Quality assurance for the physical and technical factors affecting treatment planning of head and neck malignancies

In this work the effect of patient immobilization was studied in cases of head and neck malignancies, which treated in the supine position with a cobalt-60 machine at Clinical Oncology Department in Tanta University Hospitals. Four patients were immobilized using orfit and planned on the x-ray diagnosis machine with and without the orfit. Different headrest types were used to detect which of them help in the reproducibility from day to day. Then portal images were obtained to perform weekly "on-line" setup errors. Comparison between manually dose distribution and those calculated using C.T. planning images and calculated by planning system were investigated are done. By measurements and calculation the HORTON's equation of shadow tray factor must be development

Verification of radiation dose calculation for patients treated by Co-60 using 2-D planning system

In this study, experimental verifications is done for output, dose profile percentage depth dose for open and modified [wedged and partially blocked] fields as compared with the calculated using Multidata code. Four typical configurations of irradiation were selected, regular fields, wedged fields, blocked fields and cases of internal inhomogeneity. Measurements were performed on cobalt - 60 unit Theratron 780E using Multidata water phantom. For blocked fields dose profiles were measured using radiographic films and then scanned using PTW densitometer. Data were analyzed in both of the low and high dose gradient regions of the measured and calculated profiles. Differences between the measured and the calculated dose were determined. The results indicate that the Multidata planning system calculations agree with the measured ones in situations. However, in the blocked field the mean deviation between measured and calculated dose under the block was [15.2%] although the blocks is drown according to the instructions by the system manufactures. The reason for such errors was found to be due to the implemented algorithm in the system

practical determination method of potassium traces in foodstuffs by the use of natural [40]k radiation

A new approach is presented for experimental determination of the potassium traces in foodstuffs, soil, sediment and plants, by use of natural [40]K radiation. Potassium maintains the salt balance in plant and animal cells and is important for healthy metabolis. Its role is often likened to that of the oil in an engine. There are actually three potassium isotopes'. [39]K, a stable isotope, is the most abundant, at 93.26% of the total; [41]K is next in abundance at 6.73% and is also a stable isotope. The potassium isotope of interest is a radioactive isotope, [40]K. It is present in all potassium at a very low concentration, 0.0118%. It has a very long half-life, 1,260,000,000 years. When it decays 89% of the events give rise to the emission of a beta ray with maximum energy of 1.33 Mev. The other 11% of the decays produce a gamma ray with an energy of 1.46 Mev. The long half-life and low abundance might seem to imply that this radioisotope, [40]K, is of little or no consequence, so it is usually ignored. In fact the knowledge that all potassium contains this radioactive isotope does not seem to be widely known. Very few of the discussions about potassium mention its radioactivity, which seems to imply that either it is not known or that this trivial level can be safely ignored. This radioactive element is vital for our good health. It is an element that is essential for the body's growth and maintenance. Potassium is also necessary in order to maintain normal water transport between the cells and body fluids. It also plays an essential role in the response of nerves to stimulation and in the contraction of muscles

Cigarette smoking may aggravate liver disease in patients with hepatitis C virus [HCV] infection

Egypt has a high prevalence of hepatitis C virus [HCV] infection, resulting in a high morbidity and mortality from chronic hepatitis, cirrhosia, and hepathocellular carcinoma. It is unclear why some patients with HCV infection do better than others with the same physical and epidemiological characteristics, Recently, environmental pollution was accused in many chronic diseases including liver disease. We designed this study to clarify the impact of heavy metals and oxidative stress in cigarette smoke on liver disease in HCV patients. Fifty male Egyptian patients with positive HCV-RNA were studied. Twenty-five of them were smokers with an average smoking index of 183.16 and the other 53 were non-smokers. Both groups were matched as regards age and have no home or occupational exposure to heavy metals. The antioxidant defense system of erythrocytes, liver function tests, serum trace elements, and serum heavy metals were measured for all patients. A significant increase in serum cadmium and lead was found in smoker patients. Also, the liver enzymes [alanine aminotranserferase; ALT, aspartate aminotranseferase; AST, and alkaline phosphatase; ALP], were significantly elevated in the serum of smoker patients. The histologic activity index [HAI] was higher in smokers than non-smoker patients, but the difference was statistically non-significant. On the other hand, a significant decrease in serum albumin and serum selenium was found in smoker patients. Also, the activities of the antioxidant enzymes in the erythrocytes [glutathione reductase; GR, superoxide dismutase; SOD, catalase; CAT, and reduced glutathione; GSH] were significantly lower in smoker than non-smoker patients. The results of this study concluded that patients with hepatitis C should be informed about the possible hepatotoxsicity of heavy metals and oxidants in cigarette smoke and advised to quit smoking as a part of their life style modification. Further studies are encouraged to discover other aspects of tobacco toxicities on the human liver and the pathogenesis of this potential harmful effect

Microwave adverse exposure changes of blood and brain levels of some elements in rats

In this work, four groups of adult male albino rats were used; the first as control, the second was exposed to microwave radiation 11/2 hr/day for seven consecutive days at a dose of 15 mW/cm2 and frequency 10.525 CHz. The third was exposed like the second but for 24 consecutive days, while the fourth was treated as the third and then left for two weeks as a rest period. Then animals were sacrificed and the blood and brain levels of some major and trace elements [calcium. iron, manganese, copper, nickel, zinc, selenium and molybdenum] were estimated by the Energy Dispersive X-ray Fluorescence technique [EDXF]; an easy, rapid, multi-elemental and need low weight of samples. Calcium, iron and manganese showed a significant increase in the exposed groups, while zinc, copper and molybdenum showed a significant decrease in both blood and brain when compared to control. Nickel of blood exposed groups showed a significant drop in the acute and chronic exposure groups and restored its normal figure in the chronic exposure then rest group, but it gave no readings in the brain sample for all groups. As for selenium it showed a significant drop in both acute and chronic exposure groups and a significant rise in the chronic then rest group in the blood; but in brain it gave no readings for the control and chronic exposure groups and a significant rise in the other two. These changes were explained by the microwave variant effects on ion fluxes via the effect on the ion channel properties of cell membrane, interaction between the cellular membrane molecules containing these ions, voltage changes across the cell membrane. etc

Evaluation of the possible effects of microwaves on some vasoactive substances serotonin [Part I] and some metabolite [part II] steptozotocin induced diabetic rats

The objective of this study was the evaluation of the possible adverse effects of microwaves [e.g. mobile, microwave ovens, etc.] on some vasoactive substances as catecholamine [norepinephrine and epinephrine], 5 hydroxy tryptamine [serotonin] and histamine as well as histaminase enzyme activity and the possible role of Nigella sativa oil [NSO] administration in albino rats. Male adult albino rats were divided into control group [n=10], group II [n=10] received microwaves for 7 days consecutively at a dose of 170 mW/Cm2 and frequency of 2.06 GHz for 3 hours [acute group], the third group [group III] [n=10] received the same dose as group II but for 28 consecutive days [chronic group], the fourth group [group IV] was treated as group II with concomitant administration of Nigella sativa oil [NSO] 100 mg/kg/day/orally by gastric tube. The fifth group [n=10] was treated as group III with concomitant oral administration of Nigella sativa oil in the same dose as group IV for 28 days. At the end of experiments, the animals were sacrificed and blood examined for norepinephrine, epinephrine, serotonin, histamine and histaminase enzyme activity. The result of the present study showed that microwaves produced significant reduction of histaminase activity significant increase in histamine, serotonin, norepinephrine and epinephrine, all were highly significantly changed in acute group of irradiation

Radiation responses of the power of skeletal muscle of rats

In radiotherapy, the maximum accumulated dose that can be administered is usually limited by the probability of inducing unacceptable early and/or late complications in normal tissues. To prevent such complications and toxic effects, data radiation tolerance doses should be available for many types of normal tissues which may be exposed during treatment with different types of radiations. Examples of normal tissues for which detailed data are available in the literatures are the haemopoietic tissue, the intestinal epithelium, the skin and tissues of the nervous system.. etc However, few data are available of radiation tolerance of skeletal muscle, This lack of information may be attributed to the fact that skeletal muscular tissue is supposed to be relatively radioresistant. Therefore, new testing instruments have been designed and modified in order to obtain more sensitive data on dose response relationships, as well as to increase insight into the mechanism involved in the development of loss of the muscular power of the hind limb induced by ionizing radiations in skeletal muscle. For this purpose, 60 male and female albino rats were subjected to different gamma irradiation doses, under anaesthesia with pento-barbital sodium. The irradiated rats lost most of the muscle power suddenly after the irradiation dose, then this power was restored gradually, but not reached the initial power before irradiation, the half recovery period [H.R.P.], as well as the loss of muscle power related directly to dose factor