Comparison of dose from radiological examination for scoliosis in children among two pediatric hospitals by Monte Carlo simulation

The radiation exposures of children undergoing full spine radiography were investigated in two pediatric hospitals in Greece. Entrance surface kerma (Ka,e) was assessed by thermoluminescence dosimetry and patient's effective dose (E) was estimated by Monte Carlo simulation. All required information regarding patient age and sex, the irradiation geometry, the x-ray spectra, and other exposure parameters (tube voltage and current) were registered as well. Values of Ka,e were measured to range from 0.22 mGy to 2.12 mGy, while E was estimated to range from 0.03 mSv to 0.47 mSv. In general, all values were greater in one of the two hospitals, as higher tube currents and exposure times were used in the examinations because of the difference in radiographers' training and practice. Moreover, dose to red bone marrow was found to be between 0.01 to 0.23 mSv and dose to breast ranged between 0.02 and 1.05 mSv depending on the age, projection, and hospital. These values are comparable with literature sources.     

Bone marrow dose estimates from work-related medical x-ray examinations given between 1943 and 1966 for personnel from five U.S. nuclear facilities

Inclusion of dose from work-related medical x-ray examinations with occupational external dose in an epidemiological study may reduce misclassification of exposures and provide more accurate assessment of leukemia risk from occupational exposure to ionizing radiation. In a multi-site leukemia case-control study, annual bone marrow doses due to work-related x-ray examinations given between 1943 and 1966 were estimated for cases and controls employed at five nuclear facilities. Only active bone marrow dose from photofluorographic chest and routine lumbar spine x rays were included. Bone marrow dose assigned for a single exposure ranged from 1.0 to 1.4 mGy. Mean and median cumulative bone marrow doses for each of the five sites from work-related x-ray examinations ranged from 2.0 to 14 mGy and 2.1 to 8.8 mGy, respectively. Results suggest that bone marrow dose from work-related photofluorographic and lumbar spine x-ray examinations given during the time period of this study may be significant compared to occupational bone marrow dose.     

Estimates of embryonic and fetal doses from 239Pu.

Previously reported studies on the transfer of 238Pu from the maternal circulation to the developing embryo and fetus in rats and guinea pigs have provided data for developing dosimetric models. The highest concentrations of 238Pu were measured in the yolk sac. In late gestation, preferential uptake of 238Pu in liver and bone was observed. The data obtained, together with other published information, have been used to estimate in utero doses to hemopoietic tissues, taking account of transfer to the blastocyst/egg cylinder, yolk sac, liver, and bone marrow. From animal data, the concentration ratios relative to maternal liver for these tissues were taken to be 0.1, 2, 0.01, and 0.02, respectively, and were applied to periods of human gestation of 0-2.5 wk, 2.5-6 wk, 6-12 wk, and 12-38 wk, respectively. Doses to fetal tissues from 239Pu were calculated for chronic ingestion by the mother for a total of 1.8 kBq 239Pu during the year of pregnancy, giving a committed effective dose to the mother of 1 mSv. On this basis, the total in utero dose to hemopoietic tissue was about 2 microSv compared with red bone marrow doses of 34 microSv to the mother for the year. The yolk sac and bone marrow dominated in utero doses. The total dose to hemopoietic tissue in the offspring to age 70 y, taking into account the activity present at birth and including in utero doses, was estimated as 24 microSv compared with a maternal dose to red bone marrow of 2.5 mSv. An acute maternal intake of 1.8 kBq by ingestion during the period of yolk sac hemopoiesis would result in the highest in utero dose, estimated at about 36 microSv. However, activity at birth would be lower, giving only a small additional dose.     

Medical x-ray exposure doses as contaminants of atomic bomb doses

Since 1967 at the times of their biennial ABCC/RERF radiological examinations, all Adult Health Study (AHS) subjects have been interviewed to determine the exposures to medical x-rays they experienced in institutions other than RERF in order to estimate the numbers of examinations and corresponding doses which they received. These data have been stored on computer tapes together with the doses these subjects received during their radiological examinations in the ABCC/RERF Department of Radiology. Thus, their medical x-ray doses are available along with their atomic bomb doses (tentative 1965 doses revised, T65DR) for assessment of the role of ionizing radiation in the development of diseases. The medical x-ray doses incurred at RERF were assessed by means of phantom dosimetry. Those at other institutions were determined using phantom dosimetry data and results of surveys for trends in radiological examinations in Hiroshima and Nagasaki. By the end of 1982, the average medical x-ray doses to the active bone marrow were 12.04 mGy for A-bomb exposed groups and 8.92 mGy for control groups (not-in-cities); to the male gonads, 2.26 mGy and 1.89 mGy, respectively; and to the female gonads, 17.45 mGy and 12.58 mGy, respectively. Results for Hiroshima and Nagasaki were similar. The main impact of medical x-ray doses was in the lowest T65DR group. Medical x-ray active bone marrow doses ranged from 0.05-500% (mean, 35%) of A-bomb doses in the 10-99 mGy T65DR group. In the 100-999 mGy T65DR group, medical x-ray active bone marrow doses ranged from 0.005-50% (mean, 5%) of their T65DR. In the greater than 1,000-mGy T65DR group, medical x-ray exposures were proportionally less. Female active bone marrow and gonad doses were similar in magnitude to the male active bone marrow doses. Medical x-ray exposures produced smaller doses to the gonads of males than to those of the females. The use of medical x-rays is steadily increasing. Careful consideration of doses from medical sources is essential for reliable assessments of the effects from exposures to the atomic bombs.     

Individual doses for women undergoing screening mammography examinations in Poland in 2007

Exposure doses to women undergoing screening mammography examinations should be kept as low as reasonably achievable, but they should ensure high enough image quality for adequate diagnosis. The aim of this study was to estimate the radiation risk according to the 'European guidelines for quality assurance in breast cancer screening and diagnosis', fourth edition (European Commission 2006). Materials for this study were obtained from data from 250 screening mammography facilities in Poland. For every mammography facility, a standard average glandular dose for routine exposure was calculated. Furthermore, average glandular doses for individual mammography examinations obtained according to the methods proposed by Dance et al (2000 Phys. Med. Biol. 45 3225-40) were calculated. The average glandular doses determined for 250 mammography facilities ranged from 0.12 to 14.56 mGy (the mean values ranged from 0.62 to 4.53 mGy). Only for 39 mammography facilities were all exposures found to be below the acceptable level for an average glandular dose, and for only 18 mammography facilities did no exposures exceed the achievable levels for an average glandular dose. Average glandular doses to women undergoing mammography screening attained unnecessary high values, and they were found to depend on the technical parameters of the mammography equipment and maintenance of mammography units by personnel in various mammography facilities.     

The effects of dialysis on 131I kinetics and dosimetry in thyroid cancer patients--a pharmacokinetic model

Currently, an accepted post-surgical treatment of patients with thyroid carcinoma is administration of an ablative dose of I. This treatment is well established based on extensive experience and modeling. However, for patients with renal disease, reduced iodine removal rates result in controversial thyroid doses and potentially excessive red bone marrow doses. There are differences of opinion regarding I dose recommendations ranging from a reduction in dose to an increase in dose compared with conventional amounts. Determination of suitable doses must take into account varying dialysis protocols and absorbed dose considerations to the thyroid and sensitive tissues such as red bone marrow. The specific aim of this study was to develop a simple yet comprehensive compartmental model for I kinetics in patients with thyroid carcinoma and end stage renal disease, which accounts for dialysis and provides absorbed dose estimates for the thyroid as well as the red bone marrow. STELLA, a compartmental modeling software program, was used to develop a kinetic model that includes the blood pool, thyroid, gastrointestinal tract, kidneys, bladder, and a conventional dialysis machine. Benchmarking was performed to demonstrate the validity of the model with data obtained from ICRP 30 and MIRD Dose Estimate Report No. 5. Iodine kinetics were simulated for normal patients, thyroid cancer patients, and patients with thyroid cancer and renal failure undergoing two standard types of dialysis, hemodialysis and continuous ambulatory peritoneal dialysis (CAPD). Results in this work show that thyroid doses to patients with thyroid cancer and renal failure on hemodialysis or CAPD are slightly higher than doses to patients with thyroid cancer and normal renal function. These results further indicate that red bone marrow doses to patients with thyroid cancer and renal failure on dialysis can be significantly higher than red bone marrow doses to patients with thyroid cancer and normal renal function, and thus these patients could benefit from a reduction in administered activity. Thyroid doses and red bone marrow doses to patients on standard hemodialysis depend on both dialysis frequency and the time interval between administration and first dialysis. The results in this study provide guidelines on how much activity a patient on dialysis should receive based on thyroid and red bone marrow absorbed dose (Gy MBq) considerations. This study should help to clarify some of the contradictory recommendations regarding I dose for thyroid carcinoma patients with renal failure.     

Estimating active bone marrow dose from occupational exposure to uranium at a former gaseous diffusion plant

Active bone marrow absorbed doses were estimated for 581 workers as part of a nested case-control study of multiple myeloma mortality at the Oak Ridge Gaseous Diffusion Plant (K-25). Uranium urinalysis results obtained by fluorometric and gross alpha measurements were available for about 20% of the 581 study subjects. These data were used to determine intakes of uranium as a result of occupational exposure during operation of the K-25 facility. Uranium solubility was inferred from the observed urinary excretion rate, job titles, and department codes. Data suggest that most study subjects were exposed to uranyl fluoride, a relatively soluble uranium compound. The median cumulative bone marrow dose determined for subjects with bioassay data was 0.06 mGy with a geometric standard deviation of 4.48. Subjects without bioassay data were assigned cumulative bone marrow dose based upon job titles and department codes.     

福建省育龄妇女X线透环受照量水平的调查

本文应用国产氟化锂热释光剂量计调查本省924例或环妇女常规透视检查的局部体表X线照射量。并采用有关资料计算了性腺剂量和骨髓剂量。获得一次透环的平均皮肤剂量为3.32毫戈瑞;性腺剂量为0.166毫戈瑞;骨髓剂量为0.23毫戈瑞。并应用危险度对X线透环可能产生的随机性效应的危害进行了卫生评价。     

Reconstruction of individual radiation doses for a case-control study of thyroid cancer in French Polynesia

Forty-one atmospheric nuclear weapons tests (plus five safety tests) were conducted in French Polynesia between 1966 and 1974. To evaluate the potential role of atmospheric nuclear weapons testing on a high incidence of thyroid cancer observed since 1985 in French Polynesia, a population-based case-control study was performed. The study included 602 subjects, either cases or controls, all aged less than 40 y at the end of nuclear weapons testing in 1974. Radiation doses to the thyroids of the study subjects were assessed based on the available historical results of radiation measurements. These were mainly found in the annual reports on the radiological situation in French Polynesia that had been sent to the UNSCEAR Secretariat. For each atmospheric nuclear weapons test that contributed substantially to the local deposition of radionuclides, the radiation dose to the thyroid from I intake was estimated. In addition, thyroid doses from the intake of short-lived radioiodines (132I, 133I, 135I) and 132Te, external exposure from gamma-emitted radionuclides deposited on the ground, and ingestion of long-lived Cs were reconstructed. The mean thyroid dose among the study subjects was found to be around 3 mGy while the highest dose was estimated to be around 40 mGy. Doses from short-lived iodine and tellurium isotopes ranged up to 10 mGy. Thyroid doses from external exposure ranged up to 3 mGy, while those from internal exposure due to cesium ingestion did not exceed 1 mGy. The dose estimates that have been obtained are based on a rather limited number of radiation measurements performed on a limited number of islands and are highly uncertain. A thorough compilation of the results of all radiation monitoring that was performed in French Polynesia in 1966-1974 would be likely to greatly improve the reliability and the precision of the dose estimates.     

Age-dependent dose assessment of 226Ra from bottled water intake

Water may present a source of prolonged exposure to naturally occurring radionuclides. One of the most frequently occurring radionuclides in natural mineral and spring waters is 226Ra and its decay products. The contribution of drinking water to the total exposure is very small, at about 5% of the average effective dose attributable annually to natural background radiation, but that exposure contributes to the risk of adverse health consequences. In this study the mean values of 226Ra concentration determined in natural mineral and spring bottled waters range from 6 to 412 mBq L(-1), which is in accord with Croatian legislation. 226Ra effective doses per year from spring water consumption range up to 86 microSv, while 226Ra effective doses per year from mineral water consumption show much higher values. The highest 226Ra effective doses per year from mineral waters consumption, which are up to seven times higher than the dose recommended by WHO (100 microSv), were found in infants and teens. Based on this study, drinking of certain brands of bottled mineral water is not recommended for these age groups because assessed 226Ra effective doses per year exceed the recommended limits. From other research it is known that testosterone appears in elevated concentration during these life periods and affects bone calcification. Therefore, testosterone could affect the retention of 226Ra into the bone. To make more precise conclusions further research is necessary. Adults and especially elderly people are much less susceptible to the presence of 226Ra. According to the results obtained in this study, 226Ra effective doses per year assessed for these age groups were considerably lower (i.e., 10 microSv).     

Radium-226 dose to a boy from playing on mill tailings

Two boys born in September 1949 played on uranium mill tailings from about ages 8 to 12. One of these boys was diagnosed as having leukemia at age 15.5. The 226Ra body burden of the survivor was measured at age 38. The whole-body 226Ra content measured by counting in vivo was 0 +/- 17 Bq and independently by Rn breath analysis as 4.3 +/- 2.1 Bq. At the same time, a control subject with no known exposure to 226Ra, matched in age, height, and weight, was also measured. The whole-body content was estimated as 4 +/- 15 Bq and independently by Rn breath analysis as 5.5 +/- 3.7 Bq. The body burden of the control subject was not significantly different from that of the exposed person. The radiation dose to the marrow-free skeleton assuming a constant 226Ra:Ca ratio since birth was 0.49 and 1.33 mGy at ages 14 and 38, respectively. The radiation dose to the marrow-free skeleton assuming 226Ra intake only between ages 8 to 12 was 1.4 and 2.8 mGy at ages 14 and 38, respectively. The best estimate is the mean of these two estimates: 0.9 and 2.1 mGy at ages 14 and 38, respectively. The alpha-particle dose to the red marrow from 226Ra and its decay products was 0.05 mGy at age 14 and 0.10 mGy at age 38. Since no excess was found for the radium dial painters whose doses were much higher, the induction of leukemia by doses of this magnitude would seem quite unlikely.     

Mammography in New Zealand: radiation dose and image quality.

The mean glandular doses to the breast, image quality and machine performance have been determined for all mammographic x-ray facilities in New Zealand, during 1988-89. For 30 mm and 45 mm phantoms the mean doses per film were 1.03 +/- 0.56 mGy and 1.97 +/- 1.06 mGy. These doses are within international guide-lines. Image quality (detection of simulated microcalcifications, and contrast-detail performance) was found to depend on focal spot size/FFD combination, breast thickness, and film processing. The best machines could resolve 0.2 mm aluminium oxide specks with the contact technique. The use of a grid improved image quality as did magnification. Extended cycle film processing reduced doses, but the claimed improvement in image quality was not apparent from our data. The machine calibration parameters kVp, HVL and timer accuracy were in general within accepted tolerances. Automatic exposure controls in some cases gave poor control of film density with changing breast thickness.     

The performance of a NERO 8000 non-invasive x-ray beam analyser when measuring tube voltage under fluoroscopic conditions

A NERO 8000 non-invasive x-ray beam analyser was examined under fluoroscopic conditions with respect to the measurement of tube voltage. An invasive measurement of tube voltage was performed concurrently to test the accuracy of the NERO device over a range of tube voltages and currents. The data indicated that for the NERO 8000 the accuracy of kVp average measurement is dependent on input doserate. With the tube current set to 1 mA the doserates ranged from 2.1 to 6.5 mGy/min over the range of tube voltages measured. The associated kVp average measurement errors ranged from 6 to 28%. At 5 mA the doserates ranged from 20.4 to 66.0 mGy/min and the associated errors ranged from 0 to 3%. A possible explanation for the drop in accuracy of kVp measurements at low doserates is a decreased signal to noise ratio. The kV waveforms from inaccurate measurements appeared noisier than waveforms from more accurate measurements. NERO may be interpreting noise spikes as voltage readings and including them in the kVp average calculations, causing an erroneously high kVp average reading. The data from this experiment suggest that when performing non-invasive measurements of tube voltage accuracy in fluoroscopy mode, the doserate must be taken into consideration.     

The low-dose ionizing radiation stimulates cell proliferation via activation of the MAPK/ERK pathway in rat cultured mesenchymal stem cells

Hormesis induced by low-dose ionizing radiation (LDIR) is often mirrored by its stimulation of cell proliferation. The mitogen-activated protein kinases (MAPK)/ extracellular-signal- regulated kinases (ERK) pathway is known to play important roles in cell growth. Therefore, this study was to examine the effects of LDIR on rat mesenchymal stem cell (MSC) proliferation and MAPK/ERK signaling pathway. Rat MSCs were isolated from the bone marrow from 6 to 8-week-old male Wistar rats and cultured in vitro. Exponentially growing cells within 4-5 passages were irradiated with low doses of X-rays at 20, 50, 75 and 100 mGy with a dose rate of 100 mGy/min. Cell proliferation was evaluated by counting total viable cell number with trypan-blue staining and MTT assay. Cell cycle changes were also evaluated by flow cytometry and the activation of MAPK/ERK signaling pathway was assayed by Western blotting. Results showed that LDIR at 50 and 75 mGy significantly stimulated the proliferation of rat MSCs with the most stimulating effect at 75 mGy. There was a significant increase in the proportion of S phase cells in MSCs in response to 75 mGy X-rays. Activation of several members in the MAPK/ERK signaling pathway, including c-Raf, MEK and ERK were observed in the cells exposed to 75 mGy X-rays. To define the role of ERK activation in LDIR-stimulated cell proliferation, LDIR-treated MSCs were pre-incubated with MEK specific inhibitor U0126, which completely abolished LDIR-increased phosphorylation of ERK and cell proliferation. These results suggest that LDIR stimulates MSC proliferations in the in vitro condition via the activation of MAPK/ERK pathway.     

锰对小鼠骨髓细胞微核率的影响

为研究锰对小鼠骨髓微核率的影响 ,给小鼠腹腔注射二价锰 (Mn2 + ,MnCl2 ) ,剂量分别为 0、2 5、5 0和 10 0mg kgBW ,然后计数胸骨骨髓 10 0 0个嗜多染红细胞中的微核细胞数。结果表明 ,在中、高浓度组 ,小鼠骨髓微核率分别为 1 2 0 %和 1 6 4% ,明显高于阴性对照组 (P <0 0 1)。低浓度组与阴性对照组比无显著性差异 ,但有增高趋势 ,提示Mn2 + 浓度越高 ,对小鼠骨髓嗜多染红细胞毒性作用越强 ,可以认为MnCl2 具有致染色体突变性及潜在的遗传毒性。     

Occupational radiation doses to operators performing cardiac catheterization procedures

Cardiac catheterization procedures using fluoroscopy reduce patient morbidity and mortality compared to operative procedures. These diagnostic and therapeutic procedures require radiation exposure to patients and physicians. The objectives of the present investigation were to provide a systematic comprehensive summary of the reported radiation doses received by operators due to diagnostic or interventional fluoroscopically-guided procedures, to identify the primary factors influencing operator radiation dose, and to evaluate whether there have been temporal changes in the radiation doses received by operators performing these procedures. Using PubMed, we identified all English-language journal articles and other published data reporting radiation exposures to operators from diagnostic or interventional fluoroscopically-guided cardiovascular procedures from the early 1970's through the present. We abstracted the reported radiation doses, dose measurement methods, fluoroscopy system used, operational features, radiation protection features, and other relevant data. We calculated effective doses to operators in each study to facilitate comparisons. The effective doses ranged from 0.02-38.0 microSv for DC (diagnostic catheterizations), 0.17-31.2 microSv for PCI (percutaneous coronary interventions), 0.24-9.6 microSv for ablations, and 0.29-17.4 microSv for pacemaker or intracardiac defibrillator implantations. The ratios of doses between various anatomic sites and the thyroid, measured over protective shields, were 0.9 +/- 1.0 for the eye, 1.0 +/- 1.5 for the trunk, and 1.3 +/- 2.0 for the hand. Generally, radiation dose is higher on the left side of an operator's body, because the operator's left side is closer to the primary beam when standing at the patient's right side. Modest operator dose reductions over time were observed for DC and ablation, primarily due to reduction in patient doses due to decreased fluoroscopy/cineradiography time and dose rate by technology improvement. Doses were not reduced over time for PCI. The increased complexity of medical procedures appears to have offset dose reductions due to improvements in technology. The large variation in operator doses observed for the same type of procedure suggests that optimizing procedure protocols and implementing general use of the most effective types of protective devices and shields may reduce occupational radiation doses to operators. We had considerable difficulty in comparing reported dosimetry results because of significant differences in dosimetric methods used in each study and multiple factors influencing the actual doses received. Better standardization of dosimetric methods will facilitate future analyses aimed at determining how well medical radiation workers are being protected.     

平板探测器血管造影机冠脉造影患者吸收剂量研究

目的了解平板探测器心血管造影机在冠脉造影时患者吸收剂量。方法应用INNOVA 2000全数字平板探测器心血管造影机,和常规机器(Advantx LCV)比较冠脉造影患者吸收剂量。结果INNOVA 2000的平均吸收剂量是1145mGy,而Advantx LCV为2140mGy。与Advantx LCV比较,INNOVA 2000的剂量在Lowmode减少了76%,Normal mode是52%;即使考虑到INNOVA 2000是方形增强器而Advantx LCV是圆形增强器的不同及其他方面的差异,INNOVA 2000仍具有降低剂量的优点。结论INNOVA 2000平板探测器心血管造影机具有量子检出效率高,患者的照射剂量降低等优点。     

Measurement of entrance skin dose and estimation of organ dose during pediatric chest radiography

Entrance skin dose (ESD) was measured to calculate the organ doses from the anteroposterior (AP) and posteroanterior (PA) chest x-ray projections for pediatric patients in an Indian hospital. High sensitivity tissue-equivalent thermoluminescent dosimeters (TLD, LiF: Mg, Cu, P chips) were used for measuring entrance skin dose. The respective organ doses were calculated using the Monte Carlo method (MCNP 3.1) to simulate the examination set-up and a three-dimensional mathematical phantom for representing an average 5-y-old Indian child. Using this method, conversion coefficients were derived for translating the measured ESD to organ doses. The average measured ESDs for the chest AP and PA projections were 0.305 mGy and 0.171 mGy, respectively. The average calculated organ doses in the AP and the PA projections were 0.196 and 0.086 mSv for the thyroid, 0.167 and 0.045 mSv for the trachea, 0.078 and 0.043 mSv for the lungs, 0.110 and 0.013 mSv for the liver, 0.002 and 0.016 mSv for the bone marrow, 0.024 and 0.002 mSv for the kidneys, and 0.109 and 0.023 mSv for the heart, respectively. The ESD and organ doses can be reduced significantly with the proper radiological technique. According to these results, the chest PA projection should be preferred over the AP projection in pediatric patients. The estimated organ doses for the chest AP and PA projections can be used for the estimation of the associated risk.     

Low dose radiation increased the therapeutic efficacy of cyclophosphamide on S(180) sarcoma bearing mice

We examined whether low dose radiation (LDR) exposure (75 mGy) could increase the therapeutic efficacy of cyclophosphamide (CTX) by comparing the effects of tumor suppression, tumor cell apoptosis, cell cycle and proliferation of bone marrow in vivo. Kunming mice implanted with S(180) sarcoma cells were given 75 mGy whole body gamma-ray radiation exposure and CTX (300 mg/kg) by intraperitoneal injection 36 hours after LDR. Proliferation of bone marrow and tumor cells was analyzed by flow cytometry. Cytochrome c leakage from the tumor was measured by Western-blot. We discovered that tumor growth was significantly reduced in the group exposed to CTX add to LDR. The apoptosis of tumor cells increased significantly after LDR. The tumor cells were arrested in G(1) phase in the groups treated with CTX and CTX + LDR, but cell cycle was more significantly arrested in mice exposed to LDR followed by CTX than in mice exposed only to LDR or CTX chemotherapy. Concentration of bone marrow cells and proliferation index in CTX + LDR mice were higher than those in the untreated mice. LDR or CTX + LDR could induce greater cytochrome c levels and caspase-3 activity in tumors. These results suggest that low dose radiation can enhance the anti-tumor effect of the chemotherapy agent CTX markedly. Furthermore, LDR significantly protects hematopoetic function of the bone marrow, which is of practical significance on adjuvant chemotherapy.     

Measurements of occupational exposure for a technologist performing 18F FDG PET scans

Radiation doses to one PET technologist performing 100 18F FDG (18F fluorodeoxyglucose) imaging procedures were measured in a clinical setting using two types of thermoluminescent dosimeter (TLD) badges, one finger-ring TLD and one electronic pocket dosimeter (EPD). 18F FDG was handled either with unshielded or with viewing window tungsten shielded syringes. The resulting doses using unshielded syringes were 13.8 +/- 0.8 microSv/370 MBq and 14.3 +/- 0.4 microSv/370 MBq, measured with TLD 100 and with TLD 700H/600H, respectively. For the same series of measurements, the doses obtained using shielded syringes were 10.7 +/- 0.4 microSv/370 MBq and 7.2 +/- 2.1 microSv/370 MBq with TLD700H/600H and with EPD, respectively. The dose to the right hand from shielded syringes was 69.3 +/- 5.5 microSv/370 MBq. All these values are within the ICRP recommended dose limits. Extrapolated to 725 examinations per year, the resulting effective dose measured with TLD would be 10 mSv with unshielded and 7.5 mSv with shielded syringes, respectively (25% dose reduction). The doses measured by TLD were consistently higher than those measured by EPD, suggesting that EPD measurements might underestimate occupational doses.