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A kappa value that equals 0 indicates that the observed agreement is equal to the chance agreement lady era 100 mg cheap. For data with three or more possible responses or for ordered categorical data buy 100mg lady era free shipping, weighted kappa should be used so that the responses that are further away from concordance are more heavily weighted than those close to concordance purchase cheap lady era on line. The assumptions for Cohen’s kappa are that partic- ipants or items to be rated are independent lady era 100mg online, and also that the raters and categories are independent. Kappa values are influenced by the prevalence of the condition or disease being rated which is demonstrated in the research question below. With two observers rating a binary variable or a questionnaire administered on two occasions, the null hypothesis is that the kappa value equals zero (two-tailed). The questions were administered on two occasions to the same 50 peo- ple at an interval of 3 weeks. Null hypothesis: The proportion in agreement is no greater than that expected by chance (i. Variables: Questions (nominal) and time (ordinal) It is important to establish how reliable questions are because questions that are prone to a significant amount of random error or bias do not make good outcome or explana- tory variables. This command sequence can then be repeated to obtain the following tables and statis- tics for questions 2 and 3 of the questionnaire. From the Crosstabulation table for question 1, the per cent in agreement is estimated from the per cent who are concordant, which is shown on the diagonal of the table in the No at Time 1-No at Time 2 and Yes at Time 1-Yes at Time 2 cells. The Symmetric Measures table Tests of reliability and agreement 319 shows that the P value of 0. Since the level of significance is two-tailed, the P value does not indicate whether the agreement is worse or better than chance. However, agreement worse than that expected by chance rarely occurs in clinical contexts. It should be noted that the P value is not a good indication of reliability because its interpretation is that the kappa value is significantly different from zero. Measurements taken from the same people on two occasions are closely related by nature and thus 320 Chapter 10 the P value is expected to indicate some degree of agreement. The standard error is also reported and can be used to calculate a confidence interval around kappa. In the Crosstabulation table for question 2, the per cent in agreement is 68% + 10%, which is 78% or 0. Crosstabs Question 2 − Time 1 * Question 2 − Time 2 crosstabulation Question 2 − time 2 No Yes Total Question 2 − time 1 No Count 34 5 39 Percentage of total 68. In the Crosstabulation table for question 3, although the per cent in agreement is 34% + 44%, which is also 78% or 0. With a higher per cent of ‘Yes’ replies (56% for question 3 compared with 22% for question 2), kappa increases from the fair to moderate range. Crosstabs Question 3 − Time 1 * Question 3 − Time 2 crosstabulation Question 3 − time 2 No Yes Total Question 3 − time 1 No Count 17 5 22 Percentage of total 34. Tests of reliability and agreement 321 A feature of kappa is that the value increases as the proportion of ‘No’ and ‘Yes’ responses become more equal and when the proportion in agreement remains the same. This feature is a major barrier to comparing kappa values across measurements or between different studies. For this reason, the value of kappa, the percentage of positive responses and the per cent in agreement must all be reported to help assess reliability and agreement. It is difficult to say which question is the most reliable and has the least non-systematic bias because all three questions have a different percentage of positive responses and therefore the kappa values cannot be compared. However, both questions 2 and 3 have a higher per cent in agreement than question 1. The differences in per- centages of positive responses suggest that the three questions are measuring different entities. A measure is reliable if it produces the same value under all possible situations, that is, with different raters, in different settings and at different times. A measurement that has poor reliability will not be accurate at measuring the construct that it has been designed to measure and will also be unstable over repeated adminis- trations, that is have poor test–retest reliability. Variations in continuous measurements can result from inconsistent measurement practices, from equipment variations or from ways in which results are read or interpreted. These sources can be measured as within-rater (intra-rater) variation, between-rater (inter-rater) variation, or within-participant variation (see Table 10. Variations that result from the ways in which researchers administer, read, or interpret tests are within-rater or between-rater variations. Variations that arise from patient 322 Chapter 10 compliance factors or from biological changes are within-participant variations. To quantify these measurement errors, the same measurement is taken from the same participants on two occasions, or from the same participants by two or more raters, and the results are compared. The remaining 5% of the variance is due to measurement error or the variance within the participants or between the raters. That is, there are different raters and not the same raters are used for all participants. This is the model most frequently encountered in clinical research when the same raters carry out measurements on all of the participants. This is uncommon because the raters usually represent an unlimited number of people who could make the observations. The value for ‘single measures’ statistic is an index of reliability for typical single raters, which is the most common situation in clinical research. The ‘average measures’ statistic is an index of reliability for different raters averaged together for example when the measurements are a mean of the measurements obtained by different raters. Consistency is used when a systematic difference between raters is not of interest. To determine how well a measurement assesses the true value of a participant, the option ‘absolute agreement’ is used. This is a test of reliability that can be used to assess the internal consistency of a scale. This statistic measures whether the items of a tool are measuring the same constructs. Intra-class Correlation Coefficient 95% confidence interval F test with true Value 0 Intra-class correlationb Lower bound Upper bound Value df1 df S ig. In addition, the size of the correlation coefficient value is influenced by the range of the variable. The statistics that are used to assess agreement between measurements are shown in Table 10. To visually examine the data, the weights measured by both nurses could be plotted against each other in a scatter plot. To assess the level of agreement between the two measurements the limits of agreement can be calculated. Then the difference between the two measurements is calculated as a simple subtraction, that is measurement 1 – measurement 2. The subtraction can be in either direction but the direction must be indicated in the summary results and graphs. The size of the error can then be calculated from the standard deviation around the differences, which can be obtained using the Analyze → Descriptive Statistics → Descriptives commands with the ‘differences’ variable entered as the Variable(s). A problem with using the mean of the differences is that large positive difference values and large nega- tive difference values are balanced out by one another and therefore negated. A scatter that is evenly distributed above and below the zero line of no difference indicates that there is no systematic bias between the two raters. A scatter that is largely above or largely below the zero line of no difference or a scatter that increases or decreases with the mean value indicates a systematic bias between raters. A recommendation for the axes of differences-vs-means plots is that the y-axis should be approximately one-third to one-half of the range of the x-axis. The columns for the coordinate data are as follows: Column 3 Column 4 Column 5 Column 6 3. This will show whether the differences are related to the means of the measurements.

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Doxorubicin (Adriamycin order lady era with a visa, Doxil) lady era 100 mg lowest price, daunorubicin (daunomycin lady era 100 mg without a prescription, [Cerubidine]) purchase 100mg lady era mastercard, idarubicin (Idamy- cin), and the analogs of doxorubicin, epirubicin (Ellence), valrubium (Valstar), and mitoxan- trone (Novantrone) a. Daunorubicin and idarubicin are used primarily in the treatment of acute lymphocytic and myelogenous leukemias, often in combination with cytarabine. Structure and mechanism of action (1) Bleomycin is a mixture of copper-chelating glycopeptides produced by Streptomyces verticillus. The most serious adverse effect is a cumulative dose-related pulmonary tox- icity that may be fatal. Acute reactions that can be fatal occur in 1% of patients with lymphoma; this reaction consists of the anaphylac- toid-like reactions of profound hyperthermia, hypotension, and cardiorespiratory collapse. Toxicity of this drug includes diarrhea, which can be severe, and myelosuppression. Cisplatin is a small platinum coordination complex that enters cells by diffusion and active transport. The dose-limiting toxicity of cisplatin is cumulative damage to the renal tubules that may be irreversible following high or repeated doses, but which is routinely prevented by hydration and diuresis of the patient. It is ototoxic, with tinnitus and hearing loss, and it also produces peripheral neuropathy. Procarbazine is a weak monoamine oxidase inhibitor that may cause hypertension, particu- larly in the presence of sympathomimetic agents and food with high tyramine content. Hydroxyurea is primarily used in the management of chronic granulocytic leukemia and other myeloproliferative disorders. L-asparaginase is an enzyme that reduces levels of L-asparaginase, an amino acid not synthe- sized by some tumors, to inhibit protein synthesis and cell division. This agent is synergistic with methotrexate when the folic acid analogue is administered prior to L-asparaginase. L-asparaginase is minimally marrow suppressive; it is toxic to the liver and pancreas. Bortezomib is approved for treatment of multiple myeloma in patients who have received at least two prior courses of therapy. Biologic response modifiers are compounds that influence how an individual responds to the presence of a neoplasm. Interferon alfa-2b (Intron-A) is approved for treatment of hairy cell leukemia, and Kaposi sarcoma. Interleukin-2 (aldesleukin) (Proleukin) is approved for metastatic kidney cancer and melanoma. Thalidomide (Thalomid) and lenalidomide (Revlimid) are tumor necrosis factor modifiers. These agents are used in treatment of brain tumors, Kaposi sarcoma, multiple myeloma, and many noncancerous conditions. Thalidomide’s most common adverse effects are sedation, constipation, and pe- ripheral neuropathy (30%). Lenalidomide is an ana- log of thalidomide with increased potency and an apparent decreased toxicity. Imatinib (Gleevec), Dasatinib (Sprycel) (1) Imatinib and dasatinib are tyrosine kinase inhibitors that are specific for Bcr-Abl onco- protein (dasatinib also inhibits several other kinases). Gefitinib (Iressa) (1) Gefitinib is an inhibitor of epidermal growth factor receptor tyrosine kinase that is over- expressed in many cancers. Erlotinib (Tarceva) (1) Erlotinib is another inhibitor of epidermal growth factor receptor tyrosine kinase. The net effect of this interaction is cell lysis, possibly secondary to antibody-dependent cy- totoxicity or complement cytotoxicity. Expression of this protein is associated with decreased survival due to more aggressive disease. The net effect is the arrest of the cell cycle via antibody-mediated cytotoxicity. Its mechanism of action differs from that of imatinib in that cetuximab actually blocks the receptor. The action of this drug results in inhibition of cancer cell growth and induction of apoptosis. Use of these agents in neoplasia is predicated on the presence of steroid hor- mone receptors in target cells and on the ability of the hormone to stimulate or inhibit cell growth. In the former case, hormonal antagonists are used; in the latter, hormonal agonists. Adrenocorticosteroids have significant systemic effects, and long-term use is not recommended. Mitotane is an oral agent specific for the treatment of inoperable adrenocortical carcinoma. Mitotane inhibits glucocorticoid biosynthesis and selectively causes atrophy of the tumors within zona reticularis and fasciulata by an unknown mechanism. Progestins are useful in the management of endometrial hyperplasia and carcinoma and as second-line therapy for metastatic hormone-dependent breast cancer. Estrogens inhibit the effects of endogenous androgens and androgen-dependent metastatic prostatic carcinoma. Cardiac and cerebrovascular complications and carcinoma of breast, endometrium, and ovary are potential adverse effects. Tamoxifen and toremifene are used in postmenopausal women with or recovering from meta- static breast cancer. Tamoxifen is also used as adjunctive therapy to oophorectomy and to leuprolide or goserelin (see below) in premenopausal women with estrogen receptor-positive tumors. Tamoxifen and raloxifen are used as prophylactic agents in women at high risk for breast cancer. Moderate nausea, vomiting, and hot flashes are the major adverse effects of tamoxifen; endo- metrial cancer and thrombosis are potential adverse effects of long-term therapy. Pure antiestrogens, Fulvestrant (Faslodex) Fulvestrant is a pure anti-estrogen; it has no agonist activity in any tissue. It is approved for use in hormone receptor positive metastatic breast cancer in postmenopausal women with disease pro- gression following antiestrogen therapy H. Gonadotropin-releasing hormone analogues: leuprolide (Lupron), triptorelin (Trelstar), and goser- elin (Zoladex) 1. Use of these agents results in castration levels of testosterone in men and postmenopausal levels of estrogen in women. These agents are effective in prostatic carcinoma and in estrogen-positive breast cancer. Leuprolide and goserelin are often administered with antiandrogen fluta- mide (Eulexin) or bicalutamide (Casodex), which block the translocation of androgen receptors to the nucleus and thereby prevent testosterone action. Aromatase inhibitors: Anastrozole (Arimidex), Letrozole (Femara), Exemestane (Aromasin), Amino- glutethimide (Cytadren) 1. Anastrozole and letrozole are reversible aromatase inhibitors that have no effect on synthesis of steroids other than estrogens. Anas- tozole is approved for use in women who have received 2–3 years of tamoxifen and are switch- ing to anastrazole for a total of 5 years of adjunct therapy. Recent studies have shown that anastrozole offers advantage over tamoxifen in these circumstances. This agent is used for postmenopausal women with breast cancer who have progressed on tamoxifen. Aminoglutethimide inhibits corticosteroid synthesis as well as the enzyme aromatase, which aids in conversion of androstenedione to estrone. This agent is used in treatment of metastatic receptor-positive breast cancer (both estrogen and progestin receptors); it has also been used in prostate cancer. Hydrocortisone has to be administered at the same time to prevent adrenal insufficiency. All of the above agents are thrombolemic but with a reduced incidence compared to tamoxifen. Androgen antagonists: flutamide (Eulexin), bicalutamide (Casodex), nilutamide (Nilandron) 1. Flutamide and bicalutamide are competitive antagonists of the androgen receptor; nilutamide is an irreversible inhibitor of the androgen receptor. These agents are used in combination with either chemical or surgical castration for the treat- ment of prostate cancer. Adverse effects are due to decreased androgen activity and include fatigue, loss of libido, and impotence.

The caries in the upper right molars would be clinically obvious but the early approximal lesions in the lower left molars would not discount 100mg lady era free shipping. Bitewing radiographs not only enable an accurate diagnosis cheap lady era 100mg, but early lesions can be compared on successive radiographs to enable a judgement to made about caries activity and progression buy 100 mg lady era with mastercard. There is often a failure to appreciate that those aspects of care we refer to as prevention are actually a fundamental part of the treatment of dental caries lady era 100 mg lowest price. Repairing the damage caused by dental caries is also important, but this will only be successful if the causes of that damage have been addressed. A structured approach to prevention should form a key part of the management of every preschool child. Key Point • Preventive measures are the cornerstone to the successful treatment of dental caries in children. For children considered to be at low risk of developing caries a toothpaste containing 450-600 p. Toothpastes with a lower fluoride concentration are available, but there is some question about their efficacy. Many authorities now support the prescribing of toothpastes containing higher concentrations of fluoride (around 1000 p. Where higher concentration toothpastes are prescribed for preschool children, parents should be counselled to ensure that brushing is supervised (see Section 7. Key Point • In areas without optimum levels of fluoride in the water supply, fluoride toothpaste is the most important method of delivering fluoride to preschool children. Such supplementation is only maximally effective if given long term and regularly. Unfortunately, studies have shown that long-term compliance with daily fluoride supplement protocols is poor. Parental motivation and regular reinforcement are essential for such measures to be effective. Dosage should follow the protocol advised by the British Society of Paediatric Dentistry (Table 7. No supplements should be prescribed if the water fluoride level is greater than 0. Professionally applied fluorides Site-specific application of fluoride varnish can be valuable in the management of early, smooth surface and approximal carious lesions (Fig. Hence, when using these products in young children great care should be taken to avoid overdosage (see below). Fluoride overdosage A dose of 1 mg of F/kg body weight can be enough to produce symptoms of toxicity and a dose of 5 mg of F/kg is considered to be potentially fatal. Subsequently, depression of plasma calcium levels results in convulsions, and cardiac and respiratory failure. All containers with fluoride tablets should have childproof tops and be kept out of reach of young children. Preschool children need help from their parents if effective oral hygiene is to be maintained, so parental involvement in oral hygiene instruction is essential. Supervision of toothbrushing is also important to avoid overingestion of toothpaste. Hence, reducing the frequency of sugar-containing food and drinks is a key dietary message to deliver to parents. Young children have a high metabolic rate and their dietary calorific requirements are high. Such children often make up the calories missed at meal times by consuming fruit-based drinks between meals, which are high in calories. Parents frequently misinterpret this, and think the child asks for drinks because of thirst. Once established, such cycles of behaviour can be difficult to break and many parents have a sense of guilt that their child has dental decay, feeling that they must have done something wrong. For counselling to be effective it is essential to avoid making the parent feel excessively guilty, but to concentrate on the aetiology of the condition and practical strategies to deal with these problems. Stopping a night-time bottle habit can be achieved quickly by some parents, but can prove difficult for others. Weaning children from a night or daytime bottle of juice can often be achieved by gradually making the juice in the bottle more dilute over a period of a few weeks until the contents become just water. At this point the child will either discard the bottle or will continue to suckle on water alone, which is, of course, non- cariogenic. Where possible, restorative treatment should be carried out under local analgesia alone, but strategies such as sedation, by either the inhalation or oral route, or general anaesthesia are sometimes indicated, especially in young children with extensive disease who are in acute pain, or where a non- pharmacological approach to behaviour management has failed (Chapter 4294H ). Whichever strategy is chosen, it is essential to involve the parent in the decision and to obtain written consent. The fundamental principles of effectively managing child behaviour in the surgery are fully covered in Chapter 2295H. However, there are some specific aspects that relate particularly to very young children. Dentistry for children is complicated by the fact that the dentist must establish a working relationship and communicate effectively with both child and parent. Only one reasonably well-designed study, by Frankl in 1962 (from which came the useful Frankl scale), has ever suggested that parental presence might affect child behaviour. In most of the aforementioned studies, parents were carefully instructed to sit quietly in the surgery and not to interfere with dentist-child communication, so as to avoid the introduction of inconsistent variables. Frankl commented upon this in his concluding comments: the presence of a passively observing mother can be an aid to the child. Certainly having the parent present in the surgery when treating young children facilitates effective communication and helps to fulfil the requirements of informed consent. Having said this, in the absence of any convincing evidence one way or the other, having the parent present during the treatment of preschool children remains a matter of individual choice. Several routes of administration are available and of these, two are generally suitable for outpatient use: inhalation and oral. Inhalation sedation with nitrous oxide and oxygen produces both sedation and analgesia. The technique works most effectively on children who wish to co-operate, but are too anxious to do so. Its use for preschool children is limited to those who are able to tolerate the nasal hood, but where this can be achieved, the technique is often effective. Orally administered sedation has the advantage that, once administered, no further active co-operation of the child is required for the drug to take effect. Over the years, many agents have been advocated for use in dentistry as oral sedative agents, and none of these are ideal. In studies, most of the more popular agents produce a successful outcome in 60-70% of cases. For this reason, some workers, especially in the United States of America, advocate combinations of oral drugs, sometimes supplemented with inhaled nitrous oxide and oxygen, in order to achieve a more reliable result. Of the orally administered sedation agents available, the most useful for preschool children are the chloral derivatives and some of the benzodiazepines. Chloral derivatives Chloral hydrate is a long-standing and effective sedative hypnotic. However, its bitter taste makes it unpleasant to take and it is a potent gastric irritant, producing vomiting in many children. Trichlofos, a derivative of chloral hydrate, causes less gastric irritation, but otherwise appears to produce similar results, although there has been little research to confirm this. Diazepam can be used for oral sedation, but produces prolonged sedation and has proved somewhat unpredictable in young children. Temazepam was popular some years ago, especially as its duration of action is shorter than diazepam. However, idiosyncratic reactions in some children have caused temazepam to fall from favour. Recent studies using midazolam, another short-acting benzodiazepine, have reported good results. Midazolam is easy to take orally and seems to offer safe and reliable sedation, with far fewer idiosyncratic reactions than with temazepam. Onset of sedation is rapid (around 20 minutes) and recovery is also relatively quick. The preparation designed for intravenous administration is used, often mixed into a small volume of a suitable fruit drink.

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Skin should not be abraded by a heavy brush buy lady era 100mg cheap, as this may facilitate internal absorption order online lady era. Radiation Biology the external contamination lady era 100mg low price, the patient must be first managed for the con- dition before decontamination is carried out cheap lady era 100mg with amex. Burns and wounds that are not contaminated should be first covered and then decontamination of the other affected areas carried out. If you are outside and close to the explosion of a dirty bomb, cover the nose and mouth with a mask or cloth to reduce the risk of breathing in radioactive dust or smoke. If possible, immediately go inside the building that is not affected by the explosion and remove the outer layer of cloth- ing and shoes and seal them in a plastic bag, if available. If you are inside and close to the incident that has occurred outside, close all the doors and windows and do not leave the building. Local or federal authorities are likely to monitor the food and water in the area of explosion and inform the public of their suitability for consumption. Verification Card for Radioactive Patients After the September 11, 2001 attack on the World Trade Center in New York, numerous security measures have been adopted by the U. Congress has passed laws to establish the Department of Homeland Security to implement and monitor different aspects of these security measures. Security checks of airline passengers, background scrutiny of many visitors and suspected terrorist groups, and implementa- tion of the Patriot Act are some of the examples of these security actions Radiation Phobia 263 that are currently in place. In view of the concerns over the use of dirty bombs by miscreants, the Homeland Security has established checkpoints at various strategic locations such as airports, tunnels, mass transit, bridges, border crossing points, historical monuments, landmarks, and the like, to monitor the transport of dirty bombs containing radioactivity by using radi- ation detectors. One pitfall of this measure is that patients who received radioactive materials for diagnostic and therapeutic purposes may trigger the monitors while passing through these checkpoints and undergo undue hassle with authorities to provide proof that the radioactivity was really from medical uses. Many hospitals are adopting this policy and instruct the patients to carry the card for the period discussed below. A question arises as to how long the patient who has undergone nuclear studies should carry the card. It depends on the half-life of the radionuclide, types of radiations the radionuclide emits, and the biological elimination of the radiotracer from the body. Zuckier (2004) in a paper presented at The Radiological Society of North America annual meeting in Chicago sug- gested the following periods for different radionuclides for the patients to carry the card. One important factor is the graphic images of the devastating effects of the atomic bombs detonated in Hiroshima and Nagasaki in 1945, and to a lesser extent, the images of the Chernobyl reactor accident in 1986. The most noticeable effects of these incidents are death of living species and destruction of property at the site of the explosion and its immediate vicin- ity. Because of these images, many people associate radiation exposure with adverse health effects and death. These images are firmly embedded in the minds of the public causing perpetual fear of radiation. Another flashpoint in creating radiation phobia in the public’s mind is the knowledge of assumption that any level of ionizing radiation is dan- 264 15. Psychological warfare with anecdotal rhetoric among the rival countries possessing nuclear weapons also creates fear of radiation among the public. Dreading effects of radiation on children and future offspring, and long-term damage to property are major concerns of the public. Furthermore, the media often play a role in exacerbating the problem of exposure from radiation accidents. Def- initely, nuclear detonation causes an instantaneous devastating effect on the population and property, and so can be reason for fear and panic. But the long-term effects of low doses of radiations, even from the fallout of the atomic bombs in Japan and Chernobyl accident, have been shown to be rel- atively small. The average individual lifetime dose from the Chernobyl fallout is estimated to be 0. By comparison, the worldwide average annual dose rate of natural radiation an individual receives on earth is 220mrem (2. In the United States, an individual receives an annual dose of about 300mrem (3mSv) including radon and a lifetime dose of 21rem (210mSv). These values are even ten times higher in some regions in India and Brazil, and yet incidence of excess cancer is not shown to be higher in these places. People face risk of cancer, injuries, and even death from day-to-day living activities, such as driving, smoking cigarettes, drinking alcohol, eating food, and breathing air, in addition to hazardous job-related activities. If the population is exposed to 1rem (10mSv) of radiation exposure, the risk of cancer increases only by 0. Based on these arguments, it can be said that although nuclear explosions can be a cause for grave concern, low-dose radiations from medical facilities, natural back- ground, and the like, are fairly safe relative to the hazards of different living activities, and the risk from such radiation exposure is small. People knowledge- able in radiation should talk to laymen explaining the relatively small risk of low-level radiations compared to many other day-to-day living activities. The media should play an important role in communicating this informa- tion to the public. Radiation experts should hold regular public seminars to explain the minimal risk of low-level radiation. Radiation-related profes- sional organizations such as the Society of Nuclear Medicine, The Radio- logical Society of North America, Health Physics Society, and American Association of Physicists in Medicine should undertake appropriate approaches of communication with the public to shed their concern and fear of radiation. What are the two most common chromosome aberrations that are responsible for carcinogenesis? Elucidate the mechanisms of sublethal damage repair and potentially lethal damage repair. What is the recent value of cancer death attributable to radiation exposure in Japanese survivors of the atomic bomb? What are the different dose-response models preferred for solid tumors and leukemia? What are the recommended steps one should take in the case of the explosion of a dirty bomb? Homeland Security monitors radioactivity for dirty bombs at strategic points of commuting. The patients undergoing nuclear studies are given cards by the hospitals to provide proof of radioactive exam- inations. References and Suggested Readings 267 References and Suggested Readings American Cancer Society. Sensitivity of personal homeland security radiation detectors to medical radionuclides and implications for counseling of nuclear medicine patients. To minimize their risks, international and national organizations have been established to set guide- lines for safe handling of radiations. They make recommendations and guidelines for radiation workers to follow in handling radiations. The regulations pertinent to the practices of nuclear medicine are briefly described here. On the other hand, naturally occurring and accelerator-produced radionuclides are regulated by indi- vidual states. Sources of Radiation Exposure The population at large receives radiation exposure from various sources such as natural radioactivity, medical procedures, consumer products, and occupational sources. The estimates of annual effective dose equivalents from different radiation sources to the U. Excluding radon exposure, the average exposure from natural background consisting of cos- mic radiations, terrestrial radiations, and so on amounts to about 100mrem (1mSv)/year. For example, the annual cosmic ray exposure in cities such as Denver is about 50mrem (0. It varies from about 16mrem (160mSv)/year in the Atlantic ocean to 63mrem (630mSv)/year in the Rockies with an average of 28mrem (280mSv)/year. Radionuclides ingested through food, water, or inhalation include 40K and decay products of thorium and uranium, particularly 210Po, and contribute about 39mrem (390mSv) annually. Medical procedures contribute the highest exposure of all man-made ra- diation sources. The most exposure comes from diagnostic radiographic procedures with about 39mrem (390mSv) annually compared to 14mrem (140mSv) for nuclear medicine procedures.

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