Fluoroscopically guided interventional procedures: a review of radiation effects on patients' skin and hair

Feasibility of transthoracic echocardiographic guidance for multicatheter electrophysiological mapping studies in horses

BACKGROUND

Improved characterization of arrhythmias is based on minimally invasive catheterizations. However, these catheterizations have been poorly explored in horses because apart from 3-dimensional (3D) mapping systems, continuous guidance of the catheter's position with adequate detail is difficult using current imaging modalities.

HYPOTHESIS

Position multiple electrophysiology catheters simultaneously at predetermined strategical positions in the heart using transthoracic echocardiographic guidance.

ANIMALS

Eight adult healthy horses.

METHODS

Observational study. Two electrophysiological studies were performed: 1 procedure with catheters positioned in the right heart in the standing sedated horse and 1 procedure under general anesthesia with catheters positioned in the left heart. Except for the coronary sinus catheter, each catheter positioning was simultaneously guided by right-parasternal transthoracic echocardiography and 3D electro-anatomical mapping.

RESULTS

For each catheter position, a central imaging plane was taken as the starting point, after which the imaging probe was shifted, rotated, and angulated to visualize the catheter over its entire length, including its distal electrode. Catheter positionings in the right heart and left ventricle were successfully guided in the majority of the horses whereas catheter positionings in the left atrium, and especially the pulmonary veins, were challenging to guide echocardiographically.

CONCLUSIONS AND CLINICAL IMPORTANCE

Ultrasound guidance of catheters to specific positions useful for electrophysiological mapping was feasible in the right heart and left ventricle but challenging for the left atrium. This approach creates a perspective for minimally invasive arrhythmia diagnosis without the need for a 3D mapping system. Left parasternal views and intracardiac echocardiography might provide better guidance for left atrial positions.

Deciphering the Radiation Dose Summary Page in Interventional Fluoroscopy

Fluoroscopy is an advanced medical imaging modality that utilizes x-rays to acquire real-time images throughout a medical examination. It is commonly used in various procedures such as in interventional radiology, cardiac catheterization, and gastrointestinal and genitourinary studies. While fluoroscopy is a valuable diagnostic and therapeutic tool, it exposes patients and medical staff to ionizing radiation, which carries health risks. A radiation dose summary page is a report generated by the fluoroscope that displays important information about the procedure. It provides an overview of the radiation doses administered during a fluoroscopic procedure, as well as certain technical parameters used during the irradiation events. The contents of a radiation dose summary page may vary depending on the make and model of the fluoroscope but some common elements include the cumulative reference air kerma, which serves as a surrogate of radiation dose delivered to the patient, and the dose-area product, which takes account of the x-ray beam area and is a measure of the total amount of energy imparted on the patient. Other imaging acquisition parameters may be also included in the dose summary page, including tube voltage, tube current, pulse width, pulse rate, spectral filters, primary and secondary angles, and source-to-image distance. The radiation dose summary page for fluoroscopy is a useful tool for physicians, technologists, and medical physicists, allowing them to comprehend the technical details of a fluoroscopically guided procedure. ©RSNA, 2024.

Association of radiation-induced epilation and interventional neuroradiology procedures

INTRODUCTION

The aim of this study is to quantify the association of temporary epilation following interventional neuroradiology (INR) procedures and compare the peak skin dose (Dskin,max) threshold to published values.

METHODS

Gold Coast University Hospital (GCUH) is a major centre for INR with over 500 primarily interventional procedures performed every year. Dskin,max is calculated when the reference air kerma (Ka,r) exceeds 3 Gy. If the Dskin,max exceeds 3 Gy, the patient is followed up for any skin effects. An audit was undertaken of these results over a 2-year period.

RESULTS

From January 2020 to December 2021, 140 patients who underwent INR procedures had a Ka,r > 3 Gy, 66 resulted in a calculated Dskin,max >3 Gy, and 45 were successfully followed up. Twenty patients (44%) reported no skin effects and 25 (56%) reported skin effects, which were almost exclusively epilation. The mean (range) Dskin,max for patients with no reported skin effects and those with observed skin effects was 4.6 Gy (3.0-11.1 Gy) and 4.2 Gy (3.0-7.0 Gy), respectively.

CONCLUSION

These results demonstrate that temporary epilation was observed in 56% of patients, in a cohort of 45 patients who underwent an INR procedure with calculated Dskin,max >3 Gy and successful follow-up. The results support evidence in the literature that suggests the approximate threshold for temporary epilation reported by the International Commission on Radiological Protection (ICRP) may be too high for incidence of this effect, specifically on the scalp, when Dskin,max is calculated from Ka,r (using commonly used corrections and assumptions in the calculation).

Expected role of photodynamic therapy to relieve skin damage in nuclear or radiological emergency: Review

Nuclear and radiological accidents can occur due to poor management, in transportation, radiation therapy and nuclear wards in hospitals, leading to extreme radiation exposure and serious consequences for human health. Additionally, in many of previous radiological accidents, skin damage was observed in patients and survivors due to the high radiation exposure. However, as part of a medical countermeasures in a nuclear/radiological emergency, it is critical to plan for the treatment of radiation-induced skin damage. Hence, the new, non-invasive technology of photodynamic therapy (PDT) is projected to be more effectively used for treating skin damage caused by high-dose radiation. PDT plays an important role in treating, repairing skin damage and promoting wound healing as evidenced by research. This review, highlighted and recommended potential impacts of PDT to repair and decrease radiation-induced skin tissue damage. Moreover, we have suggested some photosensitizer (PS) agent as radio-mitigator drugs to decrease radiobiological effects.

Factors affecting radiation dose, radiation exposure time and procedural time in arterial embolization for active hemorrhage

PURPOSE

To evaluate patient and procedure-related factors contributing to the radiation dose, cumulative fluoroscopy time (CFT), and procedural time (PT) of Arterial Embolization (AE) for suspected active bleeding.

METHODS

Data on patients who underwent AE for suspected bleeding was retrospectively gathered between January 2019 and April 2022. Data collected included the dependent variables consisting of dose-area product (DAP), CFT, PT, and independent variables consisting of demographic, bleeding-specific, and procedure-specific parameters. All statistical computations were performed in SPSS statistics. The alpha value was set at 0.05.

RESULTS

Data from a total of 148 AE were collected with an average patient's age of 61.06 ± 21.57 years. Higher DAP was independently associated with male sex (p < 0.002), age ranges between 46 and 65 years (p = 0.019) and > 66 years (p = 0.027), BMI above 30 (p = 0.016), attending with less than 10 years of experience (p = 0.01), and bleeding in the abdomen and pelvis (p = 0.027). Longer CFT was independently associated with attending with less than 10 years of experience (p < 0.001), having 2 (p = 0.004) or > 3 (p = 0.005) foci of bleed, and age between 46 and 65 years (p = 0.007) and ≥ 66 years (p = 0.017). Longer PT was independently associated with attending with less than 10 years of experience (p < 0.001) and having 2 (p = 0.014) or > 3 (p = 0.005) foci of bleed.

CONCLUSION

The interventionist experience influenced radiation dose, CFT and PT. Dose was also affected by patients' sex, age, BMI, as well as bleeding location. CFT was also affected by patients' age, and both CFT and PT were also affected by the number of bleeding foci. These findings highlight the multifaceted factors that affect radiation dose and procedural time, emphasizing the importance of interventionist expertise, patient's age, sex, BMI, location and number of bleeds.

A comprehensive assessment of a prototype high ratio antiscatter grid in interventional cardiology using experimental measurements and Monte Carlo simulations

Objective. To assess the performance of a new antiscatter grid design in interventional cardiology for image quality improvement and dose reduction using experimental measurements and Monte Carlo (MC) simulation.Approach.Experimental measurements were performed on an angiography system, using a multi-layered tissue simulating composite phantom made from of poly(methyl methacrylate), aluminium and expanded polystyrene (2/0.2/0.7 cm). The total phantom thickness ranged from 20.3 cm to 40.6 cm. Four conditions were compared; (A) 105 cm source-image receptor distance (SID) without grid, (Bi) 105 cm SID with grid ratio (r) and strip density (N) (r15N80), (Bii) 120 cm SID without grid, and (Biii) 120 cm SID with high ratio grid (r29N80). The system efficiency (η), defined by the signal-to-noise ratio, was compared from theBconditions against caseA. These conditions were also simulated with MC techniques, allowing additional phantom compositions to be explored. Weighted image quality improvement factor (ηw(u)) was studied experimentally at a specific spatial frequency due to the SID change. Images were simulated with an anthropomorphic chest phantom for the different conditions, and the system efficiency was compared for the different anatomical regions.Main results.Good agreement was found between theηandηw(u) methods using both measured and simulated data, with average relative differences between 2%-11%. CaseBiiiprovided higherηvalues compared toA, andBifor thicknesses larger than 20.3 cm. In addition, caseBiiialso provided higherηvalues for high attenuating areas in the anthropomorphic phantom, such as behind the spine.Significance.The new antiscatter grid design provided higher system efficiency compared to the standard grid for the parameters explored in this work.

Science-informed Policy Making for Protecting People and the Environment from Radiation

ABSTRACT

The process to arrive at the radiation protection practices of today to protect workers, patients, and the public, including sensitive populations, has been a long and deliberative one. This paper presents an overview of the US Environmental Protection Agency's (US EPA) responsibility in protecting human health and the environment from unnecessary exposure to radiation. The origins of this responsibility can be traced back to early efforts, a century ago, to protect workers from x rays and radium. The system of radiation protection we employ today is robust and informed by the latest scientific consensus. It has helped reduce or eliminate unnecessary exposures to workers, patients, and the public while enabling the safe and beneficial uses of radiation and radioactive material in diverse areas such as energy, medicine, research, and space exploration. Periodic reviews and analyses of research on health effects of radiation by scientific bodies such as the National Academy of Sciences, National Council on Radiation Protection and Measurements, United Nations Scientific Committee on the Effects of Atomic Radiation, and the International Commission on Radiological Protection continue to inform radiation protection practices while new scientific information is gathered. As a public health agency, US EPA is keenly interested in research findings that can better elucidate the effects of exposure to low doses and low dose rates of radiation as applicable to protection of diverse populations from various sources of exposure. Professional organizations such as the Health Physics Society can provide radiation protection practitioners with continuing education programs on the state of the science and describe the key underpinnings of the system of radiological protection. Such efforts will help equip and prepare radiation protection professionals to more effectively communicate radiation health information with their stakeholders.

The addition of a leaded arm sleeve to leaded aprons further decreases operator upper outer quadrant chest wall radiation dose during fluoroscopically guided interventions

OBJECTIVE

Breast cancer most commonly occurs in the upper outer quadrant (UOQ) chest wall (CW). The effectiveness of routine leaded aprons to protect this region of the body in interventionalists during fluoroscopically guided interventions (FGIs) is unknown. Given the high lifetime attributable risks of prolonged occupational exposure to ionizing radiation and the increasing number of practicing female vascular surgeons and interventionalists, we sought to determine if the use of a leaded arm shield would offer additional protection to the lateral CW and axilla in operators compared with routine leaded aprons.

METHODS

Effectiveness of leaded sleeves in attenuating radiation dose to the axilla and UOQ was evaluated in clinical practice and simulated scenarios. In the clinical setting, optically stimulated luminescence nanoDot detectors were placed at the UOQ lateral CW position, both over and under a standard leaded apron vest with and without the addition of an antimony/bismuth Enviro-Lite sleeve on two vascular surgeons performing FGIs. In the simulation, nanoDots were similarly placed on an anthropomorphic phantom positioned to represent a primary operator performing right femoral access. Fluorography was performed on 12-inch-thick acrylic scatter phantom at 80 kVp for an exposure of 3 Gy reference air kerma. Experiments were done with and without the sleeve. Paired Wilcoxon and χ2 tests were performed to identify the statistical significance of radiation attenuation.

RESULTS

Operator UOQ CW dose was measured during 61 FGIs: 33 cases (54%) with and 28 cases (46%) without the sleeve. Median procedure reference air kerma and fluoroscopy time was 180 mGy (interquartile range [IQR], 85-447 mGy) and 21 minutes (IQR, 11-39 minutes) when the sleeve was worn vs 100 mGy (IQR, 67-270 mGy) and 11 minutes (IQR, 6.3-25 minutes) without the sleeve. Radiation dose to the operator's UOQ was reduced by 96% (IQR, 85%-96%) when the sleeve was present and by 62% (IQR, 44%-82%; P < .001) without the sleeve. In the simulated setting, the sleeve reduced the radiation dose to the UOQ compared with the apron alone (96% vs 67%; P < .001).

CONCLUSIONS

Routine leaded aprons do attenuate the majority of UOQ chest wall radiation dose; however, the addition of a lead-equivalent sleeve further significantly reduces this dose. Because this area of the body has a high incidence of cancer formation, additional protection, especially to female interventionalists, seems prudent. Vascular surgeons should consider using a protective sleeve with their personal protective equipment when performing complex fluoroscopically guided procedures.

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.

Assessing and improving radiation safety in cardiac catheterization: a study from Cairo University Hospital

BACKGROUND

Catheter laboratories are high-radiation exposure environments, especially during X-ray procedures like percutaneous transluminal coronary angioplasty and electrophysiological studies. Radiation exposure poses risks of stochastic (e.g., cancer) and deterministic (e.g., skin changes) effects. This study assessed radiation safety and health practices in a cardiac catheterization unit to optimize radiation safety. A cross-sectional study in Cairo University Hospital (March-September 2019) evaluated 700 patients and healthcare workers. Real-time radiation measurements, educational lectures, and radiation protection measures were implemented in three phases. Data on radiation exposure, procedures, and compliance were collected and analyzed.

RESULTS

The total procedure time and fluoroscopy time per cardiologist did not significantly differ between phases, but there was a statistically significant reduction in the mean total cumulative radiation doses between Phase I and Phase III for cardiologists (P = 0.013). Among nurses and technicians, there was no significant difference in radiation doses between the two phases. Significant correlations were found between operators' radiation doses, procedure time, and fluoroscopy time. Patients' radiation doses decreased significantly from Phase I to Phase III, with correlations between dose, procedure time, and gender. Compliance with radiation protection measures was suboptimal.

CONCLUSIONS

Compliance with radiation safety standards in the cardiac catheterization unit at the Cairo University Hospital needs improvement. The study highlights the importance of adhering to radiation safety principles and optimizing protective measures to reduce radiation exposure for both patients and healthcare personnel. Despite low compliance, significant reductions in radiation doses were achieved with increased awareness and adherence to specific protection measures. Future efforts should focus on enhancing radiation safety protocols and organ-specific radiation impact assessments.

Whether the Unilateral Transverse Process-pedicle Approach has Advantages over the Traditional Transpedicle Approach: A Systematic review and Meta-analysis

PURPOSE

To summarize the literature and compare the advantages and disadvantages of the unilateral transverse process-pedicle approach (UTPA) and conventional transpedicular approach (CTPA) vertebral augmentation in the treatment of osteoporotic vertebral compression fractures (OVCF).

METHODS

A single researcher performed a systematic literature review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Online scientific databases were searched in September 2021 for English- and Chinese-language publications. A series of comparative studies were included, with UTPA as the main intervention and CTPA as the comparison indicator. A meta-analysis was performed for studies that reported clinical outcome indicators. The χ2 was used to study heterogeneity between trials, and the I2 statistic was calculated to estimate variation across studies.

RESULTS

A total of eight studies were included for meta-analysis, all of which were observational studies with mixed bias risk. There were 613 subjects in the UTPA group and 488 subjects in the CTPA group. The results of the meta-analysis showed that there was no difference between the UTPA group and the CTPA group in terms of visual analogue scale scores (p = 0.31), Oswestry Disability Index scores (p = 0.50), correction of kyphosis angle (p = 0.65), and the amount of bone cement (p = 0.13), but the UTPA group had a shorter operative time (p < 0.001), bone cement leakage rates (p = 0.02), and fluoroscopy times than the CTPA group (p < 0.001). Partial analysis results had a high risk of bias, and the most common source of bias was that there was high heterogeneity between studies, and the sensitivity can only be reduced by a random effect model, and some studies (four items) did not clearly describe the confounders that they controlled.

CONCLUSION

The limited evidence obtained in this study proves that the new puncture method does not have more advantages than the traditional technique, so it is no longer meaningful to continue to obsess over the impact of the puncture method on surgical outcome.

Patient skin dose measurement and risk of deterministic effect during fluoroscopy cardiac procedures

This study aimed at assessing patient's peak skin doses (PSD) during fluoroscopy cardiac procedures and proposed a look up table to enhance patient's dose management. Perspex phantom and thermoluminescent dosemeters (TLD) were irradiated for different dose levels with X-ray equipment (Philips Azurion 7). It was found that PSD measures were higher than the kerma at the interventional reference point [K (IRP)] reported with factors 1.55, 1.75 and 2.88 for anterior posterior (AP0o), left anterior oblique (LAO45o) and right anterior oblique (RAO45o), respectively. The equations describing the correlation between the PSD measured kerma area product and cumulative air kerma were found with R-square values of 0.98 and 0.99, respectively. The statistical analysis shows a strong linear correlation between PSD and K (IRP) (P-value = 0.05). It was also found that 27% of the patients population considered in this work, received a skin dose higher than the threshold of deterministic effect of 2 Gy and a look up table with the equation of fitness were proposed to be implemented in the facility for K (IRP) higher than 500 mGy.

Nano-Architecture of Persistent Focal DNA Damage Regions in the Minipig Epidermis Weeks after Acute γ-Irradiation

Exposure to high acute doses of ionizing radiation (IR) can induce cutaneous radiation syndrome. Weeks after such radiation insults, keratinocyte nuclei of the epidermis exhibit persisting genomic lesions that present as focal accumulations of DNA double-strand break (DSB) damage marker proteins. Knowledge about the nanostructure of these genomic lesions is scarce. Here, we compared the chromatin nano-architecture with respect to DNA damage response (DDR) factors in persistent genomic DNA damage regions and healthy chromatin in epidermis sections of two minipigs 28 days after lumbar irradiation with ~50 Gy γ-rays, using single-molecule localization microscopy (SMLM) combined with geometric and topological mathematical analyses. SMLM analysis of fluorochrome-stained paraffin sections revealed, within keratinocyte nuclei with perisitent DNA damage, the nano-arrangements of pATM, 53BP1 and Mre11 DDR proteins in γ-H2AX-positive focal chromatin areas (termed macro-foci). It was found that persistent macro-foci contained on average ~70% of 53BP1, ~23% of MRE11 and ~25% of pATM single molecule signals of a nucleus. MRE11 and pATM fluorescent tags were organized in focal nanoclusters peaking at about 40 nm diameter, while 53BP1 tags formed nanoclusters that made up super-foci of about 300 nm in size. Relative to undamaged nuclear chromatin, the enrichment of DDR protein signal tags in γ-H2AX macro-foci was on average 8.7-fold (±3) for 53BP1, 3.4-fold (±1.3) for MRE11 and 3.6-fold (±1.8) for pATM. The persistent macro-foci of minipig epidermis displayed a ~2-fold enrichment of DDR proteins, relative to DSB foci of lymphoblastoid control cells 30 min after 0.5 Gy X-ray exposure. A lasting accumulation of damage signaling and sensing molecules such as pATM and 53BP1, as well as the DSB end-processing protein MRE11 in the persistent macro-foci suggests the presence of diverse DNA damages which pose an insurmountable problem for DSB repair.

Reduction in Primary Operator Radiation Dose Exposure During Coronary Angioplasty Using Radiation Absorbing Drape

Background Percutaneous coronary intervention (PCI) involves the use of ionizing radiation and is a common procedure in a cardiac catheterization suite. The RADPAD® surgical drape (Worldwide Innovations & Technologies, Inc., Lenexa, KS) has been developed to reduce scatter radiation exposure to primary operators during routine PCI procedures. This study aims to assess the efficacy of RADPAD drapes in reducing radiation dose in the catheterization laboratory. Methods This was a single-center, prospective, observational study that aimed to compare the primary operator dose received with and without the use of a commercially available shield (RADPAD) during PCI. A total of 53 consecutive patients undergoing PCI were randomized in a 1:1 pattern to receive either the RADPAD (study group) or no RADPAD (control group). Standard shielding and personal protective equipment were used. Radiation exposure to the primary operator, total fluoroscopy time, number of cine acquisitions, and air kerma were recorded for each procedure. A one-way ANOVA calculator, including the Tukey honestly significant difference (HSD) test, was used to compare the mean values of radiation exposure. Scatterplot analysis and linear regression slopes of dose relative to air kerma were performed. All shields were reused once only. Results The study compared radiation exposure during PCI procedures between patients who received radiation attenuation devices (RADPAD) and those who did not. The RADPAD group had 30 patients, while the NO RADPAD group had 23 patients. There was a significant difference in the number of coronary angiography and single/multi-vessel PCI procedures between the two groups. There was no significant difference in procedural time or air kerma dose between the groups, but the RADPAD group had a significantly lower radiation dose (mean dose of 3.679 mrem) compared to the NO RADPAD group (mean dose of 8.12 mrem) (p < 0.00001). The primary operator dose per unit of air kerma was also significantly lower in the RADPAD group. Overall, the use of RADPAD resulted in a significant reduction in radiation exposure during PCI procedures. Conclusion The present study provides further evidence for the efficacy of using radiation-absorbing drapes (RADPAD) in reducing primary operator radiation dose exposure during coronary angioplasty. The equipment for radiation dose reduction of patients also reduces the radiation dose of medical staff. Therefore, the use of RADPAD is recommended as a safe and effective measure for reducing operator radiation dose exposure during coronary angioplasty.

Leveraging Radiopharmaceutical Programmatic Collaboration for Management of Pretherapy and On-treatment Urinary Incontinence

ABSTRACT

Many parenteral radiopharmaceuticals available as anticancer therapy are filtered by the kidneys and excreted in the urine. Here, physician leaders of radiation medicine, nuclear medicine/molecular imaging, and the radiotheranostics programs as well as radiation safety officers, collaborated to develop a decision-making guideline for the administration of therapeutic radiopharmaceuticals in patients with pretherapy or day-of-treatment incontinence. We discussed challenges and opportunities in the screening of patients in urine collection strategies according to grade of urinary incontinence and in subsequent coordination of care. Lutetium-177 ( 177 Lu)-based radiopharmaceutical therapies provided clinical examples of how our procedures were operationalized. Our key management issues of urinary incontinence were cutaneous radiation injury and redness, infection, or pain. In response, we developed clinical practice guidelines for the recognition and management of incontinence-related adverse events. Common adverse events of urinary incontinence were noted in this study. Our how-to guideline for the safe administration of therapeutic radiopharmaceuticals for patients with urinary incontinence warrants further investigation and should continue to be evaluated across all radiopharmaceutical therapy agents.

Clinical Pathobiology of Radiotherapy-Induced Alopecia: A Guide toward More Effective Prevention and Hair Follicle Repair

Because hair follicles (HFs) are highly sensitive to ionizing radiation, radiotherapy-induced alopecia (RIA) is a core adverse effect of oncological radiotherapy. Yet, effective RIA-preventive therapy is unavailable because the underlying pathobiology remains underinvestigated. Aiming to revitalize interest in pathomechanism-tailored RIA management, we describe the clinical RIA spectrum (transient, persistent, progressive alopecia) and our current understanding of RIA pathobiology as an excellent model for studying principles of human organ and stem cell repair, regeneration, and loss. We explain that HFs respond to radiotherapy through two distinct pathways (dystrophic anagen or catagen) and why this makes RIA management so challenging. We discuss the responses of different HF cell populations and extrafollicular cells to radiation, their roles in HF repair and regeneration, and how they might contribute to HF miniaturization or even loss in persistent RIA. Finally, we highlight the potential of targeting p53-, Wnt-, mTOR-, prostaglandin E2-, FGF7-, peroxisome proliferator-activated receptor-γ-, and melatonin-associated pathways in future RIA management.

Real-time 3D reconstruction of guidewires and stents using two update X-ray projections in a rotating imaging setup

BACKGROUND

Vascular diseases are often treated minimally invasively. The interventional material (stents, guidewires, etc.) used during such percutaneous interventions are visualized by some form of image guidance. Today, this image guidance is usually provided by 2D X-ray fluoroscopy, that is, a live 2D image. 3D X-ray fluoroscopy, that is, a live 3D image, could accelerate existing and enable new interventions. However, existing algorithms for the 3D reconstruction of interventional material require either too many X-ray projections and therefore dose, or are only capable of reconstructing single, curvilinear structures.

PURPOSE

Using only two new X-ray projections per 3D reconstruction, we aim to reconstruct more complex arrangements of interventional material than was previously possible.

METHODS

This is achieved by improving a previously presented deep learning-based reconstruction pipeline, which assumes that the X-ray images are acquired by a continuously rotating biplane system, in two ways: (a) separation of the reconstruction of different object types, (b) motion compensation using spatial transformer networks.

RESULTS

Our pipeline achieves submillimeter accuracy on measured data of a stent and two guidewires inside an anthropomorphic phantom with respiratory motion. In an ablation study, we find that the aforementioned algorithmic changes improve our two figures of merit by 75 % (1.76 mm → 0.44 mm) and 59 % (1.15 mm → 0.47 mm) respectively. A comparison of our measured dose area product (DAP) rate to DAP rates of 2D fluoroscopy indicates a roughly similar dose burden.

CONCLUSIONS

This dose efficiency combined with the ability to reconstruct complex arrangements of interventional material makes the presented algorithm a promising candidate to enable 3D fluoroscopy.

Optimized radiological alert thresholds based on device-dosimetric information to predict peak skin dose between 2 and 4 Gy during vascular fluoroscopically guided intervention

OBJECTIVES

To provide radiologists and physicists with methodological tools to improve patient management after vascular fluoroscopically guided intervention (FGI) by providing optimized thresholds (OT) values that could be used as a surrogate to the thresholds classically proposed by the National Council on Radiation Protection (NCRP) or could be useful to adapt their own substantial radiation dose levels (SRDL) values.

METHODS

PSD of 2000-4000 mGy after FGI were calculated for 258 patients with dedicated software. Overall, the kerma and KAP 3D-ROC curves were used to assess the sensitivity (SEN) and specificity (SPE) of NCRP thresholds and OT for each PSD. Kiviat diagram and density curves were plotted for the best SEN/SPE pair of 3D-ROC curves and compared to the NCRP thresholds.

RESULTS

OT for both kerma and KAP generating the best SEN/SPE couple for PSD of 2000-4000 mGy were obtained. The SEN/SPE couple of each OT was always better than that obtained using NCRP ones. The best OT among all those calculated providing the highest SEN/SPE values for kerma (3020.5 mGy) and KAP (741.02 Gy.cm2) were obtained when PSD was equal to 3300 mGy.

CONCLUSIONS

We have calculated OT in terms of kerma and KAP based on 3D-ROC curves analysis and peak skin dose calculations that can be obtained to better predict high skin dose. The use of OT that predicted PSD greater than 3000 mGy is likely to improve patient follow-up. The methodology developed in this work could be adapted to other institutions in order to better define their own SRDL.

KEY POINTS

• Optimized dose thresholds in terms of kerma and KAP based on 3D-ROC curves analysis and peak skin dose calculations between 2000 and 4000 mGy can be obtained to better predict high skin dose. • Patients receiving a peak skin dose between 2000 and 4000 mGy have their follow-up enhanced by using the optimized thresholds instead of the NCRP thresholds. • The best-optimized thresholds, corresponding to 3020.5 mGy and 741.02 Gy.cm2 for kerma and KAP respectively can be used instead of NRCP ones to trigger patient follow-up after fluoroscopically guided vascular interventions.

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.

A Tutorial on Diagnostic Benefit and Radiation Risk in Videofluoroscopic Swallowing Studies

The videofluoroscopic swallowing study (VFSS) is a key tool in assessing swallowing function. As with any diagnostic procedure, the probable benefits of the study must be weighed against possible risks. The probable benefit of VFSS is an accurate assessment of swallowing function, enabling patient management decisions potentially leading to improved patient health status and quality of life. A possible (though highly unlikely) risk in VFSS is carcinogenesis, arising from the use of ionizing radiation. Clinicians performing videofluoroscopic swallowing studies should be familiar with both sides of the risk benefit equation in order to determine whether the study is medically justified. The intent of this article is to provide the necessary background for conversations about benefit and risk in videofluoroscopic swallowing studies.

Prostaglandin E2 prevents radiotherapy-induced alopecia by attenuating transit amplifying cell apoptosis through promoting G1 arrest

BACKGROUND

Growing hair follicles (HFs) harbor actively dividing transit amplifying cells (TACs), rendering them highly sensitive to radiotherapy (RT). Clinically, there is still a lack of treatment options for radiotherapy-induced alopecia (RIA).

OBJECTIVE

Our present study aimed to investigated the effect and mechanism of local prostaglandin E2 (PGE2) treatment in RIA prevention.

METHODS

We compared the response of growing HFs to radiation with and without local PGE2 pretreatment in a mouse model in vivo. The effect of PGE2 on the cell cycle was determined in cultured HF cells from fluorescent ubiquitination-based cell cycle indicator mice. We also compared the protective effects of PGE2 and a cyclin-dependent kinases 4/6 (CDK4/6) inhibitor against RIA.

RESULTS

The local cutaneous PGE2 injection reduced RIA by enhancing HF self-repair. Mechanistically, PGE2 did not activate HF stem cells, but it preserved more TACs for regenerative attempts. Pretreatment of PGE2 lessened radiosensitivity of TACs by transiently arresting them in the G1 phase, thereby reducing TAC apoptosis and mitigating HF dystrophy. The preservation of more TACs accelerated HF self-repair and bypassed RT-induced premature termination of anagen. Promoting G1 arrest by systemic administration of palbociclib isethionate (PD0332991), a CDK4/6 inhibitor, offered a similar protective effect against RT.

CONCLUSIONS

Locally administered PGE2 protects HF TACs from RT by transiently inducing G1 arrest, and the regeneration of HF structures lost from RT is accelerated to resume anagen growth, thus bypassing the long downtime of hair loss. PGE2 has the potential to be repurposed as a local preventive treatment for RIA.

Operator Lower Leg Radiation Dose during Fluoroscopically Guided Interventions is Effectively Reduced by Wearing Lead-Equivalent Leg Wraps

BACKGROUND

The intensity of radiation scatter that emanates from the X-ray beam during fluoroscopically guided interventions is greater below the fluoroscopy table than above. Yet interventionalists' lower legs are typically unshielded and table skirts are often positioned incorrectly. We sought to characterize the efficacy of the leg protector wraps (Leg Wraps, Burlington Medical Inc.) in reducing the radiation dose to the operator's lower leg during fenestrated and branched endovascular aneurysm repair (F-BEVAR).

METHODS

A prospective cohort study was performed evaluating the lower leg radiation dose reduction of one vascular surgeon during F/BEVAR using antimony/bismuth Enviro-Lite leg wraps (0.35 mm lead equivalency, 99.7% attenuation at 50 kVp; Burlington Medical, Hampton Roads, Virginia). Optically Stimulated Luminescence nanoDot detectors (microSTARii System, LANDAUER, Inc., Glenwood, Illinois) were placed over and under the left leg wrap at the anterior tibial tuberosity position to compare operator leg dose with and without this additional protection. The table-mounted lead skirt was used consistently in all cases. The nanoDot detectors were cross-calibrated with a survey meter (RaySafe X2 survey sensor, Fluke Biomedical, Cleveland, Ohio) by measuring scattered radiation at a position equivalent to an operator's mid-tibia while performing digital acquisitions of a 25-cm thick, 30 cm × 30 cm acrylic phantom with a Philips FD20 fluoroscope (Philips Healthcare, Best, The Netherlands) with the table skirt removed. The measured radiation doses were converted to a Hp (0.07) skin dose, assuming an RQR6 beam spectrum (IEC-61267). Paired Wilcoxon test was performed to identify significant attenuation of radiation exposure.

RESULTS

Leg dose measurements from 40 F-BEVARs were analyzed. The patients had a median (interquartile range) body mass index of 27 (24-32) kg/m². Median procedure reference air kerma was 1,100 (728-1,601) mGy, kerma-area product was 127 (73-184) Gycm², and fluoroscopy time was 69 (54-86) min. The median skin dose H_p (0.07) over the leg wraps (n = 40) was 54.2 (24-100) μSv and under the leg wraps (n = 40) was 2.7 μSv (1.0-5.8). The leg wraps attenuated the radiation dose by 95% (89-98%) (P < 0.001). The unprotected, H_p (0.07) per kerma-area product was determined to be 0.38 (0.30-0.55) μSv/Gycm².

CONCLUSIONS

The 0.35-mm lead-equivalent leg wraps significantly decreased scattered radiation to the lower leg during F-BEVAR. Protective leg wraps should be recommended to operators performing complex fluoroscopically guided procedures.

Patient follow-up for possible radiation injury from fluoroscopically-guided interventions: Need to consider high cumulative exposure from multiple procedures

PURPOSE

Patient skin dose from interventional fluoroscopy procedures may exceed the threshold of tissue injuries and established guidelines recommend patient follow-up for air kerma at reference point (K_a,r) ≥ 5 Gy for individual procedures. Patients may undergo multiple procedures and skin injuries may be possible by cumulative exposure, even when individually insufficient to cause injury. This study sought to quantify the frequency of patients whose individual procedure doses are below 5 Gy but whose cumulative K_a,r is ≥ 5 Gy.

METHODS

This retrospective study analyzed 37,917 consecutive procedures in interventional radiology and vascular surgery at a tertiary-care hospital between January 2016 and June 2021. Radiation dosage was retrieved from the fluoroscopy acquisition systems. For a patient receiving multiple procedures, but each with K_a,r < 5 Gy, cumulative K_a,r within 2, 7, 14, 30, 183, and 365 days was assessed.

RESULTS

Nearly 1/3rd (37.4 %) patients underwent multiple procedures. With individual procedures of K_a,r < 5 Gy exclusively, 1.9, 4.4, and 5.6 in 1000 patients received cumulative K_a,r of 5-14.1 Gy from the procedures within 30, 183, and 365 days, respectively. From the procedures within 14 days, 1.3 in 1000 patients received cumulative K_a,r of 5-11.4 Gy; and from those within 7 days, 0.87 in 1000 patients received 5-9.1 Gy. In comparison, 4.3 in 1000 patients received K_a,r of 5-12 Gy from a single procedure.

CONCLUSIONS

In the absence of guidelines on patient follow-up for multiple procedures, our study may provide good material for setting up such guidelines.

ICRP PUBLICATION 153 Approved by the Commission in September 2022

Veterinary use of radiation in the diagnosis, management, and treatment of disease has expanded and diversified, as have the corresponding radiological protection concerns. Radiological exposure of personnel involved in veterinary procedures and, where applicable, members of the public providing assistance (e.g. owners or handlers) has always been included within the system of radiological protection. Veterinary practice is now addressed explicitly as the modern complexities associated with this practice warrant dedicated consideration, and there is a need to clarify and strengthen the application of radiological protection principles in this area. The Commission recommends that the system of radiological protection should be applied in veterinary practice principally for the protection of humans, but with explicit attention to the protection of exposed animals. Additionally, consideration should be given to the risk of potential contamination of the environment associated with applications of nuclear medicine in veterinary practice. This publication focuses primarily on justification and optimisation in veterinary practice, and sets the scene for more detailed guidance to follow in future Recommendations. It is intended for a wide-ranging audience, including radiological protection professionals, veterinary staff, students, education and training providers, and members of the public, as an introduction to radiological protection in veterinary practice.© 2022 ICRP. Published by SAGE.

Therapeutic targets and signaling mechanisms of dasatinib activity against radiation skin ulcer

Objective

To reveal the potential targets and signaling pathways of dasatinib in the treatment of radiation ulcers through network pharmacology and molecular docking technology.

Methods

Pathological targets of radiation ulcers were screened using GeneCards database. At the same time, the pharmacological targets of dasatinib were obtained through SwissTargetPrediction (STP), Binding DB and Drugbank databases. Subsequently, the potential targets of dasatinib for anti-radiation ulcers were obtained after intersection by Venn diagram. Next, a protein-protein interaction (PPI) network was constructed through the STRING database and core targets were screened. Finally, the identified core targets were subjected to GO and KEGG enrichment analysis, co-expression network analysis, and molecular docking technology to verify the reliability of the core targets.

Results

A total of 76 potential targets for anti-radiation ulcer with dasatinib were obtained, and 6 core targets were screened, including EGFR, ERBB2, FYN, JAK2, KIT, and SRC. These genes were mainly enriched in Adherens junction, EGFR tyrosine kinase inhibitor resistance, Focal adhesion, Bladder cancer and PI3K-Akt signaling pathway. Molecular docking results showed that dasatinib binds well to the core target.

Conclusion

Dasatinib may play a role in the treatment of radiation ulcers by regulating EGFR, ERBB2, FYN, JAK2, KIT, and SRC. These core targets may provide new insights for follow-up studies of radiation ulcers.

Retrospective Analysis of Doses Delivered during Embolization Procedures over the Last 10 Years

Background: This study aimed to retrospectively analyze dosimetric indicators recorded since 2012 for thoracic, abdominal or pelvic embolizations to evaluate the contribution of new tools and technologies in dose reduction. Methods: Dosimetric indicators (dose area product (DAP) and air kerma (AK)) from 1449 embolizations were retrospectively reviewed from August 2012 to March 2022. A total of 1089 embolizations were performed in an older fixed C-Arm system (A1), 222 in a newer fixed C-Arm system (A2) and 138 in a 4DCT system (A3). The embolization procedures were gathered to compare A1, A2 and A3. Results: DAP were significantly lower with A2 compared to A1 for all procedures (median −50% ± 5%, p < 0.05), except for uterine elective embolizations and gonadal vein embolization. The DAP values were significantly lower with A3 than with A1 (p < 0.001). CT scan was used for guidance in 90% of embolization procedures. Conclusions: The last C-Arm technology allowed a median reduction of 50% of the X-ray dose. The implementation of a CT scan inside the IR room allowed for more precise 3D-guidance with no increase of the dose delivered.

Application of reference air kerma alert levels for pediatric fluoroscopic examinations

The purpose of this study was to provide an empirical model to develop reference air kerma (RAK) alert levels as a function of patient thickness or age for pediatric fluoroscopy for any institution to use in a Quality Assurance program. RAK and patient thickness were collected for 10&663 general fluoroscopic examinations and 1500 fluoroscopically guided interventions (FGIs). RAK and patient age were collected for 6137 fluoroscopic examinations with mobile-C-arms (MC). Coefficients of linear regression fits of logarithmic RAK as a function of patient thickness or age were generated for each fluoroscopy group. Regression fits of RAK for 50%, 90%, and 98% upper prediction levels were used as inputs to derive an empirical formula to estimate alert levels as a function of patient thickness. A methodology is presented to scale results from this study for any patient thickness or age for any institution, for example, the patient thickness dependent RAK alert level at the top 1% of expected RAK can be set using the 98% upper prediction interval boundary given by:RAK 98 % = e m . x avg + s 98 . c ̂ ${\rm{RAK}}_{98\% } = {e}^{m.{x}_{{\rm{avg}}} + {s}_{98}.\hat{c}}\ $ , where xavg is the institute's average patient thickness or age, andc ̂ $\hat{c}$ is the intercept based on the average RAK of the patient population calculated asc ̂ = ln ( RAK avg ) - m . x avg . RA K avg $\hat{c} = \ln ( {{\rm{RAK}}_{{\rm{avg}}}} )\ - m.{x}_{{\rm{avg}}}{\rm{.RA}}{{\rm{K}}}_{{\rm{avg}}}$ is the institution's average RAK (mGy). m and s98 are constants presented for each type of fluoroscope and RAK group and represent slope of the fit and scale factor, respectively. An empirical equation, which estimates alert levels expressed as air Kerma without backscatter at the interventional reference point as a function of patient thickness or age is provided for each fluoroscopic examination type. The empirical equations allow any facility with limited data to scale the results of this study's single facility data to model their practice's unique RAK alert levels and patient population demographics to establish pediatric alert levels for fluoroscopic procedures.

Cumulative Radiation Exposure in Aneurysmal Subarachnoid Hemorrhage: A Single-Institution Analysis

OBJECTIVE

Diagnosis and management of aneurysmal subarachnoid hemorrhage (aSAH) depend heavily on imaging modalities that repeatedly expose patients to ionizing radiation. There is limited literature on cumulative radiation exposure in this patient population, which is a problem compounded by wide variation among institutions. The present study quantifies the cumulative cranial exposure to ionizing radiation resulting from diagnostic medical imaging and medical procedures during initial hospitalization for ruptured aSAH at a single academic institution and estimates the risk of future adverse events related to radiation injury.

METHODS

We performed a retrospective observational study of adults who presented to our institution during a nearly 3-year period with acute-onset aSAH, which was confirmed with diagnostic imaging, and had the aneurysm treated with either surgical clip ligation or endovascular embolization.

RESULTS

A total of 131 patients met the inclusion criteria. Eighty-eight patients (67%) were treated with endovascular embolization and 43 (32%) were treated with clip ligation. We found the average radiation dose to the head during the incident hospitalization for aSAH to be 4.40 Gy (95% confidence interval, 3.91-4.89). Angiography and interventional radiology procedures accounted for most of this exposure.

CONCLUSIONS

Most patients were exposed to levels of ionizing radiation that put them at considerable risk of deterministic radiation injury. Providers should be aware of the potential consequences of acute and long-term radiation exposure in this patient population, so they can monitor and counsel individuals accordingly and take steps to safely limit radiation exposure during aSAH management.

Technical Report of Color Doppler Ultrasonography-Assisted Lumbar Spinal Interventions

ABSTRACT

Ultrasonography (US) has recently been used more frequently during interventions involving the lumbar spine. However, physicians who are more familiar with musculoskeletal US targeting muscles, tendons, and nerves may find it challenging to perform US-guided lumbar spine interventions using only bony landmarks. This study described the use of color Doppler US for the visualization of the lumbar spinal blood supply to identify vascular landmarks in addition to bony landmarks and thus more easily and accurately perform lumbar spine interventions.

Anagen Effluvium after Neurointerventional Radiation: Trichoscopy as a Diagnostic Ally

Minimally invasive procedures for vascular brain lesions are being performed more frequently. Radiation exposure caused by endovascular embolization of cerebral aneurysms may give rise to nonscarring scalp alopecia located in the treated area. Clinical and trichoscopic features of this type of alopecia are similar to alopecia areata (AA). Herein, we performed a comprehensive review to describe the clinical and trichoscopic characteristics of radiation-induced anagen effluvium. Predominant trichoscopic findings include black dots, yellow dots, short vellus hairs, and absence of exclamation marks hairs. It is important to consider this diagnosis in patients who have recently undergone such procedures that can easily be misdiagnosed as AA.

Patient radiation dose during angiography and embolization for abdominal hemorrhage: the influence of CT angiography, fluoroscopy system, patient and procedural variables

Background

Angiography and embolization (AE) is a lifesaving, high radiation dose procedure for treatment of abdominal arterial hemorrhage (AAH). Interventional radiologists have utilized pre-procedure CT angiography (CTA) and newer fluoroscopic systems in an attempt to reduce radiation dose and procedure time.

Purpose

To study the factors contributing to the radiation dose of AE for AAH and to compare to the reference standard.

Materials and methods

This retrospective single-centre observational cohort study identified 154 consecutive AE procedures in 138 patients (median age 65 years; interquartile range 54–77; 103 men) performed with a C-arm fluoroscopic system (Axiom Artis DTA or Axiom Artis Q (Siemens Healthineers)), between January 2010 and December 2017. Parameters analysed included: demographics, fluoroscopy system, bleeding location, body mass index (BMI), preprocedural CT, air kerma-area product (PKA), reference air kerma (K_a,r), fluoroscopy time (FT) and the number of digital subtraction angiography (DSA) runs. Factors affecting dose were assessed using Mann–Whitney U, Kruskal–Wallis one-way ANOVA and linear regression.

Results

Patients treated with the new angiographic system (NS) had a median PKA, median K_a,r, Q3 PKA and Q3 K_a,r that were 74% (p < 0.0005), 66%(p < 0.0005), 55% and 52% lower respectively than those treated with the old system (OS). This dose reduction was consistent for each bleeding location (upper GI, Lower GI and extraluminal). There was no difference in PKA (p = 0.452), K_a,r (p = 0.974) or FT (p = 0.179), between those who did (n = 137) or did not (n = 17) undergo pre-procedure CTA. Other factors significantly influencing radiation dose were: patient BMI and number of DSA runs. A multivariate model containing these variables accounts for 15.2% of the variance in K_a,r (p < 0.005) and 45.9% of the variance of PKA (p < 0.005).

Conclusion

Radiation dose for AE in AAH is significantly reduced by new fluoroscopic technology. Higher patient body mass index is an independent key parameter affecting patient dose. Radiation dose was not influenced by haemorrhage site or performance of pre-procedure CTA.

Real-time Detection of Patient Head Position and Cephalometric Landmarks from Neuro-Interventional Procedure Images Using Machine Learning for Patient Eye-Lens Dose Prediction

A deep learning (DL) model has been developed to estimate patient-lens dose in real-time for given exposure and geometric conditions during fluoroscopically-guided neuro-interventional procedures. Parameters input into the DL model for dose prediction include the patient head shift from isocenter and cephalometric landmark locations as a surrogate for head size. Machine learning (ML) models were investigated to automatically detect these parameters from the in-procedure fluoroscopic image. Fluoroscopic images of a Kyoto Kagaku anthropomorphic head phantom were taken at various known X (transverse) and Y (longitudinal) shifts, as well as different magnification modes, to create an image database. For each image, anatomical landmark coordinate locations were obtained manually using ImageJ and are used as ground-truth labels for training. This database was then used to train the two separate ML models. One ML model predicts the patient head shift in both the X and Y directions and the other model predicts the coordinates of the anatomical landmarks. From the coordinates, the distance between these anatomical landmarks is calculated, and input into the DL dose-prediction model. Model performance was evaluated using mean absolute error (MAE) and mean absolute percentage error (MAPE) for the head-shift and landmark-coordinate models, respectively. The goal is to implement these two separate models into the Dose Tracking System (DTS) developed by our group. This would allow the DTS to automatically detect the patient head size and position for eye-lens dose prediction and eliminate the need for manual input by the clinical staff.

Reduction of radiation exposure during transcatheter edge-to-edge mitral valve repair

BACKGROUND

Transcatheter mitral valve repair is an increasingly used therapy for mitral regurgitation which requires fluoroscopic guidance. Limiting radiation exposure during lengthy procedures is important for both patient and operator safety. This study aimed to investigate radiation dose during contemporary use of MitraClip implantation and the effects of a dose reduction program.

METHODS

A total of 115 patients who underwent MitraClip implantation were prospectively enrolled in a single-center observational study. During the inclusion period, our institution adopted a radiation dose reduction program, comprising lowering of fluoroscopy pulse rate and image target dose. The first 58 patients were treated with conventional fluoroscopy settings, while the following 57 patients underwent the procedure with the newly implemented low dose protocol.

RESULTS

Radiation dose area product significantly decreased after introduction of the low dose protocol (693 [366-1231] vs. 2265 [1517-3914] cGy·cm² , p < 0.001). After correcting for fluoroscopy time, gender and body mass index, the low dose protocol emerged as a strong negative predictor of radiation dose (p < 0.001), reducing dose area product by 64% (95% confidence interval [57-70]). Device time, device success, and procedural safety did not differ between the normal dose and low dose group. Furthermore, the low dose protocol was not associated with an increased incidence of a combined endpoint consisting of death, repeat intervention, or heart surgery during 12 months follow-up.

CONCLUSION

Reduction of radiation exposure during transcatheter mitral valve repair by 64% is feasible without affecting procedural success or safety.

Cutaneous and local radiation injuries

The threat of a large-scale radiological or nuclear (R/N) incident looms in the present-day climate, as noted most recently in an editorial in Scientific American (March 2021). These large-scale incidents are infrequent but affect large numbers of people. Smaller-scale R/N incidents occur more often, affecting smaller numbers of people. There is more awareness of acute radiation syndrome (ARS) in the medical community; however, ionising radiation-induced injuries to the skin are much less understood. This article will provide an overview of radiation-induced injuries to the skin, deeper tissues, and organs. The history and nomenclature; types and causes of injuries; pathophysiology; evaluation and diagnosis; current medical management; and current research of the evaluation and management are presented. Cutaneous radiation injuries (CRI) or local radiation injuries (LRI) may lead to cutaneous radiation syndrome, a sub-syndrome of ARS. These injuries may occur from exposure to radioactive particles suspended in the environment (air, soil, water) after a nuclear detonation or an improvised nuclear detonation (IND), a nuclear power plant incident, or an encounter with a radioactive dispersal or exposure device. These incidents may also result in a radiation-combined injury; a chemical, thermal, or traumatic injury, with radiation exposure. Skin injuries from medical diagnostic and therapeutic imaging, medical misadministration of nuclear medicine or radiotherapy, occupational exposures (including research) to radioactive sources are more common but are not the focus of this manuscript. Diagnosis and evaluation of injuries are based on the scenario, clinical picture, and dosimetry, and may be assisted through advanced imaging techniques. Research-based multidisciplinary therapies, both in the laboratory and clinical trial environments, hold promise for future medical management. Great progress is being made in recognising the extent of injuries, understanding their pathophysiology, as well as diagnosis and management; however, research gaps still exist.

Radiation exposure during angiographic interventions in interventional radiology - risk and fate of advanced procedures

PURPOSE

Advanced angiographic procedures in interventional radiology are becoming more important and are more frequently used, especially in the treatment of several acute life-threatening diseases like stroke or aortic injury. In recent years, technical advancement has led to a broader spectrum of interventions and complex procedures with longer fluoroscopy times. This involves the risk of higher dose exposures, which, in rare cases, may cause deterministic radiation effects, e.g. erythema in patients undergoing angiographic procedures. Against this background, these procedures recently also became subject to national and international regulations regarding radiation protection. At the same time, individual risk assessment of possible stochastic radiation effects for each patient must be weighed up against the anticipated benefits of the therapy itself. Harmful effects of the administered dose are not limited to the patient but can also affect the radiologist and the medical staff. In particular, the development of cataracts in interventionalists is a rising matter of concern. Furthermore, long-term effects of repeated and prolonged x-ray exposure have long been neglected by radiologists but have come into focus in the past years.

CONCLUSIONS

With all this in mind, this review discusses different efforts to reduce radiation exposition levels for patients and medical staff by means of technical, personal as well as organizational measures.

Technical Note: Relationship between peak skin dose and fluoroscopic Ka,r : Clinical variations and application in establishing substantial radiation dose levels

BACKGROUND

The reference point cumulative air kerma (K_a,r ) is a commonly used dose quantity for establishing substantial radiation dose levels (SRDLs) that can provide guidance for patient dose management actions following fluoroscopically guided procedures. However, the K_a,r may not correlate well with the patient peak skin dose (D_skin,max ) because the relationship between K_a,r and D_skin,max may vary widely due to clinical variations. Therefore, it may be prudent for institutions to establish different K_a,r -based SRDL values based on the clinical procedure type.

PURPOSE

The present study investigates the relationship between K_a,r and D_skin,max for different clinical services and how that variation may overestimate or underestimate the need for patient follow-up. Additionally, the study suggests a possible framework for establishing K_a,r SRDLs based on the clinical data analysis.

METHODS

A retrospective analysis was performed for fluoroscopically guided interventions exceeding 5 Gy K_a,r . For each procedure, the patient D_skin,max was estimated and the ratio of D_skin,max to K_a,r (DKR) was calculated. Results were pooled into one of three clinical service categories: body interventions (n = 33), cardiac interventions (n = 81), or neurological (neuro) interventions (n = 44). The distributions in K_a,r , D_skin,max , and DKR were analyzed in aggregate and by the clinical service category.

RESULTS

The median K_a,r values for procedures exceeding 5 Gy were 6.0 Gy (95% CI [5.6, 6.4]) for body interventions, 5.8 Gy (95% CI [5.5, 6.0]) for cardiac interventions, and 6.3 Gy (95% CI [5.9, 6.6]) for neuro interventions. D_skin,max for the same procedure data sets were 5.0 Gy (95% CI [4.4, 5.6]) for body interventions, 5.5 Gy (95% CI [5.2, 5.8]) for cardiac interventions, and 3.7 Gy (95% CI [3.4, 4.0]) for neuro interventions. This resulted in median DKR values of 0.81 for body interventions, 0.91 for cardiac interventions, and 0.59 for neuro interventions.

CONCLUSIONS

This study illustrates the need to understand the relationship between the reported K_a,r and the patient D_skin,max for different types of interventional procedures. This is especially important when an institution uses K_a,r as the parameter for establishing an SRDL threshold to identify patients who may require clinical follow-up. The implications of this research and a guide for how to implement these findings are elaborated on in the Discussion.

Transient rectangular alopecia after endovascular embolization: A case series of four patients describing dermoscopic and histopathologic findings

Transient rectangular alopecia after endovascular embolization (TRAEE) is considered a specific form of radiodermatitis that is probably underreported in the literature. We present a case series of four patients from our hospital describing dermoscopic and histopathologic findings. Dermoscopic findings overlap with those of alopecia areata; therefore, TRAAE may be misdiagnosed without a precise history. Histopathology analysis of one of our cases showed different characteristics from the only report in the literature (high proportion of follicles in telogen phase). Initial reports considered that total radiation doses between 3 and 5 Gy produced TRAEE, whereas doses higher than 7Gy could trigger permanent alopecia. However, one of our patients exposed to a total dose of 7.6 Gy had complete hair regrowth.

Monte Carlo simulations and phantom validation of low-dose radiotherapy to the lungs using an interventional radiology C-arm fluoroscope

PURPOSE

To use MC simulations and phantom measurements to investigate the dosimetry of a kilovoltage x-ray beam from an IR fluoroscope to deliver low-dose (0.3-1.0 Gy) radiotherapy to the lungs.

MATERIALS AND METHODS

PENELOPE was used to model a 125 kV, 5.94 mm Al HVL x-ray beam produced by a fluoroscope. The model was validated through depth-dose, in-plane/cross-plane profiles and absorbed dose at 2.5-, 5.1-, 10.2- and 15.2-cm depths against the measured beam in an acrylic phantom. CT images of an anthropomorphic phantom thorax/lungs were used to simulate 0.5 Gy dose distributions for PA, AP/PA, 3-field and 4-field treatments. DVHs were generated to assess the dose to the lungs and nearby organs. Gafchromic film was used to measure doses in the phantom exposed to PA and 4-field treatments, and compared to the MC simulations.

RESULTS

Depth-dose and profile results were within 3.2% and 7.8% of the MC data uncertainty, respectively, while dose gamma analysis ranged from 0.7 to 1.0. Mean dose to the lungs were 1.1-, 0.8-, 0.9-, and 0.8- Gy for the PA, AP/PA, 3-field, and 4-field after isodose normalization to cover ∼ 95% of each lung volume. Skin dose toxicity was highest for the PA and lowest for the 4-field, and both arrangements successfully delivered the treatment on the phantom. However, the dose distribution for the PA was highly non-uniform and produced skin doses up to 4 Gy. The dose distribution for the 4-field produced a uniform 0.6 Gy dose throughout the lungs, with a maximum dose of 0.73 Gy. The average percent difference between experimental and Monte Carlo values were -0.1% (range -3% to +4%) for the PA treatment and 0.3% (range -10.3% to +15.2%) for the 4-field treatment.

CONCLUSION

A 125 kV x-ray beam from an IR fluoroscope delivered through two or more fields can deliver an effective low-dose radiotherapy treatment to the lungs. The 4-field arrangement not only provides an effective treatment, but also significant dose sparing to healthy organs, including skin, compared to the PA treatment. Use of fluoroscopy appears to be a viable alternative to megavoltage radiation therapy equipment for delivering low-dose radiotherapy to the lungs.