Radiation cancer risk from doses to newborn infants hospitalized in neonatal intensive care units in children hospitals of Isfahan province

Background: This study aimed to investigate dose area product [DAP], effective dose, and radiation risk in newborn infants hospitalized in neonatal intensive care units in Isfahan and Kashan

Materials and Methods: During a period of six months, DAP for chest X-ray examinations for newborn infants hospitalized in NICUs of five special hospitals including Beheshti [in Kashan], Al-Zahra, Imam Hossein, Amin and Goldis [in Isfahan] were measured using DAP meter. Then, using the dose area product [DAP] and conversion coefficients, the effective dose was calculated. Radiation risk per single exposure was estimated by applying 2.8 × 10-2 and 13 × 10-2 factors per Sievert. Also, to estimate the radiation risk in the exposed population, the collective effective dose and the mentioned factors were used

Results: The mean DAP, the effective dose, the radiation risk per single exposure, and the radiation risk in the exposed population were found to be 15.37 +/- [1.19], 45.52 +/- [3.28], [1.27-5.91] × 10-6, and [0.0045-0.021], respectively

Conclusion: Findings indicate that the effective dose and therefore radiation risk in NICUs for newborn infants is higher than that of other studied cities in Iran. Consequently, it is necessary to attempt to reduce radiation dose while maintaining the image quality. In addition, theoretical and practical training programs are needed to increase the knowledge and skills of radiologic technologists on the concept of As Low As Reasonably Achievable [ALARA] and possible radiation cancer risks

Evaluation of dosimetric characteristics of diodes and ionization chambers in small megavoltage photon field dosimetry

Background: modern radiation therapy such as intensity modulated radiation therapy [IMRT] and volumetric modulated arc therapy [VMAT] has resulted in using small therapeutic photon beams. The scope of this work is to investigate the variation in efficiency of different ionization chambers and semiconductor diodes in small multi leaf collimator [MLC] defined fields of ARTISTE linear accelerator

Materials and Methods: dose distributions measurements was done in field sizes ranging from 0.5×0.5 to 10×10 cm2 combining with Monte Carlo [MC] simulation. The treatment head of linac and the detectors were simulated by means of BEAMnrc/DOSXYZnrc of EGSnrc MC. The parameters such as output ratio [OR], penumbral width, dosimetric field size and the percentage surface dose in small radiation fields was evaluated using ionization chambers and semiconductor dosimeters

Results: ORs and beam profiles resulting from various measurements showed significant difference between ionization chambers and diodes in small fields. Derivation of less than 2% was observed between EDGE and Diode P. ORs vary by more than 30% for 1×1 cm2 field size but in larger field sizes differences was less than 1%. Penumbra underestimation was seen in Semiflex relative to pinpoint ionization chamber. No difference was seen in the pattern of surface dose among the applied detectors

Conclusion: dosimetric characteristics of different detectors showed significant differences in small photon beams. Profiles and ORs analysis with different dosimeters showed that not only water equivalency of detectors, but also dosimeter active volume is important factors for determination of dosimetric behavior in small photon beams

Detection of breast cancer using non-invasive X-ray diffraction technique of hair: a preliminary study

Background: An early diagnosis of breast cancer relates directly to an accurate treatment plan and strategy. Early detection of breast cancer before its development would be a significant reduction of morbidity and mortality rates. The aim of this preliminary study is to investigate the sensitivity of Wide Angle X-ray diffraction [WAXRD] method on women hair samples of healthy and breast cancer patients in comparison with other modalities such as synchrotron based XRD beam and mammography. Materials and Methods: Hair samples were taken from occipital region of skull from healthy and breast cancer patients [43 women] were analyzed using X-ray diffraction and the results were analyzed and compared with mammography and pathology reports. Results: The results of analyzed samples showed the sensitivity for purposed WAXRD method was 86% in comparison with synchrotron based XRD beam [64%] and also with mammography [70%]. Conclusion: This non-invasive method is less harmful and is more sensitive than the two other methods and help the physicians for choosing accurate treatment plan

Determination of organ doses in radioiodine therapy using medical internal radiation dosimetry [MIRD] method

Radioiodine therapy has proven to be an effective method in the treatment of patients with differentiated thyroid carcinoma after thyroidectomy. The scope of this study is to describe a method to obtain the dose of organs using medical internal radiation dosimetry [MIRD] method. At the end, the results of MIRD calculations were compared with thermoluminescent dosimeter [TLD-100]. The study was performed on 27 patients using TLD for thyroid, sternum and cervical vertebra. There were 5 TLDs for each organ which they were taken after 4, 8, 12, 20 and 24 hr. To calculate the amount of activity in the thyroid a head and neck phantom with a source of 10 mCi of 131I was used. A head and neck phantom was used to determine the absorbed dose. A source of 10 mCi of [131]I was putted on phantom. Several TLDs were placed on the surface of thyroid on phantom for 24 hr and then compared with the dose of phantom and patients followed by calculation of the activity in patient's thyroid. Finally, MIRD formula was used to calculate absorbed dose in cervical vertebra and sternum. The average of measurements of TLDs on phantom for 10 mCi of iodine was 33.3 cGy. The absorbed activity in thyroid in three groups for 100, 150 and 175 mCi administered 131I were 94.9, 104.6 and 108.8 mCi cumulated activity in 24 hrs. The absorbed dose obtained by MIRD calculations was found to be 419.9, 463.2, and 481.5 for thyroid, 288.9, 252.4 and 252.4 for sternum and 288.9, 252.4 and 252.4 for cervical vertebra. The results of MIRD method was similar to the results obtained experimentally. It was shown that 75% of absorbed dose calculated by the MIRD method is detectable by the TLD method

Determination of absorbed dose of organs [thyroid, sternum, cervical vertebra] in thyroid cancer patients following radioiodine therapy

In patients with thyroid carcinoma, radiation absorbed doses of the thyroid and surrounding tissues is important to weigh risk and benefit considerations. In nuclear medicine, the accuracy of absorbed dose of internally distributed radionuclides is estimated by different methods such as MIRD and direct method using TLD. The aim of this study is using TLD and a phantom to determine the amount of cumulated activity in thyroid and surrounding tissues. Thermoluminescent dosimeter [TLD] measurements were performed on 27 patients on the skin over the thyroid, sternum and cervical vertebra. There were 5 TLDs for each organ which they were taken after 4, 8, 12, 20 and 24 hr. To calculate the amount of activity in the thyroid a head and neck phantom with a source of 10 mCi of [131] I was used. Several TLDs were placed putted on the surface of thyroid on phantom [similar to patients] for 24 hr and then compared the dose of phantom and patients followed by calculation of the activity in patient's thyroid. TLD measurements showed cumulated radiation absorbed doses [cGy] of 315.6, 348.1 and 361.9 for thyroid with administration of 100, 150 and 175 mCi of [131] I, respectively. For sternum the values found to be 201.5 cGy, 275.2 cGy and 242.6 cGy. For cervical vertebra results were 311.5 cGy, 184.1 cGy and 325.9 cGy. The average of measurements was 33.3 cGy using of TLDs on phantom and absorbed activity in thyroid were 94.9, 104.6 and 108.8 mCi in 24 hr for mentioned doses administration. In this work a method to obtain the absorbed activity in the thyroid and other surrounding tissues is described. By this method, the amount of [131] I needed for each patient also could be determined. The results of this work can be used in estimation of absorbed dose in thyroid and other organs using of MIRD method

[Relationship between occupational exposure and concentration of some trace elements in radiology and radiotherapy workers]

Investigating the chronic radiation effects in radiotherapy workers requires consideration of those parameters in which any small changes could result in profound effect on biological system. In this regard, body trace elements are believed to have important roles. To assess the biological effect of occupational exposure on blood trace elements concentrations. This was a case-control study performed at Isfahan University of Medical Sciences in 2006. Fifty radiotherapy workers were selected as case group and an equal number of hospital staff with similar social class and no radiation exposure as control group. Blood samples were collected from all members of two groups followed by determination of serum content of trace elements including copper, iron, zinc and magnesium. The data were analyzed using variance and regression tests. The mean concentrations of copper, iron, zinc and magnesium in technician group were 1.026 +/- 0.287, 1.052 +/- 0.185, 0.768 +/- 0.143, 21.112 +/- 1.272 and in control group 0.903 +/- 0.208, 1.00 +/- 0.134, 0.872 +/- 0.156, and 21.105 +/- 1.372, respectively. Values obtained for copper in technicians group were found to be higher than those of control group [p<0.02]. Zinc concentration was shown to be significantly lower in female technicians [p<0.03] than in males. No significant difference was found for magnesium or iron between two study groups. Based on data found in present study, the likelihood of the idea that chronic exposure to radiation could affect the concentration of body trace element is highlighted

Dosimetric characteristics of 137Cs sources used in after loading selectron system by Monte Carlo method

For an effective treatment planning in brachytherapy, it is necessary to know the accurate source dosimetric information such as air kerma strength, exposure rate constant, dose rate constant and redial dose distribution. The usual method to determine these factors is thermo luminescent dosimeter [TLD] dosimetry. Nowadays, another more accurate method is known to be the Monte Carlo simulation, and it is widely used in determining of brachytherapy sources dosimetric factors. The aim of the present study has been determine to dose distribution of 137Cs sources configuration used in interacavitary low dose rate [LDR] Selectron brachytherapy by Monte Carlo simulation method. Simulation has been performed for 137Cs stainless-steel encapsulated source in 2.5 mm in diameter of Selectron system. Six different combinations of 137Cs sources were simulated and each combination was put into different applicator. The Monte Carlo MCNP4C code was used for simulation. The number of history was taken 1 million for the calculation of air kerma strength and exposure rate constant and 0.1 million for calculating dose rate constant and redials dose distribution. Maximum air kerma strength was obtained for the combination with fourteen active sources and found to be 919.3 microGym2h-1 while its minimum value was 133.9 microGym2h-1 for the case with two active sources. Maximum and minimum dose rate constant of 4.3 cGyh-1mCi-1 and 2.1 cGyh-1mCi-1 were obtained for the combination with eight and fourteen active sources, respectively. The results indicated that the Monte Carlo simulation method may be useful to determine dosimetric characteristics of brachytherapy sources

Entrance surface dose measurements for routine X-ray examinations in Chaharmahal and Bakhtiari hospitals

There is not any report on the radiation doses received by patients in diagnostic radiology sections in hospitals under control of Chaharmahal and Bakhtiari Medical Sciences University, in the south west of Iran. The aim of this study is measurement of entrance surface doses [ESD] for the most routine types of X-ray procedures in radiology centers as part of ongoing dose reduction program. Geiger-Muller and thermoluminescence dosimeters [TLD], were used to measure entrance surface doses for four common radiographic views in six hospitals [7 X-ray machines]. The entrance surface dose was measured on 20 randomly selected patients [male and female] for each X-ray examination. Patients were not exposed to any additional radiation and the radiographs were used for diagnostic purposes. The entrance surface doses for the PA and lateral chest X-ray examinations were found to be in the range of 0.22-1.45 and 0.34- 4.90 mGy, respectively. The ESD values for the AP or PA skull and LAT skull were in the range of 2.55-8.45 and 2.85-9.12 mGy, respectively. Most of the ESD measured doses were slightly greater than the ICRP and NRPB reference doses. The results of the present study indicate a need for quality assurance [QA] programs to be undertaken to avert considerable cost and high patient doses. The recommendations to avoid unnecessary radiation exposure are also given without lose of image quality

[ rate of exposure of patients in common X-ray examinations in radiology centers of Chaharmahal and Bakhtiari province]

Among the man-made radiation sources, X-ray machines cause most of the patient exposures. The aim of this study was to measure the radiation doses received by patients in diagnostic radiology departments in Chaharmahal and Bakhtiari province. Seven X-ray machines from six hospitals were studied. Entrance surface dose [ESD] was measured for twenty randomly selected patients for each X-ray machine. The amoluminescence, LiF [Litium floride] and Geiger-Muller dosimeters were used to measure patient's exposure in four common radiographic views. The ESD for the PA and lateral chest x-ray examinations were found to be in the range of 0.22-1.45 and 0.34-4.90 mGy respectively. The ESD values for the AP [Anteroposterior] or PA [Posteroanterior] skull and LAT [Lateral] skull were in the rage of 2.55-8.45 and 2.85-9.12 mGy respectively. The results indicated that quality assurance [QA] programs should be taken seriously to reduce high patient doses. Also it is recommended to avoid unnecessary radiation exposure

Gadolinium-hematoporphyrin: new potential MRI contrast agent for detection of breast cancer cell line

Gadolinium-porphyrins have been synthesized and are currently being investigated as magnetic resonance imaging [MRI] contrast agents. This study aimed to synthesize Gd-hematoporphyrin and applicate it for in vitro detection of breast cancer cell line [MCF-7]. The naturally occurring porphyrin [hematoporphyrin] was inserted with gadolinium [III] nitrate hexahydrate to yield Gd-H. T1 relaxation times and signal enhancement of the contrast agents were presented, and the results were compared. UV spectrophotometer measured the attachment of Gd to the cell membrane of MCF-7. Most of gadolinium chloride [GdCl3] was found in the washing solution, indicate that it didn't fixed to the breast cell membranes during incubation. Gd-DTPA showed some uptake into the MCF-7 cell membranes with incubation, however, its uptake was significantly lower than Gd-H. Good cell memberan uptake of Gd-porphyrin is comparable to controls, indicating selective delivery it to the breast cell line and considerable potency in diagnostic MR imaging for detection of breast cancer

Annual background radiation in Chaharmahal and Bakhtiari province

Measurement of background radiation is very important from different points of view especially for human health. The aim of this survey was focused on determining the current background radiation in one of the highest altitude regions [Zagros Mountains], Chaharmahal and Bakhtiari province, in the south west of Iran. Materials and The outdoors-environmental monitoring exposure rate of radiation was measured in 200 randomly chosen regions using portable Geiger-Muller and Scintillation detectors. Eight measurements were made for each region and an average value was used to calculate the exposure rate from natural background radiation. The exposure dose rate was found to be 28.4 m Rh-1 and the annual average effective equivalent dose was found to be 0.49 mSv. An overall population weighted average outdoor dose rate was calculated to be 49 nGyh-1, which is higher than the world-wide mean value of 44 nGyh-1 and is comparable to the annual effective equivalent dose of 0.38 mSv. A good correlation between the altitude and the exposure rate was observed, as the higher altitude regions have higher natural background radiation levels