Aneurysm clipping is routinely performed with high efficacy and low complication rates in specialized neurovascular centers. Postoperative aneurysm remnants bear the risk of growth/rupture. Study aim was to analyze remnants in postoperative angiography (pDSA) and follow-up (FU) and to evaluate whether use of intraoperative CT-angiography (iCTA) can intraoperatively detect remnants and enable therapeutic consequences.

All patients undergoing elective aneurysm clipping at our center between 11/2012 and 12/2019 were included for FU in 01/2024. All patients received Indocyanin-green-videoangiography (ICGVA) and postoperative angiography (pDSA). After iCTA implementation in 10/2016, the majority of patients received additionally iCTA. Baseline characteristics, treatment-related morbidity/outcome, resulting operative conclusions in distinct cohorts with/without iCTA, and management of remnants according to Sindou classification were analyzed.

270 patients (367 enrolled/97 excluded) were clipped using iCTA in 74 patients. In 12/270 patients (4.5%) clip repositioning was performed due to ICGVA results, but iCTA further detected large remnants intraoperatively in 3/74 patients (4.1%) correctly resulting in re-clipping in two patients and recommendation for endovascular therapy in one patient. The specificity, sensitivity, and accuracy for detection of Sindou grade (SG) III-IV remnants by iCTA were 100%, 75%, and 98.6%, respectively. Overall, pDSA detected SG I-II remnants in 32/270 (11.9%) and SG III-V remnants in 8/270 (3.0%) patients with 3/270 requiring retreatment (n = 1 resurgery, n = 2 endovascular therapy). Frequency of SG I-V and III-V remnants were slightly lower in iCTA than non-iCTA group (10.8 vs. 16.3%, p < 0.173 and 1.4 vs. 3.6%, p < 0.306). All SG I-II and five SG III-V remnants did not reveal growth/rupture after a mean FU of 29 months.

Aneurysm remnants after clipping are rare and predominantly small (SGI-II)-not harbouring a risk of growth/rupture during short-term FU. Intraoperative CTA can detect large aneurysm remnants (SG III-IV) and may prompt adjustment of surgical strategy in individual cases.

Valemetostat tosylate (valemetostat) is an oral, selective, dual inhibitor of enhancer of zeste homolog (EZH)2 and EZH1. This article reports findings on the mass balance and pharmacokinetics of valemetostat in a phase I study; valemetostat metabolite identification in plasma, urine, and fecal samples; and plasma-protein-binding of valemetostat in vitro.

Eight healthy participants received a single 200-mg oral dose of [14C]-valemetostat under fasting conditions. Blood, urine, and feces samples were collected to determine total radioactivity and/or unchanged valemetostat, and for metabolite identification. The binding of valemetostat 600-10,000 ng/mL to plasma, 4% human serum albumin (HSA), and 0.1% alpha-1-acid glycoprotein (AAG) was assessed in vitro.

Mean cumulative recovery of administered radioactivity was 95.3% by 360 h post-dose, with a mean recovery of 15.6% in urine and 79.8% in feces. Valemetostat accounted for the most radioactivity in the excreta, at 10% and 64.9% of the administered dose in the urine and feces, respectively. CALZ-1809a was the most abundant metabolite, present in all biological samples, and accounted for 5.6% of total radioactivity in the feces. Valemetostat was minimally associated with red blood cells, with a blood-to-plasma total radioactivity ratio of 0.54. In vitro, valemetostat was highly plasma-bound (> 94%) at clinically relevant concentrations, with a higher affinity to AAG than to HSA.

Valemetostat was rapidly absorbed into the systemic circulation, mainly excreted via the biliary/fecal route, primarily metabolized by CYP3A enzymes to CALZ-1809a, and highly bound to plasma proteins, with a greater affinity to AAG than HSA in vitro.

Trop2 exhibits significantly elevated expression in numerous solid malignancies, playing a crucial role in tumor advancement, whereas its presence in healthy tissues is minimal. In this study, we investigated Trop2 expression in bladder cancer models using [64Cu]Cu-NOTA-Trodelvy for immunoPET imaging. In HT-1376 models, [64Cu]Cu-NOTA-Trodelvy effectively visualized tumor as early as 12 h p.i. (10.30 ± 1.45% ID/g), with tumor uptake increasing and peaking at 48 h p.i. (13.73 ± 1.16% ID/g), highlighting its potential for tumor imaging. Control groups also demonstrated low tumor uptake (5.27 ± 1.14% ID/g at 48 h in the blocking group; 6.33 ± 0.74% ID/g at 48 h in UM-UC-3; 4.50 ± 0.30% ID/g at 48 h in the [64Cu]Cu-NOTA-IgG group). Long-term fluorescence imaging further confirmed the tumor uptake rate in the IRDye 800CW-Trodelvy group was significantly higher than in the IRDye 800CW-Trodelvy blockade group (P < 0.001). Our findings demonstrated that [64Cu]Cu-NOTA-Trodelvy enables specific and prolonged tumor accumulation in bladder cancer models, providing precise and noninvasive monitoring of Trop2 expression.

X-ray computed tomography (CT) is a standard tool for diagnosing bone abnormalities. CT dose optimization is strongly recommended, due to the stochastic effects of x-ray. This study aims to assess the effectiveness of ultra-low-dose CT (ULD-CT) imaging, reconstructed using an Iterative Reconstruction (IR) algorithm, in detecting bone trauma and disorders.

In the present cross-sectional study, 71 patients with CT requests for spine or extremity (limb) bone underwent scanning using standard dose (SD) and ULD-CT protocols, in Shahid Faghihi Hospital, Shiraz, Iran from June 2019 to June 2020. The SD and ULD-CT protocols used 120 kVp and 80 kVp, respectively. The CT images were reconstructed using the standard and IR algorithms. CT dose indices, including the volume CT dose index (CTDIvol), dose-length product (DLP), and effective dose (ED), were employed. To assess image quality, a five-point scoring system was used. The sensitivity and specificity of the ULD-CT images were calculated.

The findings indicated that ULD-CT images accurately identified 113 out of 118 bone trauma and disorders. The quality of ULD-CT images received "very good", "good" and "acceptable" scores for both spine and extremity (limb) bones. The sensitivity and specificity of ULD-CT images for bone trauma and disorders were 67%-95% and 100%, respectively, with about a 98% dose reduction.

The ULD-CT protocol for bone imaging achieved a remarkable dose reduction, while the image quality was reported as acceptable. Consequently, ULD-CT images reconstructed using an IR are suitable and can be tuned further in the future for acceptable use in patients with bone trauma and disorders.

To assess whether the use of different types of facial sunscreen influences the quality of radiographic images and the absorbed radiation dose during radiographic acquisitions.

In this in vitro study, two types of facial sunscreens (Bioderma®), both with a sun protection factor of 50, were tested: one organic and one inorganic. A polystyrene plate was used, containing a thermoluminescent dosimeter and a photostimulable phosphor plate for the radiographs. The sunscreen was applied to the plate, and five radiographs were taken for each group: control (without sunscreen), organic sunscreen, and inorganic sunscreen. Image quality was assessed by noise, brightness, and uniformity, and the radiation dose was measured in milligrays. The results were compared using one-way analysis of variance with Tukey post-hoc test (α = 5%).

Inorganic sunscreen produced images with higher brightness and lower uniformity, with no significant differences in noise. Additionally, this group showed a lower radiation dose (0.50 mGy) compared to the control group (0.60 mGy) and the organic sunscreen (0.58 mGy) (p < 0.05).

The inorganic sunscreen altered image quality by increasing brightness and decreasing uniformity, while also reducing the absorbed radiation dose.

Radiation risk through seafood consumption is a big public concern under the discharge of nuclear contaminated water. Plutonium is an important radionuclide in view of radiation risk due to its high radiological and chemical toxicity, as well as consistent presence in the environment. The distribution and level of plutonium isotopes (239Pu, 240Pu) in marine biota collected along the coast of China in 2022-2023 were investigated. The 239,240Pu concentrations showing an increasing tendency from fish, shrimp to macroalgae, depending on species and growing environment. The atomic ratios of 240Pu/239Pu (0.158-0.275) in marine biota in the China Seas indicated other source in addition to the global fallout of Pu. The elevated 240Pu/239Pu ratios observed in the East and South China Sea in comparison with the Yellow Sea and Bohai Sea were attributed to the intrusion of the Kuroshio Current carrying Pacific Proving Grounds (PPG) sourced plutonium with high 240Pu/239Pu ratios, accounting for up to 70 % of total plutonium. The annual radiation dose of plutonium through seafood consumption is in a secure level at present by the public. Macroalgae serves as an ideal marine indicator for plutonium isotopes pollution. The PPG-derived dissolved and colloidal plutonium dominates the enrichment of plutonium in Ulva linza.

The building materials industry encounters naturally occurring radioactive materials problems and elicits growing attention in radiation protection regulations. However, the availability of useful, comprehensive data on radiological hazard in building materials is unfortunately scant: data are few and far between. In the Italian region of Emilia-Romagna, there is a flourishing ceramic industry, with a vast production of building materials, particularly tiles and bricks. Our laboratory of Environmental Chemistry and Radioactivity has collaborated with this industry since the year 2000, collecting over time a vast number of samples and processing them through high-resolution gamma spectrometry, to obtain a large dataset of radionuclide contents. This paper presents a radiation protection study based on said dataset, aimed at assessing the radiological risk associated with these materials: in particular, different indexes, internationally accepted, and dose rates are calculated in compliance with well-established EU algorithms. Statistical treatment of data is also presented.

This study aimed to evaluate the dose-exposure reduction effect of a crystalline lens with a bismuth eye shield using cone-beam computed tomography (CBCT) for head image-guided radiation therapy. The ocular surface dose of the head phantom (THRA-1) is defined as a crystalline lens exposure dose and is measured using a radiophotoluminescence dosimeter (RPLD, GD-352 M) with and without an eye shield (CT eye shield) while moving the head phantom from the reference position that is set at the center of the head in either the X or Z direction from -5 to +5 cm. The exposure doses were measured thrice at each movement position. The crystalline lens exposure doses at the reference position were 0.896 ± 0.024 mGy and 0.892 ± 0.016 mGy for the right and left sides, respectively. The exposure doses at the position where the head phantom was moved 5 cm in the -Z direction from the reference position were 2.812 ± 0.053 mGy and 2.576 ± 0.038 mGy for the right and left sides, respectively, with the highest doses at all movement positions. The crystalline lens exposure doses were reduced to 1.909 ± 0.046 mGy and 1.768 ± 0.043 mGy for the right and left sides with an eye shield in this position, causing an exposure dose reduction rate of -32% and -31%, respectively. The crystalline lens exposure dose reduction rate was approximately 10%-15% in the movement directions, except for the -Z direction. Head CBCT with an eye shield effectively reduced the crystalline lens exposure dose when the CBCT isocenter was set close to the eye. Head CBCT using an eye shield is a useful method that reduces the crystalline lens exposure dose.

To determine dose-optimized image acquisition parameters for good image quality (IQ) in neonatal chest radiography with a computed radiography (CR) CsBr needle detector vs. a wireless digital radiography (DR) CsI detector using different doses and filters.Physical resolution of the two detectors in unprocessed imaging of a contrast-detail phantom was automatically evaluated. Post-processed chest radiographic imaging of a neonatal phantom was used for Visual Grading Analysis (VGA) by three radiology raters. Different kVp, mAs, and filter settings were used. The VGA score (VGAS) and dose area product (DAP) were used to determine image acquisition parameters and dose levels for good image quality. Pixel data from segments corresponding to visual grading characteristics (VGC) was used to calculate signal-to-noise ratio, contrast-to-noise ratio (CNR), and signal profile curves. These results were compared to the raters' "ground truth" by Spearman's correlation.The CR detector had the highest resolution in unprocessed imaging, although this was dependent on a tube voltage of 66 kVp (P < 0.001), and more so than the DR detector. The VGAS showed no significant difference between the CR needle and the DR CsI detectors at the same DAP, or when using standard pediatric filtering of 3.5 mm Al + 0.1 mm Cu (P > 0.05). A lung dose level of 0.017 mSv was needed for good IQ (effective dose (E): 0.010 mSv). This was achievable with different acquisition parameters. Out of 24 segments, only the CNR of bone-to-soft-tissue had a good Spearman's correlation (ρ > 0.50) to raters' VGAS (P < 0.0001), mostly due to problems with image registration.The CR needle and DR CsI detectors have comparable IQ in neonatal chest radiography. In this study, an E of approximately 0.010 mSv was needed for good IQ. · CR needle and DR detectors have comparable image quality in neonatal chest radiography.. · CR needle technology has higher absolute raw image resolution, although this is voltage-dependent and more so than the DR detector.. · We propose ideal image acquisition parameters for neonatal chest radiography.. · Rama K, Esser M, Spogis J et al. Dose-Optimized Image Acquisition Parameters for Neonatal Chest Radiography: A Phantom Study Comparing Computed Radiography and Wireless Digital Radiography Needle Detectors. Rofo 2025; DOI 10.1055/a-2525-9430.

Bitewing examinations are used to examine the pediatric dental status. The aim of this study was to compare the image quality and radiation dose between two different X-ray systems used for pediatric bitewing imaging.

Data were obtained from both pediatric in vivo bitewing studies and phantom studies. Two X-ray systems were used: Trophy CCX digital (TCCX) (Trophy Irix 70, Marne-la-Vallee, France) and Planmeca Pro X (PPX) (Planmeca, Helsinki, Finland). An Unfors dosimeter (Unfors EDD-30, Billdal, Sweden) was used to measure the skin dose. Image quality was evaluated blindly by three experienced dentists using a Likert scale of 1-5 based on the visual representation of the anatomical structures with emphasis on caries.

The highest scoring in vivo bitewing images were obtained with TCCX, but the skin dose was 36% higher (mean 3029 ± 613 μGy) and 113% higher (mean 1364 ± 276 μGy) with standard settings than with compared to PPX. The evaluation of image quality revealed a higher median value for all ratings of TCCX compared to PPX for both the patient and phantom studies, meaning that the images of TCCX were rated as higher quality than the images from PPX. No correlation was found between the median score and the skin dose or between the median score and the exposure times.

A significant difference in radiation dose and image quality was found between TCCX and PPX in bitewing imaging. TCCX generally produced higher doses and better graded images, although all images were suitable for diagnosis.

To evaluate the reliability of 3T MRI nerve-bone fusion in assessing the lingual nerve (LN) and its anatomical relationship to the lingual cortical plate prior to the impacted mandibular third molar (IMTM) extraction.

The MRI nerve and bone sequences used in this study were 3D T2-weighted fast field echo (3D-T2-FFE) and fast field echo resembling a CT using restricted echo-spacing (FRACTURE), respectively. Both sequences were performed in 25 subjects, and the resulting 3D-T2-FFE/FRACTURE fusion images were assessed by 2 independent observers. Semi-quantitative analyses included assessments of overall image quality, image artefacts, nerve continuity, and the detectability of 5 intermediate points (IPs). Quantitative analyses included measurements of the lingual cortical plate thickness (LCPT), vertical distance (V1* and V2*), and the closest horizontal distance (CHD) between the LN and the lingual cortical plate. Reliability was evaluated using weighted Cohen's kappa coefficient (κ), intraclass correlation coefficient (ICC), and Bland-Altman plots. Differences in LCPT between 3D-T2-FFE/FRACTURE fusion images and cone-beam computed tomography (CBCT) were compared using independent samples t-tests or Mann-Whitney U tests.

The fusion images demonstrated that the LN continuity score was 3.00 (1.00) (good), with 88% (44/50) of LNs displayed continuously at the IMTM level. Intra-reader agreement for nerve continuity was moderate (κ = 0.527), as was inter-reader agreement (κ = 0.428). The intra-reader and inter-reader agreement for LCPT measurements at the neck, mid-root, and apex of the IMTM were all moderate (ICC > 0.60). Intra-reader agreements for V1*, V2*, and CHD were moderate to excellent (ICC = 0.904, 0.967, and 0.723, respectively), and inter-reader agreements for V1*, V2*, and CHD were also moderate to excellent (ICC = 0.948, 0.941 and 0.623, respectively). The reliability of LCPT measurements between 3D-T2-FFE/FRACTURE fusion and CBCT was moderate (ICC = 0.609-0.796).

The 3D-T2-FFE/FRACTURE fusion technique demonstrated potential feasibility for the identification of the LN and its relationship to the lingual cortical plate, as well as for the measurement of LCPT. This study has generated a dataset that is capable of simultaneously defining the LN and LCPT.

The evolution of man on Earth took place under conditions of constant exposure to background ionizing radiation (IR). From this point of view, it would be reasonable to hypothesize the existence of adaptive mechanisms that enable the human organism to safely interact with IR at levels approximating long-term natural background levels. In some situations, the successful operation of molecular mechanisms of protection against IR is observed at values significantly exceeding the natural background level, for example, in cancer cells. In 15-25% of cancer patients, cancer cells develop a phenotype that is resistant to high doses of IR. While further investigations are warranted, the current evidence suggests a strong probability of observing positive health effects, including an increased lifespan, a reduced cancer risk, and a decreased incidence of congenital pathologies, precisely at low doses of ionizing radiation. This review offers arguments primarily based on a phenomenological approach and critically reconsidering existing methodologies for assessing the biological risks of IR to human health. Currently, in the most economically developed countries, there are radiation safety rules that interpret low-dose radiation as a clearly negative environmental factor. Nowadays, this approach may pose significant challenges to the advancement of radiomedicine and introduce complexities in the regulation of IR sources. The review also examines molecular mechanisms that may play a key role in the formation of the positive effects of low-dose IR on human radioadaptive capabilities.

Since the genotoxicity of ionizing radiation was demonstrated in the 1920s, its hereditary effects have remained a serious concern for human society. The International Commission on Radiological Protection has highlighted the need for appropriate protection against hereditary effects of radiation in humans. In this paper, we review the literature on the possible multigenerational and transgenerational effects following testicular exposure to radiation, focusing on sperm epigenetic alterations as possible mechanisms.

This mini-review highlights that hereditary effects following testicular exposure occur via epigenetic changes of germ cells in animal models, providing implications on human radiation protection.

A great amount of epigenomic research data has emerged rapidly since the beginning of this century; thus, a revision of the radiological protection protocols against the hereditary effects of radiation would be no longer inevitable. The collection and analysis of evidence on these effects must be enhanced and further accelerated to formulate appropriate protection protocols in the future.

In diagnostic radiology, entrance surface air kerma (ESAK) is one of the patient radiation dose quantities, and the effective dose is used as an estimator of possible risk for radiation exposure level. Calculation of the ESAK and effective dose requires both X-ray machine parameters and patient exposure parameters. Due to the high performance of smartphones and the increase in mobile applications, this study aimed to develop a mobile application to estimate the ESAK and effective dose in general radiography. The ESAK calculator was then developed using Android studio software, which is a standalone application operating on Android operating system version 5.0 or higher. X-ray machine parameters are initially required for calculating X-ray output. For the ESAK and effective dose calculation, exposure parameters for each examination are needed. The results showed that the average score of satisfaction was 4.64±0.13, which was very satisfactory. In conclusion, the ESAK calculator could be used for estimating ESAK and effective dose for individual radiographic examination.

Conventional mammography remains the primary imaging modality for state-of-the-art breast imaging practice and its benefit (both on diagnostic and screening) was largely reported. In mammography, the typical Mean Glandular Dose (MGD) from X-ray radiation to the breast spans, on average, from 1 to 10 mGy, depending on breast thicknesses, percentage of fibroglandular tissue, and on the examination purpose.

The aim of this narrative review is to describe the extent of radiation risk in X-ray breast imaging and discuss the main steps and parameters (e.g. MGD, screening frequency and number of examination views) that may have an influence on the radiation risk assessment.

Even though the radiation doses used with these examinations are very low, as compared to other medical or natural radiation exposures, there is a non-negligible associated risk of radiation-induced cancer. Accurate radiation risk assessment permits to better balance the overall estimation of the benefit-to-risk ratio in X-ray breast imaging.

It is expected that a better knowledge about radiation-induced cancer risk among population could improve the communications skills between patients and clinicians and could help to increase the awareness in women about radiation risk perception for a transparent and proper informed choice of imaging exam.

Radiological assessment of the environment in expansive territories poses significant challenges due to the complexity of spatial and environmental variables. The aim of this study was to use and present the advantages of a physico-geographical regionalisation methodology to improve the precision and effectiveness of radiological assessments in large areas. The study area was a region of the Polish Carpathian mountains with a territory of 19,600 km2. By integrating geographic information systems (GIS) and radiological data, this research analysed a similarity of environmental attributes (soil type, lithology, mineralogy) and absorbed dose rate (ADR) level from the terrestrial origin for populations. Consistency in terms of the nature and origin of the relief and lithological diversity was a key aspect that distinguished the radiological characteristics. Therefore, consistency was observed at the macroregional level according to physiographic mapping. The study demonstrates the utility of macroregionalisation in capturing spatial ADR heterogeneity and provides a new strategy in radiological monitoring.

Experimental single-centre study of X-ray absorption using a phantom skull.

This experimental study aimed to compare the radiation doses of different 3D imaging devices used in maxillofacial surgery, including one Multidetector CT (MDCT), two Conebeam CT (CBCT) and four intraoperative 3D C-arms.

Thermoluminescent dosimeters (TLD) were used to determine the absorbed radiation in an Alderson-Rando phantom skull. The phantom skull was positioned in the before mentioned seven devices and a defined 3D facial skull image was acquired. Subsequently, the TLD'S were read out and the effective doses (ED) and the organ doses (OD) were calculated and compared.

OD varied significantly between tissues as well as between the 3D X-ray devices. The OD of the 3D C-arms were significantly lower than those of all other devices. The OD of the CT, especially in the standard setting, was the highest. Only by special adjustments of the scan protocol regarding CMF requirements for traumatology, the MDCT could achieve almost equivalent doses as the two tested CBCT-scanners. The calculated effective doses were also lowest for the 3D C-arm devices (11.2 to 129.9 μSv). The ED of the MDCT were significant higher (284.52-844.97 μSv) than in all other devices. The ED of the CBCTs (173.7-184.9) were lower than for MDCT but still higher than those of the 3D C-arms.

Intraoperative imaging using 3D C-arm devices is an effective method to verify reduction results in maxillofacial surgery intraoperatively with significantly lower ED than postoperatively CBCT and MDCT imaging.

Crewed spaceflight missions require careful scrutinization of the health risks including alterations to the tear film lipid layer in astronauts. We review the current literature and prior published work on tear film lipid layer biophysics and secondary spaceflight-associated dry eye syndrome (SADES). We define the term spaceflight-associated dry eye syndrome to describe the collection of ocular surface signs and symptoms experienced by astronauts during spaceflight. Our review covers the ocular surface and lipidomics in the spaceflight environment. From our literature review, we extrapolate biophysical principles governing the tear film layer to determine the changes that may arise from the harsh conditions of spaceflight and microgravity. Our findings provide vital information for future long-duration spaceflight, including a return to the Moon and potential missions to Mars.

A fire in one of the Windscale nuclear reactors at Sellafield (Cumbria, England) in October 1957 released 1,800 TBq of 131I (half-life, 8 days) to atmosphere. Measurements of 131I activity in thyroids of exposed children showed typical thyroid doses of tens of milligray, but with some exceeding 100 mGy. Radiation exposure in childhood is known to increase the risk of thyroid cancer. Consequently, an investigation was conducted into whether raised numbers of thyroid cancer cases occurred in those exposed to 131I as young children in Cumbria. A database of Cumbrian births from 1950 onwards allowed cohorts of 56,086 births during 1950-1958 and 137,444 births during 1959-1980 to be constructed, periods including children potentially exposed and unexposed, respectively, to 131I. Three areas of Cumbria with different 131I contamination levels were identified from monitoring data, and births assigned to these three areas for the two periods of birth. Members of these six sub-cohorts were linked to incident thyroid cancer cases in Great Britain during 1981-2020 using national cancer registration databases, providing thyroid cancer incidence rates. Incidence rate ratios (IRRs), with the lowest contamination area as a reference, were computed. No IRR differed discernibly from unity. For births during 1950-1958, the IRR for the combined highest and intermediate 131I contamination areas was 0.68 (95% confidence interval: 0.24, 1.56), and no case of thyroid cancer was found in the small cohort born in the highest contamination area. In conclusion, no increased risk of thyroid cancer in those exposed to 131I as young children in Cumbria in 1957 was detected. This study adds to the evidence on the long-term risk of thyroid cancer following childhood exposure to low and moderate levels of 131I, such as occurred following the Fukushima nuclear accident in 2011.

Multidrug resistance-associated protein 1 (MRP1) is a transport protein with a widespread tissue distribution, which has been implicated in the pathophysiology of Alzheimer's and chronic respiratory disease. PET with 6-bromo-7-[11C]methylpurine ([11C]BMP) has been used to measure MRP1 function in rodents. In this study, [11C]BMP was for the first time characterised in humans to assess the function of MRP1 and other MRP subtypes in different tissues.

Thirteen healthy volunteers (7 men, 6 women) underwent dynamic whole-body PET scans on a long axial field-of-view (LAFOV) PET/CT system after intravenous injection of [11C]BMP. Three subjects of each sex were scanned a second time to assess reproducibility. Volumes of interest were outlined for MRP-expressing tissues (cerebral cortex, cerebellum, choroid plexus, retina, lungs, myocardium, kidneys, and liver). From the time-activity curves, the elimination rate constant (kE, h- 1) was derived as a parameter for tissue MRP function and its test-retest variability (TRTV, %) was calculated. Radiation dosimetry was calculated using the Medical Internal Radiation Dose (MIRD) methodology.

Mean kE and corresponding TRTV values were: cerebral cortex: 0.055 ± 0.010 h- 1 (- 4 ± 24%), cerebellum: 0.033 ± 0.009 h- 1 (1 ± 39%), choroid plexus: 0.292 ± 0.059 h- 1 (0.1 ± 16%), retina: 0.234 ± 0.045 h- 1 (30 ± 38%), lungs: 0.875 ± 0.095 h- 1 (- 3 ± 11%), myocardium: 0.641 ± 0.105 h- 1 (11 ± 25%), kidneys: 1.378 ± 0.266 h- 1 (14 ± 16%), and liver: 0.685 ± 0.072 h- 1 (7 ± 9%). Significant sex differences were found for kE in the cerebellum, lungs and kidneys. Effective dose was 4.67 ± 0.18 µSv/MBq for men and 4.55 ± 0.18 µSv/MBq for women.

LAFOV PET/CT with [11C]BMP potentially allows for simultaneous assessment of MRP function in multiple human tissues. Mean TRTV of kE in different tissues was in an acceptable range, except for the retina. The radiation dosimetry of [11C]BMP was in the typical range of 11C-tracers. LAFOV PET/CT holds great potential to assess at a whole-body, multi-tissue level molecular targets relevant for drug disposition in humans.

EudraCT 2021-006348-29. Registered 15 December 2021.

This study aimed to investigate the impact of three-dimensional (3D)-printed guide plate-assisted percutaneous pedicle screw implantation on minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) surgery.

Overall, 162 patients who underwent MIS-TLIF at Tai'an City Central Hospital were retrospectively reviewed. The studied variables included operative time, volume of intraoperative blood loss, fluoroscopy time, postoperative drainage volume, visual analogue scale (VAS) score, Oswestry disability Index (ODI) score (preoperatively and at 2 weeks, 3 months, 6 months, and 12 months after surgery), and intervertebral fusion rate at 6 months after surgery.

The conventional group included 99 patients who underwent a conventional procedure, while the 3D printing group included 63 patients who underwent 3D-printed guide plate-assisted percutaneous pedicle screw implantation. The conventional group required more times of positioning needle punctures than the 3D printing group (22.2 ± 5.9 vs. 16.1 ± 4.9). The operation and fluoroscopy time were also longer in the former group (183.5 ± 51.1 min vs. 148.8 ± 40.3 min and 30.2 ± 5.9 s vs. 24.1 ± 4.9 s, respectively). In 3D printing group, lower back pain VAS scores and ODI scores at 2 weeks and 3 months after surgery were observed. There were no significant differences in terms of the volumes of intraoperative blood loss; postoperative lower limb pain VAS scores; and interbody fusion rate (P > 0.05).

The novel 3D-printed guide plate-assisted percutaneous pedicle screw implantation can achieve better amelioration of back pain and recovery of function. It also reduced the times of positioning needle puncture and fluoroscopy time during percutaneous screw placement surgery and reduced the duration of surgery.

Digital tomosynthesis (DTS) has broad non-orthopaedic applications and has seen limited use within orthopaedics for imaging of the wrist. The utility of DTS for assessing reduction and hardware placement following operative treatment of pelvic ring injuries and acetabular fractures has not previously been investigated.

All operatively treated acetabular fractures and pelvic ring injuries that underwent surgical fixation within a one-year time span received both a computed tomography (CT) scan and a DTS scan as part of their routine postoperative imaging workup. Three orthopaedic traumatologists independently reviewed the images for face-value clinical utility. Radimetrics and PCXMC software were utilized on a subset of the study population's DTS and CT studies to calculate the effective and organ radiation doses delivered.

52 patients (22 acetabular fractures, 22 pelvic ring injuries, 7 pelvic ring and acetabular fractures, 2 femoral head & acetabular fractures) were included. DTS was considered adequate to assess reduction 83% of the time, hardware position 83% of the time, and sufficient to replace the CT scan 67% of the time. DTS was associated with an 8.3 times lower effective radiation dose than CT. All organ doses were lower for DTS than CT.

DTS appears to have face-value clinical utility for assessing reduction and hardware position following surgical treatment of acetabular fractures and pelvic ring injuries. Given that DTS is associated with significantly lower radiation doses to patients, further study utilizing more objective criteria is warranted.

Objective.Relative biological effectiveness (RBE) differs between radiation qualities. However, an RBE of 1.0 has been established for photons regardless of the wide range of photon energies used clinically, the lack of reproducibility in radiobiological studies, and outdated reference energies used in the experimental literature. Moreover, due to intrinsic radiosensitivity, different cancer types have different responses to radiation. This study aimed to characterize the RBE of clinically relevant high and low photon energiesin vitrofor three human cancer cell lines: HCT116 (colon), HeLa (cervix), and PC3 (prostate).Approach.Experiments were conducted following dosimetry protocols provided by the American Association of Physicists in Medicine. Cells were irradiated with 6 MV x-rays, an192Ir brachytherapy source, 225 kVp and 50 kVp x-rays. Cell survival post-irradiation was assessed using the clonogenic assay. Survival fractions were fitted using the linear quadratic model, and survival curves were generated for RBE calculations.Main results.Cell killing was more efficient with decreasing photon energy. Using 225 kVp x-rays as the reference, the HCT116 RBESF0.1for 6 MV x-rays,192Ir, and 50 kVp x-rays were 0.89 ± 0.03, 0.95 ± 0.03, and 1.24 ± 0.04; the HeLa RBESF0.1were 0.95 ± 0.04, 0.97 ± 0.05, and 1.09 ± 0.03, and the PC3 RBESF0.1were 0.84 ± 0.01, 0.84 ± 0.01, and 1.13 ± 0.02, respectively. HeLa and PC3 cells had varying radiosensitivity when irradiated with 225 and 50 kVp x-rays.Significance.This difference supports the notion that RBE may not be 1.0 for all photons through experimental investigations that employed precise dosimetry. It highlights that different cancer types may not have identical responses to the same irradiation quality. Additionally, the RBE of clinically relevant photons was updated to the reference energy of 225 kVp x-rays.

Objectives: The linear no-threshold (LNT) model, which has been used for radiation protection purposes, was developed based on the assumption that exposure to even a small amount of radiation may cause cancer. However, although it is known in carcinogenesis that there is variation in radiation sensitivity among individuals, the LNT model does not adequately consider radiosensitive subgroups. In this paper, we represent susceptibility to contract cancer by radiation exposure by means of the threshold of a dose-response function, introduce an assumption that the thresholds are random to represent the variation of the radiosensitivity among individuals in a susceptible subgroup. We propose a novel method, the random threshold (RT) model, for determining the safe dose limit for the subgroup to protect cancer-susceptible individuals from radiation exposure. Conclusion: The proposed method is illustrated by targeting ATM gene (a cancer-susceptible gene) mutation carriers as a radiosensitive subgroup. For cancer risk associated with low-dose radiation exposure, the contribution of radiosensitivity cannot be ignored, thus the RT model would be more suitable for risk protection for radiosensitive subgroups instead of the LNT model. We also notice that it could be widely applicable for risk protection of not only low-dose radiation but also environmental pollutants.

Frequent chest CTs within a short period during follow-up of long COVID patients may increase the risk of radiation-related health effects in the exposed individuals. We aimed to assess the image quality and diagnostic accuracy of ultra-low-dose CT (ULDCT) chest compared to standard-dose CT (SDCT) in detecting lung abnormalities associated with long COVID.

In this prospective study, 100 long COVID patients with respiratory dysfunction underwent SDCT and ULDCT chest that were compared in terms of objective (signal-to-noise ratio, SNR) and subjective image quality (image graininess, sharpness, artifacts, and diagnostic accuracy along with the European guidelines on image quality criteria for CT chest), detection of imaging patterns of long COVID, CT severity score, and effective radiation dose. Additionally, the diagnostic performance of ULDCT was compared among obese (BMI≥30 kg/m2) and non-obese (BMI<30 kg/m2) subjects.

The mean age of study participants was 53 ± 12.9 years, and 68% were male. The mean SNR was 31.4 ± 5.5 and 11.3 ± 4.6 for SDCT and ULDCT respectively (p< 0.0001). Common findings seen on SDCT included ground-glass opacities (GGOs, 77%), septal thickening/reticulations (67%), atelectatic/parenchymal bands (63%) and nodules (26%). ULDCT provided sharp images, with no/minimal graininess, and high diagnostic confidence in 81%, 82% and 80% of the cases respectively. The sensitivity of ULDCT for various patterns of long COVID was 72.7% (GGOs), 71.6% (interlobular septal thickening/reticulations), 100% (consolidation), 81% (atelectatic/parenchymal bands) and 76.9% (nodules). ULDCT scans in non-obese subjects exhibited a significantly higher sensitivity (88% vs. 60.3%, p < 0.0001) and diagnostic accuracy (97.7% vs. 84.9%, p < 0.0001) compared to obese subjects. ULDCT showed very strong correlation with SDCT in terms of CT severity score (r = 0.996, p < 0.0001). The mean effective radiation dose with ULDCT was 0.25 ± 0.02 mSv with net radiation dose reduction of 94.8% ± 1.7% (p < 0.0001) when compared to SDCT (5.5 ± 1.96 mSv).

ULDCT scans achieved comparable diagnostic accuracy to SDCT for detecting long COVID lung abnormalities in non-obese patients, while significantly reducing radiation exposure.

In cone-beam computed tomography (CBCT) for image-guided radiation therapy (IGRT) of the head, we evaluated the exposure dose reduction effect to the crystalline lens and position-matching accuracy by narrowing one side (X2) of the X-ray aperture (blade) in the X-direction. We defined the ocular surface dose of the head phantom as the crystalline lens exposure dose and measured using a radiophotoluminescence dosimeter (RPLD, GD-352 M) in the preset field (13.6 cm) and in each of the fields when blade X2 aperture was reduced in 0.5 cm increments from 10.0 to 5.0 cm. Auto-bone matching was performed on CBCT images acquired five times with blade X2 aperture set to 13.6 cm and 5.0 cm at each position when the head phantom was moved from - 5.0 to + 5.0 mm in 1.0 mm increment. The maximum reduction rate in the crystalline lens exposure dose was - 38.7% for the right lens and - 13.2% for the left lens when blade X2 aperture was 5.0 cm. The maximum difference in the amount of position correction between blade X2 aperture of 13.6 cm and 5.0 cm was 1 mm, and the accuracy of auto-bone matching was similar. In CBCT of the head, reduced blade X2 aperture is a useful technique for reducing the crystalline lens exposure dose while ensuring the accuracy of position matching.

The effective dose resulting from computed tomography (CT) scans provides an assessment of the risk associated with stochastic effects but does not account for the patient's size. Advances in Monte Carlo simulations offer the potential to obtain organ dose data from phantoms of varying stature, enabling derivation of a size-specific effective doses (SEDs) representing doses to individual patients. This study aimed to compute size-specific k-conversion factors for SED in routine CT examinations for adult and pediatric patients of different sizes. Radiation interactions were simulated for adult and pediatric phantom models of various sizes using National Cancer Institute CT version 3.0.20211123. Subsequent calculations of SED were performed, and coefficients for SED were derived, considering the variations in body sizes. The results revealed a strong correlation between effective diameter and weight, observed with size-specific k-conversion factors for adult and pediatric phantoms, respectively. While size-specific k-conversion factors for CT brain remained constant in adults, values for pediatric cases varied. When using the tube current modulation (TCM) system, size-specific k-conversion factors increased in larger phantoms and decreased in smaller ones. The extent of this increase or decrease correlated with the set TCM strength. This study provides coefficients for estimating SEDs in routine CT exams. Software utilizing look-up tables of coefficients can be used to provide dose information for CT scanners at local hospitals, offering guidance to practitioners on doses to individual patients and improving radiation risk awareness in clinical practice.

Objective. The rapid and accurate assessment of internal exposure dose is a crucial safeguard for personnel health and safety. This study aims to investigate a precise and efficient GPU Monte Carlo simulation approach for internal exposure dose calculation. It directly calculates doses from common radioactive nuclides intake, like60Co for occupational exposure, allowing personalized assessments.Approach. This study developed a GPU-accelerated Monte Carlo program for internal exposure on radionuclide intake, successfully realizing photoelectronic coupled transport, nuclide simulation, and optimized acceleration. The generation of internal irradiation sources and sampling methods were achieved, along with the establishment of a personalized phantom construction process. Three irradiation scenarios were simulated to assess computational accuracy and efficiency, and to investigate the influence of posture variations on internal dose estimations.Main results. Using the International Commission on Radiological Protection (ICRP) voxel-type phantom, the internal dose of radionuclides in individual organs was calculated, exhibiting relative deviation of less than 3% in comparison to organ dose results interpolated by Specific Absorbed Fractions in ICRP Publication 133. Employing the Chinese reference phantom for calculating internal irradiation dose from the intake of various radionuclides, the use of GPU Monte Carlo program significantly shortened the simulation time compared to using CPU programs, by a factor of 150-500. Internal dose estimation utilizing a seated Chinese phantom revealed up to a 75% maximum difference in organ dose compared to the same phantom in a standing posture.Significance. This study presents a rapid GPU-based simulation method for internal irradiation doses, capable of directly simulating dose outcomes from nuclide intake and accommodating individualized phantoms for more realistic and expeditious calculations tailored to specific internal irradiation scenarios. It provides an effective and feasible tool for precisely calculating internal irradiation doses in real-world scenarios.

The αvβ6-integrin targeting trimeric ligand [68Ga]Ga-Trivehexin has emerged as a promising candidate for clinical application due to its clinical imaging potentials in various malignant cancers. Our objective was to develop a simplified and reproducible module-based automated synthesis protocol to expand its availability in clinical application.

The pH value and the precursor load of radiolabeling were explored using an iQS-TS fully-automated module. Radiochemical purity was evaluated by radio-HPLC and radio-TLC. The ethanol content, radionuclide purity and identity, bacterial endotoxins, sterility, and stability of the final product [68Ga]Ga-Trivehexin were all tested. Biodistribution of [68Ga]Ga-Trivehexin in healthy volunteers was also conducted.

The synthesis was explored and established using fully-automated module with outstanding radiochemical purity (>99%). Considering molar activity and economic costs, a pH of 3.6 and precursor dose of 30 μg were determined to be optimal. All relevant quality control parameters were tested and met the requirement of European Pharmacopoeia. In vitro stability test and imaging in healthy volunteer indicated the practical significance in clinical routines.

A fully-automated synthesis protocol for [68Ga]Ga-Trivehexin using the iQS-TS synthesis module was achieved and conformed to the clinical quality standards.

ClinicalTrials.gov, NCT05835570. Registered 28 April 2023, https://www.clinicaltrials.gov/study/NCT05835570.

In this study tissue equivalency of the polymeric materials was investigated by comparing with ICRP 110 Male Adult Computational Phantom tissues. For this purpose, radiological properties of polyamide (PA), high density polyethylene (HDPE), ultra-high molecular weight polyethylene (UHMWPE), polypropylene (PP), polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET), polyoxymethylene (POM) and polyurethane foam (PU FOAM) were evaluated in the diagnostic energy range (15-150 keV). The radiological properties of the materials and ICRP 110 Male and Female Adult Computational Phantom tissues were calculated with Phy-X/PSD software. No major differences were seen except for sex-specific organs, and comparisons were made using an adult male phantom. To confirm the results experimentally, a chest phantom was designed with the polymeric materials. The phantom was scanned by Siemens SOMATOM Edge CT device with tube voltage of 120 kVp and Hounsfield Unit (HU) values were measured. In addition, HU values were calculated using theoretical relationships and significant agreement was obtained between measured and calculated HUs. It was determined that PA, PP, UHMWPE and HDPE were equivalent to muscle and adipose tissue, PVC and PTFE were equivalent to mineral bone, PET and POM were equivalent to spongiosa bone and PU FOAM was equivalent to lung tissue.

Computed tomography (CT) is an important imaging technique that produces detailed cross-sectional images for diagnosing medical conditions. However, the associated radiation exposure raises concerns. Establishing diagnostic reference levels (DRLs) helps identify unusual radiation doses and optimize exposure while maintaining diagnostic image quality. The purpose of this systematic review is to review the radiation doses received by adult patients in the head, chest, abdomen, pelvis, abdomen-pelvis (AP), and combined chest, abdomen, and pelvis (CAP) CT scans in Saudi Arabia. A search was conducted in several databases including PubMed and Google Scholar to identify studies that have established DRLs or determined radiation dose for adult CT examinations. Only studies that specifically assessed DRLs in actual adult patients were considered for inclusion. Out of a total of 31 articles that were identified as eligible, 13 were included after a thorough screening process. The values of CTDIv, DLP, and effective doses were determined. The review discovered that CTDIv and DLP were the most frequently used dosimetric quantities. The mean values in terms of CTDIv for head, chest, abdomen, pelvis, AP, and CAP ranged from 40.67 to 61.80 mGy, 5.80 to 14.90 mGy, 8.60 to 16.15 mGy, 10.80 to 17.35 mGy, 14.10 to 16.84 mGy, and 12.00 to 22.94 mGy, respectively. The mean values in terms of DLP for head, chest, abdomen, pelvis, AP, and CAP ranged from 757 to 1212 mGy.cm, 243 to 657 mGy.cm, 369.5 to 549 mGy.cm, 379.6 to 593 mGy.cm, 658 to 940.43 mGy.cm, and 740 to 1493.8 mGy.cm, respectively. There is a fluctuation in radiation dose among CT centers, highlighting a need to provide proper education and training to radiographers. It is recommended to establish a universally accepted standardized protocol based on weight, equivalent diameter, or cross-sectional area for accurate comparisons with national and international DRLs.

[18F]Fluorodeoxyglucose ([18F]FDG) positron emission tomography (PET) is recommended during diagnostic work-up for ovarian cancer; however, [18F]FDG PET has several inherent limitations. The novel oncologic PET-tracer fibroblast activation protein inhibitor (FAPI) has demonstrated promising results in multiple cancer types, including ovarian cancer, and could overcome the limitations of [18F]FDG PET; however, high-quality clinical studies are lacking. The primary objective of the present study is to compare the diagnostic accuracy of [68Ga]Ga-FAPI-46 PET/CT and [18F]FDG PET/CT in ovarian cancer patients and to investigate how this potential difference impacts staging and patient management.

Fifty consecutive ovarian cancer patients will be recruited from Aalborg University Hospital, Denmark. This study will be a single-center, prospective, exploratory clinical trial that adheres to the standards for reporting diagnostic accuracy studies (STARD). This study will be conducted under continuous Good Clinical Practice monitoring. The eligibility criteria for patients are as follows: (1) biopsy verified newly diagnosed ovarian cancer or a high risk of ovarian cancer and referred for primary staging with [18F]FDG PET/CT; and (2) resectable disease, i.e., candidate for primary debulking surgery or neoadjuvant chemotherapy followed by interval debulking surgery. All recruited study subjects will undergo [68Ga]Ga-FAPI-46 PET/CT at primary staging, before primary debulking surgery or neoadjuvant chemotherapy (Group A + B), in addition to conventional imaging (including [18F]FDG PET/CT). Study subjects in Group B will undergo an additional [68Ga]Ga-FAPI-46 PET/CT following neoadjuvant chemotherapy prior to interval debulking surgery. The results of the study-related [68Ga]Ga-FAPI-46 PET/CTs will be blinded, and treatment allocation will be based on common clinical practice in accordance with current guidelines. The histopathology of surgical specimens will serve as a reference standard. A recruitment period of 2 years is estimated; the trial is currently recruiting.

To our knowledge, this trial represents the largest, most extensive, and most meticulous prospective FAPI PET study conducted in patients with ovarian cancer thus far. This study aims to obtain a reliable estimation of the diagnostic accuracy of [68Ga]Ga-FAPI-46 PET/CT, shed light on the clinical importance of [68Ga]Ga-FAPI-46 PET/CT, and examine the potential applicability of [68Ga]Ga-FAPI-46 PET/CT for evaluating chemotherapy response.

clinicaltrials.gov: NCT05903807, 2nd June 2023; and euclinicaltrials.eu EU CT Number: 2023-505938-98-00, authorized 11th September 2023.

Even at low levels, exposure to ionising radiation can lead to eye damage. However, the underlying molecular mechanisms are not yet fully understood. We aimed to address this gap with a comprehensive in silico approach to the issue. For this purpose we relied on the Comparative Toxicogenomics Database (CTD), ToppGene Suite, Cytoscape, GeneMANIA, and Metascape to identify six key regulator genes associated with radiation-induced eye damage (ATM, CRYAB, SIRT1, TGFB1, TREX1, and YAP1), all of which have physical interactions. Some of the identified molecular functions revolve around DNA repair mechanisms, while others are involved in protein binding, enzymatic activities, metabolic processes, and post-translational protein modifications. The biological processes are mostly centred on response to DNA damage, the p53 signalling pathway in particular. We identified a significant role of several miRNAs, such as hsa-miR-183 and hsamiR-589, in the mechanisms behind ionising radiation-induced eye injuries. Our study offers a valuable method for gaining deeper insights into the adverse effects of radiation exposure.

Magnetic growing rods (MGRs) are one of the most common procedures to treat early-onset scoliosis (EOS). Radiographic examinations (X-ray) or ultrasonographic (US) assessments are used to evaluate the lengthening of the rods. X-ray exposes patients to radiation, while the US has not been validated and may be affected by the radiologist's ability to assess elongation. The research question of the present study is to compare the difference between US and X-ray growth assessments in EOS patients treated with MGRs.

The study enrolled 65 patients consecutively from July 2011 to July 2022. Noninvasive lengthening was performed every four months, and X-ray follow-up was performed at different intervals. An experienced radiologist assessed the mean US rod elongation per session. The mean elongation/session of T2-T12 and T2-S1 was calculated, and the results were compared using an independent t-test.

The mean age at operation was 8.8 ± 2 years, and the mean follow-up was four ± two years. The average rod elongation assessed by the US was 3.1 ± 0.1 mm. The average rod elongation evaluated by X-ray was 1.2 ± 2.9 mm (T2-T12) and 1.8 ± 1.9 mm (T2-S1). The difference between the values measured by US and X-ray was statistically significant in the T2-T12 group (p < 0.05) and not significant in the T2-S1 group (p = 0.34).

This is the most extensive single-center study comparing US and X-ray data for MGRs in EOS patients. US overestimates thoracic spine elongation compared to X-ray. US elongation analysis could be appropriate in long thoracolumbar curves.

Periodontal and implant radiography, mainly including intra-oral peri-apical and cone beam computed tomography images, are crucial in the diagnosis and treatment planning process. However, radiation safety concerns have been a chronic concern over the years, leading to uncomfortable situations. It is therefore crucial to understand the actual radiation exposure to determine if the patients' fear of necessary diagnostic exams is justified. In this perspective article, we aimed to provide concise information on dental imaging exposure, risks, and benefits, comparing them to that of absorbed radiation from daily life activities; and secondarily, to help periodontists choose the best option for each case and become more confident in addressing patients' concerns and providing a summary of safety guidelines as a reference for them.

The biokinetics of radioiodine (RAI) in thyroid cancer patients are complex. This study aims to develop a practical approach for assessing RAI biokinetics to predict patient discharge time and estimate radiation exposure to caregivers.

We retrospectively reviewed data from patients with differentiated thyroid carcinoma undergoing RAI treatment. Serial radiation dose rates were dynamically collected during hospitalization and fitted to a biexponential model to assess the biokinetic features: RAI uptake fraction of thyroid tissue (Ft) and effective half-life of extra-thyroid tissue (Tet). Correlations with 99mTc thyroid uptake ratio (TcUR), radiation retention ratio (RR), renal function, and body mass index (BMI) were analyzed.

Thirty-five patients were enrolled. The derived Ft was 0.08 ± 0.06 and Tet was 7.57 ± 1.45 h. Pearson's correlation analysis revealed a significant association between Ft and both TcUR and RR (p < 0.05), while Tet correlated with renal function and BMI (p < 0.05).

This novel and practical method assessing RAI biokinetics demonstrates consistency with other parameters and related studies, enhancing the model reliability. It shows promise in predicting an appropriate discharge time and estimating radiation exposure to caregivers, allowing for modifications to radiation protection precautions to follow ALARA principle and minimize the potential risks from radiation exposure.

In patients with prostate cancer (PCa), imaging with gastrin-releasing peptide receptor (GRPR) ligands is an alternative to PSMA-targeted tracers, particularly if PSMA expression is low or absent. [99mTc]Tc-N4-BTG is a newly developed GRPR-directed probe for conventional scintigraphy and single photon emission computed tomography (SPECT) imaging. The current study aims to investigate the safety, biodistribution and dosimetry of [99mTc]Tc-N4-BTG in patients with biochemical recurrence (BCR) of PCa.

No adverse pharmacologic effects were observed. Injection of [99mTc]Tc-N4-BTG resulted in an effective dose of 0.0027 ± 0.0002 mSv/MBq. The urinary bladder was the critical organ with the highest mean absorbed dose of 0.028 ± 0.001 mGy/MBq, followed by the pancreas with 0.0043 ± 0.0015 mGy/MBq, osteogenic cells with 0.0039 ± 0.0005 mGy/MBq, the kidneys with 0.0034 ± 0.0003 mGy/MBq, and the liver with 0.0019 ± 0.0004 mGy/MBq, respectively. No focal tracer uptake suggestive of PCa recurrence could be revealed for any of the patients.

[99mTc]Tc-N4-BTG appears to be a safe diagnostic agent. Compared to GRPR-targeted PET tracers, this 99mTc-labelled SPECT agent could contribute to a broader application and better availability of this novel approach. Further research to assess its clinical value is warranted.

The most accurate method for estimating patient effective dose (a principal metric for tracking patient radiation exposure) from computed tomography (CT) requires time-intensive Monte Carlo simulation. A simpler method multiplies a scalar coefficient by the widely available scanner-reported dose length product (DLP) to estimate effective dose. We developed new adult effective dose coefficients using actual patient scans and assessed their agreement with Monte Carlo simulation.

A multicenter sample of 216,906 adult CT scans was prospectively assembled in 2015-2020 from the University of California San Francisco International CT Dose Registry and the University of Florida library of computational phantoms. We generated effective dose coefficients for eight body regions, stratified by patient sex, diameter, and scanner manufacturer. We applied the new coefficients to DLPs to calculate effective doses and assess their correlations with Monte Carlo radiation transport-generated effective dose.

Effective dose coefficients varied by body region and decreased in magnitude with increasing patient diameter. Coefficients were approximately twofold higher for torso scans in smallest compared with largest diameter categories. For example, abdomen and pelvis coefficients decreased from 0.027 to 0.013 mSv/mGy-cm between the 16-20 cm and 41+ cm categories. There were modest but consistent differences by sex and manufacturer. Diameter-based coefficients used to estimate effective dose produced strong correlations with the reference standard (Pearson correlations 0.77-0.86). The reported conversion coefficients differ from previous studies, particularly in neck CT.

New effective dose coefficients derived from empirical clinical scans can be used to easily estimate effective dose using scanner-reported DLP.

Scalar coefficients multiplied by DLP offer a simple approximation to effective dose, a key radiation dose metric. New effective dose coefficients from this study strongly correlate with gold standard, Monte Carlo-generated effective dose, and differ somewhat from previous studies.

• Previous effective dose coefficients were derived from theoretical models rather than real patient data. • The new coefficients (from a large registry/phantom library) differ from previous studies. • The new coefficients offer reasonably reliable values for estimating effective dose.

For many cancer sites low-dose risks are not known and must be extrapolated from those observed in groups exposed at much higher levels of dose. Measurement error can substantially alter the dose-response shape and hence the extrapolated risk. Even in studies with direct measurement of low-dose exposures measurement error could be substantial in relation to the size of the dose estimates and thereby distort population risk estimates. Recently, there has been considerable attention paid to methods of dealing with shared errors, which are common in many datasets, and particularly important in occupational and environmental settings. In this paper we test Bayesian model averaging (BMA) and frequentist model averaging (FMA) methods, the first of these similar to the so-called Bayesian two-dimensional Monte Carlo (2DMC) method, and both fairly recently proposed, against a very newly proposed modification of the regression calibration method, the extended regression calibration (ERC) method, which is particularly suited to studies in which there is a substantial amount of shared error, and in which there may also be curvature in the true dose response. The quasi-2DMC with BMA method performs well when a linear model is assumed, but very poorly when a linear-quadratic model is assumed, with coverage probabilities both for the linear and quadratic dose coefficients that are under 5% when the magnitude of shared Berkson error is large (50%). For the linear model the bias is generally under 10%. However, using a linear-quadratic model it produces substantially biased (by a factor of 10) estimates of both the linear and quadratic coefficients, with the linear coefficient overestimated and the quadratic coefficient underestimated. FMA performs as well as quasi-2DMC with BMA when a linear model is assumed, and generally much better with a linear-quadratic model, although the coverage probability for the quadratic coefficient is uniformly too high. However both linear and quadratic coefficients have pronounced upward bias, particularly when Berkson error is large. By comparison ERC yields coverage probabilities that are too low when shared and unshared Berkson errors are both large (50%), although otherwise it performs well, and coverage is generally better than the quasi-2DMC with BMA or FMA methods, particularly for the linear-quadratic model. The bias of the predicted relative risk at a variety of doses is generally smallest for ERC, and largest for the quasi-2DMC with BMA and FMA methods (apart from unadjusted regression), with standard regression calibration and Monte Carlo maximum likelihood exhibiting bias in predicted relative risk generally somewhat intermediate between ERC and the other two methods. In general ERC performs best in the scenarios presented, and should be the method of choice in situations where there may be substantial shared error, or suspected curvature in the dose response.

The purpose was to assess the impact of irradiation technique type and beam energy on the mixed radiation field around the medical linear accelerator (linac) in terms of radiation quality and related radiation protection quantities.

Seven radiotherapeutic plans with Alderson-Rando anthropomorphic phantom [different techniques: conventional three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT) and intensity modulated arc therapy (IMAT), different beams: 6 MV or 18 MV, and their arrangements) were prepared for the case of prostate malignancy. Recombination chambers REM-2 and GW2 were positioned on the treatment couch 100 cm from the beam axis at the height of the isocentre. Recombination chambers REM-2 and GW2 were used for recombination index of radiation quality Q4 determination, measurement of total tissue dose Dt and calculation of gamma and neutron components to Dt. Estimation of Dt and Q4 allowed for the ambient dose equivalent H*(10) calculations for each plan.

For plans prepared with 6 MV beams, Q4 values within the limits of uncertainty were equal to one, which confirms the correctness of the measurement method. For plans implemented with 18 MV beams, the value of Q4 was in the range of 3.7-5.7. Comparison between treatment techniques indicates that the lowest exposure resulting from out-of-field doses comes from 6 MV IMAT (0.7 mSv), whereas the highest one is from 18 MV IMRT (55.1 mSv).

With the recombination chambers technique it was confirmed that the choice of beam energy directly affects the generation of photoneutrons. The treatment plan technique can have a significant impact on the out-of-field dose.

The purpose of this study was to provide benchmark data for discussing the tolerability of cancer risk associated with occupational radiation exposure. It focused on differences in cancer mortality risk by occupation among Japan's working population and examined baseline cancer mortality risks and its variations from 1995 through 2020. Data were collected every five years from national vital statistics sources. By focusing on the same types of cancer among radiation induced effects, cumulative mortality risks were calculated for colorectal, lung, and breast cancer (females only) for those aged 15-74. The average cumulative mortality risk for the working population in Japan has decreased by 30%-60% over the past 25 years. Service workers and male managers were at an average risk, among all workers, while clerical workers and transportation and manufacturing workers had about half the average risk. The risks were higher for professionals and female managers, about 1.5-2 times the average for professionals and up to 5 times the average for female managers. The decrease in the average cancer mortality risk in the working population as a baseline suggests that risk tolerance in society might have changed over time. Since differences in mortality by occupation were confirmed, the usefulness of occupational data as a benchmark needs further investigation, as high-risk/low-risk occupations vary by country and region. The results of this study contribute to put radiation risks into perspective with the background risk of cancer.