Radiation dosimetry (Physics) Research Papers (original) (raw)

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.

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- Radiation Physics, Medical Radiation Physics, Radiation dosimetry (Physics)

Questa tesi è stata dedicata alla verifca degli indicatori dosimetrici negli esami più comuni di radiologia proiettiva. Per questo lavoro, in cui sono state eseguite misure di dose in entrata con backscatter (ESD), misure di dose senza backscatter (Kin) e misure di dose in uscita dal fantoccio (Kout), sono stati utilizzati tre fantocci antropomorf e, come strumentazione di misura, una camera a ionizzazione e due dosimetri allo stato solido.
Il lavoro di tesi è stato svolto all'interno del Servizio di Fisica Sanitaria del Policlinico Sant'Orsola-Malpighi, mentre le misure sono state eseguite all'interno di alcune sale radiologiche del Policlinico Sant'Orsola-Malpighi, in due Unità Operative: Radiologia Golferi Albertoni e Radiologia Golferi Palagi.
I dati acquisiti hanno permesso di confrontare le dosi erogate per la radiografa computerizzata (CR, Computed Radiography) o dispositivi per la più moderna radiografa diretta (DR, Direct Radiography) verifcando la corrispondenza dei risultati ottenuti con la letteratura esistente in materia.
É stato inoltre possibile calcolare i fattori di backscatter (BSF) che sono risultati in pieno accordo con le indicazioni fornite dalle linee guida europee. Infne sono stati calcolati, sempre partendo dalle misure di dose, i fattori di trasmissione dei tre fantocci antropomorf nelle 11 proiezioni eseguite.
Il fatto di aver misurato sperimentalmente quali siano i valori reali di BSF per i vari esami radiologici potrà essere utile nella eventuale implementazione di algoritmi matematici per il calcolo di dose nelle procedure radiologiche. Inoltre un altro potenziale sviluppo futuro potrebbe esser il calcolo di ulteriori parametri dosimetrici a partire dai dati ottenuti in questa tesi.

- by Alice Zanna Bonacorsi
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- Radiation dosimetry (Physics), CT scanning, Dosimetry, LDR

The code EDEPOS to compute the depth-dose curve of electrons normally incident on the semi-infinite absorber has been revised to improve its own output and the output of the multilayer depth-dose code EDMULT, in which EDEPOS serves as a subprogram. The values of adjustable parameters in the algorithm of EDEPOS have been determined by the least-squares fit to the depth-dose data collected from the literature. The data used cover the energies from 0.1 to 20 MeV, and the atomic numbers from 5.28 (an effective atomic number for polyethylene) to 82. The revision has removed the spurious cusp in the depth-dose curve generated by the old code, and has resulted in better agreement with a majority of the data. Illustrative results of computation by the revised version of EDMULT are given.

- by Tatsuo Tabata
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- Radiation dosimetry (Physics), Algorithm, Electron Beam, Depth-Dose Curves

Proccedings of the International Symposium on Solid State Dosimetry, Volume 3. 2016

The biological damage produce by radiation is closely related to the amount of energy absorbed in the case of x-rays. Measurement of produced ionizing is provided a useful assessment of the total energy absorbed. This study was performed in Khartoum teaching hospital in period of January to June 2014. This study performed to assess the effective dose (ED) received in lumbosacral radiographic examination and to analyze effective dose distributions among radiological departments under study. The study was performed in Khartoum teaching hospital, covering two x-ray units and a sample of 50 patients. The following parameters were recorded age, weight, height, body mass index (BMI) derived from weight (kg) and (height (m)) and exposure factors. The dose was measured for lumbosacral x-rays examination. For effective dose calculation, the entrance surface dose (ESD) values were estimated from the x-ray tube output parameters for Lumbosacral Spine AP and lateral examinations. The ED values were then calculated from the obtained ESD values using IAEA calculation methods. Effective doses were then calculated from energy imparted using ED conversion factors proposed by IAEA. The results of ED values calculated showed that patient exposure were within the normal range of exposure. The mean ED values calculated were 2.49 + 0.03 and 5.60 + 0.22 for Lumbosacral Spine AP and lateral examinations, respectively. Further studies are recommended with more number of patients and using more two modalities for comparison.

Proccedings of the International Symposium on Solid State Dosimetry, Volume 1. 2016

- by Gamal Alkirshi
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- Radiation dosimetry (Physics), Experments

Undoped and dysprosium doped lithium borate glass system with empirical formula (70–x) B2O3 – 30 Li2O – (x) Dy2O3 (x=0.1,0.3,0.5,0.7,1.0 mol%) were prepared using the melt-quenching technique. The dosimetric measurements were performed by irradiating the samples to 6 MV photon beam using linear accelerator (LINAC) over a dose range of 0.5–5.0 Gy. The glass series of dysprosium doped lithium borate glass produced the best thermoluminescence (TL) glow curve with the highest intensity peak from sample with 1.0 mol% Dy2O3 concentration. Minimum detectable dose was detected at 2.24 mGy, good linearity of regression coefficient, high reproducibility and high sensitivity compared to the undoped glass are from 1.0 mol% dysprosium doped lithium borate glass. The results indicated that the series of dysprosium doped lithium glasses have a great potential to be considered as a thermoluminescence dosimetry (TLD).

- by Atiqah Ab Rasid and +1
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- Radiation dosimetry (Physics), Thermoluminescence Dosimetry, Glasses

The present work validates the Geant4 Application for Tomographic Emission Monte Carlo software for the simulation of a 6 MV photon beam given by Elekta Synergy Platform medical linear accelerator treatment head. The simulation includes the major components of the linear accelerator (LINAC) with multi‑leaf collimator and a homogeneous water phantom. Calculations
were performed for the photon beam with several treatment field sizes ranging from 5 cm × 5 cm to 30 cm × 30 cm at 100 cm distance from the source. The simulation was successfully validated by comparison with experimental distributions. Good agreement between simulations and measurements was observed, with dose differences of about 0.02% and 2.5%
for depth doses and lateral dose profiles, respectively. This agreement was also emphasized by the Kolmogorov–Smirnov goodness‑of‑fit test and by the gamma‑index comparisons where more than 99% of the points for all simulations fulfill the quality assurance criteria of 2 mm/2%.

Le médulloblastome est un type de tumeur primitive neuroectodermale qui se trouve à l'arrière de l'encéphale, dans le cervelet. Cette partie de l'encéphale coordonne le mouvement, l'équilibre et la posture, et elle joue un rôle dans certaines des fonctions du cerveau de façons encore mal comprises. Le traitement du médulloblastome par la radiothérapie externe est complexe. Cette technique consiste à utiliser des images en 3D de la tumeur et des organes avoisinants obtenues par un scanner dosimétrique, parfois associées à d'autres examens d'imagerie (IRM, TEP scan…). En plus, des logiciels permettent de simuler virtuellement, toujours en 3D, la forme des faisceaux d'irradiation et la distribution des doses. Cela permet de délivrer des doses efficaces de photons X en limitant l'exposition des tissus sains. L'objectif de ce travail est d'étudier l'effet de la jonction des champs sur les organes à risque au cours de traitement du cancer de médulloblastome par la radiothérapie conformationnelle 3D, et de comparer les histogrammes doses-volumes de la tumeur et les organes à risque afin de réaliser et optimiser une balistique pour le traitement de ce type de cancer.

- by Abdelaali RAHMOUNI
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- Medical Physics, Radiation dosimetry (Physics), Radiotherapy, Cancer Research

Nanocrystalline samples of Mn-doped CaF2 were synthesized by chemical coprecipitation method. The
impurity concentration was varied in the range of 0.5e4.0 mol%. The structure of the synthesized material
was confirmed using powder XRD analysis. TEM images of the nanoparticles show their size
occurring mostly in the range of 35e40 nm, with clusters of some impurity phases formed on annealing
of the material at higher temperatures. Detailed studies on TL showed that the structures of glow curves
depend on Mn concentrations and annealing temperatures. Optimization of the concentration and
annealing temperature showed that the sample (doped with 3.0 mol% and annealed at 673 K) has almost
a single dosimetric glow peak appearing at around 492 K. EPR and PL spectra were further studied to
understand the reasons for changes in the glow curve structures. All detailed studies on TL, PL and EPR
showed that the changes in glow curve structures are caused not only by the stress connected with the
difference in ionic radii of host Ca2þ and the guest impurity Mn3þ/Mn2þ, but are also governed by other
reasons, like diffusion of atmospheric oxygen and formation of impurity aggregates, such as, MnO2,
Mn3O4, etc. This is true not only for nanocrystalline CaF2:Mn but could also be so for the bulk CaF2:Mn
(TLD-400) and would thus help in understanding complex glow curve structure, high fading and the loss
of reusability on annealing beyond 673 K.

- by P. Sahare and +3
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- Physics, Spectroscopy, Photonics, X-ray imaging

Radiation has been found to be beneficial on one hand and harmful on the other hand and is encountered in everyday activities in various forms and different intensities. Some of the harmful effects are: cancer, cataract, gene mutation destruction of bones and blood cells and it can cause the death of an individual This work therefore aimed at investigating the indoor and outdoor background radiation General Hospital Nasarawa, Nasarawa State, Nigeria using a hand held Inspector Alert Nuclear Radiation Monitor. A total of 10 offices were surveyed and the results obtained showed that the mean indoor and outdoor annual effective dose rate varies from 0.011 mSv/y (indoor) at LR (Laboratory Room) and 0.03 mSv/y (outdoor) at RR (Record Room) and LR (Laboratory Rom) to 0.36 mSv/y (indoor) at EA (Accident and Emergency) and 0.09 mSv/y (outdoor) at EA (Accident and Emergency) with an average value of 0.19 mSv/y and 0.05 mSv/y for indoor and outdoor respectively. The evaluated results for indoor and outdoor excess lifetime cancer risk at different offices of the Nasarawa general hospital. The mean indoor and outdoor excess lifetime cancer risk varies from 0.39 × 10-3 (indoor) at LR (Laboratory Room) and 0.11 × 10-3 (outdoor) at RR (Record Room) and LR (Laboratory Rom) to 1.26 × 10-3 (indoor) at EA (Accident and Emergency) and 0.32 × 10-3 (outdoor) at EA (Accident and Emergency) with an average value of 0.67 × 10-3 and 0.18 × 10-3 for indoor and outdoor respectively. 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, general Hospital Nasarawa is radiologically safe.

- by Rilwan Usman
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- Environmental Science, Radiation safety, Radiation Physics, Radiation Dosimetry

Background: Practice of Unflattened or Flattening filter free (FFF) beam has become the highdose standard in radiotherapy (RT), such as stereotactic radio-surgery (SRS) and stereotacticradiotherapy (SRT). The removal of a flattening filter (FF) from the path of a photon beamalters the characteristics of FFF beam. Since the conventional route for dosimetric analysisof FF beam cannot be applied to FFF beam, the procedure of analyzing beam characteristicsfor FFF beam based on inflection points (IPs) is used. IP is a point where the concavity changeobserved corresponds to its change in sign (±) of the second derivative.Aim: The objective of the study is to determine IPs for dosimetric analysis of the FFF beamprofile.Methods and materials: In this study, IPs are determined through the python code program-ming based on the mathematical first principle of the derivative. They are compared with IPsestimated by the conventional graphical manual method using Microsoft Excel (MS). IPs andtheir dependent dosimetric parameters determined by both mathematical and graphicalmanual methods are compared.Result: Percentage differences between the IPs determined by both methods, for 6MVFFFinline and crossline beam profile are found to be 2.7% and 0.8% respectively. Similarly, theaverage penumbra differences for 6MVFFF inline and crossline beam profile are found tobe 0.15 mm and 0.9 mm, respectively. However, differences in the field width between bothmethods are found insignificant.Conclusion: Graphical manual method is very time-consuming, tedious and user dependent.However, the mathematical method through python code programming is more precise,faster and independent of individual users.

- by ravindra shende
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- Radiation dosimetry (Physics)

The term head and neck cancer refers to a group of biologically similar cancers originating from the upper aero digestive tract, including the lip, oral cavity , nasal cavity, Para nasal sinuses, pharynx, and larynx. 90% of head and neck cancers are squamous cell carcinomas, originating from the mucosal lining (epithelium) of these regions. Radiation therapy is the most common form of treatment along with surgery and chemotherapy. Radiotherapy is the art of using ionizing radiation to destroy malignant cells while minimizing damage to normal tissue. Radiotherapy has become astandard treatment option for a wide range of malignancies, but adverse tissue reactions associated with the use of radiotherapy in the management of patients with head and neck cancer are painful and they diminish the quality of life. So a novel approach has been made to fabricate customized intraoral stents that can help prevent
the unnecessary irradiation of the surrounding normal tissues, thus reducing the severity ofreactions. However, when properly designed and used, these stents are effective in reducing the treatment morbidity.

- by British Biomedical Bulletin
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- Radiation, Radiation Oncology, Radiation Shielding, Radiation safety

The next generation wireless communications systems need to be of a higher standard in order to provide the customers with the multitude of high quality services they demand. In recent years, Orthogonal Frequency Division Multiplexing (OFDM) has been successfully used in terrestrial digital video broadcasting and showed it is a strong candidate for the modulation technique of future wireless systems. In order to investigate this, a simulation model was created and implemented using MATLAB. This letter focuses on the design of an OFDM system with the interleaver stage for a specific convolutional code operating with OFDM modulation. The interleaver is an important part in the design of a communication system. The performance of different interleavers (Matrix and Random) are compared over AWGN channel with digital and analog modulation schems in OFDM, Numerical results also evidence the importance of the interleaver choice when comparing the performance of different interleavers. Simulation results show that matrix interleaver can be very competitive to random interleaver.

- by Vineet Chaturvedi
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- Radiation dosimetry (Physics)

The aim of radiation therapy treatment planning is to achieve an optimal balance between delivering a high dose to target volume and a low dose to healthy tissues. The integral dose, conformity and homogeneity indexes, hence, are the important guidance for predicting the radiation effects and choosing the optimal treatment plan. The goal of this study is to compare and investigate the aforementioned parameters in 3DCRT vs. IMRT plan. In order to evaluate dosimetric parameters, data from five patients with prostate cancer, planned by IMRT and 3DCRT were obtained. Prescribed doses for IMRT procedure and 3DCRT were 80Gy and 70 Gy, respectively. Also, the target coverage was achieved with 95% of the prescribed dose to 95% of the PTV in 3DCRT and 95% of the prescribed dose to 98% of the PTV in IMRT method. A total of thirty IMRT and 3DCRT plans were performed for evaluation of dosimetric parameters (for each patient both treatment plans, step and shoot IMRT and 3DCRT with 6, 10 and 18MV energies) were done. The integral dose was calculated as the mean- dose times the volume of the structure. The mean integral dose (ID) received by rectum for 3DCRT was almost 1.01% greater than IMRT while in bladder mean value of ID for IMRT was approximately 1.68% higher than 3DCRT. For PTV in IMRT the ID of target volume had the biggest value (1.14%) compared to that of 3DCRT. Dose conformity in PTV volume in S.A.S and 3DCRT was almost equal. The same outcome was achieved in homogeneity index. The results of this study shows that IMRT method leads to adequate target dose coverage while the prescribed dose for this modality is higher than 3DCRT. IMRT has the ability of increasing the maximum dose to tumor region and improves conformity and homogeneity indexes in target volume and also reduces dose to OAR.

- by Hossein Hassani and +1
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- Radiation Oncology, Cancer, Radiation Dosimetry, Medical Radiation Physics

Fractional energies f _BE of backscattered electrons and the photon yields Y from semi-infinite absorbers bombarded by electrons have been calculated with the ITS Monte Carlo system, and analytic expressions have been formulated for these parameters. Besides the Monte Carlo results, experimental data collected from the literature have been used to determine the expression for f _BE. The two expressions are applicable to absorbers of atomic numbers from 4 to 92. The region of incident-electron energy considered is from 5 keV to 100 MeV for f _BE, and from 0.1 to 100 MeV for .

- by Tatsuo Tabata
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- Monte Carlo, Radiation dosimetry (Physics), Electron Beam, Empirical Formula

Abstract: (LiF:Mg,Ti) Thermo Luminescent Detectors are widely used for monitoring patient dose in radiotherapy treatments whereas Radio-Photoluminescent Dosimeters (RPL) are increasingly devoted to radiological protection purposes. A study, aiming at extending the use of RPL glasses to clinical applications, is conducted by comparing the dosimetric characteristics of a RPL glass dosimeter, commercially known as GD-301 to those of a TLD -100 detector. In this paper, preliminary Monte Carlo simulation results describing these dosimeters responses in terms of absorbed dose, source-detector distance and characteristics of the incident gamma field are presented.

In modern CT, CTDI100 measurements would underestimate accumulated dose at the gantry center. AAPM TG 111 report proposed improved metrics for CT dosimetry, mainly for helical and wide beam width scanning. In this study, a methodology to assess CT dose, inspired on TG 111, was applied. Dosimeters were firstly calibrated in lab in beams like those utilized clinically. Using a reference 0.6cc Farmer chamber, two CT " pencil " chambers were calibrated in PKL by substitution method. Results showed differences ≤ 2% in the calibration coefficients, for three col-limation apertures. A small 0.6cc chamber was calibrated in air kerma with this setup, without any collimator. After this, in a private Brazilian hospital, the small chamber was applied in dosimetry tests of a CT scanner, according to TG 111, determining Dose profiles and Equilibrium dose free-in-air (Deq,air) for some protocols and pitch values. Results showed that Deq,air increased when reducing pitch and Equilibrium dose-pitch product free in air (p.Deq,air) remain constant. In measurements with a 450mm CT phantom, differences between Planar Average Equilibrium Dose (Deq,p) and CTDIvol ranged between 30-37%. This occurs because CTDIvol cannot include dose profile "tail" contribution, caused by scattering in phantom, especially for wide beam widths. Campelo, et. al. ● Braz. J. Rad. Sci. ● 2016 2

- by Ricardo A Terini and +2
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- Medical Physics, Radiation dosimetry (Physics), Thermoluminescence Dosimetry, Radiation doses

Many thermoluminescence dosimetry (TLD) materials exhibit a variation in read-out with light exposure (including both visible and UV radiation energy) which may cause problems in environmental dosimetry. The aim of the present study was to investigate this for three newer preparations of TLD material — LiF:Mg,Ti (GR-100, DML, China), LiF:Mg,Cu,P (MCP-N, TLD Niewiadomski & Co., Poland) and Al2O3:C (Stillwater Sciences, USA). TLDs irradiated to 1 or 10 Gy were exposed to light from a calibrated spectral lamp with three to four times higher UV component than sunlight. MCP-N proved to be approximately five times less light sensitive than GR-100. For both materials, the decay of the major glow peaks with increasing light exposure could be described by a single or dual exponential equation. Half lives for the major dosimetry peaks of GR-100, fit to a single exponential, were 1132 min (∼19 h) for peak 4 and 275 min (∼4 h) for peak 5. The half lives for peak 4 of MCP-N, fit to a dual exponential, were 309 min (∼5 h) and 6627 min (∼4 days). For MCP-N, this relates to approximately a loss of half the signal in 14 days of sun exposure (Polish summer). The readout of Al2O3:C increased with increasing light exposure and saturated after only 5 min at a level 26 times higher than the signal without light exposure.

The organ doses and the effective dose of patients exposed at an X-ray beam, having photon energies between 10–150 keV, are analyzed by using a new method named IradMed. Three major radiological procedures, mammography, radiography and Computer Tomography are considered. The Rayleigh scattering, the Compton scattering and the photoelectric effect were taken into account for patient dose calculations. The Compton scattering is modeled by using “classic”, Kahn, Wielopolski and EGS procedures. The best results for angular distribution was
obtained when the EGS-based algorithm was used. It can be noted that patient doses determined by using Kahn or “classic” procedures are in good agreement with data from literature when similar computing methods are used. From our data, for patient
dose calculations, the EGS procedure is recommended.

Total skin electron beam therapy (TSEBT) is internationally considered as a treatment modality for cutaneous T-cell lymphoma for either curative purpose or palliative care. The first attempt to apply TSEBT in Iran took place at department of clinical oncology of Rock Center of Karaj. Irradiation was done by precise linear accelerator (ELEKTA) and was performed in the standing position of patient. To evaluate the treatment reliability and determination of physical characteristics of the clinical electron fields, specific measurements were done using thermoluminescent dosimeters. The results revealed that TSEBT can be routinely used by providing accurate dosimetric measurements to get homogenous dose coverage.

- by Hossein Hassani
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- Oncology, Radiation Oncology, Radiation Dosimetry, Medical Radiation Physics

The possibility to combine the track-etched CR-39 or Makrofol detectors with charcoal to increase the detector sensitivity was shown in the last years. Special requests are necessary in the case of a personal dosimeter when the detector must be active only during working activity. Regarding the combination of charcoal with TL detectors our preliminary investigations indicate that the TLD intensity in normal indoor air (~80 Bq/m3) is about two times higher for TLD + charcoal in comparison with simple uncombined TLD. This paper presents a study on the charcoal combined with TLDs and some remarks about charcoal properties. The results show a linear dependence between TLD+charcoal signal versus radon air concentration. Using Carboxen 564, a special carbon molecular sieve, the detection limit for indoor radon can be lowered under 60 Bq/m3/day, rather small and promising to be used for a radon personal dosimeter at workplaces

- by Ioan Pop
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- Radiation dosimetry (Physics), Radon mapping

Regulatory entities require that for any radiation facility the surrounding areas must be restricted unless the dose equivalent is less than 0.02 mSv in any one hour. Two Monte Carlo radiation transport simulation codes, MCNP5 and Mercurad, were used to design a facility to shield a 3.48 × 105 MBq 137Cs irradiator that meets these requirements. Simulations showed that the dose equivalent rates were below the legal limit for unrestricted access and the facility was constructed using available concrete block and student labor to minimize costs. To verify the accuracy of the Monte Carlo radiation transport codes, an ion chamber was used to characterize the facility. Ion chamber measurements in the actual, as-built irradiation facility showed that the Monte Carlo codes, MCNP5 and Mercurad, agreed by a factor of better than 6% and better than 11%, respectively.

- by Abhijeet Nayak and +2
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- Materials Science, Composite Materials and Structures, Ceramics (Ceramics), Spectroscopy

In recent years, there has been increasing interest in constructing a series of deformable phantoms which follow the statistical distributions of some anatomical variations, known as 'statistical phantoms'. The main purpose of this study was to develop statistical phantoms by considering the variations in lung volume and shape, in order to evaluate the lung dose uncertainty for individuals undergoing chest computed tomography. Calculations were performed for 100 statistical lung volume phantoms and 70 statistical lung shape phantoms at tube voltages of 80 and 120 kVp, with the use of Monte Carlo MCNP code. The obtained results indicate that dose fluctuations for low tube voltage (80 kVp) are higher than those at 120 kVp. Moreover, it shows that the impact of statistical variations in lung volume on dose discrepancy (5% to 7%) is higher than the impact of statistical lung shape variations (around 2%).

A study has been carried out to analyse the distribution of radioactive elements U, Th and 40K in the soil of some areas of Punjab State, India. The samples collected from different parts of the state were analysed using gamma spectrometry technique. The concentration of 226Ra in the state varies from a minimum value of 18.6 Bq/kg to a maximum value of 68.9 Bq/kg. Similarly 232Th concentration varies from a minimum of 10.6 Bq/kg to a maximum of 94.2 Bq/kg. The activity concentration of 40K varies from 48.8 Bq/kg to160.1 Bq/kg. No significant correlation was observed between indoor radon/thoron levels and 226Ra/232Th contents of the soil adjacent to the dwellings. Annual effective dose received by population in these areas is also reported.

Internal radioactivity cancer risk was investigated after 1950 through analysis of Radiyum exposed individuals. The studies were mainly funded by the US Atomic Energy Commission. This study shows that the conclusions of the Radium Studies were dishonest and that y re-examining the results it is clear that the ICRP risk model and its dose coefficients for Radium ar in error by a very significant amount. This supports the other work carried out that indicates a very large error in the ICRP model for internal exposure.

When we look at objects giving off light (or reflecting light) we find three types of spectra. They are produced in different ways, and can actually tell us about the physical properties of the materials producing the spectra. These spectra are known as “a continuous spectrum” (or continuum emission), “an emission line spectrum” and “an absorption line spectrum”. Here, in this project we have tried to analyze all these spectra obtained from common light sources and KMnO4. All the spectra were obtained with the help of a diffraction grating & spectrometer. Later, the spectra corresponding to different wavelengths and energy levels were observed. The electronic transitions and material involved in the formation of spectra were found out. Also, the wavelength of the light emitted, absorbed by a specific light source or molecule was determined along with the vibrational energy level of phosphor coating and energy lost in collision in case of a CFL.

Clatterbridge Cancer Centre is the first proton therapy facility within UK, treating different types of
ocular tumours using a 60 MeV cyclotron. The proton beam is delivered to the patient using the
passive scattering method. Therefore, for radiation protection purposes we calculated the dose
equivalent and the fluence of the secondary particles produced in the beam delivery system during
the treatment. The aim of these calculations is to estimate the contribution of the secondary particles
to the total dose received by the patient during the proton therapy treatment.
Initially, the simulations were performed with FLUKA Monte Carlo code. The results were
reviewed with MCNPX Monte Carlo code in order to validate the calculations. This work presents
the results obtained with both codes and the discrepancies and agreements between the codes are
discussed.

Este trabajo describe las características termoluminiscentes de arena proveniente de las playas de Coveñas para su uso como dosímetro en dosis terapéuticas. Las muestras seleccionadas, tratadas térmicamente a 400◦C por una hora, fueron irradiadas a diferentes dosis usando una unidad de 60Co Theratron 780C en aire a temperatura ambiente. La lectura se realizó en un Harshaw TLD 4500. Las principales propiedades dosimétricas del material (curva de brillo, reproducibilidad de la respuesta, reutilización, linealidad y decaimiento térmico) han sido estudiadas en detalle. La curva de brillo de las muestras de arena presenta un pico TL alrededor de los 145◦C. Los resultados muestran que el material tiene una respuesta lineal con la dosis desde 50 cGy hasta 1000 cGy. Las muestras de arena estudiadas se pueden utilizar como dosímetros termoluminiscentes para aplicaciones en diferentes áreas. La importancia de este trabajo radica en que la arena es una sustancia natural disponible en grandes cantidades, tiene bajo costo y puede usarse en física clínica para evaluar la dosis recibida por el paciente durante el tratamiento médico.

- by Revista Ingeniería y Ciencia and +1
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- Engineering, Instrumentation Engineering, Mathematics, Physics

Previous studies measured the effects of 222Rn on various thermoluminescent dosemeters (TLDs). This study quantified the effects of 222Rn on LiF:Ti,Mg chips encapsulated in plastic extremity rings. For 28 d, one batch of TLDs was left in a chamber with high radon levels, and another batch in a control chamber with normal background radon levels. A few TLDs in each batch were removed from the rings for direct exposure to the ambient air in each chamber. Passive continuous radon monitors (CRMs) recorded the 222Rn levels. TLDs were processed using a third-party dosimetry company, CRM data were analyzed, and the relationship between integrated 222Rn concentration and TLD response was determined. The batch of TLDs in the experimental chamber showed a weak response to 222Rn gas, which was in the order of 0.5 nSv Bq-1 m3 d-1.

Abstract Nanocrystalline samples of Mn-doped CaF2 were synthesized by chemical coprecipitation method. The impurity concentration was varied in the range of 0.5–4.0 mol%. The structure of the synthesized material was confirmed using powder XRD analysis. TEM images of the nanoparticles show their size occurring mostly in the range of 35–40 nm, with clusters of some impurity phases formed on annealing of the material at higher temperatures. Detailed studies on TL showed that the structures of glow curves depend on Mn concentrations and annealing temperatures. Optimization of the concentration and annealing temperature showed that the sample (doped with 3.0 mol% and annealed at 673 K) has almost a single dosimetric glow peak appearing at around 492 K. EPR and PL spectra were further studied to understand the reasons for changes in the glow curve structures. All detailed studies on TL, PL and EPR showed that the changes in glow curve structures are caused not only by the stress connected with the difference in ionic radii of host Ca2+ and the guest impurity Mn3+/Mn2+, but are also governed by other reasons, like diffusion of atmospheric oxygen and formation of impurity aggregates, such as, MnO2, Mn3O4, etc. This is true not only for nanocrystalline CaF2:Mn but could also be so for the bulk CaF2:Mn (TLD-400) and would thus help in understanding complex glow curve structure, high fading and the loss of reusability on annealing beyond 673 K.

- by Dr. Manveer Singh
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- Geology, Physics, Materials Science, Spectroscopy

ABSTRACT Radiation induced cataract has been demonstrated among people who are exposed to ionizing radiation. To evaluate the deterministic effects of ionizing radiation on the eye lens, several papers dealing with the eye lens dose have been published. ICRP Publication 103 states that the lens of the eye may be more radiosensitive than previously considered. Detailed investigation of the response of the lens showed that there are strong differences in sensitivity to ionizing radiation exposure with respect to cataract induction among the tissues of the lens of the eye. This motivated several groups to look deeper into issue of the dose to a sensitive cell population within the lens, especially for radiations with low energy penetrability that have steep dose gradients inside the lens. Two sophisticated mathematical models of the eye including the inner structure have been designed for the accurate dose estimation in recent years. This study focuses on the calculations of the absorbed doses of different parts of the eye using the stylized models located in UF-ORNL phantom and comparison with the data calculated with the reference computational phantom in a broad parallel beam incident of protons with energies between 20 MeV and 10 GeV. The obtained results indicate that the total lens absorbed doses of reference phantom has good compliance with those of the more sensitive regions of stylized models. However, total eye absorbed dose of these models greatly differ with each other for lower energies.

A R T I C L E I N F O Keywords: FLUKA simulations Dose and fluence maps Radiation protection High power lasers A B S T R A C T FLUKA simulations were used to design a dosimetry monitoring system for the typical electron acceleration experiments in the E6 area of the ELI-NP building. The FLUKA geometry of the E6 experimental area was built by using data extracted from the latest available version of the corresponding Catia file, including all the building and beamline transport elements. Based on that geometry we calculated H*(10) in a Cartesian binning over E6 and neighbouring areas for the worst case scenario: a 38 GeV Gaussian electron source term. The fluence rates of the secondary prompt radiation field components were mapped throughout the E6 experimental area. The results were used to determine the most important contributor to the dose and the areas with the highest exposure, as well as the positioning of the detectors for radiation monitoring. We propose solutions for some practical issues: proper choice of the detector type and proper detector positioning in accordance with the characteristics of the radiation field (dose range, field components, energy ranges).

Nonuniform dose distributions in heterogeneous materials irradiated by high-energy electron beams were mapped by using blue cellophane thin dosimeter strip (20μm thickness). The absorbed doses and dose distributions in solid-state dosimeters and in products irradiated for practical use have been estimated from the measurements. Deviations from uniformity of absorbed doses as large as several tens of percent have been found near material interfaces.

- by Tatsuo Tabata
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- Radiation dosimetry (Physics), Heterogeneous Materials, Electron Beams, Dosimeter

This study examines the reproducibility of LiF:Mg,Ti pre-irradiation and post-irradiation fading rates. To test post-irradiation fading, 99 calibrated 3.2 × 3.2 × 0.9 mm3 LiF:Mg,Ti thermoluminescent dosimeters (TLDs) of dimensions were first annealed. The set was then irradiated to an average of 4.4 mGy using a 3.2 × 1011 Bq 137Cs source. The irradiated TLDs were allowed to fade at room temperature for 0.5, 1, 2, 3, 4, 8, or 17 d. The TLDs were then read out over a 3.5 h time period using a standard commercial hot planchet TLD reader with nitrogen gas to prevent chemiluminescence. The experiment was then repeated for the other fading times. To test pre-irradiation fading, the TLDs were annealed, then placed in storage for 0.5, 1.6, 3, 4, 8, 18, 27, or 43 d. After that time, the TLDs were irradiated and read out. A computerized glow curve deconvolution program was used to fit the glow curve data to a four-peak first-order Gaussian kinetics model. The areas of peaks 2, 3, 4, and 5 were retrieved in order to be studied alone, as well as normalized to other peaks. The peak areas and peak area ratios were then fit to two or three term exponential decay equations that allowed the determination of the fading rate by calculating their parameters. These parameters were then compared for different TLDs in order to determine if their values followed a Gaussian distribution. Then, a group mean and standard deviation could be used for each value for all TLDs for later use instead of calculating an individual mean for each TLD.

- by Kimberlee Kearfott
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- Physics, Radiation Physics, Radiation Dosimetry, Radiation Protection

Abstract The internal beta dose-rates for the thermoluminescence dating of thirty-five sherds from seven Hellenic sites have been determined by two different techniques, by thermoluminescence dosimetry using CaSO 4 : Mn phosphors and by analysis for potassium content by X-ray fluorescence or flame photometry and for Th and U content by alpha particle counting. While about two thirds of the results from the two techniques show acceptable agreement, about one third differ significantly. The two techniques are discussed in the light of these findings.

- by IOANNIS LIRITZIS
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- Archaeology, Geology, Archaeological Science, Radiation Dosimetry

Background: The diagnostic reference level (DRL) is measured with different methods in the common Computed tomography (CT) exams, but it has not been measured through the size-specific dose estimate (SSDE) method in Iran, yet. Objective: This study aimed to calculate the local DRL (LDRL) using the new quality control-based dose survey method (QC) and patients' effective diameter (MQC) and compare them with a data collection method (DC) as well as local national DRLs (NDRL).