Specific absorbed fractions (SAFs) have been calculated as a function of the content in the urinary bladder in order to allow more realistic calculations of the absorbed dose to the bladder wall. The ...SAFs were calculated using the urinary bladder anatomy from the ICRP male and female adult reference computational phantoms. The urinary bladder and its content were approximated by a sphere with a wall of constant mass, where the thickness of the wall depended on the amount of urine in the bladder. SAFs were calculated for males and females with 17 different urinary bladder volumes from 10 to 800 mL, using the Monte Carlo computer program MCNP5, at 25 energies of mono-energetic photons and electrons ranging from 10 KeV to 10 MeV. The decay was assumed to be homogeneously distributed in the urinary bladder content and the urinary bladder wall, and the mean absorbed dose to the urinary bladder wall was calculated. The Monte Carlo simulations were validated against measurements made with thermoluminescent dosimeters. The SAFs obtained for a urine volume of 200 mL were compared to the values calculated for the urinary bladder wall using the adult reference computational phantoms. The mean absorbed dose to the urinary wall from (18)F-FDG was found to be 77 µGy/MBq formales and 86 µGy/MBq for females, while for (99m)Tc-DTPA the mean absorbed doses were 80 µGy/MBq for males and 86 µGy/MBq for females. Compared to calculations using a constant value of the SAF from the adult reference computational phantoms, the mean absorbed doses to the bladder wall were 60% higher for (18)F-FDG and 30% higher for (99m)Tc-DTPA using the new SAFs.
Activity concentration of natural radionuclides in surface water and sediment from a waterfall site, Erin-Oke, Osun, Nigeria, has been determined by gamma spectrometry. The mean activity ...concentration of
40
K,
226
Ra, and
232
Th were estimated to be 61.015 ± 15.50, 8.165 ± 2.05 and 5.24 ± 1.57 Bq/l, respectively in water samples and 172.023 ± 35.433, 19.282 ± 4.95, and 17.089 ± 4.37 Bq/kg respectively in sediment samples. Total annual effective dose ingested by an individual ranges from 10.73 ± 3.36 to 15.18 ± 4.44 mSv/y, 2.50 ± 0.80 to 3.58 ± 0.96 mSv/y, and 2.30 ± 0.72 to 3.23 ± 0.93 mSv/y, with mean values of 13.25 ± 3.89, 3.10 ± 0.90, and 2.83 ± 0.83 mSv/y for infants, children, and adults, respectively. These values are greater than International Commission on Radiological Protection (ICRP) and the World Health Organization's recommended limit of 1.0 and 0.1 msv/y, respectively. Mean activity concentrations in sediment are 172.023 ± 35.433, 19.823 ± 4.95, and 17.089 ± 4.37 Bq/kg for
40
K,
226
Ra, and
232
Th, respectively, with mean absorbed dose of 26.91 nGyh
−1
. This value is lesser than UNSCEAR world average value of 55 nGyh
−1
. Health hazard index and radium equivalent for sediments showed lower values than absorbable limits.
We present a study on the radioactivity of selected Croatian agricultural soils that vary considerably with respect to geological background; physical, chemical, and biological characteristics; soil ...type; land use; and soil management. Our investigation is focused on the main naturally occurring radionuclides (
40
K,
238
U,
226
Ra,
232
Th,
235
U) and
137
Cs as the most threatening long-lived anthropogenic radionuclide. We find that the radioactivity level is not influenced by the application of different soil amendments, at least in moderate quantities, and that no effect of soil management can be detected as well. In contrast, geological and location-specific properties influence radionuclide content in soil, especially regarding the naturally occurring ones. Moreover, physical and chemical soil properties such as texture and soil adsorption complex, respectively, seem to be the main factors regarding fixation of
137
Cs in soil. Calculated dose rates for external exposure to the gamma radiation originating from soil have been found to be generally low, except for two locations where they are higher but not at a level that would lead to health problems for workers on the field.
Western Serbia is a region well-known for potato production. Concentrations of selected metals, polycyclic aromatic hydrocarbons (PAHs) and radioactivity were measured in the soil in order to ...evaluate the quality and characteristics. The examined soils (Luvisol and Pseudogley) showed unsuitable agrochemical characteristics (acid reaction, low content of organic matter and potassium). Some samples contained Ni, Mn and Cr above the maximal permissible concentration (MPC). The average concentration of total PAHs was 1.92
mg/kg, which is larger than the maximal permissible concentration in Serbia but below the threshold values in the European Union for food production. The average radioactivity of
238U,
226Ra,
232Th,
40K and the fission product
137Cs were 60.4
±
26.2, 33.2
±
13.4, 49.1
±
18.5, 379
±
108 and 36.4
±
23.3
Bq/kg. Enhanced radioactivity in the soils was found. The total absorbed dose rate in air above the soil at 1
m height calculated for western Serbia was 73.4
nGy/h and the annual effective dose was 90
μSv, which are similar to earlier reports for the study region.
Radon is a globally present and known radioactive gas with its ability to cause lung cancer as its major health implication. Ghana currently lacks national policies on radon gas and substantive radon ...vulnerability map largely due to lack of adequate baseline radon concentration data for the entire country. LR115 type II detectors were deployed in 30 sites/homes within the South-Dayi District. The detectors were retrieved after specified periods and analyzed for the radon concentration at the Nuclear Track Detection Laboratory of the Ghana Atomic Energy Commission. From the results, indoor radon concentration was found to range from 11.60 to 111.07 Bq/m3 with the mean value for the district being 34.90 ± 20.18 Bq/m3, a value lower than the mean global indoor concentration of 40 Bq/m3. The values of 0.44 mS/yr, 8.80 mSv/yr and 1.01 mSv/yr were the mean annual; absorbed dose, equivalent dose and effective dose to lungs respectively for the populace of the district. The mean soil radon concentration for the district was 1.76 ± 0.91 kBq/m3 with values ranging from 0.38 to 3.93 kBq/m3. Correlation and T-test analysis was performed to establish strength of the linear relationship between indoor radon concentration and the soil radon concentration, indoor radon concentration on altitude and soil radon concentration on altitude.
In the Panasqueira mine area of central Portugal, some environmental media show higher metal(loid) concentrations when compared with the local geochemical background and the values proposed in the ...literature for these environmental media. In order to evaluate the effect of the external contamination on selected indexes of internal dose, As, Cd, Cu, Cr, Fe, Hg, Mg, Mn, Mo, Ni, Pb, S, Se, Si, and Zn were quantified by inductively coupled plasma mass spectrometry and inductively coupled plasma optical emission spectrometry in blood, urine, hair and nail samples from individuals environmentally (N = 41) and occupationally exposed (N = 41). A matched control group (N = 40) was also studied, and data from the three groups were compared. Results obtained agreed with those reported by environmental studies performed in this area, pointing to populations living nearby and working in the mine being exposed to metal(loid)s originated from mining activities. Arsenic was the element with the highest increase in exposed populations. The concentration of other elements such as Cr, Mg, Mn, Mo, Ni, Pb, S, Se, and Zn was also increased, although at a lesser extent, specifically in the individuals environmentally exposed and in females. These findings confirm the need for competent authorities to act as soon as possible in this area and implement strategies aimed to protect exposed populations and the entire ecosystem.
Radionuclide therapy is the use of radioactive drugs for internal radiotherapy, mainly for the treatment of metastatic disease. As opposed to systemic cancer therapies in general, the use of ...radioactively labeled drugs results not only in a targeted therapy but also the possibility of imaging the distribution of the drug during therapy. From such images, the absorbed doses delivered to tumors and organs at risk can be calculated. Calculation of the absorbed dose from 3-D images such as single-photon emission computed tomography (SPECT)/CT, and in some cases positron emission tomography (PET)/CT, relies on image-based activity quantification. Quantification is accomplished by modeling the physics involved in the image-formation process, and applying image-processing methods. From a time-sequence of such quantitative images, the absorbed doses are then calculated. Although individual-patient dosimetry is a standard component of other forms of radiotherapy, it is still overlooked in the majority of radionuclide therapies. In this review, we summarize the physical and technical problems that need to be addressed in image-based dosimetry. The focus is on SPECT, since most of the radionuclides used are single-photon emitters, although the use of PET is also discussed. Practical issues of relevance for the practical implementation of personalized dosimetry in radionuclide therapy are also highlighted.
The radiation absorbed dose to blood and organs from activity in the blood is relevant for nuclear medicine dosimetry and for research in biodosimetry. The present study provides coefficients for the ...average absorbed dose rates to the blood from blood-borne activity for radionuclides frequently used in targeted radiotherapy and in PET diagnostics. The results were deduced from published data for vessel radius-dependent dose rate coefficients and reasonable assumptions on the blood-volume distribution as a function of the vessel radius. Different parts of the circulatory system were analyzed separately. Vessel size information for heart chambers, aorta, vena cava, pulmonary artery, and capillaries was taken from published results of morphometric measurements. The remaining blood not contained in the mentioned vessels was assumed to reside in fractal-like vascular trees, the smallest branches of which are the arterioles or venules. The applied vessel size distribution is consistent with recommendations of the ICRP on the blood-volume distribution in the human. The resulting average absorbed dose rates to the blood per nuclear disintegration per milliliter (ml) of blood are (in 10(-11) Gy·s(-1)·Bq(-1)·ml) Y-90: 5.58, I-131: 2.49, Lu-177: 1.72, Sm-153: 2.97, Tc-99m: 0.366, C-11: 4.56, F-18: 3.61, Ga-68: 5.94, I-124: 2.55. Photon radiation contributes 1.1-1.2·10(-11) Gy·s(-1)·Bq(-1)·ml to the total dose rate for positron emitters but significantly less for the other nuclides. Blood self-absorption of the energy emitted by ß-particles in the whole blood ranges from 37% for Y-90 to 80% for Tc-99m. The correspondent values in vascular trees, which are important for the absorbed dose to organs, range from 30% for Y-90 to 82% for Tc-99m.
Measurements of ambient gamma radiation dose and radioactivity of soil and rocks samples have been carried out in 103 sites located in the region of Marrah mountain (western Sudan) using survey ...meters and gamma spectrometry techniques, respectively. The ambient dose varied from 0.05 to 0.25 µSv/h with mean value of 0.18 ± 0.05 (SD) µSv/h. At high altitudes (> 1500 m), relatively high values were observed (0.18–0.22 µSv/h). The levels of
238
U,
232
Th and
40
K in soil–rocks were in the ranges 12–80, 12–66 and 120–937 Bq/kg with mean ± SD of (41 ± 6.9), (24 ± 12) and (540 ± 99) Bq/kg, respectively, equivalent to total gamma absorbed dose of 23–142 (66 ± 20) nGy/h. The ambient dose data were presented in cartography format, and correlation to geological maps was attempted. Surface map of the absorbed dose created using geostatistical kriging tools showed the spatial distribution of dose. Analyses showed that trends of high values were located in and around areas characterized by local flow and basaltic flow lithology, while the low values were observed at locations of basement rocks (granitic) in general. That was attributed to the differences in environmental conditions in various altitude and weathering processes. The highest readings (0.25 µSv/h and 142 nGy/h) were found in Deriba Complex Pumice air-fall deposits (younger explosive phase). Health risk was assessed by calculating annual effective dose for the inhabitants resulted in values range between 0.14 and 1.4 mSv/y (mean ± SD of 0.40 ± 0.12 mSv/y). The observed values of dose rates are comparable with some countries but higher than the worldwide average for outdoor annual affective dose of 0.07 mSv/y.
This study presents a summary of the dosimetry calculations performed for three technetium agents most commonly used in nuclear medicine diagnostic studies, namely sestamibi™, phosphonates and ...pertechnetate, labeled with cyclotron-produced technetium. Calculated patient doses were compared to those that would be delivered by the same radiotracers labeled with technetium obtained from a generator produced in a reactor. The main difference is that technetium from a generator is pure, i.e. contains only (99m)Tc and its decay product (99g)Tc, while in a cyclotron a large number of other stable and radioactive isotopes are created. In our calculations only technetium radioisotopes (ground and isomeric states) were considered as they will be included in the radiotracer labeling process and will contribute to the patient dose. Other elements should be removed by chemical purification. These dose estimates are based on our theoretical calculations of the proton-induced reaction cross sections and radioisotope production yields. Thick targets of enriched (three different compositions) and natural molybdenum, and three initial beam energies (16, 19 and 24 MeV) were considered for irradiation times of 3, 6 and 12 h with a beam current of 200 µA. The doses were calculated for injection times corresponding to 0, 2, 8, 12 and 24 h after the end of beam.
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