a Rat Model.

This study aimed to investigate the process of homeostatic restoration in the tracheal mucosa (TM) after thyroid surgery. Fifty-four rats were divided into normal controls (NC) and three experimental groups: (i) flap elevation (FE), (ii) thyroid exposure (TE), and (iii) thyroid isthmusectomy (TI). Expression of mRNA and proteins of key factors regulating homeostasis were evaluated in the TM obtained 3, 7, and 21 days after thyroid surgery. Increased mRNA expression of transforming growth factor-β1 (TGF-β1), hypoxia-inducible factor-1α (HIF-1α), and matrix metalloproteinase-9 (MMP-9) were observed 21 days after thyroid surgery in all experimental groups compared to that of NC group. Thyroid surgery leads to an actual increase of TGF-β1, HIF-1α, and MMP-9 expression in the TM. This increased expression of key regulators of homeostatic restoration in the TM lasts for a considerable period of time after surgery, especially if the extent of surgery increased.

Development of a new hand-held type thyroid monitor using multiple GAGG detectors for young children following a nuclear accident

One of the most important lessons learned from the Fukushima Daiichi Nuclear Power Plant accident is that direct (in vivo) measurements of thyroid exposure to radioiodine (mainly, 131I) in the affected populations should be initiated in a timely manner. Furthermore, the existing commercial detectors are not necessarily suitable for the measurement of young children, who are especially vulnerable to radiation exposure and therefore important to screen. This paper presents the development of a new thyroid monitor for such measurements and the results from phantom-based experiments. The monitor has two unique probes having multiple high-energy-resolution type Gd3(Al,Ga)5O12(Ce) (GAGG) detectors that can be placed directly on the young subject's anterior neck. The crystal size of the GAGG detector is 1 cm3, and a probe consisting of a 4 × 1 or 4 × 2 detector array can be selected depending on the subject's body size. The thickness of the 4 × 1 array probe is 24 mm, which is less than that for a conventional NaI(Tl) survey meter having a crystal 1 inch in diameter and 1 inch long (38 mm). Experimental and computational calibrations of the new monitor using existing and virtual phantoms allowed us to determine the full energy peak efficiency for the 131I thyroid contents of different age groups from 3-mo-old to 10-yr-old and minimum detectable activity (MDA) values under various conditions. As a result, the attainable MDA for subjects age ≤5 years under a normal background level (∼0.05 μSv h−1) was found to be ∼30 Bq, which was low enough to identify children with thyroid-equivalent doses over 10 mSv up to about 25 days after the 131I intake. Our new monitor would be useful in direct thyroid measurements for vulnerable young children following a large nuclear accident.

Multivariate NTCP Model of Hypothyroidism After Intensity-Modulated Radiotherapy for Nasopharyngeal Carcinoma.

ObjectiveTo evaluate the incidence of hypothyroidism in patients with nasopharyngeal carcinoma after intensity-modulated radiotherapy (IMRT), analyze its correlation with multiple influencing factors such as thyroid exposure dose, thyroid volume, and gender, and construct a multivariate-based normal tissue complication probability (NTCP) model for the occurrence of hypothyroidism after IMRT.Materials and MethodsThe thyroid hormone levels of patients at different points in time before and after radiotherapy were tested, and statistics on the incidence of hypothyroidism after treatment were obtained. The dose-volume data of patients’ thyroids were converted into EQD2 equivalent dose values. The correlation between hypothyroidism after radiotherapy and thyroid exposure dose, thyroid volume, gender, and other factors was analyzed, and an NTCP model was constructed.ResultsA total of 69 patients with nasopharyngeal carcinoma were enrolled in this study. Twelve months after radiotherapy, a total of 24 patients (34.8%) developed hypothyroidism. Univariate analysis and multivariate analysis revealed that the average thyroid dose and thyroid volume are the most important factors affecting hypothyroidism after radiotherapy. The NTCP model constructed based on the average dose and thyroid volume has a good degree of fit.ConclusionThe volume and average dose of the thyroid gland are the key factors affecting the occurrence of hypothyroidism in patients with nasopharyngeal carcinoma after radiotherapy. The NTCP model constructed based on multivariate construction suggests that reducing the average dose of the thyroid to the greatest extent is an effective way to protect thyroid functions.

Dosimetric evaluation in the thyroid region of individuals occupationally exposed during the liberation of the iodotherapy room

Iodotherapy is a complementary treatment to thyroid resection surgery, being performed with radioactive iodine (131I). To do the treatment, the patient must be hospitalized due to the exposure of other people to the ionizing radiation emitted by the radiopharmaceutical. The patients' hospitalization time is dependent on the activity of radioactive material administered and may be from one to two days. After the patient´s discharge from hospital, another one may be hospitalized, however, the room must be monitored by the technical staff in order to verify whether there is radioactive contamination due to the previous patient. Thus, the present study aims to verify the dose received in the staff´s thyroid region during the monitoring of the therapeutic room after discharge, since the thyroid is one of most sensitive to iodine. Two occupationally exposed staffs (called “V1” and “V2”) were monitored using TLDs positioned in the thyroid region. V1 and V2 were monitored for 7 months and 3 months, respectively, because of the workflow of the clinic where the research was performed. With the doses received, during these periods, it was estimated that the annual doses received by V1 and V2 were, respectively, (11.2 ± 5.2) mSv and (12.7 ± 1.0) mSv. These results are below the dose limits established by the ICRP and other international guideline, which reveals that the research clinic is concerned with occupational radiation protection and no other radiological protection actions, based on the thyroid exposure, are necessary.

Limitations in Japanese Public Health Research and Policy: Lessons from Fukushima and Covid-19

Background/AimThe Covid-19 pandemic revealed national differences in public health systems. Japan suppressed PCR tests, did not conduct urban lockdown, and relied on contact tracing. As a result of these unique measures, in early stage, the number of patients and deaths from Covid-19 seemed small, but as of April 30, 2020, they reached 13,929 and 415 cases, respectively, and outbreaks are ongoing. In South Korea, they ware 10,765 and 247, respectively and peak was passed in early March. The purpose of this study is to clarify why the Japanese public health system (including research, policymaking, and implementation) failed to implement Covid-19 measures and to discuss remedial measures.MethodsIn this study, we compare the responses to the Fukushima nuclear disaster and Covid-19 in terms of measurement, information disclosure, policy planning, and risk communication. Since the two cases are currently on-going, a narrative analysis will be conducted using public documents.ResultsIn Fukushima, direct measurement of thyroid exposure was limited to only 1060 children, and PCR testing was also suppressed at Covid-19. Although, in UK and US, forecast of the number of infections and deaths caused by Covid-19 are published with the models used, they are not disclosed in Japan. In both Fukushima and Covid-19, experts such as epidemiologist who appointed to advisory councils of the government, tend to provide advice that is in line with the government's desire to minimize the economic impact, rather than providing scientific advice. Due to diffusion of social media, circulation of false information such as “PCR testing is harmful due to false positives” were more serious in Covid-19 than FukushimaConclusionsIn this study, we clarified common problems in public health in Japan that would be common in Hiroshima, Nagasaki, and Minamata. There is an urgent need to improve the public health system.

Thyroid Doses to French Polynesians Resulting from Atmospheric Nuclear Weapons Tests: Estimates Based on Radiation Measurements and Population Lifestyle Data.

Thyroid doses were estimated for the subjects of a population-based case-control study of thyroid cancer in a population exposed to fallout after atmospheric nuclear weapons tests conducted in French Polynesia between 1966 and 1974. Thyroid doses due to (1) intake of I and of short-lived radioiodine isotopes (I, I, I) and Te, (2) external irradiation from gamma-emitting radionuclides deposited on the ground, and (3) ingestion of long-lived Cs with foodstuffs were reconstructed for each study subject. The dosimetry model that had been used in 2008 in Phase I of the study was substantially improved with (1) results of radiation monitoring of the environment and foodstuffs, which became available in 2013 for public access, and (2) historical data on population lifestyle related to the period of the tests, which were collected in 2016-2017 using focus-group discussions and key informant interviews. The mean thyroid dose among the study subjects was found to be around 5 mGy while the highest dose was estimated to be around 36 mGy. Doses from I intake ranged up to 27 mGy, while those from intake of short-lived iodine isotopes (I, I, I) and Te ranged up to 14 mGy. Thyroid doses from external exposure ranged up to 6 mGy, and those from internal exposure due to Cs ingestion did not exceed 1 mGy. Intake of I was found to be the main pathway for thyroid exposure accounting for 72% of the total dose. Results of this study are being used to evaluate the risk of thyroid cancer among the subjects of the epidemiologic study of thyroid cancer among French Polynesians.

Thyroid disrupting pesticides mancozeb and fipronil in mixture caused oxidative damage and genotoxicity in lymphoid organs of mice

The interference in endocrine signaling in particular of hypothyroid-pituitary-thyroid axis during embryonic/neonatal development increases the risk of long-lasting immune dysfunctioning. Anticipating that, environmentally realistic exposure of established thyroid disrupting pesticides of dithiocarbamate group mancozeb and phenylpyrazole fipronil was given to mice as individual and as mixtures (MIX-I/MIX-II) during the critical initiation phase of the immune response from postnatal day (PND) 31 till PND 60 (maturation phase). The direct exposure effect was assessed at PND 61 and the persistent effect was assessed at PND 91. Pronounced oxidative stress/genotoxicity in lymphoid organs at even low dose mixture exposure of pesticides (MIX-I/ MIX-II) continued to suppress the immune system till adulthood; might be due to the synergistic/additive action. The oxidative stress/genotoxicity effect was prevented on T4 supplementation to inhibit immunotoxicity as T4 is an immune enhancer and antioxidants. Oxidative stress/genotoxicity is suggested as a mechanism of thyroid disruption mediated immune suppression.

Prenatal dioxin exposure and thyroid hormone levels in the Seveso second generation study

BackgroundIn animal studies, perinatal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) alters thyroid homoeostasis and thyroid hormone concentrations; epidemiologic evidence is limited. ObjectivesWe aimed to determine the association of prenatal exposure to TCDD with thyroid hormone concentrations in the Seveso Second Generation Study, a unique cohort of children born to TCDD-exposed women resulting from a 1976 chemical factory explosion in Seveso, Italy. MethodsWe included 570 children (288 female, 282 male) with complete follow-up data, including a fasting blood draw. Serum levels of total and free thyroxine (T4), free triiodothyronine (T3), and thyroid stimulating hormone (TSH) were measured using immunoassays. We defined prenatal TCDD exposure as: 1) maternal initial TCDD concentration measured in serum collected soon after the explosion and 2) maternal TCDD estimated at pregnancy. ResultsCompared to the lowest quartile (Q1), maternal initial serum TCDD was associated with lower free T3 (Q2: adj-β = −0.13, 95%CI -0.26, 0.00; Q3: adj-β = −0.22, 95%CI -0.35, −0.09; Q4: adj-β = −0.14, 95%CI -0.28, 0.00; p-trend = 0.02). In participants with high thyroid antibody status, inverse associations between maternal initial serum TCDD and free T3 were significantly stronger than in participants with normal antibody status (p-interaction = 0.02). We also observed a positive association between maternal initial serum TCDD and TSH concentrations in participants with high thyroid antibody status (Q2: adj-β = 11.4%, 95%CI -25.2, 66.1; Q3: adj-β = 49.0%, 95%CI 3.0, 115.5; Q4: adj-β = 105.5, 95%CI 36.6, 209.2; p-trend < 0.01) but not in those participants with normal antibody status (p-interaction < 0.01). Similar results were found for TCDD estimated at pregnancy. DiscussionOur results suggest prenatal exposure to TCDD, a potent endocrine-disrupting compound, may alter thyroid function later in life. Populations with additional thyroid stress may be particularly susceptible to in utero exposure of thyroid disrupting chemicals.

A new thyroid monitor using multiple high resolution Gd3(Al,Ga)5O12(Ce) detectors for direct thyroid measurements of small children following a nuclear accident

We developed a new thyroid monitor using multiple high energy resolution Gd3(Al,Ga)5O12(Ce) (HR-GAGG) detectors (each crystal size = 1-cm3), in particular with an intention of measuring small children (including infants) for their internal thyroid exposure from radioiodine following a nuclear accident. The small-sized HR-GAGG detectors allowed to be placed around the human neck at the close distance to increase the geometrical efficiency for 131I localized in the thyroid. We tested two arrangements of the eight HR-GAGG detectors using four age-specific phantoms in each of which a thyroid-shaped container filled with standard 131I solution was installed. The results demonstrated that the minimum detectable activity (MDA) of the new monitor reached 20–30 Bq with a counting time of 180 s, which is significantly lower than that of a conventional NaI(Tl) survey meter (crystal size: 1-inch-dia,1-inch-thick) commonly used for measuring air dose rates.

Application of Nanocarbon in Breast Approach Endoscopic Thyroidectomy Thyroid Cancer Surgery.

Objective: This study aimed to investigate the application of nanocarbon in surgical endoscopy in patients with thyroid cancer for the clinical tracing of level VI sentinel lymph nodes (SLNs) and for parathyroid gland protection. Materials and Methods: Ninety-three patients with papillary thyroid carcinoma (PTC) who underwent an endoscopic thyroid cancer operation were included. We randomly divided these patients into a control group (n = 42) and a nanocarbon group (n = 51). For the nanocarbon group, after thyroid exposure, nanocarbon was injected into the thyroid gland, and the SLNs were resected and subjected to frozen sectioning and routine pathological examination. In addition, the postoperative calcium and parathyroid hormone (PTH) levels of both groups were analyzed to compare the features of the nanocarbon application. Results: The number of central lymph (level VI) nodes dissected and the number of metastatic lymph nodes identified were analyzed in both groups. The number of dissected lymph nodes from both unilateral and bilateral thyroid surgeries was significantly larger in the nanocarbon group than in the control group. At the same time, the number of identified metastasis lymph nodes dissected were higher in the nanocarbon group than in the control group. We assessed the postoperative calcium and PTH level to evaluate the parathyroid function. Our results show that the nanocarbon group had a better protective effect on parathyroid function than the control group. Conclusions: As a lymph node trace agent, nanocarbon could better evaluate and permit a more clear lymph dissection for patients with PTC. Nanocarbon contributes to a decrease in the incidence rate of parathyroid damage, which has great clinical value.