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Backgrounds: Bleomycin (BLM) has been labeled with radioisotopes and widely used in therapy and diagnosis. In this study BLM was labeled with [⁶²Zn] zinc chloride for oncologic PET studies.

Materials and methods: The complex was obtained at the pH=2 in normal saline at 90 ° C in 60 min. Radio-TLC showed an overall radiochemical yield of 95-97% (radiochemical purity > 97%). Stability of complex was checked in vitro in mice and human plasma/urine.

Results: Preliminary in vivo studies performed to determine complex stability and distribution of [⁶²Zn] BLM in normal and fibrosarcoma-bearing mice. [⁶²Zn] BLM accumulated significantly in induced fibrosarcoma tumors in mice according to bio-distribution/imaging studies.

Conclusion: [⁶²Zn] BLM can be used in PET oncology studies due to its suitable physico-chemical properties as a diagnostic complex in vitro and in vivo. Further studies should be performed for evaluation of the complex behavior in higher animals. Iran . J. Radiat. Res., 2003 1(1): 37 - 44.

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Background: Measurement of back ground concentration of uranium in drinking water is very important for many reasons, specially, for human health. The uranium concentration in drinking water in many counties is a matter of concern for clinical and radioactive poisoning.

Materials and Methods: The uranium concentration in drinking water is determined using laser flourimatric uranium analyzer. For this purpose after sampling, sample handling and sample preserving, sample preparation and treatment for reduction of organic matter, the concentration of uranium is measured.

Results: To determine the uranium concentrations in drinking water in Iran , nearly 200 water samples were collected from all sources supplying drinking water in 21 provincial centres in the country. The wells were found to be the main source for drinking water. Uranium in the samples was measured by a laser fluorimetry technique. According to results, the concentration values found in the wells ranged from 1.0 to 10.90 μgL^-1, while nearly 95 percent of the cities had uranium concentrations in the wells at less than 4.70 μgL^-1. Surface waters showed uranium concentrations in the range of 0.75 to 2.58 μgL^-1. The daily intake of uranium from drinking water was estimated to range from 2.04 to 21.80 μgd^-1, with the mean value of 5.44 μgd^-1.

Conclusion: Highest uranium mean concentration of 10.9 μgL^-1 was found in Ardabil area where more studies should be done in that province in the future. Iran . J. Radiat. Res., 2003 1(3): 139 - 142

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Background: In myocardial perfusion SPECT imaging, images are degraded by photon attenuation, the distance-dependent collimator, detector response and photons scatter. Filters greatly affect quality of nuclear medicine images

Materials and Methods: A phantom simulating heart left ventricle was built. About 1mCi of ^99mTc was injected into the phantom. Images were taken from this phantom. Some filters including Parzen, Hamming, Hanning, Butterworth and Gaussian were exerted on the phantom images. By defining some criteria such as contrast, signal to noise ratio, and defect size detectability, the best filter can be determined.

Results : 0.325 Nyquist frequency and 0.5 Nq was obtained as the optimum cut off frequencies respectively for hamming and hanning filters. Order 11 ,cut off 0.45 Nq and order 20 cut off 0.5 Nq obtained optimum respectively for Butterworth and Gaussian filters.

Conclusion : The optimum member of every filter’s family was obtained. Iran . J. Radiat. Res., 2004 1(4): 205-210

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Background: Within the context of developing techniques to facilitate the diagnosis of the thyroid diseases, the elemental composition of pathological thyroid tissue (neoplastic and non-neoplastic) was investigated by proton induced X-ray emission. The PIXE has been widely used as a sensitive technique for trace elemental analysis in both biological and medical fields.

Materials and Methods: The twenty-eight specimen of thyroid tissue (neoplastic, non-neoplastic and grossly normal tissue) were obtained from operation of 14 patients with different thyroid diseases. Determination of the heavy trace elements distribution (Fe, Co, Ni, Cu, Zn, As, Se, Br, Rb, Mo, I) was carried out by irradiating of the sample surface with a focused proton beam.

Results: Fourteen grossly normal, eleven non-neoplastic and three malignant thyroid neoplasm cases were diagnosed. Trace element contents of the International Atomic Energy Agency (IAEA) MA-B-3/TM Fish tissue was used as standard for calibration of PIXE set up.

Conclusion: The concentration of the heavy trace elements Co, Cu, Zn and Mo in neoplasm of thyroid were higher than other samples. The concentration of the heavy trace elements, Fe, As, Br, Rb, I, are found to be much lower in neoplasm of thyroid than non–malignant and grossly normal thyroid tissue. The concentration of the Se, Co and I in this study is consistent with the others study but there are differences in the concentration of Fe in our study and others works. Iodine concentrations was 11 times lower, on average in neoplasm compared with non-neoplasmic tissue of thyroid. The low levels of I in thyroid neoplasm are correlated to some pathological factors. Iran . J. Radiat. Res., 2004 1(4): 211-216

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Background: Annual patient effective dose equivalent can be considered as a quantitative physical parameter describing the activities performed in each nuclear medicine department. Annual staff dose equivalent could be also considered as a parameter describing the amount of radiation risk for performing the activities. We calculated the staff to patient dose equivalent ratio to be used as a physical parameter for quantification of ALARA law in nuclear medicine departments.

Materials and Methods: As a part of nationwide study, this paper reports the staff and patient absorbed dose equivalents from diagnostic nuclear medicine examinations performed in four nuclear medicine departments during 1999-2002. The type and frequency of examinations in each department were determined directly from hospital medical reports. Staff absorbed dose equivalents were calculated from regular personal dosimeter reports.

Results: The total number of examinations increased by 16.7% during these years. Annual
patient collective dose equivalent ( EDE ) increased about 13.0% and the mean effective dose equivalent per exam was 3.61±0.07 mSv. Annual total staff absorbed dose equivalent (total of 24 radiation workers) in four departments increased from 40.45 mSv to 47.81 mSv during four years that indicates an increase of about 20.6%. The average of annual ratios of staff to patient effective dose equivalents in four departments were 1.83×10^-3, 1.04×10^-3, 3.28×10^-3 and 3.24×10^-3, respectively, within a range of 0.9×10^-3 – 4.17×10^-3 . The mean value of ratios in four years was about 2.24×10^-3 ± 1.09×10^-3 that indicates the staff dose of about two 1000th of
patient dose.

Conclusion: The mean value of ratios in four years was about 1.89×10^-3 ± 0.95×10^-3 indicating the staff dose of about one 1000th of the patient dose. The staff to patient absorbed dose equivalent ratio could be used as a quantitative parameter for describing ALARA law in radiation protection and risk-benefit assessments. Iran . J. Radiat. Res., 2004 2 (2): 63-68

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Background: Radiosurgery is a focal brain irradiation technique that delivers, usually in a single session, high dose of ionizing radiation. The presence of lateral electronic disequilibrium and steep dose gradients in small fields demands special attention to the selection of a suitable detector with respect to its size, composition and response.

Materials and Methods : Small circular fields were produced by home-made collimators attached to a 9MV Neptun 10 PC linac ranging from 12.5mm to 25 mm at isocenter level in 2.5 mm
increment. Stereotactic beam data including percent depth dose, off axis ratio and output factor were measured using p-type silicon chip detector in a water phantom. Beam data were plotted for all available collimator sizes.

Results: Percent depth dose values at depth of 100 cm show 10 percent increase with enlargement of the field sizes from 12.5 mm to 25mm. Small overestimation of output factor has been observed using diode detector.

Conclusion: It is concluded for stereotactic radiosurgery with higher energy photon diode
detector could be a good and reasonable choice to measure percent depth dose and off axis ratio. Regarding the output factor, it is better to compare the results with those obtained by other
detectors. Iran . J. Radiat. Res., 2004 2 (2): 79-84

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Background: A set of hardware stereotactic radiosurgery is designed and constructed. The scope of this article is to describe how we have designed and developed stereotactic collimation assembly for a 9 MV Neptun 10 PC linac.

Materials and methods: One collimator holder and six collimators were made, with their
radiation field diameter between 12.5 mm to 25 mm at isocenter level. Beam data, such as depth dose percent, off axis ratio and output factor of the collimators were measured. Isocentric
accuracy and dose delivery, accuracy tests were also performed using locally made isocentric alignment control device, target simulator and plexiglass phantom.

Results: Average isocenter shifts resulting from gantry and couch motion were respectively 1.5 mm and 2 mm. Simulating a stereotactic radiosurgery with the help of a plexiglass phantom showed less than one percent radiation leakage to critical organs such as eyes and thyroid.

Conclusion: Stereotactic collimation assembly in conjunction with the rest of constructed equipments can be employed to set up SRS treatment, provided safety and to compensate operations are taken into account. Iran . J. Radiat. Res., 2004 2 (3): 135-140

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Background: Due to volatility of radioactive iodine solutions, usually internal exposure would occur in personnel that are working in nuclear medicine centers. The activities in the thyroid of individual s who work in nuclear medicine centers of North West provinces of Iran were measured using NaI (Sodium Iodide) detectors. In every center, nearly 40 - 500 mCi of ¹³¹ I and 50 - 600 μ Ci of ¹²⁵ I are used for diagnosis or treating patients, as well as monthly protein labeling.

Materials and Methods: A portable measurement instrument was made for this purpose. A collimator with thickness of 10 mm lead thickness of copper alloy with 2 mm was made to
focus the detector on thyroid gland and to reduce the background. Two NaI (Tl) detectors one with lower thickness for ¹²⁵ I and one with higher thickness for ¹³¹I were used for measurement. The goal of these measurements was to determine the activity of radioiodines in the thyroid gland of individuals in medical centers, and to give some advice such as more care at their working place and increasing the power of their venting system for reducing radioiodines exposure. The detectors had been calibrated for ¹²⁵I and ¹³¹I by a locally made ANSI/IAEA Plexiglass neck phantom (ANSI N44.3 1973).

Results: There were not any contamination and thyroid activities of ¹²⁵I in the thyroid glands of personnel. The activity of ¹³¹ I in the thyroid gland of individuals in all centers was lower than 0.4 kBq, and the activity of ¹³¹I in one center was as high as 3.4 kBq. The background of every place was determined and subtracted from each measurement.

Conclusion: The results indicate that more measurements should have been carried out in all nuclear medicine centers to determine the activity of individuals^' thyroid gland in Iran . In addition, the workers of those centers should try to reduce the intake and exposure to ¹³¹I and ¹²⁵I using more care at their working place and more efficient ventilator. Iran . J. Radiat. Res., 2004 2 (3): 141-147

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ABSTRACT

Background:

Coherent scattering leads to diffraction effects and especially constructive interferences. These

interferences carry some information about the molecular structure of the tissue. As breast cancer is

the most widespread cancer in women, this project evaluated the application of small angle

X-ray scattering (SAXS) for differentiation between normal and cancerous breast tissues.

Small angle X-ray scattering (to angles less than 10°) is predominantly coherent.

Materials and Methods:

primary collimator, sample holder, secondary collimator and HP Ge detector was used. The best

constructive interference was found to be at 6.5

at several angles of 4, 5, 6, 6.5 and 7.3 degrees. The total number of 99 breast tissue samples,

including normal and tumor were studied at the 6.5

transfer was obtained for each sample.

The energy dispersive method with a set up including X-ray tube,° after doing experiments on adipose breast tissue°. The corrected intensity versus momentum

Results:

adipose tissue and mixed tissue (adipose & fibroglandular) from tumor in peak positions (each

coherent scattering spectrum has a peak that its position is determined by momentum transfer).

Furthermore adipose tissue has shown significantly higher peaks than other breast tissues. Benign

and malignant breast tissues were differentiated by both peak positions and peak heights (each

peak has a height in coherent scattering spectrum). Preservation of samples nitrogen tank had no

effects on molecular structure of the breast tissue.

Adipose tissue shows a sharp peak in low momentum transfer region. It is easy to separate

Conclusion:

between normal, benign and malignant breast tissues.

By energy dispersive small angle X-ray scattering, it is possible to differentiateIran. J. Radiat. Res., 2005 2 (4): 205-210

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ABSTRACT

Background: Delivering the radiation dose to the target volume and minimizing the dose to normal tissues are the main objectives in radiotherapy. The aim of our study is to enhance the contrast of the portal image to increase the accuracy of delineation of the organs in the irradiation field.  

Methods: The software was written based on local enhancement of the pixel values in image matrix. The portal images were digitized by charged coupled device (CCD) in compatible format to be read with this program. This program was applied as an m-file in MATLAB imaging tool box to the matrices of the portal images. The imaging parameters before and after application of the program were compared.                                                                                                                        

Results: The quantitative information of images was obtained. Analysis of the mean and standard deviations of the results has shown that the difference of the criteria between two groups of the images is significant (p< 0.01). In qualitative analysis, final images scores were based on “special weight “. The result of this test confirms the superior quality of the post-processed images from the professional view point.

Conclusion: Superiority of final images within the three studied parameters by the experts (superiority of lung image, superiority of thorax and its soft tissue images) can be used to increase the accuracy of the treatment set up and decrease the probability of normal tissue complications.