Dosimetry Research Articles

Definition of a disability weight for human exposure to ionising radiation and its application to the justification of medical exposure

Abstract Objectives To establish a link between radiation dosimetry and disability-adjusted life-years (DALY) with the aim of quantifying the justification of medical exposures. Methods The health detriment, defined as lifetime loss of DALY at age of exposure to ionising radiation for a US-European population was calculated. A simple model of the relationship was fitted to the results. Apart from in late life within the latency period for radiation-induced cancers, most of the relationship can be adequately fitted to a straight line of negative gradient. The gradient of this line corresponds to a loss of DALY per year following exposure to radiation and is therefore equivalent to a disability weight used in the calculation of DALY. Results Radiation dose dependent disability weights for radiation exposure to a US-European population are estimated as 0.019 DALY/yr/Sv for males and 0.021 DALY/yr/Sv for females. Conclusions By comparing a range of 66 radiological examinations in terms of the disability weights of the disease or injury states with the disability weights resulting from the associated radiological exposures, it is demonstrated graphically that the resulting benefit is far greater than the detriment in every case. Advances in knowledge The definition of a disability weight for ionising radiation, proportional to effective dose as currently defined, can link radiation exposure to the existing large body of data on the DALY burden and disability weights for a wide range of diseases and injuries, providing a means for the quantitative justification of the benefit-detriment balance of medical exposures.

Design and dosimetric characterization of a transportable proton minibeam collimation system

BackgroundProton Minibeam Radiation Therapy has shown to widen the therapeutic window compared to conventional radiation treatment in pre-clinical studies. The underlying biological mechanisms, however, require more research.PurposeThe purpose of this study was to develop and characterize a mechanical collimation setup capable of producing 250µm wide proton minibeams with a center-to-center distance of 1000µm.MethodsTo find the optimal arrangement Monte Carlo simulations were employed using the Geant4 toolkit TOPAS to maximize key parameters such as the peak-to-valley dose ratio (PVDR) and the valley dose rate. The experimental characterization of the optimized setup was carried out with film dosimetry at the University Proton Therapy beamline in Dresden and the proton beamline of the University of Washington Medical Center in Seattle with 150MeV and 50.5MeV, respectively. A microDiamond detector (PTW, Freiburg, Germany) was utilized at both beamlines for online proton minibeam dosimetry.ResultsA PVDR of 10 was achieved in Dresden and a PVDR of 14 in Seattle. Dosimetry measurements were carried out with EBT3 films at a depth of 5mm in a polymethylmethacrylate (PMMA) phantom. When comparing film dosimetry with the microDiamond, excellent agreement was observed in the valleys. However, the peak dose showed a discrepancy of approximately 10% in the 150MeV beam and 20% in the 50.5MeV beam between film and microDiamond.DiscussionThe characteristics of the minibeams generated with our system compares well with those of other collimated minibeams despite being smaller. The deviations of microDiamond measurements from film readings might be subject to the diamond detector responding differently in the peak and valley regions. Applying previously reported correction factors aligns the dose profile measured by the microDiamond with the profile acquired with EBT3 films in Dresden.ConclusionThe novel proton minibeam system can be operated independently of specific beamlines. It can be transported easily and hence used for inter-institutional comparative studies. The quality of the minibeams allows us to perform in vitro and in vivo experiments in the future. The microDiamond was demonstrated to have great potential for online dosimetry for proton minibeams, yet requires more research to explain the observed discrepancies.

From reconstructed DICOM images to 3D printed models: anthropomorphic dosimetric phantoms

This study explores the construction of anthropomorphic dosimetric phantoms by leveraging Stereolithography (SLA) 3D printing technology and DICOM images processed through the Slicer software. This approach involves segmentation and processing of DICOM data bases of human subjects to extract specific anatomical structures that are to be converted into a format suitable for 3D printing. The objective is to create accurate models for radiation dosimetry applications. These phantoms hold great potential in advancing medical radiation research, allowing for more accurate and personalized assessments of radiation doses in various clinical scenarios.

Synthesis and luminescence characterizations of Ag and Na doped LiAlO2 for OSL dosimetry

Optically Stimulated Luminescence (OSL) materials are advanced technology materials widely used in critical applications from radiation dosimetry, biomedicine, and optical data storage to archaeometry. These materials store energy by trapping charge carriers and convert this energy back into light by optical stimulation. However, there are significant challenges such as control of trap distribution and complete understanding of luminescence mechanisms. This study aims to overcome these challenges by comprehensively investigating the luminescence characteristics of lithium aluminate (LiAlO2) pellet materials produced by the sol-gel method and enabling the development of a new OSL dosimetric material. The crystal structures of the synthesized materials were confirmed by X-Ray Diffraction (XRD) method and their morphologies were investigated by Scanning Electron Microscope (SEM). Detailed discussions on defect concentrations and lattice parameters of LiAlO2 are presented. To obtain promising luminescence signals for passive dosimetry, LiAlO2 were doped with various lanthanides (Ce and Gd) and metals (Cu, Ag, Na, Mg and Ca). Especially, the co-doping of Ag and Na ions provided a significant increase in Thermoluminescence (TL) and OSL signals. The effects of dopant elements on TL and OSL signals were investigated comprehensively, and the OSL components and lifetimes were analyzed in detail. As a result, it was determined that TL traps of the developed LiAlO2:Ag,Na pellets at 100 °C were the main source of OSL signals. The reusable OSL signals and almost linear dose-response ratio up to 2 Gy of this material make it a candidate for radiation dosimetry applications. While the developed LiAlO2:Ag,Na material exhibits promising OSL sensitivity and low fading over 2 weeks, the signal stability is dependent on an initial preheat treatment at 100 °C, which reduces around 80 % of the initial OSL signal associated with shallow traps. This characteristic supports the material’s application in dosimetry but may limit sensitivity in low-dose contexts.

Gadolinium doped lithium aluminum borate [Li3Al3(BO3)4:Gd] materials synthesized and characterized for its structural, optical and thermoluminescence properties for use in dosimetric application

Lithium aluminum borate materials was made ready for dosimetric uses in radiation processes. In order to enhance the structural and dosimetric qualities, varying mole concentrations of gadolinium were added to samples of lithium aluminum borate materials. High temperature solid-state technique was used in producing the lithium aluminum borate material. The characterization of the material was archived by using Scanning electron microscope, X-ray diffractometer, thermal gravimetric evaluation, UV-vis-NIR spectrophotometer and thermoluminescence reader/irradiator in other to determine for their structural, thermal analysis, optical properties and dosimetric properties respectively. The kinetic analysis of the major glow peak yielded the activation energy. The crystalline sizes of the undoped and gadolinium-doped Li3Al3(BO3)4 materials were reported to be approximately 36.38 nm and 68.84 nm, respectively, which relies on their matching peaks at a 2θ angle of 25.79o. The grain size for the undoped and gadolinium doped lithium aluminum borate were found within a given range of values 140 – 160 nm, and 80 – 100 nm respectively. The optical energy band gap was found within 3.90 eV to 4.35 eV for the gadolinium doped while the undoped is 3.00 eV for lithium aluminum borate respectively. A larger energy band gap of lithium aluminum borate was observed after gadolinium was incorporated as dopant. The phosphor of lithium aluminum borate doped with gadolinium was observed to exhibit prominent TL intensity peaks at 100 oC following irradiation. The irradiated samples of lithium aluminum borate doped with gadolinium showed a dose response that was linear between 20 and 150 Gy. This work demonstrates the potential use of Gd-doped lithium aluminum borate phosphor in radiation dosimetry.

Alumina Crucibles from Free Dispersant Suspensions: A Useful Labware to form Advanced Powders for Radiation Dosimetry

Background: Powder technology provides conditions to control particle-particle interactions that drive the formation of final-component/material, which also includes the crystalline structure, microstructure and features. Alumina (Al2O3) is the most studied ceramic based material due to its useful properties, disposal, competitive price, and wide technological applicability. This work aims to produce alumina crucibles with controlled size and shape from free dispensant suspensions. These crucibles will be used as containers for the synthesis of new materials for radiation dosimetry. Methods: The Al2O3 powders were characterized by XRD, SEM, PCS, and EPR. The stability of alumina particles in aqueous solvent was evaluated by zeta potential determination as a function of pH. Alumina suspensions with 30 vol% were shaped by slip casting in plaster molds, followed by sintering at 1600oC for 2 h in an air atmosphere. Alumina based crucibles were characterized by SEM and XRD. Results: ɑ-Al2O3 powders exhibited a mean particle diameter size (d50) of 983nm. Besides, the stability of particles in aqueous solvent was achieved at a range of pH from 2.0-6.0, and from 8.5-11.0. EPR spectra revealed two resonance peaks P1 and P2, with g-values of 2.0004 and 2.0022, respectively. The as-sintered ɑ-alumina based crucibles presented uniform shape and controlled size with no apparent defects. In addition, the final microstructure driven by solid-state sintering revealed a dense surface and uniform distribution of grains. Conclusion: The ɑ-Al2O3 crucibles obtained by slip casting of free dispensant alumina suspensions, followed by sintering, exhibited mechanical strength, and controlled shape and size. These crucibles will be useful labwares for the synthesis of new materials for radiation dosimetry.

Characterization of Ceria Powders as a Continuous Search for New Rare-earth Based Materials for Radiation Dosimetry

Background: Ceria (CeO2) belongs to rare-earth series and due to its profitable properties, presents a wide commercial use such as catalysis, energy, biological, biomedical, and pharmaceutical. The features of the starting materials in the form of free powders influence notably the processing, formation, as well as characteristics of the final structures\bodies obtained by colloidal processing. This study aims to characterize CeO2 powders. The results obtained are worthwhile data to advance toward new rare-earth based materials for radiation dosimetry. Methods: CeO2 powders were evaluated by the following techniques: PCS, SEM, XRD, FT-IR, EPR, IPC, and pycnometric density (ρ). The stability of particles in aqueous solvent was evaluated by zeta potential (ζ) determination. Results: CeO2 powders exhibited cubic C-type form, Fm-3m space group, a mean particle size (d50) of 19.3nm, and a pycnometric density (ρ) of 7.01g.cm-3. Based on the results of zeta potential determination, CeO2 powders exhibited high stability at pH 6.4 with ζ- value of |34.0|mV. Conclusion: The evaluation of CeO2 powders was reported. The results presented and discussed in this study contribute to advance in the search of new rare-earth based materials for radiation dosimetry.

Radiation Dosimetry Performance Appraisal of the Optimal Concentration of Nitro Blue Tetrazolium Dye in PVA Composite Film at Low X-ray Doses

Radiation Dosimetry Performance Appraisal of the Optimal Concentration of Nitro Blue Tetrazolium Dye in PVA Composite Film at Low X-ray Doses

A low-cost instrumentation for monitoring of the environmental radioactivity

In this work, a low-cost radiation monitoring instrumentation for measuring the environmental gamma radioactivity together with some atmospheric parameters was designed and produced. The device has been built with market available components. The detector section of the device uses a Si-PIN photo-diode as an active element. A tiny current produced from the energy deposition of gamma rays in silicon is amplified in two stages, firstly with a charge sensitive amplifier (CSA) and secondly with a shaping amplifier (SA). The amplified signal is further processed to be converted into digital pulses for counting. The monitor station is designed to be operated remotely in self-sufficient mode, equipped with LoRA module running at 500 MHz to transfer the data remotely to a base station. The base station also includes a LoRA module to receive the data and stores it in an SD card while an OLED display visualizes the recent measurement. Multiple monitor stations can be used to control the radioactivity level in a field simultaneously. This field could be used inside or outside of an interested facility. The noise limit of the detector developed was determined to be as low as 20 keV photon energy. The low-energy detection limit was conservatively set to 40 keV which was still below the 64 keV of the naturally occurring 234Th. Counting the events for hourly, daily or weekly provide statistically significant data depending on the activity of the interested region. All gamma energies above 40 keV from the decays of naturally occurring radioisotopes can be practically observed with this device. The anomalies can be detected using various mathematical algorithms that can be embedded into the microprocessor and the results can be shared with the public.

Assessment of individual external exposure doses based on environmental radiation in areas affected by the Fukushima Daiichi Nuclear Power Station accident

Assessing individual external exposure doses from ambient dose equivalents is valuable for predictive and retrospective purposes when personal dosimeters are impractical. This study developed a model to assess individual external exposure doses from ambient dose equivalents, considering daily life patterns (location and time spent in various places), and evaluated parameters associated with individual external exposure doses, such as the reduction effects of radiation due to buildings and vehicles. The model parameters were evaluated using the robust datasets of environmental radiation measured in areas affected by the Fukushima Daiichi Nuclear Power Station (FDNPS) accident. The effective dose estimated by the model was compared to 106 daily personal dose equivalents measured using personal dosimeters in the residents’ living environments near the FDNPS. The estimated effective dose well consists with the measured personal dose equivalents, particularly when considering natural radiation in indoor dose estimation. This model is adequate for radiation protection, enabling the predictive and retrospective estimation of individual external exposure doses using environmental radiation monitoring data.

Phase I study of [68Ga]Ga-HX01 for targeting integrin αvβ3 and CD13 in healthy and malignancy subjects.

Noninvasive angiogenesis visualization is essential for evaluating tumor proliferation, progression, invasion, and metastasis. This study aimed to translate the heterodimeric PET tracer [68Ga]Ga-HX01, which targets integrin αvβ3 and CD13 in neovascularization, into phase I clinical study. This study enrolled 12 healthy volunteers (phase Ia) and 10 patients with malignant tumors (phase Ib). The subjects in phase Ia were divided into low-dose (0.05 mCi/kg) and high-dose (0.1 mCi/kg) groups. For phase Ia subjects, PET/CT images, blood and urine samples were collected to analyze the biodistribution, pharmacokinetics, radiation dosimetry, and safety of [68Ga]Ga-HX01. For phase Ib patients, PET/MR scans were performed at 30 ± 5 and 60 ± 5min after injection. The safety and preliminary diagnostic value of [68Ga]Ga-HX01 were assessed. In phase Ia study, [68Ga]Ga-HX01 was distributed and metabolized similarly in two dosage groups as the highest accumulations in kidneys and urine. It possessed quick renal excretion and blood clearance with an elimination half-life (T1/2) of 28.92 ± 3.97min. The total effective dose was 2.14 × 10- 2 mSv/MBq. In phase Ib study, [68Ga]Ga-HX01 clearly detected the lesions per patient, and found a total of 59 lesions with varying uptake levels. For safety evaluation, no serious adverse events were observed during the examination. [68Ga]Ga-HX01 has proved to be a translational radiopharmaceutical with reliable security, favorable pharmacokinetics, and the ability to visualize tumors. The preliminary results in malignancy patients warrant further investigation of [68Ga]Ga-HX01 in monitoring antiangiogenic therapy of patients with malignancies. ClinicalTrials.gov, NCT06416774. Registered 11 May, 2024.

Development, characterization and radiation dosimetry evaluation of Bovine gelatin crosslinked with Gum Arabic Aldehyde as brain phantom gel material in radiation therapy

Brain phantom gel materials are of critical importance for accuracy of dosimetry, treatment planning and quality assurance in radiotherapy. Development of reliable and realistic phantoms enhances improved radiotherapy practices. Gel dosimeters have unique property to record radiation dose distribution in three dimensions. Polymer gels also have added advantages for brachytherapy dosimetry. Objective of the study was to develop an alternative polymeric gel material equivalent to human brain for conducting radiation dosimetry studies in radiotherapy. Hydrogel prepared from gelatin and gum arabic aldehyde was used to develop a brain phantom gel material for radiation dosimetry in radiotherapy. The results of comparative studies with G-GAAB gel strongly suggest, the gel can successfully be utilized as a brain equivalent material for radiation dosimetry in place of standard water phantom by measuring (a) CT number values (b) mass attenuation coefficient values at two X-ray energies used in radiation treatment (c) absorbed dose values at different depths for various setup conditions. The midrange CT number values inside gel material and that of human brain measured from CT images were 25.5HU and 25HU respectively with a variation of 2%. The mass attenuation coefficients for brain, water and gel material at 6MV photons were 0.0275cm2/g, 0.0280cm2/g,0.0270cm2/g and for 15MV photons, the attenuation coefficients were 0.0192cm2/g, 0.0190cm2/g and 0.0180cm2/g respectively. The percentage deviation of all measurements of absorbed dose values in gel phantom material, compared with the values of standard water phantom at various radiation dosimetry setup parameters, is less than 2%.

Development of patient-specific pre-treatment verification procedure for FLASH proton therapy based on time resolved film dosimetry.

Pre-clinical studies demonstrate that delivering a high dose at a high dose rate result in less toxicity while maintaining tumor control, known as the FLASH effect. In proton therapy, clinical trials have started using 250MeV transmission beams and more trials are foreseen. A novel aspect of FLASH treatments, compared to conventional radiotherapy, is the importance of dose rate next to dose and geometry. Therefore, to ensure the safety and quality of FLASH treatments, patient-specific dose-rate verification before treatment is an important additional prerequisite. Various definitions of dose rate have been reported, however, the scanning proton beam (PBS) dose rate definition of Folkerts 2020 is currently the most used. It is the ratio between delta dose (ΔD) and delta time (Δt), subject to a predefined threshold, for a given position. Gafchromic film is a widely available detector used to perform relative and absolute integrated dose measurements. Since the response time of film is in the order of micro seconds it could also be suitable for pre-treatment verification of FLASH proton therapy. Development of a patient-specific pre-treatment verification procedure for FLASH proton therapy based on time resolved film dosimetry. The detector design is presented and validated using three tests. A dedicated setup was built that holds a Gafchromic film and a high-speed camera to record the film during the irradiations. The red color channel of the camera's readings was converted into optical density (OD) and an OD-to-dose calibration curve was applied to determine the relative dose accumulation over time. To undo the film measurement (film response) of the post-irradiation coloration process, it is assumed that each dose deposit (pulse) results in a similar film response function. The convolution of the film response function over the pulse provides the film response. First the film response function was obtained by fitting this parameter onto a known film response and corresponding pulse. Post-irradiation coloration correction was performed by deconvoluting all film measurement by the obtained film response function. From the integral of each measured pulse, the Δt was obtained. Several validation tests were conducted: compare the Δt film measurement to a reference detector, exclude that revisiting spots result in an unwanted artefact on the dose accumulation measurement and thereby Δt, and compare Δt distributions of film measurement and simulation (local gamma evaluation, criteria 10%/2 mm) for nine QA fields (dose values; 12, 15, and 20Gy, and, nozzle currents; 25, 120, and 215nA). A similar analysis was performed for three dose optimized treatment beams, with and without scan patterns optimized on local dose rate. Good agreement was found for Δt comparing film to the reference detector, but for Δt values smaller than ∼20ms the error becomes larger (≥15%). Dose accumulation measured with film over time from a single spot is independent of whether the dose is delivered at once, twice or thrice. All gamma evaluations resulted in a gamma pass rate of ≥90%. Time resolved film dosimetry to perform patient-specific pre-treatment verification in FLASH proton therapy is feasible.

Novel non-thermoluminescent CaSO4:Dy dosimeters

The non-thermoluminescence afterglow-based dosimetry performance of self-agglomerating pellet-shaped CaSO4:Dy phosphors synthesized through a low-cost, environmentally friendly method is first reported. Thermoluminescence (TL) and afterglow (AG) were analyzed in samples exposed to beta particle irradiation in the dose range from 0.06 to 8.0 Gy. Characteristic TL glow curves consist of an intense TL maximum at 134 °C, a shoulder at 200 °C, and a maximum at 447 °C. CaSO4:Dy exhibits a highly sensitive AG response for 24 hours with linear behavior from 0.06 Gy to 8.0 Gy. A remarkable reproducibility of both the TL and the AG response was observed in repeated irradiation–readout cycles with no need for pre-irradiation annealing. The synthesized CaSO4:Dy exhibits promising properties to be used as an AG-based dosimeter for real-time radiation detection and dosimetry. Moreover, this phosphor might be applied as a long persistent phosphor (LPP), being a cost-effective alternative to other available LPPs.

Fabrication and characterization of PVDF/PMMA nanocomposite membranes doped with graphene oxide (GO) for separation of CO2/CH4 from flue gas

This work focuses on developing polyvinylidene fluoride/polymethyl methacrylate (PVDF/PMMA) polymer blend nanocomposites incorporating varying concentrations of graphene oxide (GO) nanoparticles fabricated via casting solution processes. XRD and FT-IR confirmed GO-induced structural modifications in PVDF/PMMA blend. The addition of GO into PMMA/PVDF blend decreased and weakened the intensity of XRD peaks, suggesting that adding GO gradually reduces the crystallinity of the films. FT-IR verified miscibility and complex formation between the pristine polymer blend and the GO-filled nanocomposite. The incorporation of GO caused shifts in the optical absorption edge to lower wavelengths, causing a decrease in the optical bandgap energy (Eg). The real and imaginary parts of the dielectric permittivity (ε′ and ε′′), electric modulus (M′, M″), and AC conductivity (σac) have been measured from 0.1 Hz to 6 MHz. Both ε′ and ε′′ declined with rising frequency. The addition of different concentrations of GO generated charge transfer complexes in the polymer nanocomposites. SEM images show good homogeny with random dispersion of GO inside the polymer blend. The thermoluminescence (TL) glow curves for the nanocomposite samples irradiated 0.5, 1.0, 1.5, and 2 Gy doses show peak cantered at 207 °C. The peak position remained unchanged with increasing irradiation dosage. The dose-dependent linear growth in maximum peak height indicates radiation detection and monitoring capability.

Dosimetric and biological impact of activity extravasation of radiopharmaceuticals in PET imaging.

The increasing use of nuclear medicine and PET imaging has intensified scrutiny of radiotracer extravasation. To our knowledge, this topic is understudied but holds great potential for enhancing our understanding of extravasation in clinical PET imaging. This work aims to (1) quantify the absorbed doses from radiotracer extravasation in PET imaging, both locally at the site of extravasation and with the extravasation location as a source of exposure to bodily organs and (2) assess the biological ramifications within the injection site at the cellular level. A radiation dosimetry simulation was performed using a whole-body 4D Extended Cardiac-Torso (XCAT) phantom embedded in the GATE Monte Carlo platform. A 10-mCi dose of 18F-FDG was chosen to simulate a typical clinical PET scan scenario, with 10% of the activity extravasated in the antecubital fossa of the right arm of the phantom. The extravasation volume was modeled as a 5.5mL rectangle in the hypodermal layer of skin. Absorbed dose contributions were calculated for the first two half-lives, assuming biological clearance thereafter. Dose calculations were performed as absorbed doses at the organ and skin levels. Energy deposition was simulated both at the local extravasation site and in multiple organs of interest and converted to absorbed doses based on their respective masses. Each simulation was repeated ten times to estimate Monte Carlo uncertainties. Biological impacts on cells within the extravasated volume were evaluated by randomizing cells and exposing them to a uniform radiation source of 18F and 68Ga. Particle types, their energies, and direction cosines were recorded in phase space files using a separate Geant4 simulation to characterize their entry into the nucleus of the cellular volume. Subsequently, the phase space files were imported into the TOPAS-nBio simulation to assess the extent of DNA damage, including double-strand breaks (DSBs) and single-strand breaks (SSBs). Organ-level dosimetric estimations are presented for 18F and 68Ga radionuclides in various organs of interest. With 10% extravasation, the hypodermal layer of the skin received the highest absorbed dose of 1.32±0.01Gy for 18F and 0.99±0.01Gy for 68Ga. The epidermal and dermal layers received absorbed doses of 0.07±0.01Gy and 0.13±0.01Gy for 18F, and 0.14±0.01Gy and 0.29±0.01Gy for 68Ga, respectively. In the extravasated volume, 18F caused an average absorbed dose per nucleus of 0.17±0.01Gy, estimated to result in 10.58±0.50 DSBs and 268.11±12.43 SSBs per nucleus. For 68Ga, the absorbed dose per nucleus was 0.11±0.01Gy, leading to an estimated 6.49±0.34 DSBs and 161.24±8.12 SSBs per nucleus. Absorbed doses in other organs were on the order of micro-gray (µGy). The likelihood of epidermal erythema resulting from extravasation during PET imaging is low, as the simulated absorbed doses to the epidermis remain below the thresholds that trigger such effects. Moreover, the organ-level absorbed doses were found to be clinically insignificant across various simulated organs. The minimal DNA damage at the extravasation site suggests that long-term harm, such as radiation-induced carcinogenesis, is highly unlikely.

NASA open science data repository: open science for life in space.

Space biology and health data are critical for the success of deep space missions and sustainable human presence off-world. At the core of effectively managing biomedical risks is the commitment to open science principles, which ensure that data are findable, accessible, interoperable, reusable, reproducible and maximally open. The 2021 integration of the Ames Life Sciences Data Archive with GeneLab to establish the NASA Open Science Data Repository significantly enhanced access to a wide range of life sciences, biomedical-clinical and mission telemetry data alongside existing 'omics data from GeneLab. This paper describes the new database, its architecture and new data streams supporting diverse data types and enhancing data submission, retrieval and analysis. Features include the biological data management environment for improved data submission, a new user interface, controlled data access, an enhanced API and comprehensive public visualization tools for environmental telemetry, radiation dosimetry data and 'omics analyses. By fostering global collaboration through its analysis working groups and training programs, the open science data repository promotes widespread engagement in space biology, ensuring transparency and inclusivity in research. It supports the global scientific community in advancing our understanding of spaceflight's impact on biological systems, ensuring humans will thrive in future deep space missions.

Optimizing radiation dosimetry: Impact of PMMA layers on electronic equilibrium for the calibration of radiation protection instruments

In radiation dosimetry, achieving electronic equilibrium is vital for accurate dose measurements in radioprotection. This study investigates the effect of Poly Methyl Methacrylate (PMMA) layers, known by its chemical formula C5H8O2 and a density of 1.19 g/cm³ (PNNL, 2011), on electronic equilibrium for the calibration of radiation protection instruments, focusing on photon beams of varying energies. Using DOSIMEX 2.0 simulation software, we modeled the influence of PMMA thickness on calibration factors across different X-ray and gamma-ray beam energies. Experimental validation with Cs-137 and Co-60 sources confirmed the reliability of the simulation. Our results highlight that while PMMA layers have a minimal impact on calibration for higher-energy beams, their role becomes significant for energies below 40 keV. For X-ray beams (From 30 to 140 kV), the results show minimal calibration factor deviation (<1.6%), whereas radionuclide beams exhibit more significant variations (4.1%), necessitating customized calibration approaches. This study underscores the importance of adhering to ISO 4037-3 standards in radioprotection, particularly in low-energy scenarios, to ensure the precision of calibration procedures and optimize radiation protection practices. Furthermore, based on the results obtained, the absence of PMMA does not have a dramatic effect on the calibration of X-ray radiation instruments, whereas for gamma-ray beams, it has a significant impact.

A systematic review and meta-analysis on the impact of institutional peer review in radiation oncology

BackgroundRadiotherapy peer review is recognized as a key component of institutional quality assurance, though the impact is ill-defined. We conducted the first systematic review and meta-analysis to date to quantify the impact of institutional peer review on the treatment planning workflow including radiotherapy contours, prescription and dosimetry. MethodsWe searched several medical and healthcare databases from January 1, 2000, to May 25, 2024, for papers that report on the impact of institutional radiotherapy peer review on treatment plans. We conducted random-effects meta-analyses of proportions to summarize the rates of any change recommendation and major change recommendation (suggesting re-planning or re-simulation due to safety concerns) following peer review processes. To explore differences in change recommendations dependent on location, radiotherapy intent, technique, and peer review structure characteristics, we conducted analyses of variance. ResultsOf 9,487 citations, we identified 55 studies that report on 96,444 case audits in 10 countries across various disease sites. The pooled proportion of any change recommendation was 28 % (95 %CI = 21–35) and major change recommendation was 12 % (95 %CI = 7–18). Proportions of change recommendation were not impacted by any treatment characteristics. The most common reasons for change recommendation include target volume delineation (25/55; 45 %), target dose prescription (18/55; 33 %), organ at risk dose prescription (5/55; 9 %), and organ at risk volume delineation (3/55; 5 %). ConclusionsOur review provides evidence that peer review results in treatment plan change recommendations in over one in four patients. The results suggest that some form of real-time, early peer review may be beneficial for all cases, irrespective of treatment intent or RT technique.

Pharmacokinetic Positron Emission Tomography Imaging of an Optimized CD38-Targeted 68Ga-Labeled Peptide in Multiple Myeloma: A Pilot Study.

Multiple myeloma (MM) is an incurable disease characterized by its clinical and prognostic heterogeneity. Despite conventional chemotherapy and autologous hematopoietic stem cell transplantation, the management of relapsed and refractory MM disease poses significant challenges, both medically and socioeconomically. CD38, highly expressed on the surface of MM cells, serves as a distinct tumor biological target in MM. Peptides offer advantages over antibodies, enabling precise tumor imaging and facilitating early tumor diagnosis and dynamic immunotherapy monitoring. In this study, we developed PF381, a CD38-targeted peptide, and investigated its role in diagnosis, biodistribution, and dosimetry through 68Ga-labeling for preclinical evaluation in tumor-bearing models. We screened a microchip-based combinatorial chemistry peptide library to obtain the amino acid sequence of PF381. Affinity for human CD38 was evaluated by SPRi. PF381 was conjugated with DOTA for radiolabeling with 68Ga, and the complex was characterized by HPLC. PET imaging was performed in murine tumor models after the administration of [68Ga]Ga-DOTA-PF381. Biodistribution analysis compared CD38-positive H929 and CD38-negative U266 tumors, and human radiation dosimetry was estimated. Tumor sections were stained for CD38 expression. SPRi showed that PF381 had a high affinity for CD38 with a KD of 2.49 × 10-8 M. HPLC measured a radiolabeling efficiency of 78.45 ± 7.91% for [68Ga]Ga-DOTA-PF381, with >98% radiochemical purity. PET imaging revealed rapid and persistent accumulation of radioactivity in CD38-positive H929 tumors, contrasting with negligible uptake in CD38-negative U266 tumors. Biodistribution confirmed higher uptake in H929 tumors (0.75 ± 0.03%ID/g) vs U266 (0.26 ± 0.08%ID/g, P < 0.001). The kidney received the highest radiation dose (3.57 × 10-02 mSv/MBq), with an effective dose of 1.41 × 10-02 mSv/MBq. Immunofluorescence imaging supported PET and biodistribution findings. We developed a novel peptide targeting CD38 and proved that 68Ga-labeled PF381 had rapid targeting and good tumor penetration capabilities. Therefore, 68Ga-labeled PF381 could achieve high sensitivity in vivo imaging for CD38-positive hematological malignancies.