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RPS8 Assessments: a 19-year review. Time for Change?

R.L. McCredie, D.M. Barnett, J. Ramnamrain, and D.W. Skerrett

Department of Medical Physics, Westmead Hospital, Hawkesbury Rd,, Westmead, NSW 2145, Australia; e-mail:
Rochelle.Mccredie@health.nsw.gov.au

Abstract– In NSW, compliance with ARPANSA Code of Practice Exposure of Humans to Ionizing Radiation for Research Purposes (RPS8) is part of the regulatory framework. A review was undertaken examining the radiation dose assessment reports provided by the Department of Medical Physics within Western Sydney Local Health District for review by the Human Research Ethics Committee (HREC). Between January 2006 and June 2019, 288 radiation risk assessment reports were provided for HREC review, 230 in the past 5 years. Ionising radiation additional to normal clinical management accounted for 60% of the reviews. The assessed radiation dose for these research protocols ranged from 0.002 - 400mSv in a single year, with 45 studies exceeding the recommended dose constraints. The increase in assessments over the past 5 years may arise from a number of factors, such as National Mutual Acceptance Scheme for Ethical review, enabling a simplified approval process, a large number of multinational trials covering a new type of cancer treatment (immunotherapy) and the increasing reliance on CT imaging as the preferred test as predictor of therapeutic response. Many issues exist in the current process, such as responsibilities of the roles outlined in RPS8 being delegated to those with no understanding or knowledge of the Code, providing assessments for external organisations where the exact protocols or standard management may be unknown, and the requirements for risk comparators and information that are helpful, rather than confusing for participants. Determination of what is considered normal clinical management, particularly in the case of multinational clinical trials is difficult, where alteration of set protocols for local requirements is often impossible. Site-specific and sometimes referrer-specific variations to normal clinical practice create further difficulties in providing dose assessments, although these variations may not alter the risk categories for subjects. Generally, the Code as written still provides a useful structure for assessing risk from ionising radiation in medical research. The Medical Physicist has an important role to play in reviewing all research that uses ionising radiation despite the administrative burden, including where the use of radiation is categorised as normal clinical management, or where optimisation and alternative techniques can be used to minimise exposure.

Operator lens exposure assessment and dose reduction in ERCP: Analysis of dose reduction effect by multiple stages of protective measures

Koichi Nakagami, Takashi Moritake, Keisuke Nagamoto, Hiromi Saruwatari, Toshiaki Abe, Koichi Morota, Satoru Matsuzaki, Naoki Kunugita

Department of Radiology, Hospital of the University of Occupational and Environmental Health, Japan, 1-1, Iseigaoka, Kitakyushu-shi, Yahatanishi-ku, Fukuoka-ken, Japan; e-mail: nakagami@clnc.uoeh-u.ac.jp, Department of Radiological Health Science, Institute of Industrial Ecological Sciences, University of
Occupational and Environmental Health, Japan, 1-1, Iseigaoka, Kitakyushu-shi, Yahatanishi-ku, Fukuokaken, Japan; e-mail: moritake@med.uoeh-u.ac.jp, Radioisotope Research Center, University of Occupational and Environmental Health, Japan, 1-1, Iseigaoka, Kitakyushu-shi, Yahatanishi-ku, Fukuoka-ken, Japan; e-mail: t-abeto@med.uoeh-u.ac.jp , Department of Radiology, Shinkomonji Hospital, 2-5, Dairishinmachi, Kitakyushu-shi, Moji-ku, Fukuokaken, Japan; e-mail: qqey494d@adagio.ocn.ne.jp , Department of Occupational and Public Health Nursing, University of Occupational and Environmental Health, Japan, 1-1, Iseigaoka, Kitakyushu-shi, Yahatanishi-ku, Fukuoka-ken, Japan; e-mail: kunugita@med.uoeh-u.ac.jp

Abstract - [Background]Based on the recommendation by the International Commission on Radiological Protection to lower the equivalent dose limit to the lens of the eye from 150 mSv/y to a 5-year average of 20 mSv/y, Japan has been preparing legal changes. However, thus far, Japan has little direct measurement data for the equivalent dose limit to the lens of the eye, and studies on the effects and provisions of the legal changes have not been conducted. [Objectives]To measure the equivalent dose to the lens of the eye per session of endoscopic retrograde cholangiopancreatography (ERCP) and to calculate the effects of sequentially adopting multiple stages of protective measures and the number of cases where 20 mSv is reached for an objective assessment of the exposure risk and discussion of suitable methods of dose reduction.[Methods]In 10 cases where a gastroenterologist performed ERCP, the equivalent dose to the lens of the eye was measured with a radio photoluminescent glass dosimeter during a multi-stage progression successively in the following conditions: (a) ERCP standard mode; (b) ERCP low-dose mode; (c) use of lead shielding device; (d) use of Pb glasses; and (e) use of both lead shielding device and Pb glasses. Fluoroscopy was conducted with an over-tube type fluoroscopic device.[Results]In conditions a, b, c, d, and e, the equivalent dose to the lens of the eye per session was 0.501, 0.182, 0.027, 0.053, and 0.014 mSv, respectively, and the number of cases where 20 mSv was reached was 40, 110, 741, 377, and 1429, respectively.[Conclusion]As the 20-mSv limit was breached in 40 cases in a year when no protective measures were employed, it is necessary to change the X-ray fluoroscopy conditions, such as using the lowdose mode. In about 200 cases in a year, use of either lead shielding device or Pb glasses in addition to the low-dose mode would significantly lower the likelihood of exceeding 20 mSv, and it would seldom occur if both lead shielding device and Pb glasses are used.

Activity estimation during accelerator-based BNCT treatment

M. Ishikawa, H. Tanaka, H. Kumada

Graduate School of Health Sciences, Hokkaido University, N-12 W-5 Kita-ku, Sapporo, 060-0812, Japan; e-mail: masayori@med.hokudai.ac.jp Institute for Integrated Radiation and Nuclear Science, Kyoto University, 2 Asashiro-Nishi, Kumatori-cho, Sennan-gun, Osaka 590-0494 Japan; e-mail: h-tanaka@rri.kyoto-u.ac.jp Proton Medical Research Center, University of Tsukuba, 2-1-1 Amakubo, Tsukuba, Ibaraki 305-0005, Japan; e-mail:kumada@pmrc.tsukuba.ac.jp

Abstract– Boron neutron capture therapy (BNCT) is one of the particle therapy that can selectively kill only cancer cells by irradiating epithermal neutron to cancer cells which uptake 10B compound. Since BNCT requires neutron irradiation for a long time, activation of all constituent elements contained in the patient's body might be a problem. Concerns regarding radiation may include exposure of the patient, exposure of medical personnel, public exposure, etc. In this report, we investigated the effective radiation dose associated with patient activation predicted by accelerator-based BNCT neutron source using a particle transport Monte Carlo code. The tissue composition and density in the body were obtained from ICRU No.44. Since activation by dental prosthetic materials might be occurred in the treatment of the head and neck region, the elements contained in dental materials and the maximum expected usage were listed. For the estimation of activation, particle transport Monte Carlo calculation code PHITS ver.2.89 and DCHAIN-SP (ver. 2014) were used. Immediately after the end of irradiation, the effective dose rate by 108Ag is the highest, but it decays quickly and falls to a level that cannot be detected within one day. Subsequently, it can be seen that the effective dose rates of 198Au and 64Cu are high. Since 198Au has a half-life of about 2.7 days, and about 7.7% of radioactivity remains even after 10 days from irradiation, there is concern about exposure to the public due to patients going out. Since the gold usage is 42.2 g in the worst case, the effective dose rate at 1 m from the patient is 3.34 μSv/h after 1 day and 2.58 μSv/h after 10 days. The cumulative effective dose for 1 year after the end of irradiation for one year from the patient is 241 μSv, and it can be reduced to 86.3 μSv after 5-days cooling. As a result of examining the activation of constitutive elements and dental materials by BNCT irradiation using an accelerator neutron source, the exposure to the public by constitutive elements was negligibly small. Among dental materials, gold has a particularly large activation cross section and a long half-life of about 2.7 days, which may exceed the exposure limit for the general public. Furthermore, since the patient himself / herself is exposed to a great deal of radiation, it is essential to take measures such as extracting a tooth in advance when the patient uses gold teeth.

A bird’s-eye view of ALARA in vascular surgery – Ruffling feathers in the angiography suite

J. Dawson

Department of Vascular & Endovascular Surgery, Royal Adelaide Hospital, Adelaide, SA, 5000, Australia; e-mail: joseph.dawson@adelaide.edu.au Faculty of Health & Medical Sciences, University of Adelaide, Adelaide, SA, 5000, Australia

Abstract–Over the last 30 years vascular surgery has gone though an evolution, moving away from open surgery towards less invasive fluoroscopically-guided endovascular interventions. This has resulted in a significant positive impact on patients, including reduced morbidity and mortality, and currently endovascular interventions comprise approximately three-quarters of all vascular procedures. However this exponential increase in not only the number, but also complexity, of endovascular interventions has resulted in vascular surgeons being amongst the highest exposed specialists to occupational radiation in medicine. Whilst there have been parallel innovations in radiation-reduction technology, such as image fusion, operator-controlled imaging and novel shielding techniques, these have failed to keep pace with interventional technology. Consequently these technologies have been unable to negate the increased use of radiation associated with modern vascular practice. This highlights the essential importance of ALARA principals, with adherence to the basic tenets having profound effects on reducing patient, and consequently, operator dose. This doctrine must also be extended out of the operating room, where the number of pre- and post-operative diagnostic imaging studies matches interventions, with a significant increase in radiation exposure observed within the general population secondary to medical imaging. Changes in behaviour amongst interventionalists is the first step in tackling increased radiation dose within the angiography suite. However, there are also a number of other factors that impede best practices in radiation safety which need to be concurrently addressed. These can be categorised as regulatory, institutional, educational, commercial, financial and patient-related. Examples include: inconsistent radiation safety practices are closely linked to an absence of leadership, with the head of unit being key to developing a culture of radiation safety; Consistency of personal dosimeter use not only reflects personal practice, but actually reflects radiation safety culture as a whole within an institution; Personal lead garment testing and labelling is notoriously opaque; Traditionally little time has been dedicated to radiation safety education and training, with existing training often heterogenous or incomplete, with large discrepancies in curriculum; In some countries renumeration of interventional procedures is intimately linked to the number of DSA runs, creating direct conflict between ALARA and income. Recent high-profile cases of cancers and cataracts amongst interventionists has brought the importance of ALARA to the forefront of the collective consciousness of interventionalists. It is hoped that the current momentum of concern will translate into action in order to create positive change.

Monte Carlo investigation of gold nanoparticle enhanced proton therapy and the enhancement mechanisms

D. Peukert, M. Douglass, I. Kempson, E. Bezak

Future Industries Institute, University of South Australia, SA, Australia; email: Dylan.Peukert@mymail.unisa.edu.au Division of ITEE, University of South Australia, SA, Australia, Department of Medical Physics, Royal Adelaide Hospital, SA, Australia, Department of Physics, University of Adelaide, SA, Australia, Cancer Research Institute and School of Health Sciences, University of South Australia, SA, Australia

Abstract–Gold nanoparticles (GNPs) are radiosensitisers which have been shown to increase the biological effect of radiation and have the potential to increase the therapeutic effect of radiotherapy. GNP enhanced proton therapy offers the prospect of combining the excellent sparing of healthy tissue of proton radiotherapy with increased biological effect in the tumour from the delivery of GNPs. While GNP enhancement of proton therapy has been observed in experiments the underlying mechanisms are not well understood and a model of the biological enhancement has not yet been developed. However, experiments have provided indications that increased indirect damage from reactive species plays a large role in the observed enhancement. The dose and reactive species distributions over time produced during proton irradiation for a GNP, a GNP cluster and a cell model containing GNP clusters within the cytoplasm (based on distributions from experimental observations) was simulated using Geant4-DNA physics and chemistry models. GNP simulations found a microscale enhancement of dose and reactive species yield by a factor of up to 10. It was determined that intermediate nanoparticle sizes of between 10 and 25 nm were an ideal balance between gold mass and self-absorption. It was found that absorption was reduced with nanoparticle coating thickness. Cluster simulations showed that for a 500 nm cluster containing 1402 15 nm GNPs, secondary electron absorption by other GNPs within the cluster reduced the dose and radiolysis yield to water from the single nanoparticle case by 60%. The simulations show that the ideal nanoparticle for enhancing proton therapy has a diameter of 10-25 nm and a thin coating which limits GNP aggregation. The effect on cell survival from direct and indirect damage to nuclear DNA due to the presence of the GNPs will be determined from cell simulation distributions. The distributions of dose and reactive species from cluster and cell simulations will also be examined to determine other potential biological targets. Optimising nanoparticle design for enhanced proton therapy, understanding the underlying mechanisms of the enhancement and being able to model GNP enhanced therapy is essential for the safe and effective introduction of this novel therapy with appropriate protection guidelines. Gaining an understanding of the mechanism is particularly pressing as nanoparticle enhanced photon therapy has already been approved for clinical use in Europe and it is likely that nanoparticle radiosensitisers will be applied to proton therapy in the near future.

An on-going review of space exploration cancer and non-cancer risk models

S. El-Jaby, S. Sebastian, F. Ali, M. Serran, J. Surette, G. Harrisson, L. Tomi, B.J. Lewis, J. Chen

Canadian Nuclear Laboratories, 286 Plant Road, Chalk River, Ontario, Canada, K0J1J0; e-mail: samy.el-jaby@cnl.ca, Canadian Space Agency, 6767 route de L’Aeroport, Saint-Hubert, Quebec, Canada, J3Y8Y9; e-mail: leena.tomi@canada.ca, Royal Military College of Canada (Emeritus), 13 General Crerar Crescent, Kingston, Ontario, Canada, K7K7B4; email: lewisb@rmc.ca, Health Canada, 775 Brookfield Road, #6302C, Ottawa, Ontario, Canada, K1A1C1; email: jing.chen2@canada.ca

Abstract - Canadian Nuclear Laboratories (CNL) in Chalk River, Canada is supporting the Canadian Space Agency (CSA) and Health Canada (HC) in reviewing the radiological health risks associated with deep space exploration. This effort is essential in preparation for anticipated, crewed exploration of the Moon and Mars where the challenges faced differ from those currently experienced in low-Earth orbit (LEO) aboard the International Space Station (ISS). Our review is specifically focused on understanding the various elements that comprise a radiological risk framework including: (1) the available environmental descriptions of space radiation sources, (2) the impact that shielding configurations have on dose received, (3) an understanding of the radiation transport tools/codes that are used in simulating/modelling dose and shielding effectiveness, (4) current approaches to dosimetry, (5) available radiobiological studies of radiation induced cancer and noncancer effects, and (6) how risk is assessed and what metrics are most appropriate. This review will be ongoing. Our current summary of this work will be presented and discussed.

Solid-state microdosimeter for personal radon dosimetry in mines and caves

Linh T. Tran, Benjamin James, Dale A. Prokopovich, David Boardman, Sylvester Werczynski, Scott Chamber, Chris Waring, Alastair Williams, Marco Povoli, Angela Kok, Michael Jackson, and Anatoly Rosenfeld

Centre for Medical Radiation Physics, University of Wollongong, NSW, 2522, Australia; e-mail: tltran@uow.edu.au, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia, SINTEF, Norway, University of New South Wales, Australia

Abstract– Radon gas can be found naturally from the materials in which it is formed that contain traces of uranium, actinium, thorium, or neptunium. Uranium and radium are commonly found in soil, rocks and water, especially in enclosed spaces such as mines, caves, cellars or poorly ventilated houses. Radon levels found in uranium, coal and metal mines, especially underground mines, can be up to orders of magnitude above ambient outdoor levels. Radon progeny attach easily to dust particles that can deposit in the lungs when inhaled. Once deposited in the lungs, the radon progeny emits alpha particles, mostly from short lived isotopes 218Po (T1/2 = 3.1 min, E = 6 MeV) and 214Po (T1/2=164.3 µs, E = 7.7 MeV), irradiating and damaging the DNA of lungs or proximal organ tissue, which may increase the risk of developing lung cancer - the second most common cause after smoking. Therefore monitoring radon levels in mines and caves is strictly required in order to protect workers from the health effects of radon exposure. Current radon detectors are bulky, expensive and only measure radon concentration, requiring conversion from concentration to dose which can result in large uncertainties [1]. This work presents a newly developed portable silicon on insulator (SOI) microdosimeter system for use in radon rich environments to measure the dose equivalent caused by 222Rn and its decay progeny. The microdosimeter used in this work is the Mushroom microdosimeters invented and developed by the CMRP, University of Wollongong and fabricated in collaboration with SINTEF MiNaLab, Oslo, Norway. The detector system directly measures in real time dose equivalent H(µSv/h) in a 222Rn gas environment rather than its calculation based on radon activity and dose conversion factor (DCF) as currently. The experiment was carried out at ANSTO environment lab where 245 kBq 226Ra source provides a radon concentration of approximately 150kBq/m3. A dose rate equivalent of 15.4 mSv/h and average quality factor ( ) of 19.96 was measured by the microdosimeter system for the given radon concentration. This result demonstrated that the microdosimeter system can be used in caves, mines for radon dose equivalent monitoring. Miniaturization of electronic personal microdosimeter is in progress and the preliminary results will be presented at the conference. [1] L. Vaillant and C. Bataille, “Management of radon: a review of ICRP recommendations," Journal of Radiological Protection, vol. 32, no. 3, 2012

The Status of NORM regulation in South Korea

Zuhee Woo

Korea Institute of Nuclear Safety, Department of Radiation Safety Research, Korea Institute of Nuclear, P.O. Box 34142, Gwahakro 62, Yuseong, Daejeon, South Korea; e-mail: k698wzh@kins.re.kr

Abstract–The social issues have arisen due to the natural radioactive materials usage since 2007. And the public concerns about radiation have increased after the Fukushima NPP accident in 2011. For these reasons, in South Korea, the Act on Protective Action Guidelines Against Radiation in the Natural Environment was enacted in 2011(effective in July 2012), to protect people against the radiation exposure from natural radioactive materials, household items, and recyclable scrap metals etc. According to the Act, raw materials (NORM), residues and products that contain the natural radioactive nuclides were subject to the Nuclear Safety and Security Commission (NSSC)’s safety management. Therefore, the usage registration of raw material or residues was regulated under the Act. Thereby, the current status of distribution was managed. The NSSC has also conducted a field investigation for safety management on the facilities using the above materials and the workers handling them. The NSSC shall also install and operate the radiation portal monitors at airports and harbors. They even let the recyclable scrap metal dealers install these devices to detect the radioactive materials in the imported goods. In addition, the Korea Institute of Nuclear Safety (KINS) has developed and operated a comprehensive information system to manage the radiation in the natural environment systemically and effectively. Recently, there have been cases that Monazite-containing products exceed safety standards. As a result, safety management for consumer products containing NORM have been significantly strengthened and the related laws are being revised. This presentation introduces the status of safety management for NORM in South Korea.

Investigation of 210Po Activity Concentration in Chinese Typical Seafood and Dose Assessment

Xinfang Dong, Ling Chen, Zhiping Luo, Hongchao Pang, Chuangao Wang, Zinqiang Pan, Ruirui Liu

Department of Radiation Safety, China Institute of Atomic Energy, P.O.Box 275-15, Beijing 102413, P.R.China, e-mail: dongxinfang2918@163.com China National Nuclear Corporation, No.1 Nansanxiang, Sanlihe, Beijing 100822, P.R. China, e-mail: panzq@cnnc.com.cn Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO 63110, US, email: liuruirui.nova@gmail.com

ABSTRACT: 210Po is an extremely toxic radioactive nuclide of 238U decay chain. Since 1960s, the concentration of 210Po in the marine phenomenon draw a great attention around the world. One issue deserves us attention is that 210Po the major contribution factor to the internal dose that is caused by the edible seafood that contains 210Po. In China, relatively few data have been collected for quantifying the concentration of 210Po in the sea food, which impedes accurately assessing the radiation risk from 210Po to Chinese consuming seafood. This paper presents an investigation for the most typical seafood from the four Chinese sea areas (the Yellow sea, Bohai sea, East China sea, and South China sea), including shellfish, cephalopoda, crustacean, fish, seaweed etc.. The total samples include 57 species, 130 marine fishing, and culture seafood. The activity concentration of 210Po and dose of the affecting residents in China were estimated. The samples went through wet ashing will be processed to measure 210Po. First, the diluted samples were deposited on silver disk using auto-depositing, then the 210Po were measured using a PIPS alpha spectrometry with 209Po tracing. The detection limit of this method is 2.2×10-2 Bq/kg (wet weight). The result showed that 210Po activity concentrations of all the marine samples ranged from 2.67E-01 to 2.17E+02 Bq/kg (fresh weight) in the edible part, and the median of activity concentration, arithmetic activity concentration, and yield weighted average activity concentration were 1.41E+01 Bq/kg, 2.44E+01 Bq/kg, and 2.45E+01 Bq/kg respectively. The distribution of 210Po concentration in the marine samples showed the relationship as: Shellfish > crustaceans > fish > cephalopods > algae and other classes. And 210Po concentration were higher in South China Sea and East China Sea than other areas overall. The estimated activity and the annual effective dose of residents consuming marine food by 210Po in 2015 were 87.6Bq and 105.2 μSv/a respectively. Demographically, the activity and annul effective dose for urban residents and rural residents throughout the country were 115 Bq and 138μSv/a, 56.3Bq and 67.6μSv/a, respectively. The minimum values appeared in the Tibet area, the maximum values were in Hainan and Fujian Province. Also, great variations existed among other provinces and cities, which is mainly related to the resident dietary structure. The shellfish, fish, and crustaceans dominated the dose contribution of 210Po intake with a ratio of 97.8%, and particularly shellfish contributed to 68.6%, whereas cephalopods, algae and other categories contributed marginally. Keyword: China sea areas, marine culture, seafood, residents' diet, 210Po, radiation dose.

Assessment of radioactivity levels and radiological hazards in building materials

Fei Tuo

Key Laboratory of Radiological Protection and Nuclear Emergency, National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Beijing 100088, China e-mail: flytuo@163.com

Abstract Building materials are one of the potential sources of radiation. Since people's daily life is inseparable from buildings with different functions, individuals receive a significant part of their radiation exposure indoors. The radioactivity of building materials poses a health hazard to humans through two aspects, which are external radiation and source of internal radiation that comes from radon released by radium. External radiation is caused by the strong penetrating gamma photons emitted by radium, thorium (including their progenies) and potassium.While the internal hazard is due to radon gas and its progeny which are alpha-emitters. In the construction industry, besides natural raw materials, some solid industrial wastes and their by-products containing large amounts of natural radionuclides can be used to produce various types of building materials. Technical, economical and environmental Radioactivity concentrations of 226Ra, 232Th, and 40K in a total of 92 samples including eight commonly used different kinds of building materials were obtained from local manufacturers and suppliers in Beijing were measured by using HPGe gamma-ray spectrometry. The 226Ra, 232Th and 40K activity concentration in all samples varied from 10.1 to 661, 3.3 to 555, and 3.2 to 2945 Bq/kg with an average of 127.8, 114.8, and 701.5 Bq/kg, respectively. The potential radiological hazards were assessed by calculating the absorbed dose rate (D), the radium equivalent activity (Raeq), the external hazard (Hex) and internal hazard (Hin) indices. The investigated building materials were classified into different types according to the radioactivity levels. The results from this research will provide a reference for the procurement, sales and use of building materials. Attention should be paid to the use of coal cinder brick and granite in the construction of dwellings.

Murapeptide protects mice and cells against ionizing radiaiton through Nod2 and ATR activation

H-R. Qin, L. Liu, H.J Qu, Y-Y. Yang, J-G. Cui, F.Gao

Department of Radiation Medicine, Faculty of Naval Medicine, Second Military Medical University,800, Xiangyin Road, Shanghai 200433, P.R. China; e-mail: hongranqin@163.com Department of Nuclear Radiation, Shanghai Pulmonary Hospital, Tongji University,507, Zhengmin Road, Shanghai 200433, P.R. China;e-mail: hongranqin@163.com

Abstract–The victims’ quality of life has been severely reduced by the damage caused by ionizing radiation
(IR). In order to reduce radiation damage, the development of radiation protection agent is considered as one
of the most effective measures. Murabutide (MBD) is an agonist of Nucleotide-binding-oligomerizationdomain-containing proteins 2 (NOD2). In this study, we investigated its radioprotective effects and elucidated its potential mechanism. Our results showed that the MBD pretreatment effectively protected cultured cells and mice from IR-induced toxicity, and inhibited IR-induced apoptosis both in vivo and in vitro. After MBD pretreatment, the decrease of γ-H2AX foci and the up-regulation of ATR signaling pathway suggested that the radioprotective effects of MBD were due to the activation of DNA damage response (DDR) pathway to repair DNA double-strand breakage (DSBs). As the radioprotection of MBD were weakened by ATR selective inhibitors rather than ATM inhibitor, the ATR pathway has been proved to be a more critical pathway that mediates MBD-stimulated DDR pathway. To sum up, our data provide a novel and effective protection measure to alleviate the damage caused by IR radiation.

Effect of Doping and Codoping on Thermoluminescence Properties of NaMgF3

Aayushi Jain, Pooja Seth, Shruti Aggarwal*

USBAS, Guru Gobind Singh Indraprastha University, Dwarka, New Delhi-110078, India; *Corresponding author: e-mail: shruti.al@gmail.com

Abstract– Fluoroperovskite materials doped with rare earth ions have shown interesting dosimetric properties like high sensitivity, linear dose response and low fading etc. In this work, the thermoluminescence (TL) properties of Tb doped and Tb/Eu codoped nearly tissue equivalent fluoroperovskite NaMgF3 having low Zeff~10.3 were studied under gamma irradiations. The samples were synthesized by conventional solid state reaction method and characterized for X-ray diffraction (XRD), Scanning electron microscopy (SEM) and TL measurements. XRD pattern of the synthesized samples were recorded and compared with standard JCPDS data which confirms their formation. The morphology of the samples were studied by SEM images. TL studies were made for samples irradiated with a gamma dose of 15 Gy from 60Co source. TL glow curves of doped and codoped samples exhibit simple glow curve structure consisting of single peak which remains same for all the samples. It was observed that codoping with Eu influences the TL intensity. Associated TL kinetic parameters such as order of kinetics, trap depth and frequency factor were calculated using standard methods for better understanding of the type of defects created in doping and codoping of rare earth ion in host matrix NaMgF3. The obtained results show that this material has great potential for its use in personal dosimetry.

Synthesis and Thermoluminescence Studies of CaSiO3:Yb Phosphor

Aayushi Jain, Pooja Seth, Shruti Aggarwal*

USBAS, Guru Gobind Singh Indraprastha University, Dwarka, New Delhi-110078, India; e-mail: aayushi3jain@gmail.com, pujaseth05@gmail.com *Corresponding author; e-mail: shruti.al@gmail.com

Abstract–High thermal and chemical stability of CaSiO3 makes it a suitable host matrix for luminescence. Also, it has been widely used as a biomaterial for bone related surgical applications. We investigated CaSiO3 as a possible material for applications in the field of radiation dosimetry. A well known biomaterial CaSiO3 doped with Yb in different concentrations ranging from (0.01 mol% - 0.05 mol%) has been successfully synthesized by solid state diffusion method. This material was characterized for (XRD), Scanning electron microscopy (SEM) and Thermoluminescence (TL) measurements. Formation of the samples has been confirmed by recording the XRD pattern and comparing them with the standard JCPDS data. From SEM micrographs, it is observed that particles are agglomerated and have irregular shape, mostly cuboidal flakes and contain several voids. Thermoluminescence (TL) properties has been studied after irradiating with dose of 15 Gy from 60Co source. TL glow curve of undoped CaSiO3 consists of two peaks with main peak at 146°C and another peak at 265°C. When doped with Yb for different concentrations, it is seen that doping with 0.02 mol% and 0.05 mol% of Yb in CaSiO3 has decreased the TL intensity due to quenching effects. However, doping with 0.01 mol% of Yb enhanced the TL intensity without much change in TL glow curve structure. The nature of the energy traps in the samples has been analyzed through glow curve deconvolution by calculating the related TL kinetic parameters. This suggests that CaSiO3:Yb (0.01 mol%) exhibits good TL intensity and hence, it can be used for monitoring of ionizing radiations.

Analysis of Dose Rate Effects on Lifetime Attributable Risks for Thyroid Cancer Incidence

Keonmin Kima*, Seunghee Leea, b, Sukhoon Kima and Hyejin Kima

FNC Technology Co., Ltd., 32F, 13, Heungdeok 1-ro, Giheung-gu, Yongin-si, Gyeonggi-do, Korea(Rep. of), Dept. of Nuclear Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, Korea(Rep. of) * Corresponding author : kkm0117@fnctech.com

Abstract– It is expected that risk estimation is significantly affected by dose rate since cancer risks per Gy at low dose rate differ from those at high dose rate. In this study, to confirm effect of dose rate on thyroid cancer incidence risk, the risk estimations were performed for scenarios exposed by different dose rates using two kinds of thyroid cancer models (i.e., BEIR VII and U.S. EPA 2011). The lifetime attributable risks (LARs) are estimated according to the exposure age (0, 10, 20, 40 and 60 years) using two cancer models and Korean statistics (i.e., cancer incidence rates, population distribution and survival rate by age). Four different exposure scenarios are considered; (1) acute exposure of 100 mSv, (2)20-year chronic exposure of 5 mSv per year, (3) acute exposure of 200 mSv, and (4) 20-year chronic exposure of 10 mSv per year. For Korean population, the lifetime baseline risk (LBR) under no radiation exposure is 2984 per 100,000 persons and LBR for 0, 10, 20, 40 and 60 years are 4379, 2980, 4382, 3365 and 1314, respectively. For all exposure ages, gender-averaged LARs (risk per 100,000 persons) from acute exposure are higher than chronic exposure of the same dose. LARs of 100 mSv acute exposure for 0, 10, 20, 40 and 60 years with BEIR VII model are 3330, 1458, 622, 78 and 3, respectively. In case of 20-year chronic exposure of 5 mSv per year, LARs for 0, 10, 20, 40 and 60 years are 1727, 736, 291, 30 and 2 respectively. For scenarios exposed by 200 mSv, the difference rate of LAR between acute and chronic exposure is larger than the case of 100 mSv. In case of U.S. EPA 2011 model, even though estimates of LARs are smaller than those calculated by BEIR VII model, LARs for acute exposure is larger than those for chronic exposure. The main reason of increased risk in acute exposure is presumed that ERR decreases as exposure age increases in both of two cancer models. Furthermore, since 1.5 of dose and dose rate effect factor (DDREF) is applied for low dose exposure less than 100 mSv, the difference of risk between acute exposure of 200 mSv and 20-year chronic exposure of 20 mSv per year becomes larger. Accordingly, for thyroid, it could be concluded that acute exposure might cause more risk than chronic exposure as the previous studies.

Radionuclide uptake mechanisms by native flora in the vicinity of uranium mines in arid South Australia

S.B. Pandelus, A. Pring, M. Johansen, T.E. Payne, A. Stopic, N.A. Spooner, C.A.G. Kalnins, R.S. Popelka-Filcoff

College of Science and Engineering, Flinders University, Bedford Park, SA 5042, Adelaide, Australia; e-mail: samantha.pandelus@flinders.edu.au, ANSTO, New Illawarra Rd, Lucas Heights, New South Wales, 2234, Australia, School of Physical Sciences, and Institute for Photonics and Advanced Sensing (IPAS), University of Adelaide, Adelaide, SA 5005, Australia, Defence Science and Technology Group, PO Box 1500 Edinburgh, SA 5111 Adelaide, Australia

Abstract–Environmental risk assessments for radiological impacts follow internationally accepted methods including use of the Environmental Risk from Ionising Contaminants: Assessment and Management (ERICA) tool. Concentration ratios (ratio of radionuclides in an organism to that of its host soil/water- CR) are an essential input for these models. However, the available international input data are primarily from temperate Europe and North America, and may not apply in arid conditions. Previous studies have shown that Australian native species accumulate radionuclides from their environment differently when compared to similar species from other climates. This research aims to develop a concentration ratio dataset relevant for U and Th series radionuclides in arid and semi-arid conditions. Olympic Dam, operated by BHP, is a large copper, uranium, gold and silver producer in South Australia, and utilises underground mining, with the ore being processed on site. To examine radionuclide uptake mechanisms by native flora, samples of flora and adjacent soil have been collected at Olympic Dam. Analyses of flora and soil samples included gamma-ray spectroscopy, neutron activation analysis, alpha-particle spectroscopy and inductively coupled plasma mass spectrometry (ICP-MS). Alternative analytical methods have been incorporated including alpha track analysis for flora samples. Alpha track analysis uses a nuclear emulsion gel layer applied to the individual leaf sample. Analysis of the gel is used to identify radionuclide accumulation and spatially-resolve its location within structures of the leaves. Soil from the surface to 10 cm below the surface was analysed by ICP-MS. Results show a gradient of uranium concentration from 4 ppm at the surface to 0.5 ppm at a depth of 10 cm. The soil depth profile data show that the most probable mechanism of radionuclide transport is airborne and therefore any potential uptake into flora is influenced by the depositional effects on the soil surface. Overall this research provides a better understanding of the behaviour of radionuclides in an arid environment and provides data on the mechanisms of radionuclide uptake in flora. It augments existing international data for use in models in Australia and other localities with similar arid environments.

Quantitative assessment of provability of radiation-related cancers considering unavoidable existence of unadjusted risk factors

M. Sasaki, H. Ogino, Y. Fujimichi, N. Hamada, T. Iwasaki, K. Yoshida, T. Hattori

Radiation Safety Research Center, Nuclear Technology Research Laboratory, Central Research Institute of Electric Power Industry, 2-11-1 Iwado kita, Komae-shi, Tokyo 201-8511, Japan; e-mail: michiya@criepi.denken.or.jp

Abstract– The attribution of stochastic effects to exposure to ionizing radiation has been qualitatively discussed by introducing two distinct concepts of provability and probability. This study aims to develop a method of quantitatively assessing the provability of radiation-related cancers. To this end, the ‘minimum provable dose’ (MPD) was developed and applied to actual cancer mortality in Japan. The background lifetime risk of cancer mortality was calculated for the esophagus, stomach, colon, liver, lungs, skin, breasts, ovaries, bladder, and bone marrow as well as the age-specific risk coefficients reproducing those given in the 2007 Recommendations of the International Commission on Radiological Protection (ICRP). Comparing the relative ratio of MPDs, which was defined herein as the ‘provability index’ (PI), we quantitatively ranked radiationrelated cancers for different tissues and organs predicated on provability for ages of 10, 30, 50, and 0–85+ years at exposure. We discuss the radiological protection of male emergency workers focusing on cancers highly prioritized according to the ranking (i.e. colon, bone marrow, and bladder). The present study proposed the system to quantitatively evaluate the level of radiological protection taking into account the variations of the background cancer risk on the provability of radiation-related cancers.

Effect of sieving size and sealing time of soil samples on radionuclide activity concentrations by gamma-ray spectrometer

Baolu Yang, Fei Tuo

National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Beijing 100088, China; e-mail: flytuo@163.com

Abstract Gamma-ray spectrometer is widely used for the determination of the activity concentrations of radionuclides in soil samples because of its simple sample preparation and simultaneous measurement of multiple radionuclides. In order to improve the accuracy of measurement, some researchers have studied the influence of sample density, volume, height and composition on the determination of radionuclides in soil, but little is currently known about the direct effects of sieving size and sealing time of soil samples. In this study, the collected brown earth soil samples were equally divided into four parts. After the samples were dried, they were ground and sieved with width of the mesh 2.0 mm, 1.0 mm, 0.5 mm and 0.25 mm respectively. The resulting fractions are then filled into a polystyrene container respectively that is sealed by gluing. The activity concentrations of 226Ra, 228Ra, 210Pb, 40K and 137Cs in different sieved soil samples were measured by HPGe gamma spectrometry at sealing intervals of 0 days, 4 days, 8 days, 12 days, 16 days, 21days, 25 days and 29 days respectively. The results revealed that there were some significant differences for the activity concentrations of 226Ra, 228Ra, 210Pb, 40K and 137Cs in the soil samples treated with four kinds of sieve diameters. The measured highest activity concentrations of 226Ra, 228Ra and 210Pb were in the soil samples of sieving size of 0.5 mm and the lowest was 0.25 mm sieving diameter. The activity concentration of 40K was the highest in the sieving size of 2.0 mm, and the lowest activity concentration was in the 0.5 mm sieving diameter. The result of 137Cs is exactly the opposite of 40K, namely, the activity concentration of 137Cs was the lowest in the sieving size of 2.0 mm, and the highest activity concentration was in the 0.5 mm sieving diameter. Additionally, the sealing time has a significant effect on the measured activity concentrations of 226Ra and 210Pb because of uranium series of disequilibrium. However, if the sample is sealed for 16 days or longer, the effect of sealing time is very small. This study showed a close relationship between radionuclides activity concentration and soil sieving size and sealing time and the information is useful for improving the accuracy of the determination of radionuclides in soil sample using gamma-ray spectrometer.

Modulatory effect of the translocator protein (TSPO) on gamma radiationinduced neurogenic, neuroinflammatory and systemic immune responses

C. Betlazar*, R.J. Middleton, N. Howell, E. Davis, J.B. Davies, R. Banati, and G.J Liu*

ANSTO, New Illawarra Road, Lucas Heights, NSW 2234, Australia., Discipline of Medical Imaging & Radiation Sciences, Faculty of Medicine and Health, Brain and Mind
Centre, University of Sydney, 94 Mallett Street, Camperdown, NSW 2050, Australia., *Correspondence: calinab@ansto.gov.au; gdl@ansto.gov.au

Abstract–Ionizing radiation is used therapeutically and diagnostically in the central nervous system, though responses to high, and particularly low, doses have not yet been well-characterised. Among the cellular responses to ionizing radiation, inflammatory responses and altered neurogenesis have been reported. These phenomena are underpinned by redox mechanisms derived from mitochondria, an important extranuclear target of ionizing radiation. To enhance current understanding of neurobiological responses to both high and low dose ionizing radiation at the cellular and subcellular level, the mitochondrial translocator protein (TSPO), a known biomarker of neuroinflammation, was investigated for its response and potential modulation of radiationinduced effects. Concomitantly, differential effects of high and low dose ionizing radiation on neurogenesis and innate immune responses were examined. Six week old male TSPO knockout and C57BL/6 wildtype mice were exposed to a single whole-body dose of gamma radiation, with doses chosen to capture low (10mGy, 100mGy) and high (2Gy) dose effects, with a sham-irradiated control (0Gy). Brain tissue and blood plasma were analysed 48 hours post-irradiation. BV2 microglial cells, along with primary microglial cell cultures harvested from wildtype and TSPO knockout mice, were exposed to the same gamma radiation doses as in vivo. Immunohistochemistry revealed increased TSPO expression in neurogenic regions of wildtype mice after 2Gy irradiation. ELISA analysis of blood plasma demonstrated increased IL-6 levels in 2Gy irradiated mice compared to sham-irradiated controls, along with decreased IL-6 levels in 10mGy irradiated wildtype and TSPO knockout mice. Primary microglial cell cultures irradiated at the same doses demonstrated analogous results, with increased TSPO expression after 2Gy irradiation and a downregulation after 10mGy. Reactive oxygen species measured in BV2 cell cultures after irradiation also revealed decreases after 10mGy irradiation and increases after 2Gy irradiation. Combined, these results reveal differential neurobiological responses to ionizing radiation, and introduce TSPO as a modulator of ionizing radiation-induced effects in the central nervous system.

The latest activity of network for low dose radiation research in Japan: PLANET

K. Suzuki, Y. Yamada, M. Sasaki, T. Iwasaki, K. Yoshida, Y. Shimada, K. Ozasa, M. Kai, J. Kobayashi, K. Sakai, M. Sasatani, T. Sugihara, H. Tauchi, S. Tanaka, K. Doi, M. Tomita, H. Yasuda, T. Imaoka and S. Kakinuma

Nagasaki University, Atomic Bomb Disease Institute, 1-12-4, Sakamoto, Nagasaki City, Nagasaki, 852-8523, Japan; e-mail: kzsuzuki@nagasaki-u.ac.jp National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1, Anagawa, Inage-ku, Chiba City, Chiba, 263-8555, Japan; e-mail: yamada.yutaka@qst.go.jp, doi.kazutaka@qst.go.jp, imaoka.tatsuhiko@qst.go.jp, kakinuma.shizuko@qst.go.jp, Radiation Safety Research Center, Nuclear Technology Research Laboratory, Central Research Institute of Electric Power Industry, 2-11-1 Iwadokita, Komae City, Tokyo 201-8511, Japan; e-mail: michiya@criepi.denken.or.jp, iwasakit@criepi.denken.or.jp, kazu@criepi.denken.or.jp, mstomita@criepi.denken.or.jp Institute for Environmental Sciences, 1-7, Ienomae, Obuchi, Rokkasho-vil., Kamikita-gun, Aomori, 039-3212, Japan; e-mail: shimada.yoshiya@ies.or.jp, sugihara@ies.or.jp, tanakas@ies.or.jp Department of Epidemiology, Radiation Effects Research Foundation, 5-2 Hijiyama Park, Minami-ku, Hiroshima City, Hiroshima, 732-0815, Japan; e-mail: ozasa@rerf.or.jp, Department of Health Sciences, Oita University of Nursing and Health Sciences, 2944-9, Megusuno, Oita City, Oita, 870-1201, Japan; e-mail: kai@oita-nhs.ac.jp, Radiation Biology Center, Graduate School of Biostudies, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto City, Kyoto, 606-8501, Japan; e-mail: kobayashi.junya.7e@kyoto-u.ac.jp, Higashigaoka-Tachikawa Faculty of Nursing, Tokyo Healthcare University, 2-5-1, Higashigaoka, Meguro-ku, Tokyo, 152-8558, Japan; e-mail: k-sakai@thcu.ac.jp, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima City, Hiroshima, 734-8551, Japan; e-mail: mtoyosh@hiroshima-u.ac.jp, hyasuda@hiroshima-u.ac.jp, Department of Science, Graduate School of Science and Engineering, Ibaraki University, 2-1-1, Bunkyo, Mito City, Ibaraki, 310-8512, Japan; e-mail: hiroshi.tauchi.sci@vc.ibaraki.ac.jp

Abstract–Regulatory policies on radiation protection need to be implemented rationally based upon accurate information. There is also a renewed awareness of the importance that such a research platform has for sufficient and effective risk communication with the public about the health effects of low-dose and low-dose rate radiation, and the need for such platform is expected to further increase in the future after the Fukushima Daiichi nuclear power plant accident in Japan. With the aim of constructing such research platform, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Sciences and Technology (NIRS-QST) set up the Radiation Risk and Protection Research Platform Preparatory Committee in 2016, and the committee summarized that results on the report about the network; name is Planning and Acting Network for Low Dose Radiation Research (PLANET). The PLANET will identify priorities of research needs, and propose strategies to improve quantitative estimation of low dose/low dose-rate radiation risk. In 2018, NIRS-QST set up the Administration Committee for PLANET instead of the Preparatory Committee, and the Working Group (WG) for dose rate effects of animal experiments. Although several epidemiological studies of subjects exposed to low dose-rate radiation have been conducted, the current knowledge on the effects of low dose-rate radiation exposure is still limited because such studies have uncertainties due to confounding factors. Animal experiment, where each subject is considered to be nearly identical, can complement the limitations of epidemiological studies. Thus, the WG conducts a joint analysis of the previously published cancer mortality data of B6C3F1 female mice chronically and acutely exposed to 137Cs γ-rays to estimate dose-rate effectiveness factor. In addition, despite that not many data with respect to dose- and dose-rate-effectiveness factor (DDREF) are available on human populations, recent animal models have made significant contributions to provide quantitative data and some mechanistic insights. Although the application of animal data to human population is always in debate, together with the biological mechanisms these data are apparently the clues to comprehensive understandings of the dose-rate effects of ionizing radiation. Thus, the WG aims to compile and discuss the animal studies with respect to the dose-rate effects with regard to the underlying biological mechanisms. Details of the results will be discussed in the poster presentation.

Stochastic models for cancer: implications for low-dose radiation and time since exposure effects

J.D. Mathews

Melbourne School of Population and Global Health, The University of Melbourne, Carlton, Vic, 3053; email mathewsj@unimelb.edu.au

Abstract–Modelling the stochastic nature of cancer, while estimating effects of radiation, can help to explain
the age-dependence, the time-related decline in ERR per unit of dose, and non-linearity of the overall doseresponse. A simple time-dependent multistage model illustrates the concepts. We assume that the rate of accrual to cancer after n events have occurred by time t can be predicted using the Poisson distribution with mean mt where m is a rate constant, w is the mean number of events present at birth, and N is the number of stem cells at risk. To a good approximation, with large N, the spontaneous cancer incidence at time (age) t is: If a person is exposed to a radiation dose D before time t, and radiation adds to the number of (mutation) events by φD, then the expected number of events is mt + w+φD and the incidence is obtained by replacing mt+w by mt+ w+φD. This gives the incidence rate ratio (IRR) in exposed relative to unexposed as: IRR=exp(-φD)(1+(φD/(mt+w))n-1 This equation predicts the observed decline of IRR (and ERR= IRR-1) with increasing attained age or time since exposure; this non-linear effect is due to radiation “selecting out” those (unlucky) cells that for stochastic reasons are already more advanced towards cancer. Model processes will differ between individual cells or people. For example, if inherited susceptibility genes act through w, n or m, relevant cells would all be at increased risk, whereas a mutation arising during foetal development could have left an at-risk clone, corresponding to a larger w or N in an “unlucky person”. The age dependence of spontaneous cancer could be partly due to cumulative doses of background radiation. For radiation in excess of background that is independent of initial conditions (N, n, w, m etc), the ERR in exposed, relative to unexposed (background only), must be causally ascribed to the added radiation. Moreover, the logic suggests that if a susceptible person would have developed cancer anyway (for stochastic reasons), the extra radiation would accelerate cancer onset. We recommend “average years of cancer free life lost” (AYCFLL) as a new metric to summarise the population impact of radiation on cancer risk. For this naïve Poisson model, AYCFLL= φD/m for exposures at young ages. We use Australian cohort data to illustrate these concepts and to model the effects of age at exposure and time since exposure.

Consideration of low-dose radiation risk in the presence of measurement error, from a statistical perspective

Munechika Misumi

Department of Statistics, Radiation Effects Research Foundation, 5-2 Hijiyama Koen, Minami-ku, Hiroshima, 732-0815, Japan email: misumi@rerf.or.jp

Abstract– Radiation risk estimates obtained from epidemiological studies inform radiation protection standards worldwide. However, observational data from those epidemiological studies frequently include risk factors that are only indirectly observable or measured with uncertainty and subject to measurement error. Statistical analyses ignoring those errors can provide biased estimates, often resulting in an underestimation of exposure-outcome associations. Errors in radiation dose estimates are of concern in radiation epidemiological studies due to the uncertainty in subjects’ information on the conditions of their radiation exposure and the methods used by dosimetry systems to quantify the radiation dose. Atomic bomb survivor studies at the Radiation Effects Research Foundation (RERF) account for such errors in dose estimates via regression calibration, assuming a multiplicative error model. In these studies, the evaluation on the shape of the doseresponse is often conducted by testing a departure from linearity by a simple statistical test based on a linearquadratic dose-response model. Then, the impact of measurement errors on a non-linear dose-response has not been thoroughly studied even for the linear-quadratic model. In this study, we evaluated the effects of measurement errors on the dose-response shape via simulation. Preliminary results showed that the biases due to measurement errors were not substantial at lower doses, but the coverage of the uncertainty estimates under the regression calibration was unstable. Effects of measurement errors in the low-dose range seemed to be carefully evaluated taking the characteristics of the methods for the measurement error correction on the shape of dose-response into account.

Effects of Radiofrequency Radiation from GSM Base Station on Reproductive performance and Sperm Head Abnormalities on (F1-F3 ) of Albino Mice, Mus musculus

Aneyo, I.A., Ameaze, H. N., Doherty, V. F., Otitoloju, A.A. and Aweda,M.A.

Department of Biological Science, Yaba College of Technology, Lagos, Nigeria, Department of Zoology, Faculty of Science, University of Lagos, Nigeria, Department of Radiation Biology, Radiotherapy and Radiodiagnosis, College of Medicine/Lagos, University Teaching Hospital, Lagos, Nigeria *Corresponding author: idowuhilda@gmail.com

Abstract This study investigated reproductive prformance and sperm morphological changes of radiofrequency radiation (RFR) from Global Systems for Mobile Communication (GSM) base station on three successive generations of albino mice Mus musculus. The model mice were placed in cages located around the base station for a period of 249 days. The reproductive performance and sperm head abnormalities were examined using standard protocol. The result of the reproductive performance of 24 female breeder mice produced a total of 76 offspring and more pups per litter were produced in control. Each female mouse had several generations of litters. The average number of pups born and offspring surviving to weaning age in each generation differed significantly (P<0.05) at F1-F3 generations evaluated. The result of sperm head morphology of mice showed that there was a significant (P<0.05) increase in sperm head abnormalities in exposed mice compared to the control. The major abnormalities observed were sperm head with no hook, pin-head and banana-shaped head which were observed at 2nd and 3rd generations. This result showed the potential adverse effects that RFR could have on humans after prolonged exposure and continued and proper monitoring of the erection of telecom base stations in and around human habitations in city centres of a developing country like Nigeria.

Design of a Wide Energy Range Neutron Rem Counter

Chen Ran, Liu Yang, Luo Zhiping, Li Chuanlong

Department of Radiation Safety, China Institute of Atomic Energy, Fangshan District, Beijing, 102413,China; email: chenran1205@126.com

Abstract: In order to improve the accuracy of dose equivalent measurement around some stray radiation fields at high energy accelerators, the energy response of the wide energy range neutron rem counter with different structure was calculated using the MCNPX code, based on the domestic and overseas investigations of wide energy range neutron rem counter in the realm of radiation protection. The results were compared with the standard curve of ICRP, and then a set of optimized detector parameters was established. The results show that the response of modified rem-meter is well corresponds to the standard curve of ICRP in the high energy neutron radiation fields, the detector includes a spherical 3He proportional counter with 2 atmospheres, a polyethylene moderator with the thickness of 3.75cm, a Cadmium absorber with the thickness of 1mm and the poriness of 20.3%, a lead layer with the thickness of 0.6cm and a polyethylene moderator with the thickness of 6.0cm, from inner to out. Its sensitivity ranges from thermal energies up to 5 GeV.
Keywords: Wide energy range; Neutron rem counter; Energy response

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