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Showing 91 results for Ji
M. Mirzaii, H. Afarideh, S.m. Haji-Saeid, G.r. Aslani, M.r. Ensaf,
Volume 1, Issue 2 (9-2003)
Abstract
Background: Thermoluminescence dosimetry is one of the dosimetry procedures used widely as routine and personal dosimeters. In order to extend this kind of dosimeters, dental tissue has been examined and was found promising as a TLD dosimeter. Materials and Methods : In this study, 70 health teeth were collected. The only criterion, which was considered for selection of the teeth, was the healthiness of them regardless of age and gender of the donors. All collected samples were washed and cleaned and milled uniformly. The final powder had a uniform grain size between 100 – 300 micrometer. The sample was divided into four groups. Group A and B were used for measurement of density and investigation of variation of thermoluminescent characteristics with temperature respectively. Groups C and D were used for investigation of variation of thermoluminescent intensity with dose and fading of this intensity with time . In all cases the results obtained with dental tissue were compared to a standard LiF, TLD dosimeter. Results : It was found that, average density of the dental tissue was 1.570 g/cm3, which is comparable to density of LiF, which is 1.612 g/cm3. It was also concluded that the range of 0-300 oC, dental tissue has a simple curve with two specific peaks at 140 and 250 oC respectively. The experiment also showed that, the variation of relative intensity versus dose is linear in the range of 0.04 – 0.1Gy . The fading rate of dental tissue is higher than LiF but still in the acceptable range (14% per month in compare to 5.2% per month) Conclusion : Dental tissue as a natural dosimeter is comparable with TLD and can be used in accidental events with a good approximation . Iran . J. Radiat. Res. 2003 1(2): 113 – 117.
Mokhtari-Dizadji, M. Vahed, M. Gity,
Volume 1, Issue 3 (12-2003)
Abstract
Background: Ultrasound propagation velocity was measured experimentally in normal, fibroadenoma and ductal carcinoma breast tissues, in order to distinguish normal breast tissue from tumors. Materials and methods: In quantitative measurements of ultrasound velocity, 403 breast tissue images were selected, comprising 130 normal breast tissue, 130 fibroadenoma, and 143 ductal carcinoma tumors. The cases were implanted in breast tissue mimicking materials and ultrasonic images (A-mode) at 35 ° C were processed and evaluated. Results: It was observed that ultrasound propagation velocity is an important factor for distinguishing in vitro specimens of fibroadenoma and ductal carcinoma from normal tissue (P-value<0.005). Evaluation of ultrasound velocities showed that from normal breast tissue, fibroadenoma and ductal carcinoma, ultrasound velocity increases respectively. The discriminant functions of types of lesions, based on ultrasound velocity, have been formulated by discriminant analysis. The results indicate that probability of discrimination, sensitivity and specificity for tumors and normal breast tissues are 72, 60 and 100 percents at 35 ° C. With measuring ultrasound velocities, we can distinguish normal breast tissue of from ductal carcinoma and fibroadenoma masses (with the probability of 100%). Conclusion: It is proposed that probably by measuring attenuation coefficient and ultrasound velocity on time, fibroadenoma and ductal carcinoma tumors can be differentiated well. Iran . J. Radiat. Res., 2003 1(3): 163 – 169
P. Abdolmaleki, M. Mokhtari Dizaji, M.r. Vahead, M. Gity,
Volume 2, Issue 1 (6-2004)
Abstract
Background: Logistic discriminant method was applied to differentiate malignant from benign in a group of patients with proved breast lesions on the basis of ultrasonic parameters. Materials and Methods: Our database include 273 patients' ultrasonographic pictures consisting of 14 quantitative variables. The measured variables were ultrasound propagation velocity, acoustic impedence and attenuation coefficient at 10 MHz in breast lesions at 20, 25, 30 and 35 º C temperature, physicsl density and age. This database was randomly divided into the estimation of 201 and validation of 72 samples. The estimation samples were used to build the logistic
discriminant model, and validation samples were used to validate the performance. Finally,
important criteria such as sensitivity, specificity, accuracy and area under the receiver operating characteristic curve (ROC) were evaluated. Results: Our results showed that the logistic discriminant method was able to classify correctly 67 out of 72 cases presented in the validation sample. The results indicate a remarkable
diagnostic accuracy of 93%. Conclusion: A logistic discriminantor approach is capable of predicting the probability of malignancy of breast cancer. Features extracted from ultrasonic measurement on ultrasound imaging is used in this approach. Iran . J. Radiat. Res., 2004 2 (1): 27-34
M. Hajizadeh Saffar, M.r. Ghavamnasiri, H. Gholamhosseinian,
Volume 2, Issue 2 (9-2004)
Abstract
Background: In radiotherapy, wedge filters are used for optimizing the tumor dose distribution in patients. The attenuation in beam intensity due to the presence of wedge filter is compensated by means of a wedge factor measured at the central axis of the beam. The field size, depth and SSD dependence of wedge factor have been assessed for 9MV radiations of Neptun PC linear accelerator. Materials and Methods: Wedge factors (WF) at different SSD, field size (FS) and depth (d) in water were measured for 8 steel wedges with different sizes and angles of 15, 30, 45, and 60 degree. Experimental data were obtained using Neptun 10PC, Linac 9MV X-ray machine, a 3D water phantom, dosimeters and an electrometer. To study the effect of field size on WF, the wedge factor was measured for square field sizes from 5 ´ 5 to 20 ´ 20 cm, with 1 cm increment intervals for all wedges and, at the depth of 10 cm, SSD of 100 cm with monitor unit (MU) of 80. Effects of depth on WF were studied by measurement in various depths from 3-19cm for all wedge angles at SSD of 100cm, field size of 10 ´ 10cm and 80 MU irradiation. Effects of SSD on WF were investigated by a variation of SSD from 90-110cm with 5cm increment intervals while the dosimeter was set at depth of 10cm and field size of 10 ´ 10cm were irradiated for 80MU. Results: Linear dependence of WF with field size and depth of measurements were confirmed with 95% certainty. Shapiro-Wilk test, showed that the residual data of the regression tests have normal distributions (P>0.05). There was also found no linear relationship between WF and SSD (P>0.05). Conclusion: WF has linear dependence with field size and depth of measurements, but the rate of variations are less than 2.2% per 10cm variation in field size and less than 1.3% per 10 cm variation in depth of measurements, therefore, correction of WF for field size and depth of
treatments in clinical trials is negligible. Iran . J. Radiat. Res., 2004 2 (2): 53-58
M. Hajizadeh Saffar, S. Nekoee, M.h. Bahrayni-Toosi, A. Sedghi,
Volume 2, Issue 4 (3-2005)
Abstract
ABSTRACT Background: as fluoroscopy or different angiographies are usually evaluated using TL dosimeter. This method is a time-consuming procedure therefore, radiologists are usually worried and unaware of their exact radiation dose received during each fluoroscopy or angiography. In this study, a new trend for quick estimation of effective dose based on measuring air-absorbed dose of the scattered radiations at body surface of the radiologists has been introduced. The radiation effective dose received by the radiologists during procedures suchMaterials and Methods: fluoroscopy unit (Shimatsu, model SF5010MD), and a water phantom (spherical plastic bag 27 cm in diameter filled with water up to 22.5 cm height). Radiation field was 20 × 20 cm on the bed and X-ray tube had 1.5 and 2 mm of Aluminum as an internal and external filtration respectively. A calibrated survey meter model RDS-110 was used to measure the scattered radiation horizontally and vertically around the phantom at different angles and distances, in front and behind of an apron. Scattered radiations of abdominal viscera were simulated by aResults: mA, was 451 µGy/h. This value reduced to 4.45 µGy/h by passing through lead ribbons of serigraph and to 1.2 µSv/h behind an apron. The scattered dose rate at different angles above the bed was constant and varied by distance from the center of the radiation field. The effective dose received by the radiologist is estimated to be about 174µGy/h, while wearing an apron and staying 50 cm away from the patient during fluoroscopy or angiography of abdominal viscera. The scattered dose rate at 1 m from the phantom, during fluoroscopy at 83 kVp and 1.7 Conclusion: different angiographies of abdominal viscera, by determining scatter radiation dose at their body surface and applying factor 0.87 for shielding effect of the body. Equivalent organ dose can also be calculated from dose rate in air after applying factor 0.87 for deep organs or 1.1 (the mass energy absorption coefficient ratio of water/tissue to air) for organs near the surface. Radiat. Res., 2005 2 (4): 185-190 The radiologist can estimate his/her effective dose following a fluoroscopy orIran. J.
P. Abdolmaleki, H. Abrishami-Moghddam, M. Gity, M. Mokhtari-Dizaji, A. Mostafa,
Volume 3, Issue 3 (12-2005)
Abstract
ABSTRACT Background: A computer aided diagnosis system was established using the wavelet transform and neural network to differentiate malignant from benign in a group of patients with histo-pathologically proved breast lesions based on the data derived independently from time-intensity profile. Materials and Methods: The performance of the artificial neural network (ANN) was evaluated using a database with 105 patients' records each of which consisted of 8 quantitative parameters mostly derived from time-intensity profile using wavelet transform. These findings were encoded as features for a three-layered neural network to predict the outcome of biopsy. The network was trained and tested using the jackknife method and its performance was then compared to that of the radiologists in terms of sensitivity, specificity and accuracy using receiver operating characteristic curve (ROC) analysis. Results: The network was able to classify correctly the 84 original cases and yielded a comparable diagnostic accuracy (80%), compared to that of the radiologist (85%) by performing a constructive association between extracted quantitative data and corresponding pathological results (r=0.63, p<0.001). Conclusion: An ANN supported by wavelet transform can be trained to differentiate malignant from benign breast tumors with a reasonable degree of accuracy.
A.h. Barati, M.mokhtari -Dizaji, H.mozdarani, S.z. Bathaei, Z.m.hassan,
Volume 3, Issue 4 (March 2006)
Abstract
ABSTRACT Background : In order to quantify effects of ultrasound irradiation parameters under therapeutic condition, especially sonodynamic therapy, it is initially necessary to evaluate inertial cavitation activity in vitro conditions therefore, in this study, the effect of 1 MHz low level ultrasound based on °OH radicals generated by acoustic inertial cavitation in aqueous solution was monitored by their reaction with terephthalic acid (TA) to produce fluorescent 2-Hydroxyterephthalate acid (HTA) by spectrofluorometry method (Terephtalic acid dosimetry). Materials and Methods: The study was designed to measure hydroxyl radicals in a field near to 1 MHz sonotherapy probe in progressive mode and low level intensity. The effect of ultrasound irradiation parameters (1MHz) containing duty factor, mode, intensity ultrasound and, time sonication in hydroxyl radical production have been considered. After preparation of solution of dosimetry and plotting calibration curve of spectrofluorescence, the effect of mode of sonication (continuous and pulsating), duty factor (20-80%), intensity (0-2 W/cm2, with step of 0.5 W/cm2), and sonication time (0-60min with step time of 10min) without increasing temperature to more than 3°C to determine the effective exposure in low level ultrasound were evaluated. The fluorescence intensity of TA solution before and after irradiation, in all cases was measured, and the results were reported as Mean ± Standard Deviation (SD). Result : The result of experiments related to sonication mode for 1MHz ultrasound irradiation (2 W/cm2) show that continuous mode of sonication is 29% higher fluorescence intensity than the pulse mode in 80% duty cycle for sonodynamic therapy. With compensation of irradiation time for 1MHz sonication in different duty cycles, fluorescence intensity in continuous mode is 22% higher than the pulse mode in average. The amount of hydroxyl radicals production versus ultrasound intensity, and sonication time show with increasing intensity or sonication time in continuous mode, the hydroxyl radical production is linearity increased (R=0.99). Conclusion: The results show that the terephthalic acid dosimetry is suitable for detecting and quantifying free hydroxyl radical as a criterion of inertial cavitation production over a range of condition in medical ultrasound fields.
Dr. D. Soyal, Dr. A. Jindal, Dr. I. Singh, Dr. P.k. Goyal,
Volume 4, Issue 4 (3-2007)
Abstract
Background: This study was carried out to observe
the radioprotective effects of Rosemarinus officinalis
leaves extract (ROE) against radiation-induced
histopathological alterations in liver of mice.
Materials and Methods: Adult Swiss albino mice
were exposed to 6 Gy gamma radiation in the
presence (experimental) or absence (control) of ROE to
study the qualitative and quantitative alterations in the
liver. Results: Normal hepatocyte counts were found
to be declined up to day 10th post-irradiation in both
the groups but thereafter such cells increased
reaching to near normal level at the last autopsy
interval, only in experimental group. Contrary,
frequency of abnormal hepatocytes increased up to
day 10th after irradiation in both the groups.
Binucleate hepatic cells showed a biphasic mode of
elevation after irradiation, first at 12 hrs and second
on day 10th in control group whereas in experimental
group, the elevation was comparatively less marked
and even the second peak was not evident. Irradiation
of animals resulted in an elevation in lipid peroxidation
(LPx) and a significant decrease in glutathione (GSH)
concentration in liver as well as in blood. Conversely,
experimental group showed a significant decline in LPx
and an elevation in GSH concentration. Conclusion:
These results indicate that Rosemarinus officinalis
leaves extract (ROE) is able to protect the liver of Swiss
albino mice against radiation induced histopathological
alterations. Iran. J. Radiat. Res., 2007 4 (4): 161-
168
Dr. A. R. Jalilian, L. Mirsadegh, R. Haji-Hosseini, S. Rajabifar, F. Bolurinovin,
Volume 4, Issue 4 (3-2007)
Abstract
Background: In order to obtain an anti-CD20
conjugate to be used in future therapeutic studies with
therapeutic radioisotopes, 67Ga-labeled antibody was
prepared as a model of metal chelated
immunoconjugate for preliminary dosimetric and
biodistribution studies. Materials and Methods:
Rituximab was labeled with [67Ga]-gallium chloride
after residulation with freshly prepared cyclic DTPAdianhydride.
The best results of the conjugation were
obtained by the addition of 1 ml of a rituximab
pharmaceutical solution (5 mg/ml, in phosphate
buffer, pH=8) to a glass tube pre-coated with DTPAdianhydride
(0.01 mg) at 25|o|C with continuous mild
stirring for 30 min. The final isotonic 67Ga-DTPArituximab
complex was checked by gel electrophoresis
for radiolysis/chemolysis control. Radio-TLC was
performed to ensure the formation of only one
species. Preliminary in vivo studies in normal rat
model were performed to determine the
biodistribution of the radioimmunoconjugate up to 6
hours. Results: Radio-thin layer chromatography
showed an overall radiochemical purity of 96-99% at
optimized conditions (specific activity =300-500
MBq/mg, labeling efficiency 77%). Gel electrophoresis
showed no protein cleavage after radiolabeling.
Conclusion: Preliminary in vivo studies in normal rat
model showed [67Ga]-DTPA-rituximab is a good probe
for bio-dosimetry of therapeutic rituximab conjugates.
Iran. J. Radiat. Res., 2007 4 (4): 187-193
Kakavand, Ghafourian, Haji-Shafeieha,
Volume 5, Issue 1 (6-2007)
Abstract
Background: Miniature neutron sources with high neutron flux have abundant applications in medicine, industry and researches. The most important general characteristic of miniature neutron sources is their diameter which is 3mm in average. In this research, we have surveyed and designed an Am-Be miniature neutron source fabrication. Materials and Methods: This investigation resulted in creation of an Am-Be neutron source, using beryllium metal powder with 98% carat and 100-200 |µm mesh and Americium source with activity of about 200 |µCi. Neutron source designing was performed under safety and protective factors. The system was designed in two different forms based on the fluent yield of neutron or cut off neutron yield. Results: The mean neutron flux of miniature neutron source was measured as 1.14 (n/sec.cm2), and it was calculated as 2.56 (n/sec.cm2) by MCNP (4C) code. Due to purity and mesh of beryllium, which were not calculated by MCNP code, the calculated flux via Monte Carlo method was approximately 2 times larger than neutron flux from fabricated miniature neutron sources. Conclusion: In order to fabricate the miniature neutron sources Am- Be with high efficiency, the americium sources with high activity and the target material (Be) in different forms are required.
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