Whole-body Radiation Dose Research Articles

Preclinical Positron Emission Tomography (PET) of Prosthetic Joint Infection Using a Nitro-Prodrug of 2-[18F]F-p-Aminobenzoic Acid ([18F]F-PABA).

Deep-seated bacterial infections are difficult to detect and diagnose due to the lack of specific clinical imaging modalities. Therefore, the bacteria-specific positron emission tomography radiotracer 2-[18F]fluoro-4-nitrobenzoic acid ([18F]FNB) was developed, which is reduced to 2-[18F]fluoro-4-aminobenzoic acid ([18F]F-PABA) by bacterial nitroreductases and has improved pharmacokinetics compared to the parent compound. PET imaging demonstrated that the uptake of 2-[18F]fluoro-4-nitrobenzoic acid in a clinically relevant Staphylococcus aureus prosthetic joint infection model was up to ∼4-fold higher in the infected joint compared to the contralateral joint. 2-[18F]Fluoro-4-nitrobenzoic acid was also able to distinguish infection from inflammation in a surgical inflammation model. Based on the mouse radiation dosimetry results, the calculated effective dose of 2-[18F]fluoro-4-nitrobenzoic acid was well below the whole-body radiation dose limit established by the Food and Drug Administration for humans. In addition, no treatment-related microscopic changes in organ histopathology were observed in a mouse acute toxicity study. Overall, these data suggest that 2-[18F]fluoro-4-nitrobenzoic acid is a specific and effective imaging agent for noninvasively diagnosing prosthetic joint infections.

Automated Injectors versus Manual Administration: A Comparative Analysis of Radiation Exposure Reduction in 18F-FDG Delivery

Abstract Background Despite the presence of safety protocols, the manual manipulation of radiopharmaceuticals continues to pose a significant occupational radiation risk. Health care professionals in nuclear medicine are at risk of radiation exposure, particularly to their hands and eyes. Despite existing protective measures, manual handling of radiopharmaceuticals remains a significant source of occupational radiation. Objective This study evaluates the effectiveness of automated injectors in reducing radiation exposure among health care workers during fluorine-18 fluorodeoxyglucose (18F-FDG) administrations, compared with traditional manual injection methods. Methods We assessed radiation exposure levels associated with manual versus automated 18F-FDG injection techniques using specialized dosimeters. Measurements focused on whole-body, extremity, and eye-lens radiation doses to evaluate the potential benefits of automation in minimizing exposure. Results Findings reveal that automated injectors significantly reduce radiation exposure, with decreases of 97.97 and 98.96% in left- and right-hand extremity doses, respectively, 43.24% in eye-lens dose, and 91.66% in whole-body dose compared with manual methods. Conclusion Automated injection systems offer considerable advantages in reducing health care worker radiation exposure in nuclear medicine. The substantial reduction in staff doses underscores the necessity of transitioning to such technology to promote safer clinical environments. This study highlights the critical role of automation in enhancing occupational safety standards within diagnostic radiology settings.

Significant Reduction of Radiation-Induced Death in Mice Treated with PrC-210 and G-CSF after Irradiation.

The search for single or combined radiation countermeasures that mitigate the development of Acute Radiation Syndrome (ARS) after radiation exposure remains a prominent goal of the U.S. government. This study was undertaken to determine whether PrC-210 and G-CSF, when administered 24-48 h postirradiation, would confer an additive or synergistic survival benefit and mitigate ARS in mice that had received an otherwise 96% lethal radiation dose. Our results show that optimum systemic doses of PrC-210 and G-CSF, when administered 24 h or later after a 96% lethal dose of whole-body irradiation, conferred: 1. strong individual survival benefits (PrC-210 44%, P = 0.003), (G-CSF 48%, P = 0.0002), 2. a profound combined 85% survival benefit (P < 0.0001) when administered together, and on day 14 postirradiation, 3. peripheral white blood cell/lymphocyte counts equal to unirradiated controls, 4. dense bone marrow cell density (>65% of unirradiated controls), 5. jejunal villi density that equaled 90% of unirradiated controls, and 6. spleen weights that equaled 93% of unirradiated controls. Our results show that PrC-210 and G-CSF given together 24 h after irradiation confer strong additive efficacy by protecting the immune system, and enabling recovery of the bone marrow, and they work synergistically to enable recovery of peripheral white blood cells in circulating blood.

Revitalizing gut health: Liangxue guyuan yishen decoction promotes akkermansia muciniphila -induced intestinal stem cell recovery post-radiation in mice

BackgroundThe efficacy of Liangxue Guyuan Yishen Decoction (LGYD), a traditional Chinese medicine, has been scientifically proven in the treatment of radiation-induced intestinal injury (RIII) and preservation of intestinal integrity and function following high-dose radiation exposure. However, further investigation is required to comprehensively elucidate the precise mechanisms underlying the therapeutic effects of LGYD in order to provide potential pharmaceutical options for radiation protection. PurposeThis study aims to elucidate the potential mechanism through which LGYD exerts its therapeutic effects on RIII by modulating the gut microbiota (GM). Methods16 s rRNA analysis was employed to assess the impact of varying doses of whole body irradiation (WBI) on GM in order to establish an appropriate model for this study. The effects of LGYD on GM and SCFA were evaluated using 16 s rRNA and Quantification of SCFA. UHPLC-QE-MS was utilized to identify the active components in LGYD as well as LGYD drug containing serum (LGYD-DS). Subsequently, immunofluorescence and immunohistochemical staining were conducted to validate the influence of LGYD and/or characteristic microbiota on RIII recovery in vivo. The effects of LGYD-DS, characteristic flora, and SCFA on intestinal stem cell (ISC) were assessed by measuring organoid surface area in intestinal organoid model. ResultsThe species composition and abundance of GM were significantly influenced by whole-body irradiation with a dose of 8.5 Gy, which was used as in vivo model. LGYD significantly improves the survival rate and promotes recovery from RIII. Additionally, LGYD exhibited a notable increase in the abundance of Akkermansia muciniphila (AKK) and levels of SCFA, particularly isobutyric acid. LGYD-DS consisted of seven main components derived from herbs of LGYD. In vivo experiments indicated that both LGYD and AKK substantially enhanced the survival rate after radiation and facilitated the recovery process for intestinal structure and function. In the organoid model, treatment with LGYD-DS, AKK supernatant or isobutyric acid significantly increased organoid surface area. ConclusionsLGYD has the potential to enhance RIII by promoting the restoration of intestinal stem cell, which is closely associated with the upregulation of AKK abundance and production of SCFA, particularly isobutyric acid.

Mild hypothermia protects against radiation-induced intestinal injury in mice via upregulation of heme oxygenase-1

Radiation can cause life-threatening intestinal damage, whether intentional or unintentional. The present study investigated the effects of mild hypothermia on radiation-induced intestinal injury and survival. For 1 h before and after a lethal dose of whole-body irradiation (13 Gy), mice were either maintained at normothermia (37 °C) or exposed to mild hypothermia (32 °C). The survival of the mice was monitored for 30 days, and the morphological changes in the intestine and the cytokine levels in the serum of the irradiated mice at normothermia or hypothermia were assessed by histological examination at 12 h, 3.5 days, and 5 days after irradiation. Hypothermia delayed the death of the mice and attenuated the damage to the intestine. Hypothermia reduced apoptosis in the jejunum 12 h after irradiation exposure and restored crypt number, villi length, and epithelial length of the jejunum after 3.5 days. Mild hypothermia also reduced serum levels of proinflammatory cytokines after radiation exposure. Furthermore, heme oxygenase-1 (HO-1) was specifically upregulated in the mouse intestine by hypothermia. The HO-1 inhibitor Sn(IV) protoporphyrin IX dichloride partially reversed the effect mild hypothermia had on HO-1. These results suggest that hypothermia is a protective factor against radiation-induced intestinal damage and can, therefore, be effectively used as a radioprotective condition. In summary, mild hypothermia reduced cell death and inflammation in radiation-induced intestinal injury, partly through the regulation of HO-1.

Cell Therapies for Acute Radiation Syndrome.

The risks of severe ionizing radiation exposure are increasing due to the involvement of nuclear powers in combat operations, the increasing use of nuclear power, and the existence of terrorist threats. Exposure to a whole-body radiation dose above about 0.7 Gy results in H-ARS (hematopoietic acute radiation syndrome), which is characterized by damage to the hematopoietic system; higher doses result in further damage to the gastrointestinal and nervous systems. Only a few medical countermeasures for ARS are currently available and approved for use, although others are in development. Cell therapies (cells or products produced by cells) are complex therapeutics that show promise for the treatment of radiation injury and have been shown to reduce mortality and morbidity in animal models. Since clinical trials for ARS cannot be ethically conducted, animal testing is extremely important. Here, we describe cell therapies that have been tested in animal models. Both cells and cell products appear to promote survival and lessen tissue damage after whole-body irradiation, although the mechanisms are not clear. Because radiation exposure often occurs in conjunction with other traumatic injuries, animal models of combined injury involving radiation and future countermeasure testing for these complex medical problems are also discussed.

Whole-body irradiation impairs naïve CD4 T cell function

Abstract Advancements in nuclear power and radiotherapy have expanded new avenues for whole-body irradiation (WBI) to humans, urging the need to understand its impact on immune cells. While most studies focus on the numerical recovery of naïve T cells post-WBI, less is known regarding its impact on their function. We subjected B6 SPF mice to 0/5Gy doses of WBI and used I-Ab tetramer enrichment to track the recovery of naïve CD4s of different antigen specificities post WBI. The number of MOG40 specific CD4 T cells is diminished 10 days post-irradiation (DPR), and recovered by 40DPR. To test if they are able to induce EAE post-WBI, we administered MOG+CFA, followed by pertussis toxin (PTX). The 10DPR mice showed delayed EAE development, likely due to diminished MOG40 naïve precursors. Interestingly, the 40DPR mice potentiated EAE compared to the 0Gy mice, evidenced by increased CD4 priming in the dLN, and spine infiltration. While WBI-mediated CD4 T cell-intrinsic changes could contribute to the timing/severity of EAE, T cell-extrinsic factors could also influence disease. To test if WBI compromises the blood-brain barrier (BBB) and facilitates EAE progression, EAE is induced in +/-WBI mice without PTX. In the absence of PTX, 0Gy mice did not develop EAE, while the 10- and 40DPR mice developed EAE suggesting BBB impairment. Overall, WBI directly impacts the number and function of autoreactive CD4 T cells, while helping them enter the spine by changing the environment.

Contribution of radioactive particles to the post-explosion exposure of atomic bomb survivors implied from their stable chromosome aberration rates.

Even today when nearly 80 years have passed after the atomic bomb (A-bomb) was dropped, there are still debates about the exact doses received by the A-bomb survivors. While initial airborne kerma radiation (or energy spectrum of emitted radiation) can be measured with sufficient accuracy to assess the radiation dose to A-bomb survivors, it is not easy to accurately assess the neutron dose including appropriate weighting of neutron absorbed dose. Particularly, possible post-explosion exposure due to the radioactive particles generated through neutron activation have been almost neglected so far, mainly because of a large uncertainty associated to the behavior of those particles. However, it has been supposed that contribution of such non-initial radiation exposure from the neutron-induced radioactive particles could be significant, according to the findings that the stable chromosomal aberration rates which indicate average whole-body radiation doses were found to be more than 30% higher for those exposed indoors than for those outdoors even at the same initial dose estimated for the Life Span Study. In this Mini Review article, the authors explain that such apparently controversial observations can be reasonably explained by assuming a higher production rate of neutron-induced radioactive particles in the indoor environment near the hypocenter.

Repurposing of FDA approved kinase inhibitor bosutinib for mitigation of radiation induced damage via inhibition of JNK pathway

Radiotherapy is a common modality for cancer treatment. However, it is often associated with normal tissue toxicity in 20–80% of the patients. Radioprotectors can improve the outcome of radiotherapy by selectively protecting normal cells against radiation toxicity. In the present study, compound libraries containing 54 kinase inhibitors and 80 FDA-approved drugs were screened for radioprotection of lymphocytes using high throughput cell analysis. A second-generation FDA-approved kinase inhibitor, bosutinib, was identified as a potential radioprotector for normal cells. The radioprotective efficacy of bosutinib was evinced from a reduction in radiation induced DNA damage, caspase-3 activation, DNA fragmentation and apoptosis. Oral administration of bosutinib protected mice against whole body irradiation (WBI) induced morbidity and mortality. Bosutinib also reduced radiation induced bone-marrow aplasia and hematopoietic damage in mice exposed to 4 Gy and 6 Gy dose of WBI. Mechanistic studies revealed that the radioprotective action of bosutinib involved interaction with cellular thiols and modulation of JNK pathway. The addition of glutathione and N-acetyl cysteine significantly reduced the radioprotective efficacy of bosutinib. Moreover, bosutinib did not protect cancer cells against radiation induced toxicity. On the contrary, bosutinib per se exhibited anticancer activity against human cancer cell lines. The results highlight possible use of bosutinib as a repurposable radioprotective agent for mitigation of radiation toxicity in cancer patients undergoing radiotherapy.

Evaluation of institutional whole-body and extremity occupational radiation doses in nuclear medicine.

This study evaluated nuclear medicine occupational radiation doses at Sultan Qaboos University Hospital, a 700-bed tertiary care teaching hospital in Oman. Personal effective whole-body doses, Hp(10), and extremity doses, Hp(0.07), were collected for 19 medical radiation workers over a 7-year period (2015-2021). Personal doses for four professional groups were measured using calibrated thermo-luminescence dosemeters ((LiF:Mg,Ti) TLD-100). The average, median and maximum cumulative doses were compared against the annual whole-body and extremity dose limits (20mSv and 500mSv y-1, respectively) and local dose investigation level (DIL; 6mSv y-1). Personal whole-body doses (average:median:maximum) for technologists, medical physicists, nuclear medicine physicians and nurses were 1.8:1.1:7.8, 0.3:0.3:0.4, 0.1:0.1:0.2 and 0.1:0.1:0.2mSv, respectively. Personal extremity doses for left and right hand (average and maximum doses) follow similar trends. Average annual effective whole-body and extremity doses were well below the recommended annual dose limits. The findings suggest lowering local DIL for all staff except for technologists.

Involvement of extracellular vesicles in the progression, diagnosis, treatment, and prevention of whole-body ionizing radiation-induced immune dysfunction.

Acute radiation syndrome (ARS) develops after exposure to high doses of ionizing radiation and features immune suppression and organ failure. Currently, there are no diagnostics to identify the occurrence or severity of exposure and there are limited treatments and preventative strategies to mitigate ARS. Extracellular vesicles (EVs) are mediators of intercellular communication that contribute to immune dysfunction across many diseases. We investigated if EV cargo can identify whole body irradiation (WBIR) exposure and if EVs promote ARS immune dysfunction. We hypothesized that beneficial EVs derived from mesenchymal stem cells (MSC-EVs) would blunt ARS immune dysfunction and might serve as prophylactic radioprotectants. Mice received WBIR (2 or 9 Gy) with assessment of EVs at 3 and 7 days after exposure. LC-MS/MS proteomic analysis of WBIR-EVs found dose-related changes as well as candidate proteins that were increased with both doses and timepoints (34 total) such as Thromboxane-A Synthase and lymphocyte cytosolic protein 2. Suprabasin and Sarcalumenin were increased only after 9 Gy suggesting these proteins may indicate high dose/lethal exposure. Analysis of EV miRNAs identified miR-376 and miR-136, which were increased up to 200- and 60-fold respectively by both doses of WBIR and select miRNAs such as miR-1839 and miR-664 were increased only with 9 Gy. WBIR-EVs (9 Gy) were biologically active and blunted immune responses to LPS in RAW264.7 macrophages, inhibiting canonical signaling pathways associated with wound healing and phagosome formation. When given 3 days after exposure, MSC-EVs slightly modified immune gene expression changes in the spleens of mice in response to WBIR and in a combined radiation plus burn injury exposure (RCI). MSC-EVs normalized the expression of certain key immune genes such as NFκBia and Cxcr4 (WBIR), Map4k1, Ccr9 and Cxcl12 (RCI) and lowered plasma TNFα cytokine levels after RCI. When given prophylactically (24 and 3 hours before exposure), MSC-EVs prolonged survival to the 9 Gy lethal exposure. Thus, EVs are important participants in ARS. EV cargo might be used to diagnose WBIR exposure, and MSC-EVs might serve as radioprotectants to blunt the impact of toxic radiation exposure.

Protective effect of pycnogenol against gamma radiation-induced lung injury in rat: DNA damage, lipid peroxidation, antioxidant levels, and histopathological changes.

The study aims to evaluate the histopathological changes, enzymatic alterations, and DNA damage in rat lungs induced by whole-body gamma irradiation as well as evaluation of the protective effect of pycnogenol. A hundred adult male rats were equally divided into ten groups including control, four antioxidants, γ-irradiation, four antioxidant + γ-irradiations. This study began the day before radiation treatment and continued for 3 days. The pycnogenol was dissolved 5% dimethyl sulfoxide and then administered orally through a gastric tube at a dose of 37.5 mg/kg, 75 mg/kg, 150 mg/kg, and 300 mg/kg in 24, 48, and 72 h before irradiation. Irradiation was applied with a whole-body irradiation dose of 900 cGy in one fraction. DNA damage, histopathological changes, catalase (CAT), and superoxide dismutase (SOD) activities and malondialdehyde (MDA) levels in lung tissue of rats were evaluated 3 days after irradiation. CAT and SOD activities were found to be significantly lower in the irradiation group than control (P < 0.001). CAT and SOD activities were higher in the antioxidant + γ-irradiation group than both irradiation and control groups. MDA levels were significantly higher in the irradiation group compared to control (P < 0.001), whereas MDA levels decreased in the antioxidant + γ-irradiation group compared to the irradiation group. The antioxidant groups were significantly increased comet parameters depend on pycnogenol doses compared to control. The antioxidant + γ-irradiation was decreased comet parameter compared to γ-irradiation. As a result of the histopathologically, the antioxidant groups were different than the control group that in the areas of alveolar sacs and connective tissue areas were seen hemorrhage areas similar to the irradiation group. We demonstrate that 300 mg/kg of pycnogenol might provide significant protection against deleterious effects from whole-body ionizing radiation on the lung tissue. P300+ γ-ray group was significantly reduced radiation-induced lung injury and was possible to observe significantly preservation.

Clinical comprehensive and experimental assessment of the radioprotective effect of Annona muricata leaf extract to prevent cellular damage in the ileum tissue

Abstract We report the radioprotective attitude of Annona muricata (AM) leaf extract as antioxidant material to prevent cellular damage in the ileum tissue. The protective effects of an ethyl acetate extract of AM leaves are comprehensively investigated against radiation-induced ileal damage in numerous rats. Thirty-two adult female rats were separated into 4 groups (3 intervention groups and 1 control) as follows: controls received 0.01 mL/kg distilled water, the AM group received 300 mg/kg AM leaf extract, the ionizing radiation (IR) group received a single dose of whole body radiation (8.3 Gy) after 0.01 mL/kg saline treatment, and the AM + IR group received 300 mg/kg AM leaf extract treatment and were subjected to whole body radiation (8.3 Gy) 1 h after the last gavage. All treatments are administered by oral gavage once a day for 9 days. At the end of the experiment, biochemical total oxidant status (TOS, interleukin-6, and caspase) and histological examinations are performed on blood samples as well as ileum tissue. TOS levels are found to be significantly high in rats, which received irradiation, and those in the AM group when compared to controls. These findings suggest that AM has radioprotective effects on ileum tissue, likely because of its antioxidative properties. The findings of this research may contribute to the minimizing of major side effects induced by excessive radiation exposure in patients undergoing radiotherapy and may serve as a significant impetus for further assessments. However, future studies are highly recommended to confirm safety and to determine extraction technique and dosage before human use can be considered.

A focusing study on radioprotective and antioxidant effects of Annona muricata leaf extract in the circulation and liver tissue: Clinical and experimental studies

Abstract Objectives This study investigates the effect of Annona muricata (AM) leaf extract against irradiation-induced damage by the evaluation of hepatic tissue and the levels of oxidative and inflammatory stress in the circulation. Methods An experimental study with 37 female Wistar albino rats randomized into four groups (controls and three intervention groups) was performed. The first interventional group (group 2) received 300 mg/kg of AM leaf extract by oral gavage once a day for 9 days, group 3 received a single dose of whole-body radiation (8.3 Gy) after a 9-day oral gavage treatment with saline, and the last group received the same irradiation of 8.3 Gy after being treated with 300 mg/kg of AM leaf extract by oral gavage once a day for 9 days. Results Radiation was found to elevate reactive oxygen species parameters, and AM administration before irradiation was found to decrease total oxidant status (TOS), increase caspase 9, and improve hepatic damage when compared with the group that received only irradiation. Conclusion The damage caused by irradiation may be ameliorated by the use of the AM extract, which appears to be effective in preventing oxidative stress and inflammatory activity.

Abstract CT178: A phase 1/2, open-label study to assess safety, tolerability, biodistribution, radiation dosimetry and PET imaging characteristics of [18F]FPyGal in comparison to in-vitro diagnostic for the assessment of senescence in oncological patients

Abstract The authors did not submit an updated abstract. The original abstract should be considered final. Citation Format: Christian LaFougere, Brigitte Gueckel, Helmut Dittmann, Martina Hinterleitner, Nils Trautwein, Jonathan Cotton, Gabriele Kienzle, Stephan Singer, Gerald Reischl, Ulrich Lauer, Bernd Pichler, Lars Zender. A phase 1/2, open-label study to assess safety, tolerability, biodistribution, radiation dosimetry and PET imaging characteristics of [18F]FPyGal in comparison to in-vitro diagnostic for the assessment of senescence in oncological patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT178.

Modulation of radiation biomarkers in a randomized phase II study of 131I-MIBG with or without radiation sensitizers for relapsed or refractory neuroblastoma: A report from the NANT Consortium.

10026 Background: 131I-metaiodobenzylguanidine (131I-MIBG) has demonstrated efficacy as a single agent for patients with neuroblastoma. Recent trials have focused on 131I-MIBG combination strategies, though little is known about the impact of combination agents on markers of radiation exposure. Methods: NANT11-01 (NCT02035137) was a multicenter, open label, randomized phase II clinical trial that evaluated 131I-MIBG therapy alone (Arm A) or in combination with vincristine/irinotecan (Arm B) or vorinostat (Arm C) for patients with resistant/relapsed neuroblastoma. We collected blood samples at baseline, 72 hours, 96 hours, and 15 days after 131I-MIBG infusion and determined levels of plasma FLT3 ligand, serum amylase, and gene expression for selected RNA transcripts (apoptosis, DNA damage response and cell cycle related). We evaluated marker association with treatment arm, clinical response using NANT response criteria, toxicity, and whole-body radiation dose. Results: The cohort included 99 patients who had at least one biomarker available for analysis (32 Arm A; 35 Arm B; 32 Arm C). We observed both positive and negative significant modulation in most biomarkers between baseline, 72 hours, and 96 hours following 131I-MIBG. Patients in Arm C had the lowest degree of modulation in FLT3 ligand. Elevated baseline levels of FLT3 ligand were significantly associated with improved Curie response but not overall response. Lower baseline BCL2 levels were associated with higher overall and Curie response. Patients with increased FLT3 ligand at 96 hours after 131I-MIBG therapy were significantly more likely to have grade 4 thrombocytopenia.Peripheral blood gene expression of the BCL2 family of apoptotic markers (BCL2/L1 and BAX) was significantly associated with grade 4 hematological toxicity. Whole-body radiation dose and PRKDC fold change at 72 hours were significantly correlated. No other individual biomarkers were correlated with whole body radiation dose at 72 or 96 hours post 131I-MIBG. Conclusions: Peripheral blood biomarkers relevant to radiation exposure demonstrate significant modulation over time after 131I-MIBG treatment. Biomarkers related to hematopoietic damage and apoptosis were associated with hematological toxicity. Patients treated with vorinostat and 31I-MIBG had differential modulation of FLT3-ligand Further use of these biomarkers may improve our ability to care for patients treated with 131I-MIBG.

Demystifying the CT Radiation Dose Sheet.

The radiation dose sheet generated by the CT scanner is a form that displays important information about an examination. It functions as a road map for the examination, detailing what CT examinations were performed and what parameters were used to perform them. One essential element of the radiation dose sheet, the volume CT dose index (CTDIvol), is a commonly used radiation dose index that is displayed on most CT scanners. The CTDIvol is used for quality control and is helpful for comparing the radiation output among different protocols and different scanners. The dose-length product (DLP) is a radiation dose index that builds on the CTDIvol by incorporation of the scan length. The DLP is combined with a conversion coefficient and used to determine the effective dose from the CT examination. Determining the effective dose is a way to estimate the whole-body radiation dose, even if the CT examination is confined to a smaller part of the body. In addition to these values, other data about the study from the CT scanner manufacturer, including the tube voltage and tube current-time product, usually are displayed on CT scanners. These values are major determinants of the image quality and radiation dose. The radiation dose sheet is a useful tool for radiologists, technologists, and physicists, allowing them to comprehend the technical details of a CT examination. The authors describe the components of the radiation dose sheet, the relationships of these components with one another, and the contributions of these components to the radiation dose. ©RSNA, 2022.

Staff eye lens dose in interventional radiology and cardiology in Finland

PurposeThe aim of this study was to investigate the eye lens and whole-body radiation doses to interventional radiology and cardiology staff in two Finnish hospitals. MethodsSimultaneous measurements of personal dose equivalent quantities Hp(3) and Hp(10) were conducted in clinical conditions during different radiological and cardiological interventional procedures. In order to study the feasibility to estimate eye lens dose with Hp(10) measured over the protective apron or thyroid shield, the ratio between measured Hp(3) and Hp(10) was investigated. Results and conclusionsApplying the obtained ratio on Hp(10) records from national dose register showed that only a small number of interventional radiologists and cardiologists in Finland may exceed eye lens equivalent dose levels of 20 mSv per year or 100 mSv in five consecutive years, but likely do not exceed 50 mSv in a single year. For the most Finnish interventionalists, the eye lens dose is well below 10 mSv per year. Nurses and radiographers assisting in interventions are, on average, less exposed than interventionalists, and will not exceed 20 mSv per year. Based on our results, Hp(10) measured over the protective apron or thyroid shield provides a conservative estimate of the eye lens dose for interventional radiologists and cardiologists, provided that appropriate protective glasses are used.

KR-31831 improves survival and protects hematopoietic cells and radiosensitive tissues against radiation-induced injuries in mice

This study explored the radioprotective effects and possible underlying mechanisms of KR-31831 against radiation-induced injury in a mouse model. KR-31831 (30 and 50 mg/kg) was administered to mice 24 h and 30 min before exposure to a single lethal or sublethal dose of whole-body irradiation (WBI) (7 or 4 Gy, respectively). These animals were then evaluated for changes in mortality, various hematological and biochemical parameters, and histological features in response to these treatments. In addition, RNA sequencing was used to profile the radiation-induced transcriptomic response in the bone marrow cells. The results showed that KR-31831 dose-dependently prolonged the 30-day survival period and prevented damage to radiation-sensitive organs, such as the intestine and testis, in response to WBI. Damage to the hematopoietic system was also notably improved in the KR-31831-treated mice, as evidenced by an increase in bone marrow and peripheral blood cells, as well as recovery of the histopathological characteristics of the bone marrow. These protective effects were achieved, at least in part, via the suppression of radiation-induced increases in apoptotic cell death and erythropoietin levels in the plasma. Furthermore, the gene expression profiles of the bone marrow cells of the WBI-treated mice suggested that KR-31831 upregulates the expression of the genes involved in regulating apoptosis and modulating the immune response, both of which are required for protecting the bone marrow. These results suggest the potential therapeutic efficacy of KR-31831 for protection against radiation-induced injury.

First in Human Evaluation and Dosimetry Calculations for Peptide 124I-p5+14-a Novel Radiotracer for the Detection of Systemic Amyloidosis Using PET/CT Imaging.

Accurate diagnosis of amyloidosis remains a significant clinical challenge and unmet need for patients. The amyloid-reactive peptide p5+14 radiolabeled with iodine-124 has been developed for the detection of amyloid by PET/CT imaging. In a first-in-human evaluation, the dosimetry and tissue distribution of 124I-p5+14 peptide in patients with systemic amyloidosis. Herein, we report the dosimetry and dynamic distribution in the first three enrolled patients with light chain-associated (AL) amyloidosis. The radiotracer was assessed in a single-site, open-label phase 1 study (NCT03678259). The first three patients received a single intravenous infusion of 124I-p5+14 peptide (≤37 MBq). Serial PET/CT imaging was performed during the 48 h post-infusion. Dosimetry was determined as a primary endpoint for each patient and gender-averaged mean values were calculated. Pharmacokinetic parameters were estimated from whole blood radioactivity measurements and organ-based time activity data. Lastly, the biodistribution of radiotracer in major organs was assessed visually and compared to clinically appreciated organ involvement. Infusion of the 124I-p5+14 was well tolerated with rapid uptake in the heart, kidneys, liver, spleen, pancreas, and lung. The gender-averaged whole-body effective radiation dose was estimated to be 0.23 (± 0.02) mSv/MBq with elimination of the radioactivity via renal and gastrointestinal routes. The whole blood elimination t1/2 of 21.9 ± 7.6 h. Organ-based activity concentration measurements indicated that AUClast tissue:blood ratios generally correlated with the anticipated presence of amyloid. Peptide uptake was observed in 4/5 clinically suspected organs, as noted in the medical record, as well as six anatomic sites generally associated with amyloidosis in this population. Peptide 124I-p5+14 rapidly distributes to anatomic sites consistent with the presence of amyloid in patients with systemic AL. The dosimetry estimates established in this cohort are acceptable for whole-body PET/CT imaging. Pharmacokinetic parameters are heterogeneous and consistent with uptake of the tracer in an amyloid compartment. PET/CT imaging of 124I-p5+14 may facilitate non-invasive detection of amyloid in multiple organ systems.