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Abstract: Computed Tomography is a diagnostic imaging modality giving higher patient dose in comparison with other radiological procedures. The level of CT radiation dose is of concern to radiologists, medical physicists, government regulators, and the media. This review addresses this problem with particular reference to radiation dose in chest CT. Specifically it outlines the topics of measurement units used to quantify radiation exposure, factors affecting CT scanner dose efficiency, scanner settings that determine the administered radiation dose, and radiation dose reduction in chest CT.The Objective: Aim of this study is to determine minimal tube current (mAs) required for good image quality on conventional chest CT (Computed Tomography).Patients & Methods: Prospectively, 35 consecutive patients (mean weight, 65 kg; range, 38-92 kg) older than 45 undergoing conventional chest CT with standard technique (120 kVp, 400 mAs) had four additional sections imaged at reduced tube current (200, 140, 80, 20 mAs) at two levels (tracheal carina and left atrium). CT scans were evaluated in random order by two independent observers who were blinded to technical factors used. Results: The 400 mAs scan was considered the reference standard. When compared with the reference technique (400 mAs), the first and second (200 mAs and 140 mAs) reduction levels showed no significant difference (p > .05) in subjective image quality. A significant difference (p < .001) was seen at the third and fourth (80 mAs and 20 mAs) reduction levels. A two fold reduction in tube current (400-140 mAs) and resultant radiation dose did not cause a significant change in subjective image quality or in detection of lung abnormalities with conventional chest CT. One hundred forty milliampere-seconds is the minimal tube current required to provide good image quality in patients of average weight.CT is a diagnostic imaging modality giving higher patient dose in comparison with other radiological procedures. CT scan parameters have been adjusted with the aim of working towards optimization of image quality and patient dose. Conclusions: The effective dose of our population is (1.8 mSv) compared with UK, Crawly et al and Hughes et al have the same value.Key words: Radiation dose, CT scan& Reduction dose.

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Silences acid has been investigated as a dosimeter for high doses of Gamma radiation through measuring the induced changes in optical absorbance from (315-900) nm at room temperature. It was found that the absorbance increased with increasing absorbed Gamma-dose. Also, the dose rate and post irradiation fading of optical absorption spectra has been studied. The results of this preliminary study show that Silences acid may be applied as a simple optical absorbance detector for dose measurement in the dose range (5 - 28 ) kGy.

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Fluoroscopy is a type of medical imaging that shows a continuous X-ray image on a screen, it is used in a wide range ofexamination and procedures for diagnosis such as in cardiac catheterization. Fluoroscopy can result in relatively highradiation doses, especially for complex interventional procedures that it needed to monitor radiation to reduce exposure.The purpose of this study is to determine the radiation doses for patients during cardiac catheterization exam andcompare it with the permissible dose limits. The main parameters which are studied in this work are the time of exposuredose rate, x-ray techniques (milliamper. second), tube voltage (kilovolt) and Dose Area Product (DAP). Twenty-sevenpatients were included and absorbed doses were measured and distributed according to Fluoroscopy (Fluo) time, mAsand Dose Area Product (DPA). It was found that the absorbed dose received by the patients has a linear relationship withthe Fluoroscopy time, mAs and DAP. Exposure dose rates were measured and compared with the maximum permissibledose (100 mGy/min), the estimated patient dose rate varied from (12-81.6) mGy/min) for 24 patients as a permissibledose in the safe side, and 3 patients exposed to higher values of the exposure dose rates ) over permissible dose) range(107.4-108) mGy/min.

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Silymarin, a flavolignans from seeds of ‘milk thistle’ “Silybum marianum” has been widely used from ancient times because of its excellent hepatoprotective action. It has been used clinically to treat liver disorders including acute and chronic viral hepatitis, toxin/drug-induced hepatitis and cirrhosis and alcoholic liver disease. The efficacy and dose-response effect of silymarin (125, 250 and 500 mg/kg) were assessed using egg albumin-induced paw edema in rats as a model of acute inflammation. In this model, 56 rats were used and allocated into 7 subgroups each containing 8 rats. All treatments were given intraperitonealy 30 minutes before induction of inflammation by egg albumin and then the increase in paw edema was measured 1h, 2h and 3h after induction of inflammation by using the vernier caliper. The results indicated that silymarin, at doses range used, significantly lowered paw edema (P<0.05) an effect comparable to that produced by the reference drugs, acetyl salicylic acid, meloxicam and dexamethazone. Paw edema suppressive effect of silymarin 250 and 500 mg/kg was comparable and both of them were significantly different from that of silymarin 125 mg/kg (P<0.05). Therefore, silymarin exert an important anti-inflammatory activity in animal model of acute inflammation, which was significantly increased as the dose increased up to 250 mg/kg.

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Samples of physiologyical solution which contain Escherichia.coli bacteria in a one size 0.5cm3 were prepared, then samples has been radiated by Nd-YAG laser with two mode working in different periods, same dose and wavelength to compare between high power and low power laser for percent of killing, the results revealed occurrence of higher percent of killing by pulsing mode than continuous mode due to destroyed cell when it is absorb a high energy in short time that won't expand the cell by heat that it is happen in long time and a low energy.

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In this study, radon concentrations were measured in dwellings at specified locations in Baghdad city using ionization chamber radon monitor (ALPHA GUARD PQ2000 PRO). The measurements were carried out at different locations of these dwellings (living rooms, bed rooms, bath rooms, and kitchens). The results of the survey showed that the overall minimum, maximum average and mean average radon concentrations in dwellings were 5.77±0.73 Bq/m3, 23.27±13.57 Bq/m3, and 10.67±4.14 Bq/m3 respectively. The lowest average radon was found in (Ameryia) city, while the highest average radon concentration was found in (Kadmiya) city. Also, the results showed that the highest average radon concentration was found in the kitchens, while the lowest average radon concentration was found in the living rooms. The maximum annual effective dose in dwelling in Baghdad city in current study is 0.59 mSv.

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Chemicals are used to increase the settling velocity for suspended deposition colloids which are not settled in sedimentation tanks in water purification plants . For this purpose, the alum is used in wide spread across the water purification projects in Iraq. This research contains studying the factors that effect on alum amount added by conducting laboratory tests of water samples from Euphrates river at the purification plant in AL-Musayyab city over ten years (with monthly rate). It was noted that the amount added depends heavily on the turbidity of water entering the purification plant, in addition to water temperature and its pH. The results of laboratory tests have been approved, which included the measurement of the turbidity, pH, temperature, and the value of alum added. Since this method is applicable in all water purification plants. The results during the period of ten years are accredited, and subjected to multi -regression analysis. A mathematical model was conducted to calculate the alum dose, which must be added depending on the raw water turbidity, temperature, and pH. This model also has been examined by using data of another years and gave satisfactory results to be up to 91% each. This model compensates the use of the Jar-test of raw water to determine the amount of alum that must be added and sufficient by measuring the turbidity, temperature, and pH of the raw water only, and then calculating the value of the required dose of alum.

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Twelve storm dust samples were collected from three cities in Iraq. The samples were collected in the same time during big storms which hit Iraq in summer, 2012 and 2013. The deposited dust on 4 by 4 nylon sheet on surfaces of selected buildings in cities of Baghdad, Fallujah and Al-Ramadi were collected. Each sample was put in sealed Marinilli beaker and kept for 4 weeks to reach the equilibrium state between radium and its short half-life daughters. Gamma spectrometry system based on HPGe was used for analysis of natural and artificial radionuclides in the dust. The activities of natural radionuclides were found to be ranged between 13-19 Bq/kg, 9-14 Bq/kg and 200-240 Bq/kg for Ra-226, Th-232 and K-40 respectively, while Cs-137 was found in all the samples to be ranged between 3-10 Bq/kg. The current study includes the estimation of doses caused by external and internal exposure and inhalation dose of these radionuclides and discusses the potential sources of these relatively elevated concentrations of radionuclides

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Background: Radioactive iodine-131 therapy is highly effective in treating patients with hyperthyroidism. An ablative dose is preferred by a number of endocrinologists, and, a fixed dose protocol seems to be better than a calculated dose in real practice.Objective: To check for hypothyroidism in hyperthyroid patients one year after RAI therapy, comparing between the results of high ablative versus usual dosages of RAI-131. Methods: This study included 174 hyperthyroid patients, 101 males and 73 females, divided into 2 groups, the first consisted of 162 patients given a usual fixed dose of RAI while the second consisted of 12 patients given a high fixed ablative dose of RAI. The study lasted about 2 years from August 2000 till July 2002 in the Specialized Centre for Endocrinology & Diabetes, Baghdad.Results: Out of 162 patients in the first group, 11 patients (6.8%), developed hypothyroidism compared to 4 patients out of 12 (33.3% ) in the second group ( p < 0.05). Conclusion: A high ablative dose RAI has a better outcome regarding hypothyroidism than a usual dose, although, endocrinologists have different opinions regarding this issue.

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The objective of the present work was to assess the distribution of radon in the University of Technology buildings, Baghdad - Iraq and to identify the effective dose of radon exposure to the staff using passive dosimeter (SSNTD) CR-39. One hundred CR-39 dosimeters were distributed over different buildings in the University campus according to the number of floors area. The exposure time started from December 2012, and the dosimeters were left inside buildings for 40 days. Only 93 dosimeters were collected, while the remaining 7 were considered lost. The average concentrations were calculated in units of Bqm-3, for each sample in each building, and then are repeated after grouping in each floor of the same building. The average radon concentrations per building and at the university as a whole were also calculated. Radon concentrations were found to vary from 80.1 to 416.7 Bqm-3. The highest radon concentration with a mean value of 416.7 Bqm-3 was found atuniversity press section building, while the lowest radon concentration was found at the welding division 2 building with a mean value of 80.1 Bqm-3. The average value of radon concentration at the university was found to have the value of 181.9 Bqm-3 which is less than the recommended value of 200 Bqm-3 UNSCEAR [18].Dose rate (in µSv/h), annual dose rate (in mSv/y & WLM/y), cumulative dose (in mSv& WLM) and cancer risk were also calculated. It was found that the university staffs are exposed annually to 2.083 mSv which equal to 0.231 Working Level Month (WLM) from radon gas and its short-lived daughters. Hence, a person takes on the average an annual effective dose equivalent to 2.56and 1.84mSv according to average value considered by UNSCEAR [18] and ICRP [19], respectively. This implies an expected value for lung cancer probability of 0.0046.

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