ICRP publication 118: ICRP statement on tissue reactions and early and late effects of radiation in normal tissues and organs--threshold doses for tissue reactions in a radiation protection context

Exceeding radiation thresholds for cataract induction in diagnostic imaging: a paediatric case report

This case report investigates the radiation dose received by a paediatric patient with a ventricular assist device who underwent four non-contrast brain computed tomography (CT) scans, two brain perfusion CT scans and two head angiographic CT scans. The total estimated absorbed dose to the lens of the eye is above the 500 mGy radiation-induced cataract threshold. It is recommended that this patient and those with similar imaging histories have routine follow-up with an ophthalmologist. It is also recommended that radiation dose tracking and an electronic medical alert program be implemented to allow the identification of patients who may exceed tissue reaction thresholds.

[The Need for Lens Radiation Protection for Healthcare Provider in Open and Internal Fixation of the Hip Joint]

Increased occupational exposure of radiation workers is a major problem during open reduction and internal fixation (ORIF) of the hip joint, as the surgeon's eye lens is in close proximity to the patient and the X-ray tube. The purposes of this study were to clarify the occupational exposure of radiation workers during ORIF of the hip joint and to examine the need for radiation protection measures. The radiation exposure of radiation workers was evaluated by making an airborne dose distribution map using phantom experiments. The radiation goggles attached with a small optically stimulated luminescence dosimeter were used in clinical practice to measure the lens dose received by the surgeon, and the necessity of radiation goggles was examined. The airborne dose distribution in ORIF of the hip joint showed a wider area of high dose rate during axial fluoroscopy of the femoral neck than during posterior-anterior fluoroscopy. In axial fluoroscopy of the femoral neck, the surgeon was always in the high dose rate range of 10 µGy/min or higher, the nurses were in the dose rate range of 4 to 10 µGy/min, and the radiologic technologists were in the dose rate range of 0.5 µGy/min or lower. The maximum 3 mm dose equivalent to the surgeon per case was 0.38 mSv. In contradiction, radiation goggles were useful in ORIF because they provided approximately 60% shielding. It is advisable to work with radiation goggles to avoid cataracts.

Trends in the use of radiation protection and radiation exposure of European endourologists: a prospective trial from the EULIS-YAU Endourology Group

INTRODUCTION

Due to the radiation exposure for the urology staff during endourology, our aim was to evaluate the trends of radiation protection in the operation room by endourologists from European centers and to estimate their annual radiation.

METHODS

We conducted a multicenter study involving experienced endourologists from different European centers to evaluate whether the protection and threshold doses recommended by the International Commission on Radiation Protection (ICRP) were being followed. A 36-question survey was completed on the use of fluoroscopy and radiation protection. Annual prospective data from chest, extremities, and eye dosimeters were collected during a 4-year period (2017-2020).

RESULTS

Ten endourologists participated. Most surgeons use lead aprons and thyroid shield (9/10 and 10/10), while leaded gloves and caps are rarely used (2/10 both). Six out of ten surgeons wear leaded glasses. There is widespread use of personal chest dosimeters under the apron (9/10), and only 5/10 use a wrist or ring dosimeter and 4 use an eye dosimeter. Two endourologists use the ALARA protocol. The use of ultrasound and fluoroscopy during PCNL puncture was reported by 8 surgeons. The mean number of PCNL and URS per year was 30.9 (SD 19.9) and 147 (SD 151.9). The mean chest radiation was 1.35 mSv per year and 0.007 mSv per procedure. Mean radiation exposure per year in the eyes and extremities was 1.63 and 11.5 mSv.

CONCLUSIONS

Endourologists did not exceed the threshold doses for radiation exposure to the chest, extremities and lens. Furthermore, the ALARA protocol manages to reduce radiation exposure.

Senescent fibroblast facilitates re-epithelization and collagen deposition in radiation-induced skin injury through IL-33-mediated macrophage polarization

BACKGROUND

The need for radiotherapy among the elderly rises with increasing life expectancy and a corresponding increase of elderly cancer patients. Radiation-induced skin injury is one of the most frequent adverse effects in radiotherapy patients, severely limiting their life quality. Re-epithelialization and collagen deposition have essential roles in the recovery of skin injuries induced by high doses of ionizing radiation. At the same time, radiation-induced senescent cells accumulate in irradiated tissues. However, the effects and mechanisms of senescent cells on re-epithelialization and collagen deposition in radiation-induced skin injury have not been fully elucidated.

RESULTS

Here, we identified a role for a population of senescent cells expressing p16 in promoting re-epithelialization and collagen deposition in radiation-induced skin injury. Targeted ablation of p16+ senescent cells or treatment with Senolytics resulted in the disruption of collagen structure and the retardation of epidermal coverage. By analyzing a publicly available single-cell sequencing dataset, we identified fibroblasts as a major contributor to the promotion of re-epithelialization and collagen deposition in senescent cells. Notably, our analysis of publicly available transcriptome sequencing data highlighted IL-33 as a key senescence-associated secretory phenotype produced by senescent fibroblasts. Neutralizing IL-33 significantly impedes the healing process. Finally, we found that the effect of IL-33 was partly due to the modulation of macrophage polarization.

CONCLUSIONS

In conclusion, our data suggested that senescent fibroblasts accumulated in radiation-induced skin injury sites participated in wound healing mainly by secreting IL-33. This secretion regulated the local immune microenvironment and macrophage polarization, thus emphasizing the importance of precise regulation of senescent cells in a phased manner.

Evaluation of novel radiation protection devices during radiologically guided interventions

BACKGROUND

In radiologically guided interventions, medical practitioners are subjected to radiation exposure, which may lead to radiation-induced diseases. In this study, novel radiation shields for the head and neck were evaluated for their potential to reduce radiation exposure.

METHOD

An anthropomorphic phantom was exposed on its left side to scattered radiation from beneath to simulate the exposure of an operator in a x-ray operating room. Thermoluminescent dosimeters (TLDs) were positioned at different depths in five slices in the phantom, measuring personal dose equivalent. Two different set up situations were evaluated: a head protector designed to reduce radiation in the upper section of the head; and a novel thyroid protector prototype extended in the front and on both sides, designed to reduce radiation in the lower and middle sections of the head. A standard thyroid collar prototype and a ceiling mounted lead glass shield were used as comparisons. Furthermore, the head protector was evaluated in a clinical study in which TLDs were positioned to measure scattered radiation exposure to the heads of operators during endovascular interventions.

RESULTS

The extended thyroid protector reduced the scattered radiation in the throat, chin, and ear slices. Some shielding effect was seen in the brain and skull slices. The head protector showed a shielding effect in the skull slice up to two cm depth where it covered the phantom head. As expected, the ceiling mounted lead glass shield reduced the scattered radiation in all measuring points.

CONCLUSIONS

A ceiling mounted lead glass shield is an effective radiation protection for the head, but in clinical practice, optimal positioning of a ceiling mounted lead shield may not always be possible, particularly during complex cases when radiation protection may be most relevant. Added protection using these novel guards may compliment the shielding effect of the ceiling mounted lead shield. The head protector stand-alone did not provide sufficient protection of the head. The extended thyroid protector stand-alone provided sufficient protection in the lower and middle sections of the head and neck.

Background Factors Affecting the Radiation Exposure of the Lens of the Eye among Nurses in Interventional Radiology: A Quantitative Observational Study

With the International Commission on Radiological Protection's (ICRP) reduction in the radiation dose threshold for cataracts, evaluating and preventing radiation exposure to the lens of the eye among interventional radiology (IR) staff have become urgent tasks. In this study, we focused on differences in lens-equivalent dose (HT Lens) to which IR nurses in three hospitals were exposed and aimed to identify factors underlying these differences. According to analyses of time-, distance-, and shielding-related factors, the magnitude of the HT Lens dose to which IR nurses were exposed could be explained not by time or shielding but by the distance between the X-ray exposure field and the location of the IR nurse. This distance tended to be shorter in hospitals with fewer staff. The most effective means of reducing the exposure of the lenses of IR nurses' eyes to radiation is to position them at least two meters from the radiation source during angiography procedures. However, some hospitals must provide IR departments with comparatively few staff. In work environments where it is infeasible to reduce exposure by increasing distance, interventions to reduce time by managing working practices and investment in shielding equipment are also important. This study was not registered.

Performance of elastic x-ray shield made by embedding Bi2 O3 particles in porous polyurethane

BACKGROUND

Many healthcare institutions have guidelines concerning the usage of protective procedures, and various x-ray shields have been used to reduce unwanted radiation exposure to medical staff and patients when using x-rays. Most x-ray shields are in the form of sheets and lack elasticity, which limits their effectiveness in shielding areas with movement, such as the thyroid. To overcome this limitation, we have developed an innovative elastic x-ray shield.

PURPOSE

The purpose of this study is to explain the methodology for developing and evaluating a novel elastic x-ray shield with sufficient x-ray shielding ability. Furthermore, valuable knowledge and evaluation indices are derived to assess our shield's performance.

METHODS

Our x-ray shield was developed through a process of embedding Bi2 O3 particles into porous polyurethane. Porous polyurethane with a thickness of 10 mm was dipped into a solution of water, metal particles, and chemical agents. Then, it was air-dried to fix the metal particles in the porous polyurethane. Thirteen investigational x-ray shields were fabricated, in which Bi2 O3 particles at various mass thicknesses (ranging from 585 to 2493 g/m2 ) were embedded. To determine the performance of the shielding material, three criteria were evaluated: (1) Dose Reduction Factor (D R F $DRF$ ), measured using inverse broad beam geometry; (2) uniformity, evaluated from the standard deviation (S D $SD$ ) of the x-ray image obtained using a clinical x-ray imaging detector; and (3) elasticity, evaluated by a compression test.

RESULTS

The elastic shield with small pores, containing 1200 g/m2 of the metal element (Bi), exhibited a well-balanced performance. TheD R F $DRF$ was approximately 80% for 70 kV diagnostic x-rays. This shield's elasticity was -0.62 N/mm, a loss of only 30% when compared to porous polyurethane without metal. Although the non-uniformity of the x-ray shield leads to poor shielding ability, it was found that the decrease in the shielding ability can be limited to a maximum of 6% when the shield is manufactured so that theS D $SD$ of the x-ray image of the shield is less than 10%.

CONCLUSIONS

It was verified that an elastic x-ray shield that offers an appropriate reduction in radiation exposure can be produced by embedding Bi2 O3 particles into porous polyurethane. Our findings can lead to the development of novel x-ray shielding products that can reduce the physical and mental stress on users.

Space agency-specific standards for crew dose and risk assessment of ionising radiation exposures for the International Space Station

The Partner Agencies of the International Space Station (ISS) maintain separate career exposure limits and shared Flight Rules that control the ionising radiation exposures that crewmembers can experience due to ambient environments throughout their space missions. In low Earth orbit as well as further out in space, energetic ions referred to as galactic cosmic radiation (GCR) easily penetrate spacecraft and spacecraft contents and consequently are always present at low dose rates. Protons and electrons that are trapped in the Earth's geomagnetic field are encountered intermittently, and a rare energetic solar particle event (SPE) may expose crew to (mostly) energetic protons. Space radiation protection goals are to optimize radiation exposures to maintain deleterious late effects at known and acceptable levels and to prevent any early effects that might compromise crew health and mission success. The conventional radiation protection metric effective dose provides a basic framework for limiting exposures associated with human spaceflight and can be communicated to all stakeholders. Additional metrics and uncertainty analyses are required to understand more completely and to convey nuanced information about potential impacts to an individual astronaut or to a space mission. Missions to remote destinations well beyond low Earth orbit (BLEO) are upcoming and bestow additional challenges that shape design and radiation protection needs. NASA has recently adopted a more permissive career exposure limit based upon effective dose and new restrictions on mission exposures imposed by nuclear technologies. This manuscript reviews the exposure limits that apply to the ISS crewmembers. This work was performed in collaboration with the advisory and guidance efforts of International Commission on Radiological Protection (ICRP) Task Group 115 and will be summarized in an upcoming ICRP Report.

Radiation Overuse in Intensive Care Units

Radiological imaging is essential for acute patient management in Intensive Care Units (ICUs); however, it introduces the risk of exposure to ionizing radiation. This review synthesizes research on radiation exposure in ICU settings, highlighting its rise during the COVID-19 pandemic and the rise in repetitive imaging. Our analysis extends to radiation safety thresholds, revealing that some ICU patients exceed the diagnostic reference level, emphasizing the need to balance diagnostic utility against potential long-term risks, such as cancer. Prospective studies have demonstrated an increase in the median cumulative effective dose in patients with trauma over time, prompting calls for improved awareness and monitoring. Moreover, innovative dose-reduction strategies and optimized protocols, especially in neuro-ICUs, promise to mitigate these risks. This review highlights the essential but risky role of radiological imaging in critical care. It advocates for rigorous radiation management protocols to safeguard patient health while ensuring the continuity of high-quality medical care.

Cineangiography versus standard digital subtraction angiography in mechanical thrombectomy: lowering the radiation exposure without sacrificing the outcome

BACKGROUND

Endovascular thrombectomy has become a standard procedure for the treatment of acute ischemic stroke caused by large vessel occlusion. Radiation exposure to the patient and operators during mechanical thrombectomy procedures is a concern.

METHODS

The use of a high frames per second unmasked protocol-cineangiography (CINE)-derived from cardiac intervention could mitigate radiation exposure without sacrificing procedural and clinical outcomes.

RESULTS

The analysis of a prospective-maintained monocentric database of 131 patients who underwent mechanical thrombectomy (65 with the CINE protocol and 66 with the conventional digital subtraction angiography (DSA) protocol) showed a significant reduction in radiation exposure for both air kerma (AK) and dose-area product (DAP) indicators (AK 463.7 mGy vs 772 mGy, P<0.01; DAP 41.35 Gy/cm2 CINE vs 83.77 Gy/cm2 DSA, P<0.01), with no differences regarding both safety and efficacy outcomes (modified Thrombolysis In Cerebral Infarction (mTICI) ≥2b 78.4% CINE and 81.5% DSA, P=0.79; overall complications rate both intracranial and extracranial 23% CINE and 19.6% DSA, P=0.65). There were no significant differences in post-thrombectomy radiographic hemorrhagic conversion rate (P=0.77) or functional independence on discharge defined as modified Rankin Scale score ≤2 (P=0.39). A post-hoc image assessment of vessel point occlusion and recanalization mTICI score performed by three experienced interventional neuroradiologists not involved in the procedure showed a non-significant difference between the two groups regarding occlusion point (0.928 vs 0.953, P=0.31) and recanalization grade (0.814 vs 0.847, P=0.62).

CONCLUSIONS

Our initial experience demonstrated that reduction of the quality of CINE images caused no modifications in safety and efficacy and should fit within the context of diagnostic requests in an intracranial revascularization procedure.

Sclerotherapy with intralesional bleomycin injection under guidance of multi-slice CT for retrobulbar orbital low-flow vascular lesions-single-center experience

OBJECTIVE

This study investigated the safety and efficacy of sclerotherapy with intralesional bleomycin injection (IBI) for retrobulbar orbital low-flow vascular lesions under multi-slice computed tomography (CT) guidance.

METHODS

Between January 2010 and September 2021, consecutive patients with retrobulbar orbital low-flow vascular lesions who underwent CT-guided IBI at a tertiary centre in Taiwan were enrolled. Their medical records and imaging data were retrospectively collected.

RESULTS

This study enrolled 13 patients (7 male and 6 female patients; age range: 1-57 years; mean age: 25.9 years) with lymphatic malformation (LM, n = 4), venolymphatic malformation (n = 1), and venous malformation (VM, n = 8). The overall radiological response rate was 76.9% (10 of 13); the radiological response rate was 75.0% in the VM group (6 of 8) and 75.0% in the LM group (3 of 4). Moreover, 3 patients (23.1%) had minor complications and 1 (7.7%) had a major complication. The mean clinical and radiological follow-up was 8.3 months and no recurrence or progression was reported.

CONCLUSION

CT-guided IBI is an effective and relatively safe minimally invasive treatment for retrobulbar orbital low-flow vascular lesions, with an overall radiological response rate of 76.9% in a mean of 1.5 sessions and a low complication rate.

ADVANCES IN KNOWLEDGE

CT-guided sclerotherapy with IBI is a relatively safe, effective, and feasible alternative treatment option for retrobulbar orbital low-flow vascular lesions.

[Fatal radiation-induced injury resulting from the deliberate use of ionizing radiation source for illegal purposes]

A rare clinical observation of death from prolonged uneven external irradiation due to the deliberate use of an ionizing radiation source for illegal purposes has been presented. The main difficulties of postmortem diagnosis of this type of radiation-induced injury, considering the features of histological examinations and special methods of retrospective dosimetric evaluations, have been identified.

Multiple exposures to low-dose ionizing radiation induced the initiation and progression of pro-atherosclerotic phenotypes in mice and vascular endothelial cell damage

OBJECTIVE

This study aimed to investigate the effects of low-dose radiation on the abdominal aorta of mice and vascular endothelial cells.

METHODS

Wild-type and tumor-bearing mice were exposed to 15 sessions of low-dose irradiation, resulting in cumulative radiation doses of 187.5, 375, and 750 mGy. The effect on the cardiovascular system was assessed. Immunohistochemistry analyzed protein expressions of PAPP-A, CD62, P65, and COX-2 in the abdominal aorta. Microarray technology, Gene Ontology analysis, and pathway enrichment analysis evaluated gene expression changes in endothelial cells exposed to 375 mGy X-ray. Cell viability was assessed using the Cell Counting Kit 8 assay. Immunofluorescence staining measured γ-H2AX levels, and real-time polymerase chain reaction quantified mRNA levels of interleukin-6 (IL-6), ICAM-1, and Cx43.

RESULTS

Hematoxylin and eosin staining revealed thickening of the inner membranes and irregular arrangement of smooth muscle cells in the media membrane at 375 and 750 mGy. Inflammation was observed in the inner membranes at 750 mGy, with a clear inflammatory response in the hearts of tumor-bearing mice. Immunohistochemistry indicated increased levels of PAPP-A, P65, and COX-2 post-irradiation. Microarray analysis showed 425 up-regulated and 235 down-regulated genes, associated with processes like endothelial cell-cell adhesion, IL-6, and NF-κB signaling. Cell Counting Kit 8 assay results indicated inhibited viability at 750 mGy in EA.hy926 cells. Immunofluorescence staining demonstrated a dose-dependent increase in γ-H2AX foci. Reverse transcription quantitative PCR results showed increased expression of IL6, ICAM-1, and Cx43 in EA.hy926 cells post 750 mGy X-ray exposure.

CONCLUSION

Repeated low-dose ionizing radiation exposures triggered the development of pro-atherosclerotic phenotypes in mice and damage to vascular endothelial cells.

Assessment of Cataract Risk after Diagnostic Head CT Scan Radiation Exposure in Ontario, Canada

Ionizing radiation is one of the known risk factors for cataract development, however, there is still debate regarding the level of risk after low dose exposures. One of the largest sources of radiation exposure to the lens of the eye is diagnostic CT scans. The aim of this study was to examine whether ionizing radiation associated with head CT scans increases cataract risk in residents of Ontario, Canada. Data were collected from January 1, 1994 to December 31, 2015 (22 years) from anonymized Ontario Health Insurance Plan (OHIP) medical records for over 16 million subjects. A lens dose was estimated for each CT scan using the National Cancer Institute dosimetry system for CT (NCICT) program combined with Canada-specific CTDIvol data. Multivariate Cox proportional hazards analysis was performed with cataract extraction surgery as the primary outcome and lens dose as the main variable of interest, with inclusion of various medical and demographic covariates. Lag periods of 3, 5 and 7 years were incorporated. When lens dose was treated as a continuous variable, hazard ratios (per 100 mGy) ranged from 0.82 (0.80-0.84) to 1.10 (1.09-1.11) depending on the lag period. As a secondary analysis, when individuals were binned based on their total cumulative dose, no significant dose response pattern was observed in the low dose region. Overall, within the bounds of this study, the data do not support an increased risk of vision impairing cataracts after diagnostic head CT scan radiation exposure.

90Y Contamination in the Interventional Radiology Suite: VARSKIN Estimation of Skin and Eye Injury and Review of Mitigation Strategies

Our objective was to demonstrate, through computer simulations, radiation exposure levels from a 90Y contamination event during radioembolization procedures to calculate the radiation doses from various contamination scenarios. We also provide reasonable safety protocols to prevent contamination and minimize radiation exposure during decontamination. Methods: Simulations were performed using the computer code VARSKIN+, version 1.0, to determine the amount of radiation exposure resulting from different contamination scenarios. Results: The annual radiation dose limit to the skin and the lens of the eye was exceeded within 23 s of exposure to a 44-MBq droplet. Double layers of surgical gloves and level 3 gowns provided some attenuation of radiation from 90Y contamination by reducing the dose rate by 39% and 44%, respectively. Two layers of surgical gloves offered the best ratio of radiation protection without compromising dexterity. Conclusion: This study demonstrated that radiation exposures during 90Y spills or contamination events can be considerable. Interventional radiology and nuclear medicine personnel must be mindful of the risks, follow strategies to prevent spills, and be familiar with recommended decontamination procedures for spills in the interventional radiology suite.

The protective effect of crocin against testicular toxicity induced by ionizing radiation via AKT/FOXO pathway

Crocin, a pharmacologically active component of Crocus sativus L. (saffron), has been informed to be beneficial in the treatment of stress-related oxidative impairment. In the present study, we examined the protective role of crocin against testicular damage induced by radiation (acute and fractionated) and the alteration of the AKT/FOXO signaling pathway. Male Wister albino rats were exposed to acute dose of 6 Gy and a fractionated dose of gamma radiation (2 Gy every 2 days up to 6 Gy total doses). Rats were pretreated intraperitoneally with crocin in a dose of 50 mg/kg for seven consecutive days prior to exposure to irradiation at a level of 6 Gy and during the fractionated irradiation of rats. Control groups were run concurrently. Ionizing radiation caused changes in the level of oxidative stress biomarkers manifested as elevation of thiobarbituric acid reactive substance, total nitrate/nitrite and reactive oxygen species (ROS) associated with a decrease in catalase as well as in the level of inflammatory parameters (decrease in expression of Nrf2 which was related to a significant increase in expression of NF-κB p65). Irradiation produced cellular damage characterized by an increase in serum lactate dehydrogenase. These findings were aligned with increased expression of the forkhead box O-1 (FOXO-1) and activation of protein kinase B (AKT) pathway. Irradiation of rats led to reduction in serum testosterone level and testicular weights. Pretreatment with the indicated dose of crocin shielded against the changes in all the evaluated parameters. Administration of crocin can be introduced as a novel preclinical approach for regulation of testicular damage induced by radiation; via controlling the ongoing oxidative stress and inflammatory reaction as well as activation FOXO/AKT signaling pathway.

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

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

Radiological protection in human research ethics using a case study: toward update of the ICRP Publication 62

The benefits of biomedical research involving humans are well recognised, along with the need for conformity to international standards of science and ethics. When human research involves radiation imaging procedures or radiotherapy, an extra level of expert review should be provided from the point of view of radiological protection. The relevant publication of the International Commission for Radiological Protection (ICRP) is now three decades old and is currently undergoing an update. This paper aims to provoke discussions on how the risks of radiation dose and the benefits of research should be assessed, using a case study of diagnostic radiology involving volunteers for whom there is no direct benefit. Further, the paper provides the current understanding of key concepts being considered for review and revision-such as the dose constraint and the novel research methods on the horizon, including radiation biology and epidemiology. The analysis revisits the perspectives described in the ICRP Publication 62, and considers the recent progress in both radiological protection ethics and medical research ethics.

A Phase 1, Open-label, Dose-Ascending Study to Evaluate the Safety and Tolerability of the Therapeutic Radiopharmaceutical 131I-MIP-1095 for the Treatment of Metastatic Castration-Resistant Prostate Cancer

PURPOSE

131I-MIP-1095 is a targeted radiotherapeutic that contains 131I, a β-particle emitter, and MIP-1095, a urea-based ligand for prostate-specific membrane antigen. We report the first phase 1, dose-escalation study of 131I-MIP-1095 in patients with metastatic castration-resistant prostate cancer (mCRPC).

METHODS

This study enrolled men with mCRPC refractory to second-generation antiandrogen(s) and taxane chemotherapy. Dosimetry/biodistribution assessments were performed. Safety and tolerability were determined in subjects who qualified for therapeutic administration of 131I-MIP-1095 with maximum tolerated activity examined in a dose-ascending manner (3 + 3 design methodology). Disease outcomes including prostate-specific antigen (PSA) change, tumor response, survival, and circulating tumor cell concentration were assessed.

RESULTS

A total of 9 subjects with mCRPC were included in this study. On the basis of dosimetry results, 5 of 9 patients were treated: 3 in cohort 1 (50 mCi) and 2 in cohort 2 (75 mCi). Accrual stopped at the cohort 2 activity level in response to the US Food and Drug Administration mandate for 131I-MIP-1095 manufacturing concerns. Parotid/salivary glands (3.5 Gy/Bq), liver (2.2 Gy/Bq), kidneys (1.3 Gy/Bq), and spleen (0.7 Gy/Bq) demonstrated the greatest extent of 131I-MIP-1095 exposure. There were no deaths, serious adverse events, or drug discontinuations due to treatment-emergent adverse events. Grade 1-2 thrombocytopenia, anemia, leukopenia, and dry mouth most commonly occurred. One subject (33.3%) exhibited maximum decline for the PSA response of 50% or greater.

CONCLUSION

131I-MIP-1095 demonstrated favorable dosimetry, biodistribution, and safety, as well as a modest PSA response supporting further investigation for treatment of men with mCRPC.Clinical Trial Registration: ClinicalTrials.gov identifier: NCT03030885, Registered January 25, 2017 (https://clinicaltrials.gov/ct2/show/NCT03030885).

Prediction of Response to 177Lu-PSMA Therapy Based on Tumor-to-Kidney Ratio on Pretherapeutic PSMA PET/CT and Posttherapeutic Tumor-Dose Evaluation in mCRPC

The aim of this study was to analyze the absorbed dose of 177Lu-PSMA in osseous versus lymphatic metastases in patients with metastatic castration-resistant prostate cancer across therapy cycles and to relate those data to therapeutic success. In addition, pretherapeutic prostate-specific membrane antigen (PSMA) PET/CT was evaluated for its ability to predict response behavior. Methods: The study comprised 30 patients with metastatic castration-resistant prostate cancer, each receiving at least 3 cycles of 177Lu-PSMA therapy. Prostate-specific antigen (PSA) values between baseline and 6 wk after the third therapy cycle were used to classify the patients as responders (PSA decline ≥ 50%) or nonresponders (unchanged or increasing PSA level). Quantitative SPECT/CT images were acquired 24, 48, and 168 h after application of 177Lu-PSMA. The absorbed dose for tumor lesions was calculated with dosimetry software. From the pretherapeutic PET/CT scan, the tumor-to-kidney uptake ratio was determined for different SUVs. Results: Regardless of patient response, the kidneys received a mean dose of 0.55 ± 0.20 Gy/GBq per cycle. In the first therapy cycle, the lymph node lesions received a mean dose of 3.73 ± 1.65 Gy/GBq in responders and 1.86 ± 1.25 Gy/GBq in nonresponders (P < 0.01). For bone lesions, the respective mean doses were 3.47 ± 2.00 Gy/GBq and 1.48 ± 0.95 Gy/GBq (P < 0.01). When successive therapy cycles were compared, the mean dose was found to have been reduced from the first to the second cycle by 27% for lymph nodes and by 33% for bone lesions. A significant difference (P < 0.01) in the ratio of lymph node and bone lesion uptake to kidney uptake between responders and nonresponders could be deduced from the pretherapeutic PET/CT scan. Conclusion: Significantly higher doses were achieved for lymph node and bone lesions in responders. The highest absorbed dose, for both lymphatic and osseous lesions, was achieved in the first cycle, decreasing in the second therapy cycle thereafter despite unchanged therapy activities. It may be possible to estimate the response to therapy from the ratio of tumor uptake to kidney uptake obtained from the pretherapeutic PSMA PET/CT scans.

Safety of fluoroless radiofrequency catheter ablation for atrial fibrillation in patients with pre-existing cardiac implantable electronic device: A single-center study

BACKGROUND

Radiofrequency catheter ablation (RFA) for atrial fibrillation (AF) is being increasingly performed without fluoroscopy. This study aims to determine the safety of fluoroless RFA for patients with pre-existing cardiac implantable electronic devices (CIED).

METHODS

This is a single-center, single-operator, retrospective, observational study of 225 consecutive fluoroless RFA procedures for AF from June 1, 2019 to June 1, 2022. All procedures were performed with intracardiac echocardiography (ICE) support. Patients with pre-existing CIED were extracted from the database. Each CIED was interrogated at the start and end of each procedure and at 30-day follow-up. Pre- and post-procedure CIED interrogations were compared for any change in device or lead parameters. Patients were tracked for any subsequent device malfunction.

RESULTS

Out of 225 fluoroless AF ablations, 25 (10.2%) had pre-existing CIED (14 dual-chamber pacemakers, three dual-chamber defibrillators, three single-chamber defibrillators, one single chamber pacemaker, and four biventricular devices). Mean patient age was 71 ± 6 years. The mean duration of indwelling CIED was 1804 ± 1645 days (range: 78-6267 days). One (4%) patient had lead-related fibrin on ICE imaging. There was no significant difference in lead(s) threshold, impedance, or sensing post procedure or at 30-day follow-up compared to pre procedure. None of the patients required lead revision. There were no intra- or post-op thromboembolic events or subsequent device infection. One patient underwent CIED extraction after 11 months for an unrelated secondary device infection.

CONCLUSIONS

Radiofrequency catheter ablation for AF can be safely performed without fluoroscopy in patients with pre-existing CIED.

Humanized Mice as a Model to Assess the Response of Human Hematopoietic Stem Cells to Irradiation

NOD SCID mice were humanized by transplanting human hematopoietic cells isolated from umbilical cord blood. A dose-dependent death of hematopoietic cells and their subsequent recovery were shown after acute external γ-irradiation in the model of humanized mice. The proposed approach can be used for preclinical studies of radioprotective agents and for assessment of the impact of adverse factors on the survival rate and functional properties of human hematopoietic stem cells in vivo.

Acral cutaneous malignant melanoma treated with linear accelerator-based boron neutron capture therapy system: a case report of first patient

This study reports the first patient treatment for cutaneous malignant melanoma using a linear accelerator-based boron neutron capture therapy (BNCT) system. A single-center open-label phase I clinical trial had been conducted using the system since November 2019. A patient with a localized node-negative acral malignant melanoma and the largest diameter of the tumor ≤ 15 cm who refused primary surgery and chemotherapy was enrolled. After administering boronophenylalanine (BPA), a single treatment of BNCT with the maximum dose of 18 Gy-Eq delivered to the skin was performed. The safety and efficacy of the accelerator-based BNCT system for treating localized cutaneous malignant melanoma were evaluated. The first patient with cutaneous malignant melanoma in situ on the second finger of the left hand did not develop dose-limiting toxicity in the clinical trial. After BNCT, the treatment efficacy was gradually observed, and the patient achieved PR within 6 months and CR within 12 months. Moreover, during the follow-up period of 12 months after BNCT, the patient did not exhibit a recurrence without any treatment-related grade 2 or higher adverse events. Although grade 1 adverse events of dermatitis, dry skin, skin hyperpigmentation, edema, nausea, and aching pain were noted in the patient, those adverse events were relieved without any treatment. This case report shows that the accelerator-based BNCT may become a promising treatment modality for cutaneous malignant melanoma. We expect further clinical trials to reveal the efficacy and safety of the accelerator-based BNCT for cutaneous malignant melanoma.

Dose-Dependent Testicular Injury and Recovery after Total-Body Irradiation in Rhesus Monkeys

Testicular injury is a well-documented acute effect of radiation exposure, though little is known about recovery years after irradiation, especially at higher doses. We examined the testes from 143 irradiated and control male rhesus monkeys, who were part of the Radiation Late Effects Cohort over a four-year period. Irradiated animals were exposed to doses ranging from 3.5 to 8.5 Gy of total-body irradiation. The testes were assessed using computed tomography (CT) volumetry, serum testosterone, and histology for deceased members of the cohort. Irradiated animals exhibited dose-dependent testicular atrophy as well as decreased serum testosterone during the winter breeding season when compared to age-matched unirradiated controls. No significant difference in summer testosterone levels was observed. Volumetric and histologic evidence of testicular recovery was present approximately three years postirradiation for animals who received ≤8 Gy. The study demonstrates dose-dependent testicular injury after total-body irradiation and provides evidence for volumetric and spermatogonial recovery even at lethal doses of total-body irradiation in rhesus monkeys.

Decreasing Lens Irradiation on Brain Imaging: A Multi-CT Scanner Quality Improvement Project

AIMS

Cataracts, a leading global cause of blindness, are associated with ionising radiation exposure. This audit aimed to enhance lens exclusion during non-contrast head computed tomography (CT) scans at Newham University Hospital (NUH) using two CT scanners.

METHODS

A retrospective audit of non-contrast head CT scans at NUH excluded scans for trauma and imaging of orbital structures. A one-week audit in April 2023 assessed lens exclusion, compared to the Royal College of Radiologists (RCR) standards. A total of 101 consecutive scans were analysed and 63 (62%) scans were included in the final study. Thirty-eight percent of the scans were excluded according to the exclusion criteria of head, neck and facial traumas, orbital infections and papilledema. Results were presented, followed by a three-month radiographer re-education period, emphasizing gantry tilt and patient positioning. A reaudit in August 2023 evaluated outcomes. For the reaudit, 183 consecutive scans were analysed, with 131 (72%) scans included in the final study and 52 (28%) scans excluded according to the same exclusion criteria as the first audit.

RESULTS

Lens exclusion in non-contrast head CT scans improved significantly from 0/63 (0%) compliance to 19/131 (14.50%) (p=0005) compliance with the standards. Variability in radiographer practices, 'near misses' and time constraints were identified as challenges. Staff turnover impacted compliance.

CONCLUSION

This audit has shed light on a critical aspect of patient care in the field of radiology. This research underscores the importance of rigorous and standardised protocols in radiological procedures, particularly when it comes to protecting the lens of the eye. By enhancing lens exclusion during non-contrast head CT scans, we have taken a significant step in mitigating the risk associated with ionising radiation exposure. Although substantial improvements were made, achieving the RCR audit standard remained elusive. Ongoing re-education, reaudits and a multidisciplinary approach are necessary to optimise radiographer adherence and reduce ionising radiation exposure to the lens during head CT scans. This quality improvement project proves that continued emphasis on gantry tilt and patient positioning in radiographer education and training can make a significant difference in patient safety. As we move forward, let us remember that even small improvements can make a big difference in safeguarding the health and well-being of patients.

Scattered Radiation Distribution Utilizing Three Different Cone-Beam Computed Tomography Devices for Maxillofacial Diagnostics: A Research Study

This study aimed to estimate scattered radiation and its spatial distribution around three cone-beam computed tomography (CBCT) devices, in order to determine potential positions for an operator to stand if they needed to be inside the CBCT room. The following devices were tested: Morita Accuitomo (CBCT1), Newtom Giano HR (CBCT2), Newtom VGi (CBCT3). Scattered radiation measurements were performed using different kVp, mA, and Field of View (FOV) options. An anthropomorphic phantom (NATHANIA) was placed inside the X-ray gantry to simulate clinical conditions. Scattered measurements were taken with the Inovision model 451P Victoreen ionization chamber once placed at fixed distances from each irradiation isocenter, away from the primary beam. A statistically significant (p < 0.001) difference was found in the mean value of the scattered radiation estimations between the CBCT devices. Scattered radiation was reduced with a different rate for each CBCT device as distance was increased. For CBCT1 the reduction was 0.047 μGy, for CBCT2 it was 0.036 μGy, and for CBCT3 it was 0.079 μGy, for every one meter from the X-ray gantry. Therefore, at certain distances from the central X-ray, the scattered radiation was below the critical level of 1 mGy, which is defined by the radiation protection guidelines as the exposure radiation limit of the general population. Consequently, an operator could stay inside the room accompanying the patient being scanned, if necessary.

Applicability of 'Toolkit for Safety Assessment' tool to interventional radiology using probabilistic risk assessment techniques

Interventional radiology brings extensive benefits to patients. Nevertheless, certain procedures may result in high doses of radiation, leading to health risks to occupationally exposed individuals (OEIs). Therefore, a more comprehensive risk analysis is essential to ensuring safety and minimising radiation exposures for all OEIs. The Toolkit for Safety Assessment (TOKSA) tool performs risk assessments based on the concepts described in 'General Safety Requirements' Part 3 (Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards) and Part 4 (Safety Assessment for Facilities and Activities). This tool was developed based on the 'Ibero-American Forum of Radiological and Nuclear Regulatory Agencies' risk models and can promote the use of the risk assessment processes by OEIs. The aim of this study was to experimentally analyse the applicability of the TOKSA tool in interventional radiology with the use/support of probabilistic risk assessment techniques. The results were used to reduce the risks associated with a hemodynamics room in a hospital in Belo Horizonte, Brazil.

Dose Optimization Using a Deep Learning Tool in Various CT Protocols for Urolithiasis: A Physical Human Phantom Study

Background and Objectives: We attempted to determine the optimal radiation dose to maintain image quality using a deep learning application in a physical human phantom. Materials and Methods: Three 5 × 5 × 5 mm3 uric acid stones were placed in a physical human phantom in various locations. Three tube voltages (120, 100, and 80 kV) and four current-time products (100, 70, 30, and 15 mAs) were implemented in 12 scans. Each scan was reconstructed with filtered back projection (FBP), statistical iterative reconstruction (IR, iDose), and knowledge-based iterative model reconstruction (IMR). By applying deep learning to each image, we took 12 more scans. Objective image assessments were calculated using the standard deviation of the Hounsfield unit (HU). Subjective image assessments were performed by one radiologist and one urologist. Two radiologists assessed the subjective assessment and found the stone under the absence of information. We used this data to calculate the diagnostic accuracy. Results: Objective image noise was decreased after applying a deep learning tool in all images of FBP, iDose, and IMR. There was no statistical difference between iDose and deep learning-applied FBP images (10.1 ± 11.9, 9.5 ± 18.5 HU, p = 0.583, respectively). At a 100 kV-30 mAs setting, deep learning-applied FBP obtained a similar objective noise in approximately one third of the radiation doses compared to FBP. In radiation doses with settings lower than 100 kV-30 mAs, the subject image assessment (image quality, confidence level, and noise) showed deteriorated scores. Diagnostic accuracy was increased when the deep learning setting was lower than 100 kV-30 mAs, except for at 80 kV-15 mAs. Conclusions: At the setting of 100 kV-30 mAs or higher, deep learning-applied FBP did not differ in image quality compared to IR. At the setting of 100 kV-30 mAs, the radiation dose can decrease by about one third while maintaining objective noise.

The potential advantages and workflow challenges of long axial field of view PET/CT

Recently developed Long (≥100 cm) axial field of view (AFOV) PET/CT scanners are capable of producing images with higher signal-to-noise ratio, or performing faster whole-body acquisitions, or scanning with lower radiation dose to the patient, compared with conventional PET/CT scanners. These benefits, which arise due to their substantially higher, by more than an order of magnitude, geometric efficiency, have been well described in the recent literature. The introduction of Long AFOV PET/CT technology into the clinic also has important implications for the design and workflow of PET/CT facilities and their effects on radiation exposure to staff and patients. Maximising the considerable benefits of this technology requires a thorough understanding of the relationships between these factors to optimise workflows while appropriately managing radiation exposure. This article reviews current knowledge on PET/CT facility design, workflows and their effects on radiation exposure, identifies gaps in the literature and discusses the challenges that need to be considered with the introduction of Long AFOV PET/CT into the clinic.

Are Magnetic Resonance Imaging-Generated 3Dimensional Models Comparable to Computed Tomography-Generated 3Dimensional Models for Orbital Fracture Reconstruction? An In-Vitro Volumetric Analysis

BACKGROUND

Magnetic resonance imaging (MRI) is being increasingly considered as an alternative for the evaluation and reconstruction of orbital fractures. No previous research has compared the orbital volume of an MRI-imaged, three-dimensional (3D), reconstructed, and virtually restored bony orbit to the gold standard of computed tomography (CT).

PURPOSE

To measure the orbital volumes generated from MRI-based 3D models of fractured bony orbits with virtually positioned prebent fan plates in situ and compare them to the volumes of CT-based virtually reconstructed orbital models.

STUDY DESIGN

This retrospective in-vitro study used CT and MRI data from adult patients with orbital trauma assessed at the Royal Brisbane and Women's Hospital Outpatient Maxillofacial Clinic from 2011 to 2012. Only those with orbital blowout fractures were included in the study.

PREDICTOR VARIABLE

The primary predictor variable was imaging modality, with CT- and MRI-based 3D models used for plate bending and placement.

MAIN OUTCOME VARIABLE

The primary outcome variable was the orbital volume of the enclosed 3D models.

COVARIATES

Additional data collected was age, sex, and side of fractured orbit. The effect of operator variability on plate contouring and orbital volume was quantified.

ANALYSES

The Wilcoxon signed rank test was used to assess differences between orbital volumes with a significance level P < .05.

RESULTS

Of 11 eligible participants, six patients (four male and two female; mean age 31 ± 8.6 years) were enrolled. Two sets of six CT-based virtually restored orbits were smaller than the intact contralateral CT models by an average of 1.02 cm3 (95% CI -0.07 to 2.11 cm3; P = .028) and 0.99 cm3 (95% CI 0.07 to 1.91 cm3; P = .028), respectively. The average volume difference between the MRI-based virtually restored orbit and the intact contralateral MRI model was 0.97 cm3 (95% CI -1.08 to 1.94 cm3; P = .75). Imaging modality did affect orbital volume difference for 1 set of CT and MRI models (0.63 cm3; 95% CI -0.11 to 1.29 cm3; P = .046) but not the other (0.69 cm3; 95% CI -0.11 to 1.23 cm3; P = .075). Single operator variability in plate bending did not result in significant (P = .75) volume differences.

CONCLUSIONS

MRI can be used to reconstruct orbital volume with a clinically acceptable level of accuracy.

Image Quality and Radiation Dose of Conventional and Wide-Field High-Resolution Cone-Beam Computed Tomography for Cerebral Angiography: A Phantom Study

There has been an increase in the use of interventional neuroradiology procedures because of their non-invasiveness compared to surgeries and the improved image quality of fluoroscopy, digital subtraction angiography, and rotational angiography. Although cone-beam computed tomography (CBCT) images are inferior to multi-detector CT images in terms of low-contrast detectability and lower radiation doses, CBCT scans are frequently performed because of their accessibility. This study aimed to evaluate the image quality and radiation dose of two different high-resolution CBCTs (HR CBCT): conventional (C-HR CBCT) and wide-field HR CBCT (W-HR CBCT). The modulation transfer function (MTF), noise power spectrum (NPS), and contrast-to-noise ratio (CNR) were used to evaluate the image quality. On comparing the MTF of C-HR CBCT with a 256 × 256 matrix and that of W-HR CBCT with a 384 × 384 matrix, the MTF of W-HR CBCT with the 384 × 384 matrix was larger. A comparison of the NPS and CNR of C-HR CBCT with a 256 × 256 matrix and W-HR CBCT with a 384 × 384 matrix showed that both values were comparable. The reference air kerma values were equal for C-HR CBCT and W-HR CBCT; however, the value of the kerma area product was 1.44 times higher for W-HR CBCT compared to C-HR CBCT. The W-HR CBCT allowed for improved spatial resolution while maintaining the image noise and low-contrast detectability by changing the number of image matrices from 256 × 256 to 384 × 384. Our study revealed the image characteristics and radiation dose of W-HR CBCT. Given its advantages of low-contrast detectability and wide-area imaging with high spatial resolution, W-HR CBCT may be useful in interventional neuroradiology for acute ischemic stroke.

The Radiobiological Characterization of Human and Porcine Lens Cells Suggests the Importance of the ATM Kinase in Radiation-Induced Cataractogenesis

Studies about radiation-induced human cataractogenesis are generally limited by (1) the poor number of epithelial lens cell lines available (likely because of the difficulties of cell sampling and amplification) and (2) the lack of reliable biomarkers of the radiation-induced aging process. We have developed a mechanistic model of the individual response to radiation based on the nucleoshuttling of the ATM protein (RIANS). Recently, in the frame of the RIANS model, we have shown that, to respond to permanent endo- and exogenous stress, the ATM protein progressively agglutinates around the nucleus attracted by overexpressed perinuclear ATM-substrate protein. As a result, perinuclear ATM crowns appear to be an interesting biomarker of aging. The radiobiological characterization of the two human epithelial lens cell lines available and the four porcine epithelial lens cell lines that we have established showed delayed RIANS. The BFSP2 protein, found specifically overexpressed around the lens cell nucleus and interacting with ATM, may be a specific ATM-substrate protein facilitating the formation of perinuclear ATM crowns in lens cells. The perinuclear ATM crowns were observed inasmuch as the number of culture passages is high. Interestingly, 2 Gy X-rays lead to the transient disappearance of the perinuclear ATM crowns. Altogether, our findings suggest a strong influence of the ATM protein in radiation-induced cataractogenesis.

Sparing and enhancing dose protraction effects for radiation damage to the aorta of wild-type mice

PURPOSE

Our previous work indicated the greater magnitude of damage to the thoracic aorta at 6 months after starting 5 Gy irradiation in descending order of exposure to X-rays in 25 fractions > acute X-rays > acute γ-rays > X-rays in 100 fractions ≫ chronic γ-rays, in which the limitations of the study included a lack of data for fractionated γ-ray exposure. To better understand effects of dose protraction and radiation quality, the present study examined changes after exposure to γ-rays in 25 fractions, and compared its biological effectiveness with five other irradiation regimens.

MATERIALS AND METHODS

Male C57BL/6J mice received 5 Gy of 137Cs γ-rays delivered in 25 fractions spread over six weeks. At 6 months after starting irradiation, mice were subjected to echocardiography, followed by tissue sampling. The descending thoracic aorta underwent scanning electron microscopy, immunofluorescence staining and histochemical staining. The integrative analysis of multiple aortic endpoints was conducted for inter-regimen comparisons.

RESULTS

Exposure to γ-rays in 25 fractions induced vascular damage (evidenced by increases in endothelial detachment and vascular endothelial cell death, decreases in endothelial waviness, CD31, endothelial nitric oxide synthase and vascular endothelial cadherin), inflammation (evidenced by increases in tumor necrosis factor α, CD68 and F4/80) and fibrosis (evidenced by increases in transforming growth factor β1, alanine blue stain and intima-media thickness). The integrative analysis revealed biological effectiveness in descending order of exposure to X-rays in 25 fractions > acute X-rays > γ-rays in 25 fractions > acute γ-rays > X-rays in 100 fractions ≫ chronic γ-rays.

CONCLUSIONS

The results suggest that dose protraction effects on aortic damage depend on radiation quality, and are not a simple function of dose rate and the number of fractions.

Noncancer Effects of Ionizing Radiation Exposure on the Eye, the Circulatory System and beyond: Developments made since the 2011 ICRP Statement on Tissue Reactions

For radiation protection purposes, noncancer effects with a threshold-type dose-response relationship have been classified as tissue reactions (formerly called nonstochastic or deterministic effects), and equivalent dose limits aim to prevent occurrence of such tissue reactions. Accumulating evidence demonstrates increased risks for several late occurring noncancer effects at doses and dose rates much lower than previously considered. In 2011, the International Commission on Radiological Protection (ICRP) issued a statement on tissue reactions to recommend a threshold of 0.5 Gy to the lens of the eye for cataracts and to the heart and brain for diseases of the circulatory system (DCS), independent of dose rate. Literature published thereafter continues to provide updated knowledge. Increased risks for cataracts below 0.5 Gy have been reported in several cohorts (e.g., including in those receiving protracted or chronic exposures). A dose threshold for cataracts is less evident with longer follow-up, with limited evidence available for risk of cataract removal surgery. There is emerging evidence for risk of normal-tension glaucoma and diabetic retinopathy, but the long-held tenet that the lens represents among the most radiosensitive tissues in the eye and in the body seems to remain unchanged. For DCS, increased risks have been reported in various cohorts, but the existence or otherwise of a dose threshold is unclear. The level of risk is less uncertain at lower dose and lower dose rate, with the possibility that risk per unit dose is greater at lower doses and dose rates. Target organs and tissues for DCS are also unknown, but may include heart, large blood vessels and kidneys. Identification of potential factors (e.g., sex, age, lifestyle factors, coexposures, comorbidities, genetics and epigenetics) that may modify radiation risk of cataracts and DCS would be important. Other noncancer effects on the radar include neurological effects (e.g., Parkinson's disease, Alzheimer's disease and dementia) of which elevated risk has increasingly been reported. These late occurring noncancer effects tend to deviate from the definition of tissue reactions, necessitating more scientific developments to reconsider the radiation effect classification system and risk management. This paper gives an overview of historical developments made in ICRP prior to the 2011 statement and an update on relevant developments made since the 2011 ICRP statement.

Electron, Photon, and Neutron Dose Conversion Coefficients of Lens and Non-Lens Tissues Using a Multi-Tissue Eye Model to Assess Risk of Cataracts and Retinitis

Previous publications describe the estimation of the dose from ionizing radiation to the whole lens or parts of it but have not considered other eye tissues that are implicated in cataract development; this is especially critical for low-dose, low-ionizing-density exposures. A recent review of the biological mechanisms of radiation-induced cataracts showed that lenticular oxidative stress can be increased by inflammation and vascular damage to non-lens tissues in the eye. Also, the radiation oxygen effect indicates different radiosensitivities for the vascular retina and the severely hypoxic lens. Therefore, this study uses the Monte Carlo N-Particle simulations to quantify dose conversion coefficients for several eye tissues for incident antero-posterior exposure to electrons, photons, and neutrons (and the tertiary electron component of neutron exposure). A stylized, multi-tissue eye model was developed by modifying a model by Behrens etal. (2009) to include the retina, uvea, sclera, and lens epithelial cell populations. Electron exposures were simulated as a single eye, whereas photon and neutron exposures were simulated employing two eyes embedded in the ADAM-EVA phantom. For electrons and photons, dose conversion coefficients are highest for either anterior tissues for low-energy incident particles or posterior tissues for high-energy incident particles. Neutron dose conversion coefficients generally increase with increasing incident energy for all tissues. The ratio of the absorbed dose delivered to each tissue to the absorbed dose delivered to the whole lens demonstrated the considerable deviation of non-lens tissue doses from lens doses, depending on particle type and its energy. These simulations demonstrate that there are large variations in the dose to various ocular tissues depending on the incident radiation dose coefficients; this large variation will potentially impact cataract development.

Assessment of Scattered Dose to the Eye in Dentistry: A Systematic Review

Cone-beam computed tomography (CBCT) is a tool for dental imaging of impactions, maxillofacial discrepancies, facial trauma, and tumors. In addition, It is used in treatment planning for dental implants, orthognathic surgery, and general maxillofacial surgery. There are no standardized methods for utilizing CBCT dosimetry, and there is no consensus among dental and medical physics health professionals regarding dental CBCT imaging procedures. The eyes and thyroid glands are radiosensitive organs that lie outside the primary beam but receive a significant amount of radiation due to scattered radiation. This study aimed to assess the dose to eye lens in patients imaged using CBCT. This review aims to evaluate the scattered doses to the eye from CBCT among adult patients seeking dental treatment. The search included published articles in the Web of Science, PubMed (MeSH and Web PubMed), Medline, and Google Scholar databases using the appropriate keywords from January 2010 to July 2022. The inclusion criteria were based on the method of dose measurement (phantom studies using Optically stimulated luminescence (OSL) and Thermoluminescent dosimeter (TLD), language, and type of protocol used. A literature search was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist and flow chart. Out of 653 articles identified, 5 met the inclusion criteria. The results show that the scattered radiation dose ranged between 0.103 mSv and 8.3 mSv. This variation exists due to the difference in the field of vision (FOV), phantom exposure, dosimeters used, degree of rotation in the protocol, and finally, the scanner used. The scattered dose to the eye from CBCT is higher than the background radiation, with huge variability in the range of the dose measured. Clear guidelines for utilizing CBCT should be implemented, and dose reference levels should be established for benchmarking and optimization in practice.

Health risks from radioactive particles on Cumbrian beaches near the Sellafield nuclear site

A monitoring programme, in place since 2006, continues to recover radioactive particles (<2 mm diameter) and larger objects from the beaches of West Cumbria. The potential risks to members of the public using the beaches are mainly related to prolonged skin contact with or the inadvertent ingestion of small particles. Most particles are classified as either 'beta-rich' or 'alpha-rich' and are detected as a result of their caesium-137 or americium-241 content. Beta-rich particles generally also contain strontium-90, with90Sr:137Cs ratios of up to about 1:1, but typically <0.1:1. Alpha-rich particles contain plutonium isotopes, with Pu:241Amαratios usually around 0.5-0.6:1. 'Beta-rich' particles have the greatest potential to cause localised skin damage if held in stationary contact with the skin for prolonged periods. However, it is concluded that only particles of >106Bq of137Cs, with high90Sr:137Cs ratios, would pose a significant risk of causing acute skin ulceration. No particles of this level of activity have been found. Inadvertent ingestion of a particle will result in the absorption to blood of a small proportion of the radionuclide content of the particle. The subsequent retention of radionuclides in body organs and tissues presents a potential risk of the development of cancer. For 'beta-rich' particles with typical activities (mean 2 × 104Bq137Cs, Sr:Cs ratio of 0.1:1), the estimated committed effective doses are about 30µSv for adults and about 40µSv for 1 year old infants, with lower values for 'alpha-rich' particles of typical activities. The corresponding estimates of lifetime cancer incidence following ingestion for both particle types are of the order of 10-6for adults and up to 10-5for infants. These estimates are subject to substantial uncertainties but provide an indication of the low risks to members of the public.

Practical guidance to reduce radiation exposure in electrophysiology applying ultra low-dose protocols: a European Heart Rhythm Association review

Interventional electrophysiology offers a great variety of treatment options to patients suffering from symptomatic cardiac arrhythmia. Catheter ablation of supraventricular and ventricular tachycardia has globally evolved a cornerstone in modern arrhythmia management. Complex interventional electrophysiological procedures engaging multiple ablation tools have been developed over the past decades. Fluoroscopy enabled interventional electrophysiologist throughout the years to gain profound knowledge on intracardiac anatomy and catheter movement inside the cardiac cavities and hence develop specific ablation approaches. However, the application of X-ray technologies imposes serious health risks to patients and operators. To reduce the use of fluoroscopy during interventional electrophysiological procedures to the possibly lowest degree and to establish an optimal protection of patients and operators in cases of fluoroscopy is the main goal of modern radiation management. The present manuscript gives an overview of possible strategies of fluoroscopy reduction and specific radiation protection strategies.

The Impact of Implementing a Radiation-Sparing Protocol for Percutaneous Kyphoplasty-A Prospective Dosemetric Study

STUDY DESIGN

Prospective cohort study.

OBJECTIVES

The purpose of this prospective study was to evaluate a protocol for radiation-sparing kyphoplasty by assessing dosemetrically recorded radiation exposures to both patient and surgeon.

METHODS

This prospective clinical study examines the radiation exposure to patient and surgeon during single-level kyphoplasty in 32 thoracolumbar osteoporotic vertebral body fractures (12 OF 2, 9 OF 3, 11 OF 4 types) using a radiation aware surgical protocol between May 2017 and November 2019. The radiation exposure was measured at different locations using film, eye lens and ring dosemeters. Dose values are reported under consideration of lower detection limits of each dosemeter type.

RESULTS

A high proportion of dosemeter readings was below the lower detection limits, especially for the surgeon (>90%). Radiation exposure to the surgeon was highest at the unprotected thyroid gland (0.053 ± 0.047 mSv), however only slightly above the lower detection limit of dosemeters (0.044 mSv). Radiation exposure to the patient was highest at the chest (0.349 ± 0.414 mSv) and the gonad (0.186 ± 0.262 mSv). Fluoroscopy time, dose area product and number of fluoroscopic images were 46.0 ± 17.9 sec, 124 ± 109 cGy×cm2, and 35 ± 13 per kyphoplasty, respectively. Back pain significantly improved from 6.8 ± 1.6 to 2.5 ± 1.7 on the numeric rating scale on the first postoperative day (P < 0.0001).

CONCLUSIONS

The implementation of a strict intraoperative radiation protection protocol allows for safely performed kyphoplasty with ultra-low radiation exposure for the patient and surgeon without exceeding the annual occupational dose limits.

TRIAL REGISTRATION

The study was registered in the German Clinical Trials Register (DRKS00011908, registration date 16/05/2017).

Radiology's Ionising Radiation Paradox: Weighing the Indispensable Against the Detrimental in Medical Imaging

Ionising radiation stands as an indispensable protagonist in the narrative of medical imaging, underpinning diagnostic evaluations and therapeutic interventions across an array of medical conditions. However, this protagonist poses a paradox - its inestimable service to medicine coexists with an undercurrent of potential health risks, primarily DNA damage and subsequent oncogenesis. The narrative of this comprehensive review unfurls around this intricate enigma, delicately balancing the indispensable diagnostic utility against the non-negotiable commitment to patient safety. In this critical discourse, the intricacies of ionising radiation are dissected, illuminating not only its sources but also the associated biological and health hazards. The exploration delves into the labyrinth of strategies currently deployed to minimise exposure and safeguard patients. By casting light on the scientific nuances of X-rays, computed tomography (CT), and nuclear medicine, it traverses the complex terrain of radiation use in radiology, to promote safer medical imaging practices, and to facilitate an ongoing dialogue about diagnostic necessity and risk. Through a rigorous examination, the pivotal relationship between radiation dose and dose response is elucidated, unravelling the mechanisms of radiation injury and distinguishing between deterministic and stochastic effects. Moreover, protection strategies are illuminated, demystifying concepts such as justification, optimisation, the As Low As Reasonably Achievable (ALARA) principle, dose and diagnostic reference levels, along with administrative and regulatory approaches. With an eye on the horizon, promising avenues of future research are discussed. These encompass low-radiation imaging techniques, long-term risk assessment in large patient cohorts, and the transformative potential of artificial intelligence in dose optimisation. This exploration of the nuanced complexities of radiation use in radiology aims to foster a collaborative impetus towards safer medical imaging practices. It underscores the need for an ongoing dialogue around diagnostic necessity and risk, thereby advocating for a continual reassessment in the narrative of medical imaging.

Reduction of Radiation Dose to Eye Lens in Cerebral 3D Rotational Angiography Using Head Off-Centering by Table Height Adjustment: A Prospective Study

OBJECTIVE

Three-dimensional rotational angiography (3D-RA) is increasingly used for the evaluation of intracranial aneurysms (IAs); however, radiation exposure to the lens is a concern. We investigated the effect of head off-centering by adjusting table height on the lens dose during 3D-RA and its feasibility in patient examination.

MATERIALS AND METHODS

The effect of head off-centering during 3D-RA on the lens radiation dose at various table heights was investigated using a RANDO head phantom (Alderson Research Labs). We prospectively enrolled 20 patients (58.0 ± 9.4 years) with IAs who were scheduled to undergo bilateral 3D-RA. In all patients' 3D-RA, the lens dose-reduction protocol involving elevation of the examination table was applied to one internal carotid artery, and the conventional protocol was applied to the other. The lens dose was measured using photoluminescent glass dosimeters (GD-352M, AGC Techno Glass Co., LTD), and radiation dose metrics were compared between the two protocols. Image quality was quantitatively analyzed using source images for image noise, signal-to-noise ratio, and contrast-to-noise ratio. Additionally, three reviewers qualitatively assessed the image quality using a five-point Likert scale.

RESULTS

The phantom study showed that the lens dose was reduced by an average of 38% per 1 cm increase in table height. In the patient study, the dose-reduction protocol (elevating the table height by an average of 2.3 cm) led to an 83% reduction in the median dose from 4.65 mGy to 0.79 mGy (P < 0.001). There were no significant differences between dose-reduction and conventional protocols in the kerma area product (7.34 vs. 7.40 Gy·cm², P = 0.892), air kerma (75.7 vs. 75.1 mGy, P = 0.872), and image quality.

CONCLUSION

The lens radiation dose was significantly affected by table height adjustment during 3D-RA. Intentional head off-centering by elevation of the table is a simple and effective way to reduce the lens dose in clinical practice.

Scatter Radiation Distribution to Radiographers, Nearby Patients and Caretakers during Portable and Pediatric Radiography Examinations

Scatter radiation from portable and pediatric X-rays could pose a risk to radiographers, nearby patients, and caretakers. We aim to evaluate the spatial scatter radiation distribution to the radiographers, nearby patients, and caretakers during common projections in portable and pediatric X-rays. We evaluated the three-dimensional scatter dose profiles of four and three commonly used portable and pediatric X-ray projections, respectively, by anthropomorphic phantoms and scatter probes. For portable X-ray, the AP abdomen had the highest scatter radiation dose recorded. Radiographer scatter radiation doses were 177 ± 8 nGy (longest cord extension) and 14 ± 0 nGy (hiding behind the portable X-ray machine). Nearby patient scatter radiation doses were 3323 ± 28 nGy (40 cm bed distance), 1785 ± 50 nGy (80 cm bed distance), and 580 ± 42 nGy (160 cm bed distance). The AP chest and abdomen had the highest scatter radiation dose in pediatric X-rays. Caretaker scatter radiation doses were 33 ± 1 nGy (50 cm height) and 659 ± 7 nGy (140 cm height). Although the estimated lens doses were all within safe levels, the use of shielding and caution on dose estimation by inverse square law is suggested to achieve the ALARA principle and dose optimization.

Deconstructing Fat to Reverse Radiation Induced Soft Tissue Fibrosis

Adipose tissue is composed of a collection of cells with valuable structural and regenerative function. Taken as an autologous graft, these cells can be used to address soft tissue defects and irregularities, while also providing a reparative effect on the surrounding tissues. Adipose-derived stem or stromal cells are primarily responsible for this regenerative effect through direct differentiation into native cells and via secretion of numerous growth factors and cytokines that stimulate angiogenesis and disrupt pro-inflammatory pathways. Separating adipose tissue into its component parts, i.e., cells, scaffolds and proteins, has provided new regenerative therapies for skin and soft tissue pathology, including that resulting from radiation. Recent studies in both animal models and clinical trials have demonstrated the ability of autologous fat grafting to reverse radiation induced skin fibrosis. An improved understanding of the complex pathologic mechanism of RIF has allowed researchers to harness the specific function of the ASCs to engineer enriched fat graft constructs to improve the therapeutic effect of AFG.

The effect of breast shielding outside the field of view on breast entrance surface dose in axial X-ray examinations: a phantom study

PURPOSE

The purpose of this study was to evaluate the effect of outside-field-of-view (FOV) lead shielding on the entrance surface dose (ESD) of the breast on an anthropomorphic X-ray phantom for a variety of axial skeleton X-ray examinations.

METHODS

Using an anthropomorphic phantom and radiation dosimeter, the ESD of the breast was measured with and without outside-FOV shielding in anterior-posterior (AP) abdomen, AP cervical spine, occipitomental 30° (OM30) facial bones, AP lumbar spine, and lateral lumbar spine radiography. The effect of several exposure parameters, including a low milliampere-seconds technique, grid use, automatic exposure control use, wraparound lead (WAL) use, trolley use, and X-ray table use, on the ESD of the breast with and without outside-FOV shielding was investigated. The mean ESD (μSv) and standard deviation for each radiographic protocol were calculated. A one-tailed Student's t-test was carried out to evaluate whether ESD to the breast was reduced with the use of outside-FOV shielding.

RESULTS

A total of 920 breast ESD measurements were recorded across the different protocol parameters. The largest decrease in mean ESD of the breast with outside-FOV shielding was 0.002 μSv (P = 0.084), recorded in the AP abdomen on the table with a grid, OM30 on the table with a grid, OM30 standard protocol on the trolley, and OM30 on the trolley with WAL protocols. This decrease was found to be statistically non-significant.

CONCLUSION

This study found no significant decrease in the ESD of the breast with the use of outside-FOV shielding for the AP abdomen, AP cervical spine, OM30 facial bones, AP lumbar spine, or lateral lumbar spine radiography across a range of protocols.

Occupational radiation exposure dose and associated factors among radiology personnel in Eastern Amhara, Ethiopia

BACKGROUND

Ionizing radiation is being used more frequently in medicine, which has been linked to recognized biological effects such as cancer and mortality. Radiology services are becoming more widely available in Ethiopian health facilities but there is no compiled record of worker's radiation dose. So, assessing the magnitude and identifying the associated factors of occupational radiation exposure dose among radiology personnel help to design strategies for radiation protection.

OBJECTIVE

The study was designed to assess the occupational radiation exposure dose and associated factors among radiology personnel in eastern Amhara, northeast Ethiopia, 2021.

METHODS

Cross-sectional study was conducted from March 25 to April 30, 2021, in 57 health institutions among 198 radiology personnel. The study comprised all eligible radiology personnel. The data were collected using an electronic-based (Google form) self-administered questionnaire, and document review. The data were entered into an excel spread sheet and then, exported to Stata 14 software. Linear regression model was used to analyse the data after checking its assumptions. Variables with a p-value < 0.25 were entered into a multiple linear regression analysis, and those with a p-value < 0.05 were judged significant. VIF was used to check for multi-collinearity. Coefficient of determination was used to check the model fitness.

RESULTS

The mean (± SD) annual shallow and deep dose equivalents of radiology personnel were 1.20 (± 0.75) and 1.02 (± 0.70) mSv, respectively. Body mass index (β = 0.104, 95% CI: 0.07, 0.14), practice of timing (β = -0.43, 95% CI: -0.73, -0.13), working experience (β = -0.04, 95% CI: -0.048, -0.032), and practice of distancing (β = -0.26, 95% CI: -0.49, -0.17) were found to be statistically significant factors of annual deep dose equivalent. In addition, body mass index (β = 0.113, 95% CI: 0.08, 0.15), practice of timing (β = -0.62 95% CI: -0.93, -0.31) and, working experience (β = -0.044, 95% CI: -0.053, -0.036 had statistically significant associations with annual shallow dose equivalent.

CONCLUSION

The annual dose equivalents were two times higher than the global average of annual per caput effective dose due to medical exposure. Body mass index, practice of timing, working experience, and practice of distancing were factors of occupational radiation exposure dose. Strategies focusing on increasing the skill, experience, and lifestyle of radiology personnel would be supreme important means to reduce occupational radiation exposure dose.

Radioprotective Effects of a Semicircular X-ray Shielding Device for Operators During CT Fluoroscopy-Guided Interventional Procedures: Experimental and Clinical Studies

PURPOSE

To evaluate, experimentally and clinically, the radioprotective effects of a semicircular X-ray shielding device for operators during CT fluoroscopy-guided IR procedures.

MATERIALS AND METHODS

During experimentation, the reduction rates of scattered radiation rates from CT fluoroscopy were evaluated using a humanoid phantom. Two shielding device positions were tested: "shielding close to the CT gantry" and "shielding close to the operator". The scattered radiation rate without shielding was also evaluated. The clinical study retrospectively evaluated the operator's radiation exposure during 314 CT-guided IR procedures. With a semicircular X-ray shielding device (with shielding group, n = 119) or without it (no shielding group, n = 195), CT fluoroscopy-guided IR procedures were performed. Radiation dose measurements were taken using a pocket dosimeter placed near the operator's eye. For shielding and no shielding groups, the procedure time, dose length product (DLP), and the operator's radiation exposures were compared.

RESULTS

Experimentation revealed the respective mean reduction rates of "shielding close to the CT gantry" and "shielding close to the operator" as 84.3% and 93.5% compared with the no-shielding setting. Although no significant differences were found in the procedure time and the DLP between "no shielding" and "with shielding" groups in the clinical study, the operators' radiation exposure in the "with shielding" group (0.03 ± 0.04 mSv) was significantly lower than in the "no shielding" group (0.14 ± 0.15 mSv; p < .001).

CONCLUSION

The semicircular X-ray shielding device provides valuable radioprotective effects for operators during CT fluoroscopy-guided IR.

Occupational radiation exposure to the lens of the eyes and its protection during endoscopic retrograde cholangiopancreatography

This study aimed to examine occupational radiation exposure to the lens of the eyes during endoscopic retrograde cholangiopancreatography (ERCP). In this multicenter, prospective, observational cohort study, we collected data regarding occupational radiation exposure to the lens of the eyes during ERCP. We measured radiation exposure of patients and examined its correlation with occupational exposure. In dosimetrically-measured ERCPs (n = 631), the median air kerma at the patient entrance reference point, air kerma-area product, and fluoroscopy time were 49.6 mGy, 13.5 Gycm², and 10.9 min, respectively. The median estimated annual radiation dose to the lens of the eyes was 3.7, 2.2, and 2.4 mSv for operators, assistants, and nurses, respectively. Glass badge over lead aprons and eye dosimeter results were similar in operators but differed in assistants and nurses. A strong correlation was shown between eye dosimeter measurements and patients' radiation exposure. The shielding rates of the lead glasses were 44.6%, 66.3%, and 51.7% for operators, assistants, and nurses, respectively. This study revealed the actual occupational exposure dose for the lens of the eyes during ERCP and the efficacy of lead glass. Values of radiation exposure to patients can help estimate exposure to the lens of the eyes of medical staff.

Occupational radiation exposure of neurointerventionalists during endovascular stroke treatment

BACKGROUND

Radiological neuro-interventions, especially endovascular stroke treatment (EST), are increasing in case numbers worldwide with increasing occupational radiation exposure. Aim of this study was to define the radiation exposure of neurointerventionalists (NI) during EST and to compare the accumulated dose reaching the left arm with the left temple.

METHODS

This is a prospective observational study in a tertiary stroke center conducted between 11/2021 and 07/2022. Radiation exposure was measured using real time dosimetry with dosimeters being carried by the NI during EST simultaneously at the left temple and left arm. The effective dose [µSV] per dose area product (DAP) and potential influencing factors were compared in univariate analysis between the two dosimeter positions.

RESULTS

In total, 82 ESTs were analyzed with a median DAP of 6179 µGy*m² (IQR 3271 µGy*m²-11720 µGy*m²). The accumulated dose at the left arm and left temple correlated with the DAP and fluoroscopy time of the EST (DAP and arm: p = 0.01, DAP and temple: p = 0.006). The radiation exposure (RE) showed a wide range and did not differ between the two dosimeter positions (median, IQR arm 7 µSV, IQR 3.1-16.9 µSV, min. 0.3 µSV max. 64.5 µSV) vs. head 7 µSv, IQR 3.2-17.4 µSV, min. 0.38 µSV, max. 48.6 µSV, p = 0.94). Occupational RE depends on the number of thrombectomy attempts, but not the target vessel occlusion location or the NI's body height.

CONCLUSION

Neurointerventionalists experience a generally low but very variable radiation exposure during EST, which depends on the intervention's fluoroscopy time and dose area product as well as thrombectomy attempts but does not differ between left temple and left arm.

Evaluation of operator eye exposure and eye protective devices in interventional radiology: Results on clinical staff and phantom

PURPOSE

To assess occupational eye lens dose based on clinical monitoring of interventional radiologists and to assess personal protective eyewear (PPE) efficacy through measurements with anthropomorphic phantom.

METHODS

Two positions of the operator with respect to X-ray beam were simulated with phantom. Dose reduction factor (DRF) of four PPE was assessed, as well as correlation between eye lens and whole-body doses. Brain dose was also assessed. Five radiologists were monitored for one-year clinical procedures. All subjects were equipped with whole-body dosimeter placed over lead apron at the chest level and eye lens dosimeter placed over the left side of the PPE. Kerma-Area Product (KAP) of procedures performed during the monitoring period was recorded. The correlation of eye lens dose with whole-body dose and KAP was assessed.

RESULTS

DRF was 4.3/2.4 for wraparound glasses, 4.8/1.9 for fitover glasses, 9.1/6.8 for full-face visor in radial/femoral geometries. DRF of half-face visor depended on how it is worn (range 1.0-4.9). Statistically significant correlation between dose value over the PPE and chest dose was observed, while there was no correlation between eye lens dose and chest dose. The results on clinical staff showed statistically significant correlation between dose values over the PPE and KAP.

CONCLUSIONS

All PPE showed significant DRF in all configurations, provided they were worn correctly. Single DRF value is not applicable to all clinical situations. KAP is a valuable tool for determining appropriate radiation protection measures.