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Showing 12 results for Das
A. Sattari, S. Dadashzadeh, G. Nasiroghli, H. Firoozabadi,
Volume 2, Issue 2 (9-2004)
Abstract
Background: People who have been administrated radiopharmaceuticals could be a source of radiation to their relatives, medical nurses, and people who are in contact with them. The aim of this work was to estimate radiation dose received by nuclear medicine nurses. Materials and Methods: In this study, the dose rates at various distances of 5 – 100 cm from 70 patients, who were administered diagnostic amounts of 201Tl-Chloride and 99mTc-MIBI, were measured using an ionization chamber. For determination of external radiation dose to the nurses, three different time intervals were used for measurements. Results: The maximum values of external dose rates of 201Tl and 99mTc-MIBI were 11.2 µSv/h ±2.3 and 43.1µSv/h ±11.9 respectively, at 5cm from the patients. Significant exposure from patients after injection of 99mTc-MIBI was limited to the day of administration. Departure dose rate of 201Tl fell gradually so, it became significant by 3 days after administration. Maximum and average absorbed dose of nuclear medicine staff from 201Tl, was 4.6 and 2.7 µSv/h, and for 99mTc-MIBI was 18.1 and 9.8 µSv/h in each scan. Conclusion: Significant exposure from the patients is limited to the few hours after administratio n, therefore patients should be recommended to urinate frequently before leaving the nuclear medicine department. Iran . J. Radiat. Res., 2004 2 (2): 59-62
Dr F. Bouzarjomehri, T. Bayat, M.h. Dashti R, J. Ghisari, N. Abdoli,
Volume 4, Issue 2 (9-2006)
Abstract
ABSTRACT
Introduction: Recently uses of
medium and high energy x-rays has been increased in Iran and radiotherapy
centers along with a variety of accelerators have been installed in some
provinces. In the other hand there is no sufficient skill in designing and
making radiotherapy treatment rooms. This study was conducted to evaluate the
efficacy of different mixtures of barite concrete for shielding the radiotherapy
rooms. In this way we emphasized on determining the size and amount of barite
aggregations to achieve the maximum radiation attenuation which leads to
minimizing wall thickness in treatment room.
Materials and Methods: To
increase concrete density, the barite aggregation was added to concrete.
Different size variations of barite aggregates mixed with different water/cement
ratio were examined. The dimension of cubic concrete specimens for compression
strength test was 15×15×15 cm. The rectangular barite concrete blocks with
different compressions as used for strength test with cross section of 10×10 cm
and thicknesses from 5 to 40 cm were used for radiation attenuation test. For
this test concrete specimens were irradiated by gamma beam of 60Co
(Phoenix Theratron). The transmission radiation through the blocks was measured
by a Farmer ionization chamber (FC65P) in Yazd radiotherapy center.
Results: Our findings showed
that in all specimens the highest mean compression strength was related to the
specimens with equal ratio of fine to coarse barite aggregates but the lowest
HVL was obtained from mixtures with fine to coarse ratio of 35/65. The concrete
sample with a 0.45 water/cement ratio, 350 kg/m3 cement and equal
amounts of fine and coarse barite sands had nearly minimum half value layer(HVL)
and maximum compression strength, so this sample was considered as the best
barite concrete sample.
Conclusion: Since HVL of the
barite concrete specimens with the same compression strength is markedly lower
than the conventional concrete and we have a plenty barite mines in our country
it is recommended to use barite concrete with the best mixture condition based
on our findings for shielding the radiotherapy rooms.
F. Bouzarjomehri, M.h. Dashti, M.h. Zare,
Volume 4, Issue 4 (3-2007)
Abstract
Background: Radiation dose knowledge through Xray
examinations and their distribution in Iran provides
useful guidance on patient dose reduction. The results
of the entrance skin dose (ESDs) of five common
radiographies in all radiology centers in Yazd province
were reported in our previous study (2003). In the
present study we have evaluated the collective
effective dose of conventional X-ray examinations, as
well as the annual per caput of Yazd population.
Materials and Methods: The annual frequencies of
18 different types of conventional radiology
examinations during April 2005 to March 2006 were
recorded from all 35 radiology centers in Yazd
province. The exposure conditions consisted of kVp,
mAs, and Focus surface distance (FSD) of the
examinations for the mode of exposure in each X-ray
unit. 620 ESD were measured by diode dosimeter in
35 hospitals and clinics. The real exposure kVp for
each radiology unit was measured by a Molt-O-Meter.
The conversion coefficient (effective dose - ESD ratio)
for each radiology examination was determined by
using SR262 tables. Finally, the patients' effective
dose was calculated by multiplying the conversion
factor to the ESD. Results: The patients' annual
collective effective dose due to the conventional
radiology examinations was 31.159 man-Sv (0.03 mSv
per inhabitant). The frequency of examinations was
311813 i.e. 0.36 examinations per head of the
population for one year. Conclusion: According to our
findings, the effective per caput dose seems to be
optimally relative to HCL-II countries, which may be
due to low mean effective dose that could obscure
high examination frequency. The number of radiology
conventional examinations and frequency of
radiologist per1000 population of Yazd was more and
lower than HCL-II countries respectively. Thus the
justification of radiography requests in this province
must be revised.
Iran. J. Radiat. Res., 2007 4 (4): 195-200
M. Atarod, Dr. P. Shokrani, A. Pourmoghadas,
Volume 10, Issue 3 (12-2012)
Abstract
Background: In most cancer cases, the treatment
choice for a pregnant patient is radiotherapy. In these
patients, the abdomen is usually not exposed
therefore fetus exposure is due to peripheral dose
(PD). The purpose of this study was to estimate the
fetal dose (the maximum PD in each pregnancy
stage) for modalities available and to fabricate and
evaluate a generally applicable fetal shield. Materials
and Methods: PD values were measured for brain,
breast and mediastinum irradiation in a whole body
anthropomorphic phantom using a NE 2571
ionization chamber. An external shield was then
designed to reduce the fetal dose to the standard
dose limit, 5 mSv. Results: The range of PD values as
a function of distance from the field’s edge were as
follows 1) 9.4-259 cGy for Mantel field 2) 6.5-95 cGy
for chest wall irradiation with 10 MeV electrons, 3)
8.5- 52.5 cGy for tangential field with Co-60 and 4)
4.8-7.8 cGy for brain radiotherapy with 9 MV photon.
PD values for the same setups using the fetal shield
were as follows: 1) 1.4-22 cGy, 2) 0.5-4 cGy, 3) 1.5-5
cGy and 4) under 1 cGy. Conclusions: The measured
PD data sets can be used to estimate fetal dose for
specific treatment setups and pregnancy stages. The
use of external shield designed in this research
reduced the fetal dose effectively to under the threshold
(a 70-90% reduction), except for the final stages
of pregnancy in Hodgkin’s patients. Iran. J. Radiat.
Res., 2012 10(3‐4): 151‐156
D.c. Soren, S.m. Toprani, V. Jain, D. Saini, Dr. B. Das,
Volume 17, Issue 1 (1-2019)
Abstract
Background: Humans are exposed to ionizing radiation from different sources that include natural, occupational, medical, accidental exposures. Evaluation of the effect of low level of neutron exposure to human cells in vitro has important implications to human health. Attempts were made to measure genome damage, transcriptional profile of DNA damage response and repair genes in peripheral blood mono-nuclear cells (PBMCs) exposed to different doses of neutron irradiation (241Am-9Be source) in vitro. Materials and Methods: Blood samples were collected from six random, healthy individuals with written informed consent. The frequency of micronuclei (MN), nucleoplasmic bridges (NPB), DNA strand breaks and gamma-H2AX foci intensity were measured in PBMCs exposed to low doses of neutron (3.0 to 12mGy). Transcription profile of ATM, P53, CDKN1A, GADD45A, TRF1, TRF2, PARP1, NEIL1, MUTYH, APE1, XRCC1, LIG3, FEN1 and LIG1 were analysed in PBMCs at 30 min and 4h post-irradiation using real time quantitative PCR. Results and Discussion: Our results revealed a significant increase (P≤0.05) in the frequency of MN at 9.0 and 12.0mGy as compared to control. A dose dependent increase in the percentage of DNA in tail and an increased intensity of gamma-H2AX foci were observed. CDKN1A and GADD45A showed marginal up-regulation at 30 min, whereas PARP1 showed increased expression at 4h post-irradiation across the doses studied. Conclusion: The present study revealed that GADD45A, CDKN1A and PARP1 can be used as early signatures for low-dose neutron exposure. However, further in vitro and in vivo studies are required to establish its implications in radiation protection science.
E. Lavdas, M. Papaioannou, A. Tsikrika, E. Pappas, G.k. Sakkas, V. Roka, S. Kostopoulos, Ph.d., P. Mavroidis,
Volume 19, Issue 3 (7-2021)
Abstract
Background: The existence of air in hollow organs in the thoracic cavity constitutes a life-threatening situation most of the times. However, sometimes in thoracic Computed Tomography (CT) there are artifacts from different sources that could mimic air densities, disorientating the diagnosis. Materials and Methods: 100 patients (46 females and 54 males, mean age: 60 years, range: 20-90 years), who had been routinely scanned in the area of thorax using three different imaging protocols (follow up, aorta, pulmonary vessels) were retrospectively studied. In 67 cases, contrast agent was used during the examination. Every case was studied by two specialists. Results: Artifacts in pulmonary veins were observed in 38 of the cases. Of these artifacts 27 stemmed from contrast agent, calcifications in the vessels, metallic implants, movement of the patient, malfunction of a detector due to the size of field of view (FOV) or due to the existence of contrast agent on the examination table of the CT scanner. In 11 cases, small amounts of air had been inserted into blood circulation during contrast injection. Conclusions: This study characterized and classified many artifacts related to thorax CT in order to separate them from other serious thoracic pathologies (e.g. aortic dissection, ulcer of veins or arteries). The knowledge and identification of the different types of artifacts is very important in order to avoid the risk of misdiagnosis.
H. Vafapour, K. Dashtian, Ph.d., Z. Salehi,
Volume 19, Issue 4 (10-2021)
Abstract
Background: Local Dose Reference Level (LDRL) values as the standard radiation dose of all radiography examinations are used in medical imaging to reveal the patient dose level or administered activity for a specified imaging procedure. Materials and Methods: The incident air kerma (Ki) was measured for five radiographic examinations (Skull AP/Lat, Chest AP/Lat, Lumbar AP/Lat, Thoracic AP/Lat and Pelvic AP) throughout the province of Kohgiluyeh and Boyer-ahmad (as a deprived area). The founding DRLs results were sort; the third quartile was selected as the average DRL and compared with the other DRLs provinces of Iran as well as the standard data of developed countries. Results: The radiographic LDRL were found to be 0.72, 1.62, 3.06, 2.96, 7.21, 9.99, 7.1, 8.42 and 5.56 mGy for Chest PA, Chest Lat, Skull AP, Skull Lat, Lumbar AP, Lumbar Lat, Thoracic AP, Thoracic Lat and Pelvic AP, respectively. Conclusion: The founding revealed that if the applied radiation protocols are as same as developed countries the DRL values in some projections such as the lumbar vertebrae could be close to international references.
V.t. Hridya, Ph.d D. Khanna, R. Aswathi, S. Padmanabhan, P. Mohandass,
Volume 21, Issue 2 (4-2023)
Abstract
Background: The primary goal of this research is to identify the best energy or energy combination for an Intensity Modulated Radiotherapy (IMRT) treatment plan of esophageal cancer. Materials and Methods: Ten retrospective oesophagus case patients were selected, treated with 6MV IMRT plans and later replanned with different energies and energy combinations. The same prescription, planning parameters and optimization constraints were applied to all plans which were analysed and compared based on certain plan parameters and dosimetric parameters. Comparisons were also made using technical specifications, such as Monitor Units (MUs) and Treatment Time (TT). Results: The study shows most significant results with (6X+10X) plan. The Planning Target Volume (PTV) mean dose, D2%, D98%, D50% and Conformity Index (CI95%) improved as 29.68±0.38, 30.86±0.38, 27.42±0.67, 29.84±0.39 and 1.103±0.08 from their respective base plan values with the p-values 0.068, 0.176, 0.006, 0.159 and 0.085 respectively. Among Organs at risks (OARs), the right lung V20, left lung V20, spine mean dose and spine D1% values reduced to 7.99±6.0, 10.59±7.7, 19.99±9.7 and 18.63±9.4 from 8.70±6.50, 11.98±7.9, 22.76±7.6 and 20.04+8.0 respectively with the p-values 0.172, 0.259, 0.090 and 0.092. Total MU and TT in the original plan were 5054.28±2286.1, and 25.12±11.2, however they were lowered to 3036.54±1556.2, and 16.52±11.2, with p-values of 0.043 and 0.137, respectively. Conclusion: This study concludes that the mixed energy plan (6X+10X) is optimal for high-quality IMRT therapy because of its superior dosimetric indices (i.e., PTV coverage, OAR doses, and technical factors like MUs, TT, and low photoneutron generation).
A. Raj, Ph.d D. Khanna, Vt. Hridya , P. Mohandass, S. Padmanabhan,
Volume 21, Issue 2 (4-2023)
Abstract
Background: The purpose of this study is to contrast the output factors using non-identical detectors with different setups and their effect on the plan of therapy. Materials and Methods: The measurements were obtained for 6MV beams with various volume chambers using Varian True beam™ STx linear accelerator (LINAC). With chambers set up at source to axis distance (SAD) and source to surface distance (SSD) at two different depths, the output factors were measured (both 5 and 10 cm). The smallest output factors were assessed with the SAD technique at 5 cm of depth and the largest output factor was observed with the SSD approach at 10 cm depth and had been moved to the system for treatment planning and variation in calculated and measured dose was noted. Results: A variation in measured dose from Treatment Planning System (TPS) calculated ranges from 0 to -2.7 % for small field plans calculated with SAD technique and -0.22 to -2.31 % for plans calculated with SSD technique. For large fields, it ranges from -0.89 to 0.8 % for SAD and -0.6 to 0.64 % for the SSD technique. The Statistical significance was checked and was found to be greater than 0.05. Conclusion: The percentage difference in output factors at two depths was more prominent for low energy beams (6 MV) than for beams of greater energy. This might be a result of the loss of lateral equilibrium as the depth is changed. The output factor measurement at 10 cm of depth and 100 cm SSD is suitable for small fields (3 x 3 cm2) as it increases the lateral equilibrium and hence reduces the error.
N. Khoirunnisa, S. Purnami, D. Tetriana, D. Dasumiati, D. Ramadhani, M.sc., H.n.e. Surniyantoro, M. Syaifudin,
Volume 21, Issue 3 (7-2023)
Abstract
Background: Mamuju is regarded as a high background radiation location (HBRA). The local population's cells may be harmed by the high ionizing radiation dosage in this region. Micronuclei (MN), nucleoplasmic bridges (NPB), nuclear buds (NBUD), and 8-shaped blood cells can be used to detect cytogenetic abnormalities. By comparing blood samples from HBRA to control site samples, this study focused on determining the impacts of high-risk levels of natural radiation in the cells. Material and Methods: The study employed a cytokinesis-block micronucleus cytome (CBMN Cyt) test. Results: In comparison to the control group, the study group had a higher nuclear division index (NDI) and a higher frequency of all abnormalities. The formation of MN and 8-shaped nuclei was significantly influenced by high natural radiation, whereas levels of NPB and NBUD were not significantly affected. Cytogenetic abnormalities were within normal limits and did not correlate with age or gender. Conclusion: Chronic high background radiation exposure impacted human lymphocyte cell growth and the levels of certain biomarkers.
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