Development of an application to visualise the spread of scattered radiation in radiography using augmented reality

Visualization of spatial dose distribution for effective radiation protection education in interventional radiology: obtaining high-accuracy spatial doses

In recent years, eye lens exposure among radiation workers has become a serious concern in medical X-ray fluoroscopy and interventional radiology (IVR), highlighting the need for radiation protection education and training. This study presents a method that can maintain high accuracy when calculating spatial dose distributions obtained via Monte Carlo simulation and establishes another method to three-dimensionally visualize radiation using the obtained calculation results for contributing to effective radiation-protection education in X-ray fluoroscopy and IVR. The Monte Carlo particle and heavy ion transport code system (PHITS, Ver. 3.24) was used for calculating the spatial dose distribution generated by an angiography device. We determined the peak X-ray tube voltage and half value layer using Raysafe X2 to define the X-ray spectrum from the source and calculated the X-ray spectrum from the measured results using an approximation formula developed by Tucker et al. Further, we performed measurements using the "jungle-gym" method under the same conditions as the Monte Carlo calculations for verifying the accuracy of the latter. An optically stimulated luminescence dosimeter (nanoDot dosimeter) was used as the measuring instrument. In addition, we attempted to visualize radiation using ParaView (version 5.12.0-RC2) using the spatial dose distribution confirmed by the above calculations. A comparison of the measured and Monte Carlo calculated spatial dose distributions revealed that some areas showed large errors (12.3 and 24.2%) between the two values. These errors could be attributed to the scattering and absorption of X-rays caused by the jungle gym method, which led to uncertain measurements, and (2) the angular and energy dependencies of the nanoDot dosimetry. These two causes explain the errors in the actual values, and thus, the Monte Carlo calculations proposed in this study can be considered to have high-quality X-ray spectra and high accuracy. We successfully visualized the three-dimensional spatial dose distribution for direct and scattered X-rays separately using the obtained spatial dose distribution. We established a method to verify the accuracy of Monte Carlo calculations performed through the procedures considered in this study. Various three-dimensional spatial dose distributions were obtained with assured accuracy by applying the Monte Carlo calculation (e.g., changing the irradiation angle and adding a protective plate). Effective radiation-protection education can be realized by combining the present method with highly reliable software to visualize dose distributions.

Evaluation of radiation protection effectivity in a cardiac angiography room using visualized scattered radiation distribution

In this study, we devised a radiation protection tool specifically designed for healthcare professionals and students engaged in cardiac catheterization to easily monitor and evaluate scattered radiation distribution across diverse C-arm angles and arbitrary physician associated staff positions-scrub nurse and technologist positions. In this study, scattered radiation distributions in an angiography room were calculated using the Monte Carlo simulation of particle and heavy ion transport code system (PHITS) code. Four visualizations were performed under different C-arm angles with and without radiation protection: (1) a dose profile, (2) a 2D cross-section, (3) a 3D scattered radiation distribution, and (4) a 4D scattered radiation distribution. The simulation results detailing the scattered radiation distribution in PHITS were exported in Visualization Toolkit format and visualized through the open-source visualization application ParaView for analysis. Visualization of the scattered dose showed that dose distribution depends on the C-arm angle and the x-ray machine output parameters (kV, mAs s-1, beam filtration) which depend upon beam angulation to the patient body. When irradiating in the posterior-anterior direction, the protective curtain decreased the dose by 62% at a point 80 cm from the floor, where the physician's gonads are positioned. Placing the protection board close to the x-ray tube reduced the dose by 24% at a location 160 cm from the floor, where the lens of the eye is situated. Notably, positioning the protection board adjacent to the physician resulted in a 95.4% reduction in incident air kerma. These visualization displays can be combined to understand the spread and direction of the scattered radiation distribution and to determine where and how to operate and place radiation protection devices, accounting for the different beam angulations encountered in interventional cases. This study showed that scatter visualization could be a radiation protection teaching aid for students and medical staff in angiography rooms.

The Usefulness of a Virtual Environment-Based Patient Setup Training System for Radiation Therapy

In radiation therapy, patient setup is important for improving treatment accuracy. The six-axis couch semi-automatically adjusts the patient's position; however, adjusting the patient to twist is difficult. In this study, we developed and evaluated a virtual reality setup training tool for medical students to understand and improve their patient setup skills for radiation therapy. First, we set up a simulated patient in a virtual space to reproduce the radiation treatment room. A gyro sensor was attached to the patient phantom in real space, and the twist of the phantom was linked to the patient in the virtual space. Training was conducted for 24 students, and their operation records were analyzed and evaluated. The training's efficacy was also evaluated through questionnaires provided at the end of the training. The total time required for patient setup tests before and after training decreased significantly from 331.9 s to 146.2 s. As a result of the questionnaire regarding the usability of training to the trainee, most were highly evaluated. We found that training significantly improved students' understanding of the patient setup. With the proposed system, trainees can experience a simulated setup that can aid in deepening their understanding of radiation therapy treatments.

Directional vector visualization of scattered rays in mobile c-arm fluoroscopy

Previous radiation protection-measure studies for medical staff who perform X-ray fluoroscopy have employed simulations to investigate the use of protective plates and their shielding effectiveness. Incorporating directional information enables users to gain a clearer understanding of how to position protective plates effectively. Therefore, in this study, we propose the visualization of the directional vectors of scattered rays. X-ray fluoroscopy was performed; the particle and heavy-ion transport code system was used in Monte Carlo simulations to reproduce the behavior of scattered rays in an X-ray room by reproducing a C-arm X-ray fluoroscopy system. Using the calculated results of the scattered-ray behavior, the vectors of photons scattered from the phantom were visualized in three dimensions. A model of the physician was placed on the directional vectors and dose distribution maps to confirm the direction of the scattered rays toward the physician when the protective plate was in place. Simulation accuracy was confirmed by measuring the ambient dose equivalent and comparing the measured and calculated values (agreed within 10%). The directional vectors of the scattered rays radiated outward from the phantom, confirming a large amount of backscatter radiation. The use of a protective plate between the patient and the physician's head part increased the shielding effect, thereby enhancing radiation protection for the physicians compared to cases without the protective plate. The use of directional vectors and the surrounding dose-equivalent distribution of this method can elucidate the appropriate use of radiation protection plates.

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.

Spatial Scattering Radiation to the Radiological Technologist during Medical Mobile Radiography

Mobile radiography allows for the diagnostic imaging of patients who cannot move to the X-ray examination room. Therefore, mobile X-ray equipment is useful for patients who have difficulty with movement. However, staff are exposed to scattered radiation from the patient, and they can receive potentially harmful radiation doses during radiography. We estimated occupational exposure during mobile radiography using phantom measurements. Scattered radiation distribution during mobile radiography was investigated using a radiation survey meter. The efficacy of radiation-reducing methods for mobile radiography was also evaluated. The dose decreased as the distance from the X-ray center increased. When the distance was more than 150 cm, the dose decreased to less than 1 μSv. It is extremely important for radiological technologists (RTs) to maintain a sufficient distance from the patient to reduce radiation exposure. The spatial dose at eye-lens height increases when the bed height is high, and when the RT is short in stature and abdominal imaging is performed. Maintaining sufficient distance from the patient is also particularly effective in limiting radiation exposure of the eye lens. Our results suggest that the doses of radiation received by staff during mobile radiography are not significant when appropriate radiation protection is used. To reduce exposure, it is important to maintain a sufficient distance from the patient. Therefore, RTs should bear this is mind during mobile radiography.

Real-time mixed reality display of dual particle radiation detector data

Radiation source localization and characterization are challenging tasks that currently require complex analyses for interpretation. Mixed reality (MR) technologies are at the verge of wide scale adoption and can assist in the visualization of complex data. Herein, we demonstrate real-time visualization of gamma ray and neutron radiation detector data in MR using the Microsoft HoloLens 2 smart glasses, significantly reducing user interpretation burden. Radiation imaging systems typically use double-scatter events of gamma rays or fast neutrons to reconstruct the incidence directional information, thus enabling source localization. The calculated images and estimated 'hot spots' are then often displayed in 2D angular space projections on screens. By combining a state-of-the-art dual particle imaging system with HoloLens 2, we propose to display the data directly to the user via the head-mounted MR smart glasses, presenting the directional information as an overlay to the user's 3D visual experience. We describe an open source implementation using efficient data transfer, image calculation, and 3D engine. We thereby demonstrate for the first time a real-time user experience to display fast neutron or gamma ray images from various radioactive sources set around the detector. We also introduce an alternative source search mode for situations of low event rates using a neural network and simulation based training data to provide a fast estimation of the source's angular direction. Using MR for radiation detection provides a more intuitive perception of radioactivity and can be applied in routine radiation monitoring, education & training, emergency scenarios, or inspections.

Visualization of dose distribution and basic study of dose estimation using plastic scintillator and digital camera

Radiation can be visualized using a scintillator and a digital camera. If the amount of light emitted by the scintillator increases with dose, the dose estimation can be obtained from the amount of light emitted. In this study, the basic performance of the scintillator and digital camera system was evaluated by measuring computed tomography dose index (CTDI). A circular plastic scintillator plate was sandwiched between polymethyl methacrylate (PMMA) phantoms, and X-rays were irradiated to them while rotating the X-ray tube to confirm changes in light emission. In addition, CTDI was estimated from the amount of light emitted by the scintillator during the helical scan and compared with the value measured from dosimeter. The scintillator emitted light while changing its distribution according to the movement of the X-ray tube. The measured CTDIvol was 33.20 mGy, the CTDIvol estimated from the scintillation light was approximately 46 mGy, which was 40% larger. In particular, when the scintillator was directly irradiated, the dose was overestimated compared with the value measured from the dosimeter. This overestimation can be because of the reproducibility of the position and the difference between the sensitivity of the scintillator to detect light emission and the sensitivity of the dosimeter, and the non-uniformity of position sensitivity due to the wide-angle lens.

What are useful methods to reduce occupational radiation exposure among radiological medical workers, especially for interventional radiology personnel?

Protection against occupational radiation exposure in clinical settings is important. This paper clarifies the present status of medical occupational exposure protection and possible additional safety measures. Radiation injuries, such as cataracts, have been reported in physicians and staff who perform interventional radiology (IVR), thus, it is important that they use shielding devices (e.g., lead glasses and ceiling-suspended shields). Currently, there is no single perfect radiation shield; combinations of radiation shields are required. Radiological medical workers must be appropriately educated in terms of reducing radiation exposure among both patients and staff. They also need to be aware of the various methods available for estimating/reducing patient dose and occupational exposure. When the optimizing the dose to the patient, such as eliminating a patient dose that is higher than necessary, is applied, exposure of radiological medical workers also decreases without any loss of diagnostic benefit. Thus, decreasing the patient dose also reduces occupational exposure. We propose a novel four-point policy for protecting medical staff from radiation: patient dose Optimization, Distance, Shielding, and Time (pdO-DST). Patient dose optimization means that the patient never receives a higher dose than is necessary, which also reduces the dose received by the staff. The patient dose must be optimized: shielding is critical, but it is only one component of protection from radiation used in medical procedures. Here, we review the radiation protection/reduction basics for radiological medical workers, especially for IVR staff.

Development and evaluation of the effectiveness of educational material for radiological protection that uses augmented reality and virtual reality to visualise the behaviour of scattered radiation

Understanding the behaviour of scattered radiation is important for learning appropriate radiation protection methods, but many existing visualisation systems for radiation require special devices, making it difficult to use them in education. The purpose of this study was to develop teaching material for radiation protection that can help visualise the scattered radiation with augmented reality (AR) and virtual reality (VR) on a web browser, develop a method for using it in education and examine its effectiveness. The distribution of radiation during radiography was calculated using Monte Carlo simulation, and teaching material was created. The material was used in a class for department of radiological technology students and its influence on motivation was evaluated using a questionnaire based on the evaluation model for teaching materials. In addition, text mining was used to evaluate impressions objectively. Educational material was developed that can be used in AR and VR for studying the behaviour of scattered radiation. The results of the questionnaire showed that the average value of each item was more than four on a five-point scale, indicating that the teaching material attracted the interest of users. Through text mining, it could be concluded that there was improved understanding of, and confidence in, radiation protection.

Radiation protection education using virtual reality for the visualisation of scattered distributions during radiological examinations

When working in radiology and patient assistance in medical facilities, radiation workers need to understand how to properly protect themselves and others from scattered radiation. In this study, a visualisation method is examined to facilitate the understanding of the spread of scattered radiation in radiography, computerised tomography (CT), and angiography rooms, and the application of this system for radiation protection education is proposed. X-ray radiography, x-ray CT, and angiography rooms were constructed using the particle and heavy ion transport code system, and the scattered radiation distributions that occurred when a patient was irradiated with x-rays were simulated. The three-dimensional (3D) distribution of each moment was continuously displayed to create a four-dimensional (4D) distribution. Using the obtained data, a radiation protection education seminar was conducted that included exercises to allow the students to confirm the presence of scattered radiation from any direction. The effectiveness of the scattered radiation visualisation data was evaluated using an interview. The position of the assistant for conducting standing chest radiographs that experienced the least scattered radiation was determined to be at the side and foot side of the patient. As a result of an interview that was provided to the participants following the seminar, the effectiveness of this system for providing education about radiation protection was confirmed. The visualisation method allowed the students to better understand the behaviour of radiation and the sources of scattered radiation. The visualisation of 3D and 4D scattered radiation distributions in radiological examination rooms can intuitively enhance the understanding of the spread of invisible radiation and the appropriate methods of mitigating radiation exposure.

Development and assessment of an educational application for the proper use of ceiling-suspended radiation shielding screens in angiography rooms using augmented reality technology

PURPOSE

An augmented reality (AR) application to help medical staff involved in interventional radiology (IR) learn how to properly use ceiling-suspended radiation shielding screens was created, and its utility was tested from the perspective of learner motivation.

METHOD

The distribution of scattered radiation in an angiography room was visualized with an AR application in three settings: when a ceiling-suspended radiation shielding screen is not used (incorrect); when there is a gap between the bottom edge of the shielding screen and the patient's torso (incorrect); and when there is no gap between the bottom edge of the shielding screen and the patient's torso (correct). This AR application was used by 33 medical staff, after which an Instructional Materials Motivation Survey (IMMS) based on the John Keller's ARCS (four categories of Attention, Relevance, Confidence, and Satisfaction) Motivation Model, consisting of 36-items with responses on a 5-point (1-5) Likert scale, was conducted.

RESULTS

The overall score was a high 4.67 ± 0.30 (mean ± standard deviation). Physician's scores tended to be lower than those of other medical staff in the categories of Attention, Relevance, and Satisfaction (not statistically significant).

CONCLUSIONS

The AR application to learn how to properly use ceiling-suspended radiation shielding screens was highly rated from the perspective of learner motivation.

Medical application of particle and heavy ion transport code system PHITS

The Particle and Heavy Ion Transport code System (PHITS) is a general-purpose Monte Carlo simulation code that has been applied in various areas of medical physics. These include application in different types of radiotherapy, shielding calculations, application to radiation biology, and research and development of medical tools. In this article, the useful features of PHITS are explained by referring to actual examples of various medical applications.