Use of real-time electronic extremity dosimeters for monitoring and optimisation of radiopharmacy technique.

Radiopharmacy staff members are subject to extremity radiation doses, particularly to the fingertips. Dosemeters, such as, thermoluminescent detectors (TLDs) are currently used for monitoring fingertip doses. This study aimed to use real-time dosemeters to monitor radiopharmacy extremity doses to identify specific procedural steps associated with higher fingertip doses and, subsequently, reduce dose through promotion of optimised radiation protection practises. Five radiopharmacy operators were monitored using an ED3 active extremity dosemeter with a detector attached to each tip of the index fingers. Dose rate and accumulated dose data were matched to the handled radioactivity data, of99mTc-labelled radiopharmaceuticals only, with the dose per activity (µSv MBq-1) calculated for each step. Once baseline dose data was established, an educational session identified technique adjustments toward improved radiation protection. A subsequent monitored session was undertaken with the dose data compared to quantify changes in operator doses. Radiopharmacy steps which significantly contributed to extremity doses were identified. The average accumulated dose per activity across all procedural steps for the99mTc-labelled radiopharmaceuticals for all operators before the educational session was 0.042 ± 0.045µSv MBq-1and 0.042 ± 0.041µSv MBq-1(n= 89) for non-dominant and dominant index fingertips, respectively, and 0.030 ± 0.044µSv MBq-1and 0.031 ± 0.032µSv MBq-1(n= 97), respectively, afterwards. Overall, there was an average 40.7% reduction in the total extremity dose received after the educational session. Real-time electronic extremity dosemeters for monitoring radiopharmacy extremity dose presented as a useful tool for incorporation into radiation protection education and training, towards optimised radiopharmacy technique.

Dosimetric Study of Heat-Treated Calcium-Aluminum-Silicon Borate Dosimeter for Diagnostic Radiology Applications.

The production of thermoluminescence (TL) dosimeters fabricated from B2O3-CaF2-Al2O3-SiO2 doped with Cu and Pr for use in diagnostic radiology is the main goal of this research. The TL samples were synthesized via the melt-quench technique processed by melting the mixture at 1200 °C for 1 h, and, after cooling, the sample thus created was divided into two samples and retreated by heating for 2 h (referred to as TLV30) and for 15 h (referred to as TLV17). SEM and EDS analyses were performed on the TL samples to confirm the preparation process and to investigate the effects of irradiation dosimetry on the TL samples. Furthermore, the TL samples were irradiated with γ-rays using a 450 Ci 137Cs irradiator and variable X-ray beams (5-70 mGy). Two important diagnostic radiology applications were considered: CT (6-24 mGy) and mammography (2.72-10.8 mGy). Important dosimetric properties, such as the glow curves, reproducibility, dose-response linearity, energy dependence, minimum dose detectability and fading, were investigated for the synthetized samples (TLV17 and TLV30), the results of which were compared with the Harshaw TLD-100. The TLV17 dosimeter showed higher sensitivity than TLV30 in all applied irradiation procedures. The dose-response linearity coefficients of determination R2 for TLV17 were higher than TLD-100 and TLV30 in some applications and were almost equal in others. The reproducibility results of TLV17, TLV30 and TLD-100 were less than 5%, which is acceptable. On the other hand, the results of the fading investigations showed that, in general, TLV17 showed less fading than TLV30. Both samples showed a significant decrease in this regard after the first day, and then the signal variation became essentially stable though with a slight decrease until the eighth day. Therefore, it is recommended to read the TL dosimeters after 24 h, as with TLD-100. The SEM images confirmed the existence of crystallization, whilst the EDS spectra confirmed the presence of the elements used for preparation. Furthermore, we noticed that TLV17 had grown dense crystals that were larger in size compared to those of TLV30, which explains the higher sensitivity in TLV17. Overall, despite the fading, TLV17 showed greater radiation sensitivity and dose-response linearity compared with TLD-100. The synthetized TL samples showed their suitability for use as dosimeters in diagnostic radiology radiation dosimetry.

Unveiling Insights: Harnessing the Power of the Most-Frequent-Value Method for Sensor Data Analysis.

The paper explores the application of Steiner's most-frequent-value (MFV) statistical method in sensor data analysis. The MFV is introduced as a powerful tool to identify the most-common value in a dataset, even when data points are scattered, unlike traditional mode calculations. Furthermore, the paper underscores the MFV method's versatility in estimating environmental gamma background blue (the natural level of gamma radiation present in the environment, typically originating from natural sources such as rocks, soil, and cosmic rays), making it useful in scenarios where traditional statistical methods are challenging. It presents the MFV approach as a reliable technique for characterizing ambient radiation levels around large-scale experiments, such as the DEAP-3600 dark matter detector. Using the MFV alongside passive sensors such as thermoluminescent detectors and employing a bootstrapping approach, this study showcases its effectiveness in evaluating background radiation and its aptness for estimating confidence intervals. In summary, this paper underscores the importance of the MFV and bootstrapping as valuable statistical tools in various scientific fields that involve the analysis of sensor data. These tools help in estimating the most-common values and make data analysis easier, especially in complex situations, where we need to be reasonably confident about our estimated ranges. Our calculations based on MFV statistics and bootstrapping indicate that the ambient radiation level in Cube Hall at SNOLAB is 35.19 µGy for 1342 h of exposure, with an uncertainty range of +3.41 to -3.59µGy, corresponding to a 68.27% confidence level. In the vicinity of the DEAP-3600 water shielding, the ambient radiation level is approximately 34.80 µGy, with an uncertainty range of +3.58 to -3.48µGy, also at a 68.27% confidence level. These findings offer crucial guidance for experimental design at SNOLAB, especially in the context of dark matter research.

Ambient Dose and Dose Rate Measurement in SNOLAB Underground Laboratory at Sudbury, Ontario, Canada.

The paper describes a system and experimental procedure that use integrating passive detectors, such as thermoluminescent dosimeters (TLDs), for the measurement of ultra-low-level ambient dose equivalent rate values at the underground SNOLAB facility located in Sudbury, Ontario, Canada. Because these detectors are passive and can be exposed for relatively long periods of time, they can provide better sensitivity for measuring ultra-low activity levels. The final characterization of ultra-low-level ambient dose around water shielding for ongoing direct dark matter search experiments in Cube Hall at SNOLAB underground laboratory is given. The conclusion is that TLDs provide reliable results in the measurement of the ultra-low-level environmental radiation background.

Eye lens dose in spine surgeons during myelography procedures: a dosimetry study.

To determine the eye lens dose (3 mm dose equivalent [Hp(3)]) received by spine surgeons during myelography and evaluate the effectiveness of radiation-protective glasses and x-ray tube system positioning in reducing radiation exposure. This study included spine surgeons who performed myelography using over- or under-table x-ray tube systems. Hp(3) was measured for each examination using a radio-photoluminescence glass dosimeter (GD-352M) mounted on radiation-protective glass. This study identified significantly high Hp(3) levels, especially in the right eye lens in spinal surgeons. The median Hp(3) values in the right eye were 524 (391-719) and 58 (42-83)µSv/examination for over- and under-table x-ray tube systems, respectively. Further, Hp(3)AK, which was obtained by dividing the cumulative air kerma from Hp(3), was 8.09 (6.69-10.21) and 5.11 (4.06-6.31)µSv mGy-1for the over- and under-table x-ray tube systems, respectively. Implementing radiation-protective glasses resulted in dose reduction rates of 54% (50%-57%) and 54% (51%-60%) for the over- and under-table x-ray tube systems, respectively. The use of radiation protection glasses significantly reduced the radiation dose in the eye lens during myelography, with the most effective measures being the combination of using radiation protection glasses and an under-table x-ray tube system.

H2 S Dosimetry by CuO: Towards Stable Sensors by Unravelling the Underlying Solid-State Chemistry.

The precise detection of the toxic gas H2 S requires reliable sensitivity and specificity of sensors even at minute concentrations of as low as 10 ppm, the value corresponding to typical exposure limits. CuO can be used for H2 S dosimetry, based on the formation of conductive CuS and the concomitant significant increase in conductance. In theory, at elevated temperature the reaction is reversed and CuO is formed, ideally enabling repeated and long-term use of one sensor. Yet, the performance of CuO tends to drop upon cycling. Utilizing defined CuO nanorods we thoroughly elucidated the associated detrimental chemical changes directly on the sensors, by Raman and electron microscopy analysis of each step during sensing (CuO→CuS) and regeneration (CuS→CuO) cycles. We find the decrease in the sensing performance is mainly caused by the irreversible formation of CuSO4 during regeneration. The findings allowed us to develop strategies to reduce CuSO4 formation and thus to substantially maintain the sensing stability even for repeated cycles. We achieved CuO-based dosimeters possessing a response time of a few minutes only, even for 10 ppm H2 S, and prolonged life-time.

Comparison of organ and effective dose estimations from different Monte Carlo simulation-based software methods in infant CT and comparison with direct phantom measurements.

PURPOSE: Computational dosimetry software is routinely used to evaluate the organ and effective doses from computed tomography (CT) examinations. Studies have shown a significant variation in dose estimates between software in adult cohorts, and few studies have evaluated software for pediatric dose estimates. This study aims to compare the primary organ and effective doses estimated by four commercially available CT dosimetry software to thermoluminescent dosimeter (TLD) measurements in a 1-year-old phantom. METHODS: One hundred fifteen calibrated LiF (Mg, Cu, P)-TLD 100-H chips were embedded within an anthropomorphic phantom representing a 1-year-old child at positions that matched the approximate location of organs within an infant. The phantom was scanned under three protocols, each with whole-body coverage. The mean absorbed doses from 25 radiosensitive organs and skeletal tissues were determined from the TLD readings. Effective doses for each of the protocols were subsequently calculated using ICRP 103 formalism. Dose estimates by the four Monte Carlo-based dose calculation systems were determined and compared to the directly measured doses. RESULTS: Most organ doses determined by computation dosimetry software aligned to phantom measurements within 20%. Additionally, comparisons between effective doses are calculated using computational and direct measurement methods aligned within 20% across the three protocols. Significant variances were found in bone surface dose estimations among dosimetry methods, likely caused by differences in bone tissue modeling. CONCLUSION: All four-dosimetry software evaluated in this study provide adequate primary organ and effective dose estimations. Users should be aware, however, of the possible estimated uncertainty associated with each of the programs.

Characterization of Thermoluminescent Dosimeters for Neutron Dosimetry at High Altitudes.

Neutrons constitute a significant component of the secondary cosmic rays and are one of the most important contributors to natural cosmic ray radiation background dose. The study of the cosmic ray neutrons' contribution to the dose equivalent received by humans is an interesting and challenging task for the scientific community. In addition, international regulations demand assessing the biological risk due to radiation exposure for both workers and the general population. Because the dose rate due to cosmic radiation increases significantly with altitude, the objective of this work was to characterize the thermoluminescent dosimeter (TLDs) from the perspective of exposing them at high altitudes for longtime neutron dose monitoring. The pair of TLD-700 and TLD-600 is amply used to obtain the information on gamma and neutron dose in mixed neutron-gamma fields due to the present difference in 6Li isotope concentration. A thermoluminescence dosimeter system based on pair of TLD-600/700 was characterized to enable it for neutron dosimetry in the thermal energy range. The system was calibrated in terms of neutron ambient dose equivalent in an experimental setup using a 241Am-B radionuclide neutron source coated by a moderator material, polyethylene, creating a thermalized neutron field. Afterward, the pair of TLD-600/700 was exposed at the CERN-EU High-Energy Reference Field (CERF) facility in Geneva, which delivers a neutron field with a spectrum similar to that of secondary cosmic rays. The dosimetric system provided a dose value comparable with the calculated one demonstrating a good performance for neutron dosimetry.

Assessment of extremity exposure to technologists working manually with99mTc-labelled radiopharmaceuticals and with an automatic injection system for18F-FDG.

The hands of nuclear medicine (NM) personnel involved in radiopharmaceutical preparation and administration can receive significant radiation doses. The dose distribution across the hand is nonuniform and the Hp(0.07) doses obtained by an individual passive ring dosimeter do not always present a real situation. The aim of this study was to assess the extremity exposure of NM workers working with99mTc-labelled radiopharmaceuticals and with an automatic IRIDE (COMECER, Italy)18F-FDG injection system. Hp(0.07) doses were measured using calibrated thermoluminescent dosimeters-100 (TLD-100) and were read by a RIALTO TLD (NE Technology) reader. It was found that the most exposed parts of the hand during work with18F and99mTc radionuclides are the fingertips of the thumb, index finger and middle finger. The maximum fingertip doses were 1.3-2.4 times higher compared with the doses from the typical monitoring position (base of the middle finger of the dominant hand). When working with99mTc, the average hand doses were relatively high, i.e. 0.17 ± 0.04 and 0.37 ± 0.13 mSv Gbq-1for the left and the right hand, respectively, during preparation, and 58 ± 20 and 53 ± 13µSv GBq-1for the left and the right hand, respectively, during administration of99mTc labelled radiopharmaceuticals. Meanwhile, the lowest doses were found for hands during administration of18F-FDG (average hand dose 28 ± 13µSv GBq-1for the left hand and 28 ± 7µSv GBq-1for the right hand), which shows the advantages of automated injection/infusion systems, thus implementation of automatic infusion/injection in hospitals could be an expedient way to optimize Hp(0.07) doses to NM workers.

Dose Field Shaping and Biological Effectiveness of the Effect of Pulsed Electron Accelerator Novac-11 on Mammalian Cells.

The development of technologies for using the Novac-11 pulsed electron accelerator in radiation therapy of animals with spontaneous neoplasms requires dosimetric and radiobiological studies. The studies were performed on cultured Chinese hamster V-79 fibroblasts after irradiation with 10 MeV electrons in a dose range up to 12 Gy and 60Co γ-radiation. Chemical dosimeters FBX and Fricke were used as additional test-systems. The depth dose curves were measured and the maximum dose depth of the electron beam was determined in tissue-equivalent phantoms. Cell survival and the data of chemical dosimetric systems showed that the effects of electron irradiation did not differ from that of 60Co γ-radiation. It was concluded that the use of Novac-11 in the therapy of animals with spontaneous neoplasms is advisable.

Biodosimetry in interventional radiology: cutaneous-based immunoassay for anticipating risks of dermatitis.

OBJECTIVES: Interventional radiology procedures expose individuals to ionizing radiation. However, existing dosimetry methods do not provide the dose effectively absorbed to the skin, and do not consider the patient's individual response to irradiation. To resolve this lack of dosimetry data, we developed a new external irradiation biodosimetry device, DosiKit, based on the dose-dependent relationship between irradiation dose and radiation-induced H2AX protein phosphorylation in hair follicles. This new biological method was tested in Clermont-Ferrand University Hospital to evaluate the assay performances in the medical field and to estimate DosiKit sensitivity threshold. METHODS: DosiKit was tested over 95 patients treated with neuroradiological interventions. For each intervention, lithium fluoride thermoluminescent dosimeters (TLD) were used to measure total dose received at each hair collection point (lateral and occipital skull areas), and conventional indirect dosimetry parameters were collected with a Dosimetry Archiving and Communication System (DACS). RESULTS: Quantitative measurement of radiation-induced H2AX protein phosphorylation was performed on 174 hair samples before and after the radiation exposure and 105 samples showed a notable induction of gammaH2AX protein after the radiological procedure. According to a statistical analysis, the threshold sensitivity of the DosiKit immunoassay was estimated around 700 mGy. CONCLUSIONS: With this study, we showed that DosiKit provides a useful way for mapping the actually absorbed doses, allowing to identify patients overexposed in interventional radiology procedures, and thus for anticipating risk of developing dermatitis. KEY POINTS: • DosiKit is a new external irradiation biodosimetry device, based on the dose-dependent relationship between irradiation dose and radiation-induced H2AX protein phosphorylation in hair follicles. • DosiKit was tested over 95 patients treated with neuroradiological interventions. • The threshold sensitivity of the DosiKit immunoassay was estimated around 700 mGy and DosiKit provides a useful way for mapping the actually absorbed doses.

Ultraviolet C lamps for disinfection of surfaces potentially contaminated with SARS-CoV-2 in critical hospital settings: examples of their use and some practical advice.

BACKGROUND: UltraViolet-C (UV-C) lamps may be used to supplement current hospital cleaning and disinfection of surfaces contaminated by SARS-CoV-2. Our aim is to provide some practical indications for the correct use of UV-C lamps. METHODS: We studied three UV-C lamps, measuring their spatial irradiance and emission over time. We quantify the error that is committed by calculating the irradiation time based exclusively on the technical data of the lamps or by making direct irradiance measurements. Finally, we tested specific dosimeters for UV-C. RESULTS: Our results show that the spatial emission of UV-C lamps is strongly dependent on the power of the lamps and on the design of their reflectors. Only by optimizing the positioning and calculating the exposure time correctly, is it possible to dispense the dose necessary to obtain SARS-CoV-2 inactivation. In the absence of suitable equipment for measuring irradiance, the calculated irradiation time can be underestimated. We therefore consider it precautionary to increase the calculated times by at least 20%. CONCLUSION: To use UV-C lamps effectively, it is necessary to follow a few simple precepts when choosing, positioning and verifying the lamps. In the absence of instruments dedicated to direct verification of irradiance, photochromic UV-C dosimeters may represent a useful tool for easily verifying that a proper UV-C dose has been delivered.

Assessment of eye doses to staff involved in interventional cardiology procedures in Kuwait.

In this study, which is the first of its kind in the gulf region, eye doses of interventional cardiologists and nurses were measured using active dosimeters for left and right eyes, in 60 percutaneous coronary interventions in three main hospitals in Kuwait. The dose given in terms of Hp(0.07) per procedure when ceiling suspended screens were used by main operators ranged from 18.5 to 30.3 µSv for the left eye and from 12.6 to 23.6 µSv for the right eye. Taking into account typical staff workload, the results show that the dose limit of 20 mSv/year to the eyes can be exceeded for interventional cardiologists in some situations, which demonstrates the need of using additional effective radiation protection tools, e.g. protective eye spectacles, in addition to the regular and proper use of ceiling suspended screens. With indications of increase in workload, the need for availability of a dedicated active dosimeter for the regular monitoring of eye doses is emphasized.

Dosimetric properties of lithium borate glass doped with dysprosium.

Characterization of thermoluminescence (TL) properties of lithium borate glass samples doped with different concentrations of dysprosium (Dy) was carried out. Samples were prepared using a melting method at 1100°C and irradiated with ß-particles. The glass samples doped with 0.1% Dy displayed the best TL dosimetric properties compared with other compositions. Deconvoluted analyses of the glow curves displayed five overlapping TL glow peaks located between 392.0 and 510.3 K. A good linear TL dose-response for ß-particles was obtained in the dose range 66.6 mGy to 33.3 Gy. The minimum detectible dose was evaluated to be 205.4 µGy and samples revealed thermal fading in 312 h to 29% of their original value.

Recent developments in phosphate materials for their thermoluminescence dosimeter (TLD) applications.

The use of phosphate-based thermoluminescence dosimeter (TLD) materials in current scenarios is presented here, particularly for the field of low dosimetry. TLD materials are currently researched for their use in for example environmental dosimetry, personal dosimetry, and medical dosimetry. There are several TLD materials available such as: sulphates, borates, fluorides, and sulphides, including some metal oxides and perovskites, which are the most used and have been widely explored. In the present scenario, new interest is being focused on the need for thermoluminescent materials for application in material science and radiation dosimetry for low-dose dosimetry. These doped TLDs are prepared using different techniques including solid-state reaction methods, combustion methods, wet chemical methods, and sol gel methods. Therefore, among the above stated TLDs, phosphates have opened a new door in radiation dosimetry, particularly in low-dose dosimetry over the last few years. This paper mainly deals with a review of various phosphate-based TLD materials and recent advancements in phosphates for TL dosimetry.

Gel and thermoluminescence dosimetry for dose verifications of a real anatomy simulated prostate conformal radiation treatment in the presence of metallic femoral prosthesis.

This study aims to verify the dose delivery of prostate radiotherapy treatments in an adult pelvic phantom with two metallic hip and femur prosthesis using a four-field box technique. The prostate planned target volume (PTV) tridimensional (3D) dose distribution was evaluated using gel dosimetry, and thermoluminescent dosimeters (TLD) were used for point-dose measurements outside it. Both results were compared to the treatment planning system (TPS) dose calculation without using heterogeneity corrections to evaluate the influence of the metal in the dose distribution. MAGIC-f gel dosimeter (Methacrylic and Ascorbic acid in Gelatin Initiated by Copper with Formaldehyde) associated with magnetic resonance imaging was used. TLD were positioned at several points at the bone metal interface and the sacrum region. The comparison of the gel measured and the TPS calculated dose distributions were done using gamma analysis (3%/3 mm), and a pass rate of 93% was achieved. The TLD dose values at the bone-metal interface showed variations from the planned dose. However, at the sacrum region, where the beams did not intercept the prosthesis, there was a good agreement between TPS planning and TLD measurements. Our results show how the combination of 3D dosimetry and measurements at specific points in the phantom allowed a comprehensive view of the dose distribution and identified that care must also be paid to regions outside the PTV.

Simultaneous Measurements of Dose and Microdosimetric Spectra in a Clinical Proton Beam Using a scCVD Diamond Membrane Microdosimeter.

A single crystal chemical vapor deposition (scCVD) diamond membrane-based microdosimetric system was used to perform simultaneous measurements of dose profile and microdosimetric spectra with the Y1 proton passive scattering beamline of the Center of Proton Therapy, Institute Curie in Orsay, France. To qualify the performance of the set-up in clinical conditions of hadrontherapy, the dose, dose rate and energy loss pulse-height spectra in a diamond microdosimeter were recorded at multiple points along depth of a water-equivalent plastic phantom. The dose-mean lineal energy (y¯D) values were computed from experimental data and compared to silicon on insulator (SOI) microdosimeter literature results. In addition, the measured dose profile, pulse height spectra and y¯D values were benchmarked with a numerical simulation using TOPAS and Geant4 toolkits. These first clinical tests of a novel system confirm that diamond is a promising candidate for a tissue equivalent, radiation hard, high spatial resolution microdosimeter in beam quality assurance of proton therapy.

Influence of the simultaneous calibration of multiple ring dosimeters on the individual absorbed dose.

Ring dosimeters for personal dosimetry are calibrated in accredited laboratories following ISO 4037-3 guidelines. The simultaneous irradiation of multiple dosimeters would save time, but has to be carefully studied, since the scattering conditions could change and influence the absorbed dose in nearby dosimeters. Monte Carlo simulations using PENELOPE-2014 were performed to explore the need to increase the uncertainty ofHp0.07in the simultaneous irradiation of three and five DXT-RAD 707H-2 (Thermo Scientific) ring dosimeters with beam qualities: N-30, N-80 and N-300. Results show that the absorbed dose in each dosimeter is compatible with each of the others and with the reference simulation (a single dosimeter), with a coverage probability of 95% (k= 2). Comparison with experimental data yielded consistent results with the same coverage probability. Therefore, five ring dosimeters can be simultaneously irradiated with beam qualities ranging, at least, between N-30 and N-300 with a negligible impact on the uncertainty ofHp0.07.

Thyroid dose and cancer risk from head and neck computed tomography at two selected centres in Nigeria.

OBJECTIVE: The objective of this study was to evaluate the thyroid glands' radiation dose and the risk of thyroid cancer induction from head or neck computed tomography (CT) examinations. METHODS: In a prospective study, we evaluated all participants of all ages and sex referred for Head or Neck CT Scan at the University College Hospital, Ibadan and Me Cure Healthcare Limited, Ibadan, Oyo State, Nigeria. Thyroid radiation dose was estimated with impact scan calculator, and real-time dose measurement with thermoluminescent badge dosimeters (TLDs). Data were analysed and P < 0.05 was considered statistically significant. RESULTS: One hundred and sixty-three participants (128 adults and 35 children) participated in the study. In most participants (74%), the tube voltage was 120 kVp. The estimated median thyroid gland dose by the imPACT scan calculator was 4.95 mGy (range = 1.20-30.0 mGy) and 4.40 mGy (range = 3.0-5.10 mGy), while the real-time dose measured by the TLD was 4.79 mGy (range = 1.73-96.7 mGy) and 2.33 mGy (range = 1.20-3.73 mGy) at Centre A and B, respectively. The estimated median thyroid cancer risk was 2.88 × 10-6 (maximum range of 52 × 10-6) at centre A and a median value of 3.20 × 10-6 with a cancer risk estimate that may reach 17.9 × 10-6 recorded at centre B, compared to a cumulative thyroid cancer risk of 0.12 × 10-5 among the general Nigerian population. CONCLUSIONS: Scanner specifications and technique may significantly contribute to variations seen in thyroid radiation doses. There may be a need to optimise centre protocols and apply dose reference levels for head and neck CT examinations to reduce thyroid cancer risk in Nigeria.

Nanoparticle dose enhancement of synchrotron radiation in PRESAGE dosimeters.

The physical absorbed dose enhancement by the inclusion of gold and bismuth nanoparticles fabricated into water-equivalent PRESAGE dosimeters was investigated. Nanoparticle-loaded water-equivalent PRESAGE dosimeters were irradiated with superficial, synchrotron and megavoltage X-ray beams. The change in optical density of the dosimeters was measured using UV-Vis spectrophotometry pre- and post-irradiation using a wavelength of 630 nm. Dose enhancement was measured for 5 nm and 50 nm monodispersed gold nanoparticles, 5-50 nm polydispersed bismuth nanoparticles, and 80 nm monodispersed bismuth nanoparticles at concentrations from 0.25 mM to 2 mM. The dose enhancement was highest for the 95.3 keV mean energy synchrotron beam (16-32%) followed by the 150 kVp superficial beam (12-21%) then the 6 MV beam (2-5%). The bismuth nanoparticle-loaded dosimeters produced a larger dose enhancement than the gold nanoparticle-loaded dosimeters in the synchrotron beam for the same concentration. For the superficial and megavoltage beams the dose enhancement was similar for both species of nanoparticles. The dose enhancement increased with nanoparticle concentration in the dosimeters; however, there was no observed nanoparticle size dependence on the dose enhancement.