International Commission On Radiation Protection Research Articles

Estimation of effective doses to whole-bodies and hands of facilitating staff from radioiodine-131 ablation therapy patients

BackgroundWorkers in the field of radiation therapy are exposed to radiation hazards, and it is necessary to take precautions to limit the radiation dose to nursing staff and physicists.ObjectiveTo evaluate the external dose rate (EDR), effective whole-body dose (EHD) and hand equivalent dose (HED) for facilitating staff from radioiodine-131 (RAI-131) ablation therapy patients.MethodsOne hundred and eighty patients were selected from two radiotherapy centers in Cairo, Egypt in this study and divided into three groups, Group-A, Group-B and Group-C according to administered activities of (RAI-131) of 3700 MBq, 4440 MBq and 5550 MBq for ablation therapy patients respectively. The EDR, EHD and HED were measured using electronic dosimeters.ResultsThe average EDR were 79.1 ± 12.1, 22.7 ± 8.5, 7.0 ± 4.0, 2.9 ± 1.3 and 1.9 ± .9.0 μSv h−1 for group-A, and about 87.8 ± 14.0, 25.6 ± 9.0, 8.1 ± 5.0, 3.4 ± 2.0 and 2.4 ± 1.0 μSv h−1 for group-B and were 93.5 ± 17.0, 31.6 ± 11.0, 10.1 ± 7.0, 4.7 ± 3.0 and 3.4 ± 1.5 μSv h−1 for group-C at 2 h, second, third, fourth and fifth days, respectively after administration of RAI-131. The average annual effective doses were 2.76 ± 0.09 and 1.55 ± 0.05 mSv at center 1, and were about 2.96 ± 0.09 and 1.71 ± 0.06 mSv at center 2 for physicists and nurses, respectively.ConclusionThe EDR as well as the EHD and the HED received by radiation therapy workers up to the fifth day of administered activity RAI-131 were within the limits of values recommended by the International Commission on Radiation Protection (ICRP).

Comparative study between radiation exposure in common urological procedures

BackgroundFluoroscopy has become essential to urological surgery since advancement of endourology. Fluoroscopy use has increased, placing urologists as well as staff members at risk for occupational radiation exposure and related dangers. This study compared radiation exposure for staff personnel in percutaneous nephrolithotomy (PCNL), ureteroscopy (URS) and extracorporeal shock wave lithotripsy (ESWL). Then, study determined the maximum number of PCNL, URS and ESWL cases that staff members can handle safely each year.ResultsRadiation exposure in PCNL group was higher than URS and ESWL especially for surgeon. Dose of radiation exposure in ESWL for surgeon, assistant and nurse was 2.4 microsievert (μSv), 0.9 μSv and 0.8 μSv, respectively. Dose of radiation exposure in URS for surgeon, assistant and nurse was 18.5 μSv, 14.3 μSv and 13.1 μSv, respectively. Dose of radiation exposure in PCNL for surgeon, assistant and nurse was 73 μSv, 51.3 μSv and 47.6 μSv, respectively.ConclusionIncreased stone size and increased fluoroscopy time were associated with high radiation exposure. PCNL procedure was 8.8 times more likely to exhibit high-dose exposure than other procedures. Urologists can perform: 274 PCNL case, 1081 URS case and 8333 ESWL case per year within safe radiation exposure limits advised by International Commission on Radiation Protection (ICRP).

Approaches to Establishing National Diagnostic Reference Levels for Computed Tomography: A Systematic Review

Background: The international commission on radiation protection (ICRP) publican 135 recommends that Diagnostic Reference Levels (DRLs) should be tied to defined technical and patient parameters for the imaging task. Whereas for computed tomography (CT) examinations, DRLs are defined in terms of two established technical parameters namely, Volume-based Computed Tomography Dose Index (CTDIvol) and Dose Length Product (DLP), a debate has ensued as to whether patient size, age and weight or clinical indication should be used as patient parameters. The objective of diagnostic reference levels (DRLs) is to assist in the optimisation of radiation dose to the patients while maintaining diagnostic image quality. It is generally accepted that each country requires having national DRLs to guide the practice of radiography regarding dose optimization as a prerequisite to good radiation protection practice. Objective: This review aimed to establish commonly used approaches to establishing national diagnostic reference levels for computed tomography. Methods: A systematic literature search in databases containing leading journals in radiography, radiology and medical physics was performed aided by the use of carefully selected search terms that relate to CT and DRLs. The literature search was achieved by the use of the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) flow chart. A total of 109 studies were screened out of which 54 were excluded and 55 sought for retrieval. After further assessment for quality, 20 studies were included in this study for review. Key Findings: 95% of the studies in this review used CTDIvol and DLP as technical parameters indicating dose. 70% of the studies reviewed used patient size, age and weight while 30% used clinical indication as patient parameters. 30% of the reviewed articles did indicate that the surveys to establish NDRLs employed a retrospective approach, while 35% employed a prospective approach and 35% did ..

Concentrations of respirable crystalline silica and radon among tanzanite mining communities in Mererani, Tanzania.

Globally, the number of small-scale miners (SSM) is estimated to be more than 25 million, but it supports the livelihoods of around 100 million individuals. In Tanzania, the number of SSM has increased from an estimated 150,000 in 1987 to ~1.5 million in 2017. The miners are at a high risk of occupational-related health challenges. The study aimed to assess the concentrations of respirable crystalline silica (RCS) and radon among the tanzanite mining communities in Simanjiro District, Tanzania. We carried out a cross-sectional study involving the Mererani mines in Tanzania. These are underground mines comprised of informally employed miners, i.e. SSM. Concentrations of RCS and radon gas were measured in 44 study units, i.e. 22 mining pits and within 22 houses in the general community, e.g. shops in the peri-mining community. A total of 132 respirable personal dust exposure samples (PDS), 3 from each of the study units were taken, but only 66 PDS from the mining pits were analysed, as this was the main interest of this study. Radon concentration was measured by continuous monitoring throughout the working shift (and overnight for residences) using AlphaGuard monitor. The medians and comparison to the reference values, OSHA USA PEL and WHO/IARC references, were done for RCS and radon, respectively, using SPSS Ver. 27.0.0). The median time-weighted average (TWA) concentration of the RCS in the mining pits was 1.23 mg/m3. Of all 66 personal dust samples from the mining pits, 65 (98.5%) had concentrations of RCS above the Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) of 0.05 mg/m3. Mining pits had a median radon concentration of 169.50 bq/m3, which is above the World Health Organization (WHO)/International Commission on Radiation Protection (ICRP) recommended reference of 100.00 bq/m3 but not above the upper reference of 300.00 bq/m3, while the community buildings had a median radon concentration of 88.00 bq/m3. Overall, 9 (20.5%) and 17 (38.6%) radon measurements were above 300.00 bq/m3 and between 100.00 and 300.00 bq/m3 references, respectively. Specifically, in the mining pits, 9 (40.9%) test results were above 300.00 bq/m3, while none of the test results in the community was above 300.00 bq/m3. The tanzanite SSM in Mererani we highly exposed to RCS, which increases the risk of pulmonary diseases, including silicosis, tuberculosis, and pulmonary malignancies. Immediate action by OSHA Tanzania should be enforcement of wearing respirators by all miners throughout the working hours. Health education programmes to the SSM must be strengthened and OSHA Tanzania should adopt the 0.05 mg/m3 PEL, and enforce other occupational health and safety measures, including regular use of dust suppression mechanisms (water spray and wet drilling) and monitoring of RCS exposures among SSM. Monitoring of radon exposure both in the mining pits and community buildings should be conducted, and mitigation measures should be implemented in areas that exceed the reference level of 100.00 bq/m3.

Organ doses, effective dose, and cancer risk estimation from head and neck CT scans

PurposeThe goal of this study was to calculate the organ doses, effective doses, and cancer risk from head and neck computed tomography (CT) scans. Material and methodsAll patients underwent topogram, base, and cerebrum sequences during their head and neck examinations. Two techniques were used to determine the effective dose (ED). The first was based on the scanner derived dose length product, while the second involved using the software that calculated the organ and effective doses. Organ doses were computed using the tissue weighting factors from Report 103 by the International Commission on Radiation Protection (ICRP). The cancer risk values were calculated using web-based software that is based on the BEIR VII Phase 2 report. ResultsThere were 293 patients in this study (189 males, 104 females). The overall mean effective dose in the females was higher than that in the males (2.19 vs. 2.06 mSv). Male patients had a mean cancer risk of 0.011%, whereas female patients had a mean cancer risk of 0.015%. The younger females had much higher cancer risk values. ConclusionThe findings of this study will assist physicians in justifying and optimizing dose administration of head and neck CT examinations by weighing the benefits of diagnosis on the one hand and awareness of cancer risk on the other.

IMPACT ASSESSMENT OF BACKGROUND RADIATION ON HABITANT AND THE MINING ENVIRONMENT AT LAPAI, AREA NIGER STATE, NIGERIA

The anticipated implication of increase in background radiation levels at mineral exploitation sites and consequence on human and environment suggested investigating the Background Ionization Radiation (BIR) levels at a mining site located at closed to the communities of Lapai LGA of Niger State, Nigeria. An in-situ method of BIR measurement at thirty points within the study area was carried out using portable GQ GMC-320 Plus radiation meter at 1.0 m elevation above ground level with GPS for geographical location. The results indicated peak BIR levels of 0.22 mR/h at some points which is abnormal compared to recommendations by International Commission on Radiation Protection (ICRP) for normal environment, while BIR at some other points it was low-ranging, with lowest at 0.0010 mR/h which is in tandem with ICRP recommendation. The absorbed doses in all the points are far below the world average value. The values for the Annual Effective Dose for the entire site agreed with the permissible limits (1.00 mSv/yr) for the general public by the ICRP for non-occupational population exposure. The study therefore revealed that the BIR levels and the doses for the mineral exploitation site does not yet constitute any negative radiological health effect at this moment on the Artesian Miners and the environs. However, there is possibility of continued increase in the BIR level due to mining activities and so continued monitoring is recommended to avert possible health hazards.

ASSESSMENT OF NATURAL IONIZING RADIATION IN TWO TERTIARY INSTITUTIONS OF NIGER STATE

Background ionizing radiation attributed to natural sources has over the years been at increase due to increase in infrastructural facilities and population inducing more human activities within campuses. This called for very great concern because of it effects on the human at higher exposure doses. Consequently, the Assessment of the Natural Ionizing Radiation was carried out at Ibrahim Badamasi Babangida University, Lapai (IBBUL) and Niger State Polytechnic, Zungeru (NSPZ) with approximate populations of 7000 and 5200 students respectively. A portable Geiger-Mueller dosimeter was used at 19 different locations within the two tertiary institutions. The results revealed the Dose Rate variation from 0.14 to 0.186 μSv⁄hr, at IBBUL, while at NSPZ the variation was from 0.12 to 0.158 μSv⁄hr. For all the locations the mean Dose Rate was 0.154 μSv⁄hr with a standard deviation of 0.0195 μSv⁄hr. Generally, average Annual Effective Dose Rate obtained is 0.27 mSv/annum which fell within the recommended alarming limit of 1 mSv/annum given by the International Commission on Radiation Protection (ICRP) for non-occupational population exposure. This implied no adverse impact on the tenements within the two tertiary Institutions. However, part of the recommendations is that more work needs to be done on the soil to characterize the areas for possible radioactive source deposits which may be up to alarming magnitude in the near future.

Analysis of paediatric ct head radiation doses as an initiation to establish local diagnostic reference levels

<p class="Body"><strong>Background and objectives</strong><strong> </strong> <p class="Body">Most of the medical imaging modalities are based on use of ionizing radiation. Ionizing radiation carries the risk of tissue damage and radiation induced malignancy. Therefore, medical imaging should be done under optimal conditions. The purpose of this study was to perform an audit on computed tomography (CT) head radiation doses at the Lady Ridgeway Hospital Colombo (LRH), as an initiation to establish local diagnostic reference levels (LDRL) for the radiology department at LRH. <p class="Body"> <p class="Body"><strong>Methodology</strong><strong></strong> <p class="Body">Computed Tomography Dose Index (CTDI₎ and Dose Length Product (DPL) are the International Commission on Radiation Protection (ICRP) recommended radiation dose indicators for CT. The study was performed by retrospective analysis of CT head records over a period of 6 weeks. Data was collected according to patient’s age, grouped as &lt;1 year, 1–5 years, 5-9 years and &gt; 9 years. Mean and median for CTDI_vol and DLP quantities in each age group were calculated. The median values were used to establish LDRL for the facility.<strong></strong> <p class="Body"> <p class="Body"><strong>Results</strong><strong></strong> <p class="Body">LDRL values for CT head across the age groups are 30 to 57.2 mGy for CTDI_vol and 535.5 to 1235 mGy cm for DLP. <p class="Body"> <p class="Body"><strong>Conclusion</strong><strong></strong> LDRL values for CT head in all age groups at LRH are higher than international DRL values. The difference for DLP is higher than CTDI_volindicating higher scan length and/or higher number of multiphasic studies.

Dosimetric Comparison of Intensity-Modulated Radiotherapy, Volumetric Modulated Arc Therapy and Hybrid Three-Dimensional Conformal Radiotherapy/Intensity-Modulated Radiotherapy Techniques for Right Breast Cancer.

This study aimed to compare different types of right breast cancer radiotherapy planning techniques and to estimate the whole-body effective doses and the critical organ absorbed doses. The three planning techniques are intensity-modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT; two methods) and hybrid 3D-CRT/IMRT (three-dimensional conformal radiotherapy/intensity-modulated radiotherapy). The VMAT technique includes two methods to deliver a dose: non-continuous partial arc and continuous partial arc. A thermoluminescent dosimeter (TLD) is placed in the RANDO phantom to estimate the organ absorbed dose. Each planning technique applies 50.4 Gy prescription dose and treats critical organs, including the lung and heart. Dose-volume histogram was used to show the planning target volume (V95%), homogeneity index (HI), conformity index (CI), and other optimized indices. The estimation of whole-body effective dose was based on the International Commission on Radiation Protection (ICRP) Publication 60 and 103. The results were as follows: Continuous partial arc and non-continuous partial arc showed the best CI and HI. The heart absorbed doses in the continuous partial arc and hybrid 3D-CRT/IMRT were 0.07 ± 0.01% and 0% (V5% and V10%, respectively). The mean dose of the heart was lowest in hybrid 3D-CRT/IMRT (1.47 Gy ± 0.02). The dose in the left contralateral lung (V5%) was lowest in continuous partial arc (0%). The right ipsilateral lung average dose and V20% are lowest in continuous partial arc. Hybrid 3D-CRT/IMRT has the lowest mean dose to contralateral breast (organs at risk). The whole-body effective doses for ICRP-60 and ICRP-103 were highest in continuous partial arc (2.01 Sv ± 0.23 and 2.89 Sv ± 0.15, respectively). In conclusion, the use of VMAT with continuous arc has a lower risk of radiation pneumonia, while hybrid 3D-CRT/IMRT attain lower secondary malignancy risk and cardiovascular complications.

Gonad dose assessment in paediatric kidney nuclear medicine test using Monte Carlo simulation.

ABSTRACTIn this study, we evaluated the effect of radiation dose on gonads during paediatric kidney nuclear medicine tests. Using Monte Carlo simulations, the distribution and effects of radiation were physically evaluated by displaying the distribution path of the source in the human body over time. In particular, the evaluation of doses in children, who are sensitive to radiation during nuclear medicine tests that use internal exposure among several types of medical exposures, was conducted to obtain data for the management of medical exposures. Our results indicated that under normal kidney function, the dose received by the target kidney was 0.430 mGy/mCi, which is ~6% higher than the dose suggested by the International Commission on Radiation Protection (ICRP). Furthermore, when kidney function was compromised, the dose estimated was 0.726 mGy/mCi, which is ~2% lower than the dose suggested by the ICRP. In the male and female gonads, namely the testicles and ovaries, the doses received were 0.359 mGy/mCi and 0.394 mGy/mCi, respectively, under normal kidney function. Similarly, under abnormal kidney function, the doses ranged from 0.187 to 0.353 mGy/mCi and 0.238 to 0.388 mGy/mCi in the male and female gonads, respectively.

Assessment of Environmental Radioactivity Level and its Health Implication in Imiringi Community Bayelsa State, Nigeria

A total forty two (42) sampled points were investigated for radioactivity level and health implication using standard method. The exposure dose rate ranged from 14 to 32μRh-1 with an average value of μ23Rh-1. Dose rate and equivalent dose rate ranged from 121.8 to 278.4nGyh-1 and 1.18 to 2.69mSvy-1 respectively. The average value of the indoor annual effective dose equivalent (AEDE), outdoor AEDE, and excess lifetime cancer risk (ELCR) were computed to be 0.936 mSvy-1, 0.311 mSvy-1 and 0.810 x 10-3 respectively. Analysis of dose to human organs; testes and ovaries, were 0.61 and 0.43 mSvy-1 respectively. Exposure rate, dose rate and ELCR exceeded the recommended values. All the outdoor AEDEs were within the permissible value of 1.0 mSvy-1 for general public and below the limit of 20 mSvy-1 for radiological workers as recommended by InternationalCommission on Radiation Protection (ICRP).&#x0D; Keywords: Assessment, Environmental radioactivity, Exposure dose, Health impact

Radiation Hazard, Safety, Control and Protection

The field of Radiology and Nuclear medicine has advanced from era of X-rays to today's modern imaging techniques, most of which use the ionizing radiation. With the benefits of better diagnosis and treatment, it has caused manifold increase in radiation exposure to the patients and the radiology and nuclear medicine personnel. Many studies done till date have clearly documented the harmful effects of ionizing radiation from radiation exposure, especially cancer. This is more important in paediatric population as their tissues are more radiosensitive, and they have more years to live. Diagnostic and therapeutic radiological procedures including nuclear medicine are integral part of modern medical practices, exposing both patients and medical staff to ionizing radiation. Without proper protective measures, this radiation causes many negative health effects. Hence, proper knowledge and awareness regarding the radiation hazards and radiation protection is mandatory for health professionals, especially the nuclear medicine and radiology professionals. International Commission on Radiation Protection (ICRP) has recommended two basic principles of radiation protection, justification of the practice and optimization of protection.&#x0D; Faridpur Med. Coll. J. Jul 2019;14(2): 100-103

Effectiveness of Post National Dose Survey (NADs1) Towards Dose Compliance Level

The increasing number of CT procedures owing to advanced CT technology requires careful monitoring by the personnel involved to ensure appropriate examinations and optimized procedures. For that reason, CT optimization is a crucial factor that could help to compensate for [[[AUTHOR: Could this sentence be clarified with more specific information? For example, you might say that optimization compensates for the poor image quality that can occur with low radiation. Thank you.]]] radiation dose and image quality. In current practice, optimization in CT is a complex procedure due to a wide range of acquisition parameters in imaging protocols. Diagnostic Reference Levels (DRLs) have been defined by the International Commission on Radiation Protection (ICRP) as a form of investigating the level of patient dose for a specified procedure used in medical imaging to indicate whether, in routine conditions, the patient dose is unusually high or low for that procedure. Hence, the Ministry of Health (MOH) has established a national DRL through a dose survey conducted from 2007 to 2009, and the project is called as NADS1. However, the study does not cover the effectiveness of image quality; in contrast, the current research focuses on both dose exposure and image quality to determine the level of effectiveness of the developed NADS1 data. This study involves several levels, including the acquisition of patient exposure data, image quality assessment, and effective dose measurement. Determination of acquisition of patient exposure data is based on the indicator of QAP CT Brain developed by the MOH, i.e., the total number of adult CT brain examinations for which the DLP value shall not exceed 10% of the national DRL values, 1050 mGy.cm. The outcome of this study can be used as a measure to optimize patients’ radiation exposures and can be a guide for implementing improvement measures. The results of this study allow radiology personnel to understand the concepts and mechanisms associated with managing patient radiation exposures. The outcome also provides the level of effectiveness of the developed QAP, which was implemented by the MOH and subsequently became a benchmark for improving the quality of healthcare services. Therefore, it is clear that this study has shown an impact on the level of optimization from the radiation exposure study, the NADS2 that is being implemented.

Living in radioactive environments: a non-human perspective

Radiation protection of non-humans has recently been integrated into the ICRP (International Commission on Radiation Protection) framework using a reference animal and plant approach matching the anthropocentric 'reference human' approach. While this is simple to implement it has many drawbacks and is essentially focusing on measurements of uptake and transfer of radionuclides in individuals. This ignores the complexity and interdependence of natural ecosystems. It also ignores the biology involved in management of radiation damage in wild populations. To address these concerns international efforts are being made to develop a more ecocentric or holistic approach. Especially important is the recognition that ecosystems are very complex and that adverse emergent properties of these systems such as biodiversity collapse are not predictable from measurement of impacts on individuals. The paper discusses the limitations of current ICRP approaches and considers some promising new ideas, which may lead to more integrated protection systems involving the ecosystem as a central focus rather than the individual.

New Eye Lens Dose Limit: Status of Knowledge in Campania Hospitals.

The International Commission on Radiation Protection (ICRP) in 2011 recommended the lowering of the annual eye lens dose limit from 150 mSv/year to 20 mSv/year in order to reduce the risk of X-ray-induced lens opacity in medical staff. The purpose of this study was to assess the status of knowledge of the new eye lens dose limit and of the radioprotection culture among operators. To this end, a questionnaire was administered to physicians, X-ray technicians, and nurses working in five hospitals of the Campania region, Italy. A total of 64 questionnaires were collected in the hospital departments in which procedures involving ionizing radiation were routinely performed. The data analyzed yielded the following results: 12 operators affirmed to know the new eye lens dose limit, 53 operators routinely wore lead aprons, and 23 operators used lead glasses. Four workers performed eye lens dosimetry through specific dosimeters. A significant lack of knowledge of the reduced eye lens dose limit suggests the need to implement radioprotection-training programs aimed at raising awareness about the importance of health care in the workplace and at reducing the risk of radio-induced effects to the eye lens.

Assessment of indoor and outdoor background radiation levels at school of technology, Kano State Polytechnic, Kano State-Nigeria

A Survey taken by the world health organization (WHO) and the international commission on radiation protection (ICRP) shows that residents of temperate climate spends only about 20% of their time outdoor and about 80% indoors and certain materials use for the construction of such buildings (rocks, soils, tiles etc) are known to be radioactive, and exposure to such radiation results in critical health challenges. Assessment of indoor and outdoor background ionizing radiation level at School of Technology, Kano State Polytechnic, Nigeria was carried out using a digital radiation meter (Radiation Alert Inspector). A total of 49 areas were surveyed and the results obtained showed that the annual indoor reading were highest at Compounding Lab. (2.368±0.35 mSv/yr) and Old Chemistry Lab. (2.169±0.35 mSv/yr), and lowest at New Biology Lab. (1.219±0.21 mSv/yr) and Press Workshop (1.303±0.35 mSv/yr). For the outdoor areas, SOT ring road was found to have the highest value of 0.557±0.17 mSv/yr, while Zoological Garden has the lowest effective value of 0.280±0.05 mSv/yr. For the lecture venues, Auditorium has the highest indoor annual equivalent dose of 2.060±0.49 mSv/yr, while H-Block ND I Textile Class recorded the lowest values of 1.275±0.27 mSv/yr. Base on the aforementioned findings, it was deduced that radiation levels are within the permissible radiation limit as stipulated by the ICRP and UNSCEAR of 2.4 mSv/yr and thus, SOT Kano is radiologically safe.Keywords: Indoor and outdoor, background radiation, equivalent dose, Digital Radiation meter

Pollution Condition and Health Risk Assessment of VOCs in Fermentation Exhaust from Penicillin Production

Penicillin is the most widely used and longest-lived antibiotic in the pharmaceutical industry. It belongs to the bio-fermentation chass of drugs, with a large amount of fermentation exhaust containing volatile organic compounds (VOCs) generated during the process of penicillin production, which have a serious impact on the environment. In this study, the pollution characteristics of the fermented exhaust are studied by using investigation and testing the souces of the pollution and via a health risk assessment model. The main results show that 23 kinds of VOCs were detected in the penicillin fermentation exhaust. The main pollutants included vinyl acetate trifluorotrichloroethane, dichlorotetrafluoroethane, and methylene chloride. In the heating stage, holding stage, cooling stage, and fermentation stage, the proportion of chlorinated hydrocarbons was the highest, followed by esters, and the total amount of these two kinds of substances accounted for more than 90% of total volatile organic compounds (TVOCs). Using the model of health risk assessment, the noncarcinogenic risk value of the total fermented exhaust was 4.98×10-5, which estimating the risk value by concentration gradient expansion is much lower than the maximum acceptable level (5×10-5 a-1) recommended by the International Commission on Radiation Protection (ICRP), which will not cause certain non-carcinogenic risk to the exposed population. VOCs in fermentation exhaust also have carcinogenic effects on human beings. The main health hazards to humans are 1,3-butadiene, dichloromethane, methyl chloride, carbon tetrachloride, benzene, and 1,1-dichloroethane.

Dosimetry of cone-beam computed tomography and multi-slice computed tomography scanning for temporal bone

Objective: To compare the effective radiation dose levels of cone-beam computed tomography (CBCT) with those of multi-slice computed tomography (MSCT) when scanning for the temporal bone. Methods: The absorbed doses of CBCT and MSCT scanners were detected using thermoluminescent dosimeters (TLDs) that were placed in a head and neck phantom and a RGD-3D dose reader.Then the effective doses were calculated and expressed according to the International Commission on Radiation Protection (ICRP) 2007 guidelines. Results: Three-dimensional images about temporal bone can obtained by both CBCT and MSCT scanners in this study.The effective dose value of CBCT scanning for bilateral and unilateral temporal bone was 164.1 μSv (bone marrow: 32.1 μSv; thyroid gland: 10.6 μSv; salivary glands: 31.0 μSv), and 98.1 μSv (bone marrow: 17.4 μSv; thyroid gland: 6.2 μSv; salivary glands: 16.1 μSv), respectively.The dose of MSCT scanning for bilateral temporal bone was 714.6 μSv (bone marrow: 95.1 μSv; thyroid gland: 127.8 μSv; salivary glands: 135.7 μSv). Conclusions: When scanning for the temporal regions, the dose levels for CBCT are lower than those for MSCT.Dose levels reduction for CBCT could be obtained when smaller regions were scanned.

Assessment of indoor radon-222 concentrations in the vicinity of Manyoni uranium deposit, Singida

This study aimed to assess indoor radon concentrations in the vicinity of the Manyoni Uranium Deposit in Singida. The concentrations were measured for two months in 32 houses in the vicinity of Manyoni Uranium Deposit and 9 houses at Manyoni town using a portable radon gas monitor (Alpha –GUARD TM ). The radon concentrations ranged from 27±3 to 518±28 Bq/m 3 with the overall mean of 166±12 Bq/m 3 which is above recommended values of 100 Bq/m 3 and 148 Bq/m 3 set by WHO (World Health Organization) and EPA (Environmental Protection Agency's), respectively. The overall mean of indoor radon concentrations from each village were Kipondoda (169±13 Bq/m 3 ), Muhalala (177±16 Bq/m 3 ), Mwanzi, (287±13 Bq/m 3 ), Mitoo (325±21 Bq/m 3 ) and Majengo (377±23 Bq/m 3 ) which exceed the limit set by WHO (World Health Organization) and EPA (Environmental Protection Agency). The value of 325±21 Bq/m 3 and 377±23 Bq/m 3 from Mitoo and Majengo respectively, exceed the limit of 300 Bq/m 3 recommended by ICRP (International Commission on Radiation Protection). Thus there is a non-negligible probability of incurring stochastic effects for people living in the vicinity of Manyoni Uranium mine. It is recommended that human activities should be controlled near the uranium deposits and dwelings should be well ventilated . Keywords: Indoor radon, Concentrations, Cancer, Manyoni uranium deposit, Alpha –GUARD

Monte Carlo simulation of the RBE of I-131 radiation using DNA damage as biomarker.

In general, a weighting factor of one is applied for low linear energy transfer radiations. However, several studies indicate that relative biological effectiveness (RBE) of low energy photons and electrons is greater than one. The aim of this current study was calculating the RBE of I-131 radiation relative to Co-60 gamma photons in 100 μm spheroid cells using Monte Carlo (MC) simulations. These calculations were compared to experimentally measured results. MCNPX2.6 was used to simulate the I-131 and Co-60 irradiation setups and calculate the secondary electron spectra at energies higher than 1keV with varying oxygen concentrations. The electron spectra at energies lower than 1keV were obtained by extrapolation (down to 10eV). The calculated electron spectra were input into the MCDS micro-dosimetric Monte Carlo code to calculate the DSB induction and related RBE. The calculated RBE of I-131 radiation relative to Co-60 photons, as the reference radiation recommended by the International Commission on Radiation Protection (ICRP), was 1.06, 1.03 and 1.02 for oxygen concentrations of 0, 5 and 100%, respectively. Results of MC simulations indicate the RBE of I-131 is greater than one. This finding, despite a 10% discrepancy with the findings of theprevious in vitro study of one of the authors of this paper, reemphasizes that I-131 radiation induces more severe biological damage than current ICRP recommendations.