Usability of sand samples in TL Radiation Dosimetry.

This study investigated natural sand thermoluminescence (TL) response as a possible option for retrospective high-dose gamma dosimetry. The natural sand under investigation was collected from six locations with selection criteria for sampling sites covering the highest probability of exposure to unexpected radiation on the Egyptian coast. Dose-response, glow curve, chemical composition, linearity, and fading rate for different sand samples were studied. Energy Dispersive X-ray Spectroscopy (EDX) analysis revealed differences in chemical composition among the various geological sites, leading to variations in TL glow curve intensity. Sand samples collected from Ras Sedr, Taba, Suez, and Enshas showed similar TL patterns, although with different TL intensities. Beach sands of Matrouh and North Coastal with a high calcite content did not show a clear linear response to the TL technique, in the dose range of 10 Gy up to 30 kGy. The results show that most sand samples are suitable as a radiation dosimeter at accidental levels of exposure. It is proposed here that for high-dose gamma dosimetry with doses ranging from 3 to 10 kGy, a single calibration factor might be enough for TL measurements using sand samples. However, proper calibration might allow dose assessment for doses even up to 30 kGy. Most of the investigated sand samples had nearly stable fading rates after seven days of storage. The Ras Sedr sands sample was the most reliable for retrospective dose reconstruction.

Thermoluminescence dosimetry (TLD) in a 3 T magnetic resonance imaging (MRI) environment: implications for personnel exposure monitoring.

Thermoluminescent dosimeters (TLDs) serve as compact and user-friendly tools for various applications, including personal radiation dosimetry and radiation therapy. This study explores the potential of utilizing TLD-100 personal dosimetry, conventionally applied in PET/CT (positron emission tomography/computed tomography) settings, in the PET/MRI (magnetic resonance imaging) environment. The integration of MRI into conventional radiotherapy and PET systems necessitates ionizing radiation dosimetry in the presence of static magnetic fields. In this study, TLD-100 dosimeters were exposed on the surface of a water-filled cylindrical phantom containing PET-radioisotope and positioned on the patient table of a 3 T PET/MRI, where the magnetic field strength is around 0.2 T, aiming to replicate real-world scenarios experienced by personnel in PET/MRI environments. Results indicate that the modified MR-safe TLD-100 personal dosimeters exhibit no significant impact from the static magnetic field of the 3 T PET/MRI, supporting their suitability for personal dosimetry in PET/MRI settings. This study addresses a notable gap in existing literature on the effect of MRI static magnetic field on TLDs.

Surface dose measurement and comparison between TLD and OSLD during modified re constructive mastectomy irradiation.

Radiotherapy (RT) is one of the major treatment modalities among surgery and chemotherapy for carcinoma breast. The surface dose study of modified reconstructive constructive Mastectomy (MRM) breast is important due to the heterogeneity in the body contour and the conventional treatment angle to save the lungs and heart from the radiation. These angular entries of radiation beam cause an unpredictable dose deposition on the body surface, which has to be monitored. Thermoluminescent dosimeter (TLD) or optically stimulated luminescent dosimeter (nano OSLD) are commonly preferable dosimeters for this purpose. The surface dose response of TLD and nano OSLD during MRM irradiation has been compared with the predicted dose from the treatment planning system (TPS). The study monitored 100 MRM patients by employing a total 500 dosimeters consisting of TLD (n = 250) and nano OSLD (n = 250), during irradiation from an Elekta Versa HD 6 MV Linear accelerator. The study observed a variance of 3.9% in the dose measurements for TLD and 3.2% for nano OSLD from the planned surface dose, with a median percentage dose of 44.02 for nano OSLD and 40.30 for TLD (p value 0.01). There was no discernible evidence of variation in dose measurements attributable to differences in field size or from patient to patient. Additionally, no variation was observed in dose measurements when comparing the placement of the dosimeter from central to off-centre positions. In comparison, a minor difference in dose measurements were noted between TLD and nano OSLD, The study's outcomes support the applicability of both TLD and nano OSLD as effective dosimeters during MRM breast irradiation for surface dose evaluation.

Effect of IRSL-BLSL-TSL reading modes combination on thermoluminescence (TL) response of BeO dosimeter.

The ultimate goal of this work is the study of the effect of luminescence stimulations and signals reading modes combinations on the thermoluminescence intensity and glow curve behaviour for the same X-ray irradiation dose. Three interesting stimulating and reading modes are considered, namely, infrared stimulated luminescence (IRSL), blue light-emitting diode stimulated luminescence (BLSL) and thermally stimulated luminescence (TSL). The studied stimulation and reading modes combination protocols are (Protocol 1) IRSL-TSL, (Protocol 2) IRSL-BLSL-TSL and (Protocol 3) BLSL-IRSL-TSL. Experiments are performed on beryllium oxide (BeO) dosimeter. Results demonstrate well that the combination of reading modes have direct impact on the TL signal in terms of intensity and glow curve shape. It was also found that when reading modes are correctly combined, particularly when IRSL is applied first, then BLSL and TL, it is possible to collect two or more exploitable signals of different stimulation types for the same irradiation that can be used for different purposes and final applications.

Investigation of zinc polycarboxylate cement used in dental treatments in terms of retrospective dosimeter.

Zinc polycarboxylate cement is one of the few dental materials that demonstrate true adhesion to tooth structure. It is suitable for use in living organisms without causing harm. Its strong adhesion to teeth and low level of irritancy are two important parameters for the dental applications. In this study, the dosimetry properties of zinc polycarboxylate cement using thermoluminescence (TL) method were investigated and determined the effectiveness of its use as a good dosimeter. According to the results of this study, the sample shows a good TL properties with three main peaks found around 140°C, 220°C and 330°C. It has a wide linear dose response between 72 Gy and 2.3 kGy and good reusability of the TL peak found at 330°C. Unfortunately, the TL peak intensity values are rapidly faded within a short waiting time interval. Zinc polycarboxylate cement, which is frequently used in dental crowns, can be used as a retrospective dosimeter for measuring the amount of radiation in space studies and nuclear accidents due to its wide linear dose-response curve in the high dose region.

Thermoluminescent dosimeters (TLD-100) for absorbed dose measurements in alpha-emitting radionuclides.

Early works that used thermoluminescent dosimeters (TLDs) to measure absorbed dose from alpha particles reported relatively high variation (10%) between TLDs, which is undesirable for modern dosimetry applications. This work outlines a method to increase precision for absorbed dose measured using TLDs with alpha-emitting radionuclides by applying an alpha-specific chip factor (CF) that individually characterizes the TLD sensitivity to alpha particles. Variation between TLDs was reduced from 21.8% to 6.7% for the standard TLD chips and 7.9% to 3.3% for the thin TLD chips. It has been demonstrated by this work that TLD-100 can be calibrated to precisely measure the absorbed dose to water from alpha-emitting radionuclides.

Automatic measurements with the Pille-ISS thermoluminescent dosimeter system on board the International Space Station (2003-2021).

The health risk of staying in space is a well-known fact, and the radiation doses to the astronauts must be monitored. The Pille-ISS thermoluminescent dosimeter system is present on the International Space Station (ISS) since 2003. We present an analysis of 60000 data points over 19 years from the 90 min automatic measurements and show a 4-day-long segment of 15 min measurements. In the case of the 15 min we show that the mapping of the radiation environment for the orbit of the ISS is possible with the Pille system. From our results the dose rates inside the South Atlantic Anomaly (SAA) are at least 1 magnitude higher than outside. From the 90 min data, we select orbits passing through the SAA. A statistical correlation in the SAA between the ISS altitude and monthly mean dose rate is presented with the Spearman correlation value of ρSAA=0.56. The dose rate and the sunspot number show strong inverse Pearson correlation (R2=-0.90) at a given altitude.

Studies of thermoluminescence properties of liquid crystalline N-phenyl substituted phenyl polysiloxane hydroxamic acids.

The investigation of thermoluminescence (TL) glow curves in liquid crystalline side chain N-phenyl-substituted phenyl polysiloxane hydroxamic acids (PHAs) has yielded significant insights. These polymers demonstrated TL behavior when exposed to ß-radiation between 0 and 220°C, indicating inherent luminescent properties when irradiated. Notably, a dose-dependent relationship was observed in reported derivatized polymers; this study elucidates the diverse TL characteristics exhibited by various liquid crystalline side chain N-phenyl-substituted phenyl PHAs when exposed to ß-radiation. Understanding these dose-dependent and dose-independent behaviors enhances the knowledge of their luminescent properties and potential applications in radiation detection.

Photoluminescence and thermoluminescence dosimetry properties of Ag/Y co-doped ZnO nanophosphor for radiation measurements.

This work explores the thermoluminescence (TL) and photoluminescence (PL) properties of Ag/Y co-doped zinc oxide (ZnO) nanophosphor. The proposed dosimeter was prepared by the coprecipitation method and sintered at temperatures from 400°C to 1000°C in an air atmosphere. Raman spectroscopy was studied to investigate the structural features of this composition. The new proposed dosimeter revealed two peaks at 150°C and 175°C with a small shoulder at high temperature (225°C). The PL spectrum showed strong green emissions between 500 to 550 nm. The Raman spectrum showed many bands related to the interaction between ZnO, silver (Ag), and yttrium oxide (Y2 O3 ). The rising sintering temperature enhanced the TL glow curve intensity. The Ag/Y co-doped ZnO nanophosphor showed an excellent linearity index within a dose from 1 to 4 Gy. The minimum detectable dose (MDD) of the Ag/Y co-doped ZnO nanopowder (pellets) equaled 0.518 mGy. The main TL properties were achieved in this work as follows: thermal fading (37% after 45 days at 1 and 4 Gy), optical fading (53% after 1 h and 68% after 6 h by exposure to sunlight), effective atomic number (27.6), and energy response (flat behavior from 0.1 to 1.3 MeV). Finally, the proposed material shows promising results nominated to be used for radiation measurements.

Measurement of Hp(10), Hp(3) and Hp(0.07) to medical staff in endoscopic retrograde cholangiopancreatography, using thermoluminescence dosimetry.

Endoscopic retrograde cholangiopancreatography (ERCP) is widely used in the diagnosis and treatment of pancreatic and bile duct disorders. The procedure is performed under the guidance of fluoroscopy. This study aims to investigate the dose received by staff in the Endoscopy Department of AbuAli Sina Medicine and Organ Transplant Hospital in Shiraz. The dosimetry was performed using thermoluminescent dosemeters (TLD), type TLD-100. The values of Hp(10), Hp(3) and Hp(0.07) were estimated for the staff for 2 months. According to the results obtained in this study, the equivalent dose of the gastroenterologist's body, eye lenses and hands was 0.045 ± 0.001 mSv, 0.111 ± 0.014 mSv and 0.357 ± 0.034 $\mathrm{mSv}$, respectively. This study showed that the annual radiation exposure for ERCP department staff of Abu Ali Sinai Hospital is less than the annual dose limit. However, if the principles of proper radiation protection and individual dosimetry are followed, the dose to staff members can be reduced.

Comparison of the performance of two thermoluminescent dosimetry systems for the personal dose-equivalent Hp(10) measurement.

The performance of two thermoluminescent dosimetry systems (RGD-3D and RE2000) manufactured in China and Finland was compared. Both of these dosimetry systems demonstrated satisfactory results as their performance met the requirements of the standard. The two dosimetry systems showed similar performance in the energy response. The RGD-3D dosimetry system performed better in nonlinear response, minimum detectable level and blind sample tests, whereas the RE2000 dosimetry system showed better stability.

The effect of cooling rate on the precision of measurement of glow peak 5 in the thermoluminescence of LiF:Mg,Ti (TLD-100).

The effect of natural rapid cooling and oven slow cooling on the precision of thermoluminescence measurements of LiF:Mg,Ti is investigated. Three separate series of measurements resulted in average precisions of 5.1 and 5.0%, respectively. However, the highest precision of 1.7% (1 SD) was achieved for an oven-cooled material.

Synthesis and characterization of high-sensitivity Dy,Eu co-doped CaSO4 thermoluminescent phosphor using coprecipitation technique.

In this work, (99 - x)CaSO4 -Dy2 O3 -xEu2 O3 , (where x = 0, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5) thermoluminescence phosphors were prepared using a coprecipitation method. The thermoluminescence (TL) dosimetry (TLD) characteristics such as TL sensitivity, dose-response, minimum detectable dose, thermal fading, and the effect of sunlight on the prepared phosphors were investigated. The obtained results indicated that the most sensitive phosphor was obtained at x = 0.05. Large thermal fading of 6% after 1 h and 26% after 24 h from irradiation followed by 71% after 1 month with no additional fading was observed within a time frame exceeding 2 months throughout the remaining duration of the investigation, which also spanned over 2 months. Despite the phosphor's high fading rate, the relative sensitivity of the prepared samples was ~90% compared with TLD-100. The marked effect of day sunlight was also determined. High dose-response within the low-dose range from 0.01 to 5 Gy was observed. The obtained results suggested that the synthesized phosphor is well suited for applications involving radiation biology and radiotherapy dosimetry.

Luminescence and dosimetry approach in terbium(III)-activated tungstate double perovskite.

A series of tungstate double perovskite Ca3 WO6 doped with Tb3+ was prepared by a combustion process using urea as a flux. The crystal structure identification of Ca3 WO6 :Tb3+ phosphors was done using X-ray diffraction patterns, and a monoclinic structure was discovered. The Fourier transform infrared spectrum of Ca3 WO6 :Tb3+ displayed characteristic vibrations of tungstate bonds. Under 278 nm excitation, Ca3 WO6 :Tb3+ exhibited intense downconversion green emission, which corresponded to the 5 D4 -7 FJ (J = 4,5) transitions of Tb3+ . The phosphor exhibited the highest photoluminescence (PL) intensity when it was doped with 1 mol% of Tb3+ ; later intensity quenching appeared to be due to the multipolar interaction at higher dopant concentrations. Moreover, high-quality thermoluminescence (TL) was detected when phosphors were irradiated using beta rays. The effects of Tb3+ concentration and beta dose on TL intensity were the two major aspects studied in detail. The TL intensity demonstrated excellent linear response to the applied range of beta dose. The trap parameters of the studied phosphors were computed by the peak shape approach and glow curve deconvolution. The fading effect on TL intensity was studied by recording the TL glow curves after 1 month of beta irradiation. Obtained results from the PL and TL characterizations showed that the phosphors under study have the potential to be used in lighting displays and in thermoluminescence dosimetry.

Technical note: High-dose and ultra-high dose rate (UHDR) evaluation of Al2 O3 :C optically stimulated luminescent dosimeter nanoDots and powdered LiF:Mg,Ti thermoluminescent dosimeters for radiation therapy applications.

BACKGROUND: Dosimetry in ultra-high dose rate (UHDR) electron beamlines poses a significant challenge owing to the limited usability of standard dosimeters in high dose and high dose-per-pulse (DPP) applications. PURPOSE: In this study, Al2 O3 :C nanoDot optically stimulated luminescent dosimeters (OSLDs), single-use powder-based LiF:Mg,Ti thermoluminescent dosimeters (TLDs), and Gafchromic EBT3 film were evaluated at extended dose ranges (up to 40 Gy) in conventional dose rate (CONV) and UHDR beamlines to determine their usability for calibration and dose verification in the setting of FLASH radiation therapy. METHODS: OSLDs and TLDs were evaluated against established dose-rate-independent Gafchromic EBT3 film with regard to the potential influence of mean dose rate, instantaneous dose rate, and DPP on signal response. The dosimeters were irradiated at CONV or UHDR conditions on a 9-MeV electron beam. Under UHDR conditions, different settings of pulse repetition frequency (PRF), pulse width (PW), and pulse amplitude were used to characterize the individual dosimeters' response in order to isolate their potential dependencies on dose, dose rate, and DPP. RESULTS: The OSLDs, TLDs, and Gafchromic EBT3 film were found to be suitable at a dose range of up to 40 Gy without any indication of saturation in signal. The response of OSLDs and TLDs in UHDR conditions were found to be independent of mean dose rate (up to 1440 Gy/s), instantaneous dose rate (up to 2 MGy/s), and DPP (up to 7 Gy), with uncertainties on par with nominal values established in CONV beamlines (± 4%). In cross-comparing the response of OSLDs, TLDs and Gafchromic film at dose rates of 0.18-245 Gy/s, the coefficient of variation or relative standard deviation in the measured dose between the three dosimeters (inter-dosimeter comparison) was found to be within 2%. CONCLUSIONS: We demonstrated the dynamic range of OSLDs, TLDs, and Gafchromic film to be suitable up to 40 Gy, and we developed a protocol that can be used to accurately translate the measured signal in each respective dosimeter to dose. OSLDs and powdered TLDs were shown to be viable for dosimetric measurement in UHDR beamlines, providing dose measurements with accuracies on par with Gafchromic EBT3 film and their concurrent use demonstrating a means for redundant dosimetry in UHDR conditions.

Thermoluminescence Characteristics of Copper and Terbium Co-Doped Lithium Tetraborate Glass.

In this study, the preparation and characterization of copper (Cu) and terbium (Tb) co-doped lithium borate glass using spectroscopic and thermoluminescence techniques are reported. A thermal treatment was introduced to increase the degree of crystallinity. The thermoluminescence glow curve signal of the samples displayed upon exposure to beta radiation was measured and analyzed. It was found that the samples doped with 0.1% of copper and co-doped with 0.3% terbium showed the highest thermoluminescent (TL) signal in response to the irradiated dose. The analyses revealed that the glow curves of the doped samples were composed of nine overlapping glow peaks with activation energies between 0.73 and 2.78 eV. As a whole area under the glow curve, the TL signals displayed a linear dose response in the range from 110 mGy to 55 Gy. The minimum detectible dose of the samples was found to be 10.39 µGy. It was found that peaks 1 and 2 disappear after one day of storage. The rest of the peaks (3-9) remain almost constant up to 74 days of storage.

Development of ring radiation dosemeters using 3D printing.

Extremity radiation monitoring is an important tool for the assessment of occupational exposures to staff at a variety of workplaces where ionising radiation is used. This work shows the feasibility of applying 3D printing for the development of customisable ring dosemeters. The rings were developed using two types of resin, hard and flexible and has the possibility of sterilisation using different techniques. The printed ring dosemeter was associated with BeO optically stimulated dosemeters. The energy and angular response were found within ±20% in the energy range from 24 to 662 keV and from 0° to 60° angle of incidence. This contributes to the reduction of measurement uncertainty when compared with currently used thermoluminescent detectors dosemeters. The new ring dosemeter showed a satisfactory response with respect to the performance criteria of the IEC 62387 Standard, in addition to providing improved ergonomics in relation to the commercial ring dosemeter.

IAEA/WHO postal dosimetry audit methodology for electron beams using radio photoluminescent dosimeters.

BACKGROUND: Independent dosimetry audits are an important intervention in radiotherapy for quality assurance. Electron beams, used for superficial radiotherapy treatments, must also be tested in dosimetry audits as part of a good quality assurance program to help prevent clinical errors. PURPOSE: To establish a new service for IAEA/WHO postal dosimetry audits in electron beams using RPL dosimeters. METHODS: A novel postal audit methodology employing a PMMA holder system for RPLDs was developed. The associated correction factors including holder dependence, energy dependence, dose response non-linearity, and fading were obtained and tested in a multi-center (n = 12) pilot study. A measurement uncertainty budget was estimated and employed in analyzing the irradiated dosimeters. RESULTS: Holder and energy correction factors ranged from 1.004 to 1.010 and 1.019 to 1.059 respectively across the energy range. The non-linearity and fading correction models used for photon beams were tested in electron beams and did not significantly increase measurement uncertainty. The mean dose ratio ± SD of the multi-center study was 1.001 ± 0.011. The overall uncertainty budget was estimated as ± 1.42% (k = 1). CONCLUSIONS: A methodology for IAEA/WHO postal dosimetry audits in electron beams was developed and validated in a multi-center study and is now made available to radiotherapy centers as a routine service.

Dosimetry of the PIM1 Pion Beam at the Paul Scherrer Institute for Radiobiological Studies of Mice.

Significant past work has identified unexpected risks of central nervous system (CNS) exposure to the space radiation environment, where long-lasting functional decrements have been associated with multiple ion species delivered at low doses and dose rates. As shielding is the only established intervention capable of limiting exposure to the dangerous radiation fields in space, the recent discovery that pions, emanating from regions of enhanced shielding, can contribute significantly to the total absorbed dose on a deep space mission poses additional concerns. As a prerequisite to biological studies evaluating pion dose equivalents for various CNS exposure scenarios of mice, a careful dosimetric validation study is required. Within our ultimate goal of evaluating the functional consequences of defined pion exposures to CNS functionality, we report in this article the detailed dosimetry of the PiMI pion beam line at the Paul Scherrer Institute, which was developed in support of radiobiological experiments. Beam profiles and contamination of the beam by protons, electrons, positrons and muons were characterized prior to the mice irradiations. The dose to the back and top of the mice was measured using thermoluminescent dosimeters (TLD) and optically simulated luminescence (OSL) to cross-validate the dosimetry results. Geant4 Monte Carlo simulations of radiation exposure of a mouse phantom in water by charged pions were also performed to quantify the difference between the absorbed dose from the OSL and TLD and the absorbed dose to water, using a simple model of the mouse brain. The absorbed dose measured by the OSL dosimeters and TLDs agreed within 5-10%. A 30% difference between the measured absorbed dose and the dose calculated by Geant4 in the dosimeters was obtained, probably due to the approximated Monte Carlo configuration compared to the experiment. A difference of 15-20% between the calculated absorbed dose to water at a 5 mm depth and in the passive dosimeters was obtained, suggesting the need for a correction factor of the measured dose to obtain the absorbed dose in the mouse brain. Finally, based on the comparison of the experimental data and the Monte Carlo calculations, we consider the dose measurement to be accurate to within 15-20%.

Comparison of absorbed doses and organ doses measured with thermoluminescent dosimeters and Gafchromic film for cone beam computed tomography examination of the posterior mandibular region in a head phantom.

OBJECTIVES: We aimed to map the correlation between thermoluminescent dosimeters (TLDs) and Gafchromic film for measuring absorbed doses and to compare minimum, maximum, and mean absorbed doses over larger regions of interest and at various craniofacial organs and tissues during cone beam computed tomography (CBCT) exposure of the mandibular third molar region. STUDY DESIGN: We positioned TLDs at 75 measurement points in a head phantom. Gafchromic film was cut to the same shape as the 5 levels of the phantom and was placed on top of the TLDs. Both dosimetry methods thus included the surface of each level simultaneously. CBCT scans were made using a 5 × 5 cm field of view and a rotation angle of 200°. Measurements included absorbed dose distributions, doses at all 75 points, and minimum, maximum, and mean doses within organs and tissues. RESULTS: The correlation of point-dose measurements at all TLD sites with doses measured on film was strong (R2 = 0.9687), with greatest correlation at lower doses (<2 mGy). Large deviations between TLD and film measurements of minimum and maximum doses and absorbed doses to the organs occurred at all 5 levels. TLD positioning failed to cover several organ sites; for these, only absorbed dose measurements from the film were available. CONCLUSIONS: TLDs were unable to sample dose distributions and gradients accurately. The characteristics of Gafchromic LD-V1 film make it a favorable alternative in dental CBCT dosimetry.