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Once the plan was completed medications ending in zole generic strattera 40mg online, the coordinates of the individual target points were determined spa hair treatment generic strattera 10 mg mastercard, and the gel was moved to the Gammaknife irradiation unit medications not to take with grapefruit buy cheap strattera 18 mg. Treatments were delivered to each of the target points symptoms 6 week pregnancy buy generic strattera 10 mg on-line, in accordance with the treatment plan. Dosimetric imaging of the flask and test tubes containing gel was performed between 25 and 36 h after irradiation. The flask was placed in the head coil of the imager and the test tubes irradiated for calibration purposes were placed around the flask. The images were transferred via network to a Macintosh computer, and the DoseMap program was used to compute the maps of transverse relaxation rate (R2). A glass rod was inserted into the gel to provide a target around which to localize the dose distribution. Images of the gel-filled test tubes were obtained, and R2 determined as a function of dose. The calibration curve was then applied to R2 maps of the flask irradiated with the Gammaknife unit. As all scans were performed with the head ring and localizer box in place, the coordinates of the image plane could be determined. These image planes were located 1 mm from each of the corresponding treatment plans shown in. Finally, isodose curves were drawn (by the DoseMap program) by interpolating within the measured dose distribution. The measured dose distributions were compared with the treatment plans prepared prior to irradiation by superimposing the two data sets. The calculated and measured dose distributions were registered by aligning the point representing the tip of the glass rod. The measured dose distributions compare favorably with the calculated dose distributions. Composite figures showing both the treatment plan prepared using a Gammaplan treatment planning computer (drawn in black, labeled in percent of maximum dose) and isodose curves measured by the technique described in the text (drawn in gray, labeled in Gy). The dose distribution is clearly visible, demonstrating the change in optical density with dose. The dose images were obtained in planes that were shifted 1 mm from the planes of dose calculation, and this shift might account partially for the difference in size and shape of the isodose curves. Instead, it appears more likely that the dose distribution was placed $ 1 mm further from the glass target rod than intended. In recent years, fractionated stereotactic radiation therapy has been seen as a desirable method of delivering high dose radiation therapy to malignancies of the brain. Techniques developed for immobilizing the patient have also been applied more recently to intensity-modulated radiation therapy, in which conformal dose distributions are delivered through multiple fractions to one or more target volumes. In both techniques, reproducible positioning of the patient is critical, to ensure that the target volume receives the intended dose, and normal tissues are spared to the extent determined by treatment planning techniques. The phantom design revision included converting the existing imaging/dosimetry insert from a block-style design to a cylindrical design. Both the imaging insert and the gel insert had an image registration system incorporated into their construction. An anthropomorphic head-and-neck phantom developed by the Radiological Physics Center (170) showing the modifications made to accommodate a gel dosimeter. The preirradiation images were subtracted from the postirradiation images using a pixel-by-pixel subtraction method. A comparison of the calculated dose distribution and the measured distribution is shown in. However, the results also showed that the techniques used to calibrate the gel (irradiation of a similar gel container with small-diameter beams delivering doses spanning the expected range) did not provide absolute dose measurements offering better agreement than 10% with the calculated data. Determining dose distributions and confirming the results of planning for brachytherapy treatment is historically difficult. No suitable methods of dosimetry have existed in the past to enable measurement and display of these 3D and complex distributions. These methods are quite unsatisfactory for anything other than distributions around single sources, or very simple source arrangements. It is necessary to immerse the applicator containing the sources into the gel, or arrange for its introduction into a catheter already placed in the gel. Isodose lines, determined from the dose map data, are superimposed on the intensity map. Points at which the dose was computed by the treatment planning system also are shown. Excellent agreement between the position of the calculated dose points and the corresponding measured isodose lines indicates the agreement between doses measured by the gel and computed by the treatment planning system. Polymerization of the gel causes an increase in the gel density and a corresponding decrease in the volume filled by the gel. The change in density causes shrinkage of the gel in the vicinity of the source, distorting the resulting measured distribution. Changes to the composition of the gel to increase the concentration of gelatin Figure 19. Studies have indicated that the diffusion of monomers (or ferrous and ferric ions in Fricke gels) across steep dose gradients can introduce errors in measurement (92,189). Data show that a polymer gel dosimeter under responds to radiation in the 2060 keV range (190). Changes in mass attenuation coefficient of polymer gels during irradiation can also introduce errors in the dose distributions measured around low energy sources. Internal Dosimetry Gel dosimetry has shown promise in the determination of dose distributions from administrations of unsealed radioactive sources (192). The authors embedded a vial of 131I into a flask of polymer gel and observed a distancedependent change in the T2 signal. They also mixed 131I into the gel and demonstrated a change in T2 signal that was dependent on distance from the concentration of activity. Measurement of Neutron Dose Distributions Some developments have been reported in characterizing fast and epithermal neutron beams with gel dosimetry (193195). Thin layers of Fricke-xylenol orange gels have been irradiated in phantoms composed of insensitive gel. Adding 10B or other nuclides with large cross-sections has increased the sensitivity of the gel dosimeter to neutrons. This technique has been used to determine the profiles of neutron beams used for boron neutron capture therapy. Some benefits of the use of gel dosimetry are the tissueequivalence of the dosimeter to these energies, and the ability to separate the components of dose. Measurement of Particle Dose Distributions Several investigators have demonstrated the use of polymer gel dosimeters to record the dose distributions produced by proton beams (88,137,196198). However, several authors have noticed disagreements between measurements with gels and conventional dosimeters such as diodes in the peak region of the distribution. Also shown is the depth dose curve for the proton beam (dotted curve), normalized to 100% at the Bragg peak. As the distance between the radicals formed in the gel decreases, the likelihood of recombination of radicals increases. Consequently, significant differences appear between depth dose measurements with gels and those with detectors such as diodes (see. Their conclusion also was that the high density of deltaray interactions close to the track of a proton resulted in high doses being delivered to the gel. This effect was greater near the end of the proton range, consistent with the results of other authors. Gels have been used also to demonstrate the dose distribution produced by 12C ions (200). Evaluation of Tissue Heterogeneities A valuable feature of gel dosimeters is that they are very nearly tissue-equivalent, particularly at photon beam energies above $ 100 kV. However, several investigators have attempted to measure the effects of nonunit density tissues on external beam dose distributions. Early measurements were performed to estimate the dose distribution behind high atomic number heterogeneities, to simulate the presence of bone (201 204).
Diseases
However symptoms of pneumonia buy strattera 40mg without prescription, while soft tissue sarcomas have a multitude of histologic subtypes subject to a variety of grading classification schemes chi infra treatment cheap 10 mg strattera mastercard, bone sarcomas have just three distinct categories: chondrosarcoma medicine used to treat chlamydia generic strattera 40 mg on-line, Ewing sarcoma medicine pills order strattera 40mg overnight delivery, and osteosarcoma. While soft tissue sarcomas are rare in young individuals and occur with increasing frequency as the middle to late decades progress, bone sarcomas, for the most part, are more common in children and young adults, with some exceptions in later years. While the gold standard of treatment for soft tissue sarcomas remains surgery and radiation therapy, with chemotherapy reserved for tumors that are deep, high grade, and large, the management of bone sarcomas varies considerably, according to histology, grade, and stage. Finally, all high-grade sarcomas, whether of bone or soft tissue, share an overall survival rate on the order of 55% to 70%. Nonetheless, even the most general reader would err in not seeking a broader fund of knowledge and a higher level of understanding of bone sarcomas, as the hopeful and instructive paradigms offered herein can be of benefit to all oncologic patients, across practice strata. This chapter therefore seeks to be a primer on the diagnosis, staging, treatment, and surveillance of sarcomas of bone, with information ranging from basic principles to detailed descriptions of complex algorithms. After reviewing incidence, etiology, anatomy, pathology, screening, diagnosis, and staging of bone sarcomas, management will be discussed by treatment modality, with attention to stage. Ewing sarcoma, the prototypical high-grade sarcoma presumed to be potentially metastatic at presentation, will be explored first, in terms of the historically agreed-upon gold standards of chemotherapy and radiation therapy. Next, high-grade conventional osteosarcoma will be discussed with regards to universally accepted chemotherapeutic concepts, and occasionally useful radiotherapy options. Surgery for low-grade chondrosarcoma and osteosarcoma lesions will then be undertaken. Limb salvage and amputation approaches for high-grade chondrosarcoma, osteosarcoma, and Ewing sarcoma lesions will be described together, as the local control decision-making process for these three categories is similar. Finally, continuing care in terms of bone sarcoma surveillance and palliation will be considered. This represents an incidence of <1 in 100,000 persons living in the United States per year. The true incidence of some bone malignancies, such as chondrosarcoma, is not well established, as low-grade lesions are relatively common, and no accurate registries exist. For high-grade osteosarcoma and Ewing sarcoma, the incidence is thought to be on the order of one per million. Another way of illustrating the rarity of these tumors is to consider that bone sarcomas, which result in the third leading cause of cancer death in young individuals, are projected to result in as few as 166 deaths in those <20 years of age in 2014. For example, ionizing radiation, either therapeutic or inadvertent, is thought to be responsible for approximately 3% of cases of bone sarcoma. Osteochondromas, whether solitary or in the multiple, autosomal dominant form, are associated with chondrosarcomas that are predominantly low to intermediate grade32; on a population level, the incidence of malignant change was estimated to be on the order of 0. Osteosarcomas are more prevalent in the appendicular skeleton, with the most prevalent sites being in the distal femur (32%), proximal tibia (15%), proximal humerus (8%), and proximal femur (5%). By contrast, Ewing sarcoma favors the axial skeleton, with the pelvis/sacrum (22%), proximal femur (10%), shoulder girdle (12%), and ribs (8%) being the most common locations, followed by the long bones and sacrum. A t h a 9 r9 i - n U Some primary bone malignancies manifest in characteristic anatomic locations. Extraskeletal osteosarcoma is a rare neoplasm that has a median survival of 46 months for patients with localized disease. Although the soft tissue component of many high-grade sarcomas of bone have a characteristic whitish, firm, "fish flesh" appearance, gross findings can run the gamut from heavily ossified areas to myxoid, friable, or frankly necrotic regions, even within the same specimen. As most high-grade bone sarcomas are >5 cm and associated with a soft tissue mass that is extracompartmental to bone, the tumor classification according to the Enneking system50,51 is most often "T2b. The prototypical bone sarcoma, a conventional high-grade osteosarcoma, consists, in most basic terms, of a spindle V d the i B figure 91. A high-grade chondrosarcoma will have a spindle cell component admixed with malignant cartilaginous matrix. From a pathologic standpoint, the World Health Organization recognizes >25 different types of primary bone malignancies. However, a number of syndromic conditions that predispose to the development of primary bone malignancies are known (Table 91. Many of the implicated genetic diseases, such as Rothmund-Thomson and Werner syndromes, are exceedingly rare, and no clear algorithms exist for cancer screening. The same is true for more commonly encountered conditions that predispose to bone cancer, such as Li-Fraumeni syndrome, for which a recent workshop concluded, "further tests are needed to test screening protocols. Plain radiographs of bones that are moderately to severely affected should be obtained yearly. In all circumstances, care should be taken to limit radiation exposure with screening tests. However, as an individual ages, sarcoma risk increases, and so routine surveillance surveys should be offered, especially for deep-seated locations such as the pelvis and shoulder girdle, where most sarcomas in these conditions will become manifest. But once concern for the possibility of a bone sarcoma has been raised, further diagnostic tests, many of which are of a specialized nature and involve radiation exposure, should be deferred, and the patient should be immediately referred to a multidisciplinary center skilled in sarcoma management. The nature of the discomfort, in terms of its intensity, frequency, duration, pattern, localization, and aggravating/alleviating factors must be carefully assessed. The patient should be questioned regarding associated symptoms such as numbness, tingling, weakness, stiffness, instability, and gait abnormalities. Documentation of the characteristics of a mass, if present, must be obtained with respect to time course, growth pattern, and presence of localized erythema, warmth, and tenderness. Systemic findings such as fever, sweats, chills, weight loss, and fatigue need to be queried. A past personal and/or family medical history of conditions that predispose to bone malignancies must be explored. Knowledge gained regarding history can direct further evaluation away from or toward nonneoplastic, pseudotumorous, aggressive, metabolic, or secondary conditions that can mimic primary bone malignancies, such as osteomyelitis, eosinophilic granuloma, giant cell tumor of bone, osteoblastoma, metastatic disease, or Paget disease. Physical Examination Although it may not narrow the differential list considerably, a thorough physical examination remains an essential part of the diagnostic pathway for sarcomas of bone. Cafй-au-lait spots can signal the presence of fibrous dysplasia; the integrity of the E A B t C h a 9 r9 i - n U V d the i G R D F G figure 91. The size, location, mobility, and consistency of any mass, if present, should be carefully described. Orthopedic parameters, including limb length, active and passive ranges of motion, joint stability, and gait pattern, need to be reviewed. Diagnostic Studies Though neither highly sensitive nor specific, laboratory testing should not be neglected in the evaluation of patients suspected of having a sarcoma of bone. A complete blood count, erythrocyte sedimentation rate, and C-reactive protein level can be helpful in ruling out infection. Alkaline phosphatase and lactic dehydrogenase are sometimes elevated in skeletal sarcomas; creatinine and calcium levels are also useful chemistry tests. Serum and urine immunoelectrophoretic analyses can assist in excluding myeloma, and a basic urinalysis can be used to screen for genitourinary health. Radiologic imaging represents the bulk of diagnostic studies for aggressive bone conditions. Plain roentgenograms include orthogonal views of the primary skeletal site and two views of chest as an initial assessment of metastatic pulmonary disease. A bone scan aids in determination of primary site activity, and the presence or absence of polyostotic or metastatic disease. In the case of suspected primary bone malignancy, supreme caution must be taken with respect to the manner in which the biopsy is undertaken. Excisional (resection) biopsy can be considered for smaller lesions that can be completely excised with negative margins and without undue functional compromise; an atypical or low-grade chondrosarcoma arising in an osteochondroma is an example of this type of biopsy procedure. Whenever an open biopsy procedure is chosen, careful attention must be paid to incisional length (short) and placement (in line with the definitive resection procedure), dissection planes (through rather than between muscular planes), and avoidance of neurovascular exposure, bleeding, and infection. The risk of diagnostic errors and complications increases by as much as 12-fold when the biopsy is improperly done. While local control measures (surgery and/or radiotherapy) are critical to the treatment of patients with Ewing sarcoma, systemic therapy is equally critical to attaining cure. These results definitively established the importance of doxorubicin in the management of Ewing sarcoma, but also demonstrated that whole lung radiation may prevent some cases of relapse even in the absence of documented lung metastasis. In addition, they identified large tumor size and poor histologic necrosis to neoadjuvant chemotherapy as potential adverse prognostic factors in this setting. Nevertheless, these results suggested that more frequent chemotherapy cycles were beneficial and/or that more protracted cyclophosphamide exposure was beneficial. In the intensive schedule, patients received higher doses of doxorubicin and cyclophosphamide given in cycles administered every 3 weeks. In the protracted schedule, patients received lower doses of these agents and exposure of the cyclophosphamide was distributed across 6 sequential weeks. This design resulted in significantly greater early doxorubicin exposure in the intensive arm as well as a slightly higher cumulative doxorubicin exposure in that arm.
Most neonates whose mothers have autoimmune thrombocytopenia do not have platelet counts below 30 treatment of bronchitis strattera 25 mg fast delivery,000 or 40 medicine zithromax discount 25 mg strattera with mastercard,000/L treatment receding gums generic strattera 40 mg visa. However symptoms pancreatitis order strattera 40mg without prescription, the platelet counts in most syndromes with dysmorphia rarely have platelet counts this low, generally not below 40,000/L. On average the donor platelets will decay after transfusion with a half-life of between 1 and 2 days. Platelet transfusion in the neonatal intensive care unit: benefits, risks, alternatives. Pooling donors results in more donor exposures, and the volume reduction needed after pooling reduces platelet viability. Reference ranges are shown for blood neutrophil counts during the first 3 days after birth. The dark-gray scale indicates the reference range for counts obtained from neonates near sea-level (identified as Manroe). The black dots represent 14 healthy term neonates in Utah who would have been termed "neutrophilic" according to the Manroe chart but were seen to be well within the high-altitude reference ranges. The infant is small for gestational age with asymmetric growth retardation; birth weight is below 5th percentile, length is at the 20th percentile, and the occipital-frontal circumference falls at the 40th percentile. It is important to consider that the hypotension, metabolic acidosis, and respiratory distress accompanying the neutropenia and left shift are manifestations of sepsis. Which of the following steps would be appropriate for evaluating the neutropenia in this neonate? Although this could be one of the subtypes of severe congenital neutropenia, those are extremely rare. Given that the patient is not ill and has no left shift, this is not the neutropenia of overwhelming sepsis. The antibodies bind to fetal neutrophils, which express an antigen inherited from the father that is absent in the mother. One such outstanding laboratory is the American Red Cross North Central Blood Services in St. These mutations each produce a gene product that folds into an incorrect three-dimensional shape. The abnormal neutrophil elastase protein accumulates in neutrophils and damages or kills these cells before they are fully mature. Expected values, also called reference ranges, for eosinophil counts on the day of birth are a function of gestational age, increasing gradually through the second and third trimesters. Reference ranges are shown for eosinophil counts of neonates on the day of birth, according to gestational age. If the eosinophil count of the neonate discussed in Questions 39 and 40 were 3500/L, the term eosinophilia would properly apply. What are the more common conditions that might be associated with such a high eosinophil count in this neonate? Eosinophils are effector cells involved in allergic and nonallergic inflammatory conditions. Circulating eosinophils are derived from myelocytic progenitors within the marrow and within extramedullary sites as well. Several pathologic conditions in neonates are associated with eosinophilic tissue infiltration, and these conditions are often accompanied by blood eosinophilia. The conditions include erythema toxicum, neonatal eosinophilic pustulosis, and bronchopulmonary dysplasia. Other inflammatory conditions associated with eosinophilia are neonatal eosinophilic esophagitis, eosinophilic colitis, subcutaneous fat necrosis with eosinophilic granules, a variety of infectious diseases, and necrotizing enterocolitis after erythrocyte transfusion. A slight increase can occasionally be expected in preterm infants corresponding to the time weight gain is established. Reference ranges are shown for eosinophil counts of neonates for the first 28 days after birth. You are asked to see a healthy term female newborn shortly after birth because the mother has von Willebrand disease. Only type 3, a very rare autosomal recessive variety completely lacking von Willebrand factor antigen and activity, is likely to result in excessive bleeding in infants. You are asked to see a healthy term female newborn shortly after birth because the mother has the factor V Leiden mutation. The parents want to discuss with you the possibility that the child might also have this condition. However, neonates with a single copy of the factor V Leiden mutation (heterozygote) appear to be at no increased risk for neonatal thrombosis. Thrombotic risks similar to that of the affected parent will be present during adolescence and adult life. The human prothrombin (F2) gene is located at 11p11-q12, and the 20210 mutation is a single nucleotide substitution. However, in the very rare instance when both father and mother have the prothrombin 20210 mutation, the fetus can be homozygous for this mutation. Such neonates have been reported to have a significant risk of neonatal thrombosis. The parents of this boy are wise to determine whether their son has hemophilia before a circumcision is done. However, if parents of such a neonate insist that a circumcision is performed, the Centers for Disease Control and Prevention recommend that a pediatric hematologist be consulted before the procedure to ensure that the child receives proper treatment to prevent excessive bleeding. Many neonates with mild or moderate hemophilia have been circumcised with little or no abnormal bleeding, but it is unwise to proceed with circumcision given this family history without first making a diagnosis and without involving a hematologist. It is helpful for parents who are planning to deliver a son with a risk of hemophilia (based on the family history) to inform you before the delivery. The presence of Barts Hgb on a Hgb electrophoresis (a gamma chain tetramer) is indicative of alpha-thalassemia trait. Subgaleal hemorrhages can result hypovolemia and shock, whereas cephalohematomas will not. The only reliable treatment for disseminated intravascular coagulation is to reverse the triggers. The innate immune system comprises cells and mechanisms that defend in a nonspecific manner. Th2 inflammatory responses are favored in the fetus, dampening the fetal immune response and preventing alloimmune reactions between mother and fetus. The nonspecific innate immune system includes host defense mechanisms that operate effectively without prior exposure. It includes the following: n Physical barriers; intact skin and mucosal membranes n Mononuclear inflammatory cells; particularly mast cells and tissue macrophages n Soluble plasma proteins; such as cytokines and complement components Nussbaum C, Sperandio M. The lipids and acid pH of the neonatal skin inhibit microbial growth and reach maturity by week 2 to 4 in term neonates (later in premature infants). Small breaks in the integrity of the skin can serve as entry points for infection. Overall activity and components of the alternative pathway are more consistently decreased than those of the classical pathway. All major lineages of the hematopoietic cells that are part of the immune system are present in the fetus by the beginning of the second trimester. Monocytes undergo tissue-specific differentation into mononuclear macrophages, which utilize a respiratory burst (biosynthesis of O2- and H2O2) to kill organisms. By week 12 of gestation, lymphocytes obtained from the human thymus respond to mitogens and foreign histocompatibility antigens. Furthermore, fetal cells stimulated with alloantigens exhibit normal antigen-specific cytotoxicity. The rate of proliferation of neuthrophil precursors in the human neonate seems to be near maximal, and therefore their capacity to increase numbers in response to infection might be limited. As a result, rather than develop neutrophilia, as might occur in the septic adult, the neonate will rapidly develop neutropenia as a result of exhaustion or depletion of the storage pools. Educational paper: defects in number and function of neutrophilic granulocytes causing primary immunodeficiency. The IgG content of the fetus and the newborn infant is mainly maternal in origin and is predominantly transferred during the latter third of pregnancy.
In order to evaluate the precision of the correction medicine university cheap strattera 25 mg, at least 10 determinations should be made medicine quotes order strattera 18 mg without prescription. Then the computer can control the gamma detector and the gamma spectra can be acquired and analyzed by computer software medicine 524 cheap strattera 10 mg online. Critical physical parameters such as starting time treatment gout discount 18 mg strattera with amex, duration, and dead-time of the acquisition are recorded together with the spectral data. Many g-spectrum analysis programs have been developed to analyze gamma spectra, which can search for g peaks, calculate their energies, and their peak areas. The energy of a gamma peak can be identified by calibration of the counting system by measurement of some known gamma-ray sources. By comparison with a database of gamma-energy and half-life of radionuclides, the identification of the nuclides can be carried out. Many techniques have been developed to calculate the peak area and to subtract the baseline under the peak, such as Gaussian shape and experimental peak shape fitting. When the peak area and the efficiency of the detector are measured, the activity of the nuclide can be calculated easily by correcting for decay and counting time. If the comparator method is used, the contents of elements of interest can then be calculated using Eq. This means that it is possible to predict the standard deviation of analytical results so well that the observed and expected variation among replicate data are in agreement. Hardly any certification of trace elements is carried out without considering this method. The insensitivity to contamination has proven particularly valuable for the establishment of a normal concentration of a number of elements in human samples. The uncertainty of irradiation is contributed from the variation of neutron flux during irradiation and inhomogeneous distribution of neutron flux in the irradiation container. The instability of neutron flux may significantly influence the analytical results of elements determined by measuring short-lived radioisotopes, because the sample and standard are not irradiated simultaneously. The neutron flux gradient is sometimes very significant in a big irradiation container, so that a flux monitor foil of Fe, Co, or Au alloy may be used to monitor the different positions to make a neutron flux correction. The uncertainty due to counting geometry can be controlled reliably by well efficiency calibration of the detector for various source shapes; software is available for appropriate calculation. The matrix effects can suppress gamma rays, especially low energy gamma rays, by self-absorption; this effect can be calibrated by measurement of a standard with a similar matrix with sample. Uncertainty in the spectra acquisition may come from dead time and pile-up losses of signals. Dead time is normally measured by the gamma spectra system, and live time is used for activity calculation. But when the dead time is quickly changed during counting, the activity may be underestimated by this method. This problem can be solved by using a loss-free counting method, which estimates the number of counts lost during a dead time interval and adds this number to the channel of the just processed pulse, thus presenting a loss-corrected spectrum. The pile-up losses are corrected by electronic or computational mean built in the counting system. Uncertainty in the spectra analysis results mainly from the evaluation of peak area and subtraction of baseline, especially for the analysis of multipeaks. A large attempt has been made to develop effective software to improve the analysis of the gamma spectra. But a blank correction will be necessary, when preseparation and sample preparation are used before irradiation. A typical example of such interference is the formation of 28Al from Al, P, and Si by reactions: 27Al(n, g)28Al, 28Si(n, p)28Al, and 31P(n, a)28Al. In biomedical materials, the concentrations of Al and Si are very low, but P is high in many kinds of samples. The contribution of P to the activity of 28Al may be very significant, especially when the fraction of fast neutron in the irradiation position is high, it will seriously interfere with the determination of aluminum. This interference can be significantly reduced by using a thermal neutron irradiation channel, where the ratio of thermal/fast neutron flux is very high; in many research reactors, such a thermal neutron channel is available. The correction can be carried out by the irradiation of the sample with and without thermal neutron shielding. Double and triple neutron activation reactions can also result in an interference, for example, the interference from 197Au(2n, g)199Au to the determination of Pt by 199 Pt(n,g)199Pt(bА)199Au reaction, and from 127I(3n, g)130I to the determination of 129I by 129(n, g)130I reaction (29). But, interference from triple reactions is normally negligible due to their very low probability. A special type of nuclear reaction interference is caused by the presence of uranium, which yields a large number of radionuclides as a result of fission. Gamma-ray spectral interference means that two radionuclides emit gamma rays with the same or nearly the same energy. For these nuclides, a separation via decay is possible practically due to their different half-lives. This problem can be resolved by measurement of 75Se by other gamma lines and correcting the contribution of 75 Se to the peak of 279. Especially at very low concentration, the trace elements distribution in samples is normally inhomogeneous and a selection of a representative sample is very important for analytical quality. In this case, a whole sample is analyzed and the uncertainty resulting from the inhomogeneity of elements in the sample can be overcome. The distribution and normal level of trace elements in blood, urine, and human tissue are basic data for the studies on biomedical trace elements. In combination with the analysis of diets and environmental samples, some trace element related endemic disorders have been investigated, such as Keshan disease found in China, which is related to the deficient intake of selenium, and normally also associated with the deficiency of iodine. The results were used as a basis for improved recommendations of safe and adequate, daily average intake of these elements. Determination of specific trace elements in a small amount of living tissue can be used to diagnose disease and to evaluate the treatment. A high environmental exposure may cause the increase of some nonessential trace elements in the human body, which may create a potential effect for human health. In recent years, rare earth elements found wide application in industry and agriculture, rare earth trace element fertilizer has widely been used in China for increasing the yield of various agricultural products. Neutron activation analysis was used to investigate the uptake of these elements in the human body via the food chain, their distribution in human tissues, and their combination with different components of tissue, especially brain tissue (7,13). Neutron activation analysis is very suitable for the analysis of hair and nails, because no decomposition of sample is necessary, therefore they are often used for the analysis of these materials for investigation of the nutrition status of trace elements, the environmental exposure level of toxic elements, and the diagnosis of various diseases related to trace elements (9). A series international conference entitled Nuclear Analytical Methods in the Life Sciences was held since 1967, and the three most recent conferences in this series were held in 1993, 1998, and 2002. The main achievements in this field can be found in the Proceedings of these conferences (35,36) and other relevant conferences (37,38). Recommendation data for use in the k(0) standardization of neutron activation analysis. Further studies in advance prediction of gamma ray spectra and detection limits in instrumental neutron activation analysis. Technical consideration for sampling and sample preparation of biomedical samples for trace element analysis. Distribution of aluminum species in normal urine as determined by chemical neutron activation analysis. Study of chemical speciation of trace elements by molecular activation analysis and other nuclear techniques. Study of chromium-containing proteins in subcellular fractions of rat liver by enriched stable isotopic tracer technique and gel filtration chromatography. Epithermal neutron activation analysis and its application in the miniature neutron source reactor. Neutron flux micro-distribution and self-shielding measurement in the Syrian Miniature Neutron Source Reactor. Hatsukawa Y, Toh Y, Oshima M, Hayakawa T, Shinohara N, Kushita K, Ueno T, Toyoda K. New technique for the determination of trace elements using multiparameter coincidence spectrometry. Fast decomposition of biological and environmental samples for radiochemical neutron activation analysis, Abstract of 11th International Conference on Modern Trends in Activation Analysis. Simultaneous radiochemical neutron activation analysis of iodine, uranium and mercury in biological and environmental samples. Selective removal of radio-sodium from neutron activated materials by retention on hydrated antimony pentoxide. Simultaneous determination of arsenic, manganese and selenium in biological materials by neutron activation analysis.
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