Moving Target — Best Practices for Reducing Dose in the IR Suite
By Keith Loria
Vol. 22 No. 3 P. 18
Responsible use of radiation in medical imaging continues to be a focus for best practices to ensure the safety and satisfaction of patients and clinicians. Fortunately, there are technologies on the market today that dramatically help lower patient dose and come equipped with high-sensitivity detectors and advanced image processing technologies.
Medical imaging used in IR, such as fluoroscopy, MRI, CT, and ultrasound, increasingly is being utilized to guide minimally invasive surgical procedures that diagnose, treat, and cure many kinds of conditions. That’s why there are continued efforts by manufacturers, regulators, and accreditors to reduce patient and occupational radiation dose by equipment type, manage protocols, and, more recently, leverage automated data collection software.
“Studies of protocols to reduce dose, based on patient parameters, are ongoing, ensuring optimized dose for image quality needed for precise diagnoses,” says Fredrik Celen, product manager for RaySafe. “Many physicians are getting more active in understanding the frame rate per second and radiation scatter concern. Such awareness and attention to detail may lead to healthy competitiveness among interventional radiologists, who review their data for quality and safety.”
Celen adds that trends in dose technology in 2021 include iterating on equipment design, with manufacturers adding a big-screen accessory to easily show the amount of scatter radiation in an interventional suite, and ensuring the use of personal protective equipment for workers, along with properly positioning staff in IR suites and utilizing screening devices in high-dose procedures.
Sanjit Tewari, MD, an academic interventional and nuclear radiologist and a reading radiologist at DocPanel, points to the old adage of radiation safety being linked to the concepts of distance and time. With regard to patients, the crux of dose safety is founded on these points, specifically reducing exposure times and increasing the patient’s distance from the radiation source as much as technologically possible. “Being closer to a source of radiation results in an exponentially higher dose, and an increase in time of exposure results in a linearly increased dose,” Tewari says. “Together, these two points form the backbone for basic radiation safety, specifically, increasing the distance from the radiation source and decreasing overall exposure time as much as technically and clinically feasible.”
However, Tewari notes some additional strategies for dose reduction. “Appropriate collimation of the radiation beam and proper case planning, including review of or having previous/correlative images available, can further reduce overall radiation usage time,” he says. “Proper patient positioning can also reduce the amount of tissue the radiation beam must penetrate and thus reduce the overall beam intensity. Occasionally, shielding of nonimaged portions of the patient’s body may reduce scatter dose from the patient to him/herself.”
For health care workers who are more regularly exposed to ionizing radiation than typical patients, there are additional precautions that can decrease dose. “Lead glasses, vests, and aprons, in addition to lead shielding, both fixed and portable, are now ubiquitous in radiation-emitting labs and can dramatically decrease overall exposure,” Tewari says. “Lead-lined gloves, if used properly, can also decrease the overall dose.”
Coordination with ancillary staff and assistants is a critical component of implementing an effective dose safety program. “Patient positioning, the appropriate positioning of mobile shielding, and vigilant use of collimation, a task often best implemented by a first or second assistant, can have significant impacts on overall dose to operators,” Tewari says. “Using appropriate settings for angiography can also decrease overall dose and/or better acquire diagnostic images the first time, resulting in fewer repeat image acquisitions.”
Aaron Kyle Jones, PhD, an associate professor in the department of imaging physics at the University of Texas MD Anderson Cancer Center in Houston and a member representative of the Society of Interventional Radiology, is excited about the new ACR Fluoroscopy Dose Index Registry, which became available last fall. “We have just completed the data acquisition of the pilot phase. We collected dose data on more than 40,000 procedures, mapped it to a common procedural lexicon, and are beginning the data analysis,” Jones says. “This is opening up to any site that wishes to participate so they can have the ability to compare their fluoroscopy dose to peer sites across the country.”
Previously, it was difficult to determine whether the dosing was optimal because there were no good benchmarks to compare, but now clinicians can use the registry to see what has worked for others. “What you’ll see over the next few years, as sites join up, is a convergence of practices as they see where they fall in relation to their peers,” Jones says.
Celen notes that the RaySafe i3 Real-Time Dosimetry System is helping to visualize the radiation flow when each health care worker wears the dosimeter, which is linked to a display unit. The immediate feedback it offers allows for just-in-time positioning adjustments.
“Additionally, after the procedure, the procedure data can be stored, analyzed, and used for safety and quality improvements within the hospital radiology department,” Celen adds. “This way, radiation safety officers can identify staff with high doses and intervene for safety.” In some US hospitals, these data are informing quality assurance and performance improvement programs, some of which are part of formal quality programs.
Over the last several years, radiation therapy technologies and X-ray solutions have gone through many positive changes to improve the target localization accuracy and dose conformity. Often, the challenges that come with sophisticated changes in technology include training the staff who are using the new equipment. To ensure technologists are using the technology in an accurate and safe manner, it is critical that both the vendor who supplied the new equipment and the medical facility offer training on the new systems.
Rise of DR Imaging
Rob Fabrizio, director of strategic marketing of digital radiography for Fujifilm Medical Systems USA, says more hospitals and medical imaging facilities are investing in DR solutions that optimize results with low dose. “From ongoing conversations with our customers, we’re hearing that hospitals are excited about the latest detector designs,” Fabrizio says. “Over the past decade, a significant percentage of hospital purchases for new X-ray equipment have transitioned to DR, especially as DR detectors have become lighter, more dose efficient, wireless, and more affordable.”
Fujifilm recently released its third generation of DR detectors with the FDR D-EVO III, which includes the company’s patented Irradiated Side Sampling (ISS) technology. ISS helps to increase sharpness by capturing signals where they are sharpest and strongest, reducing light scatter, blur, and dose. Additionally, grid simulation software, such as Fujifilm’s Virtual Grid image processing, eliminates the need for a physical grid for larger anatomy exams and can lower dose as much as 50% compared with grid exams.
“By eliminating the use of a physical grid, you are also preventing added dose from retakes caused by grid-to-tube alignment of a physical grid,” Fabrizio says. “This advanced processing performs on all patient sizes and helps make exam positioning easier and lighter for the technologist and faster and more comfortable for the patient.”
The company also offers FCT PixelShine, available with Fujifilm’s recent Persona CT system, which is a deep learning image reconstruction processing technology that improves image quality in low-dose CT scans by minimizing the effects of noise in low-dose image acquisitions.
On the Horizon
Today, many systems have built-in menus to help teach and guide users on best practices, with preset automated preferred-dose techniques based on body parts, the individual performance of the system’s sensitivity, and dose performance characteristics. “These built-in features can be particularly helpful to a technologist, especially when they are transitioning to a new system that is much more dose efficient than the prior system the facility replaced,” Fabrizio says. “These automated menus can be customized to site preferences and patient sizes, such as dedicated neonatal, pediatric, adult, and bariatric exams.”
In the years ahead, Jones believes more innovative flat-panel detectors will continue to replace image intensifiers. “We’ve already seen research published on tracking the area of interest in a fluoroscopy image and changing the collimation to only irradiate the areas of interest,” he says. “Maybe that’s detected by eye tracking, maybe by AI imaging, but we’ll be adjusting the application of X-rays to optimize our knowledge of what’s being viewed in an image.” Additionally, he sees more hybrid systems coming to market, where CT and interventional fluoroscopy are used together to do volumetric imaging of large regions.
Celen predicts continued development of smart connectivity, such as the Internet of Things, to play a bigger role in dose safety, with manufacturers bringing information forward visually and clearly for practitioner application and patient safety.
Tewari notes that technological advancements are bound to further assist radiation dose reduction, which continues to derive benefits from either decreasing time of exposure or effective distance from a radiation source. “Robotic-assisted angiography, such as the CorPath GRX system from Corindus, is one such solution that removes the operator from the angiography suite after establishing access and allows wiring/catheter selection to occur via remote manipulation, without any further radiation exposure to the operator,” he says.
In addition, advances in radiation protection suits have potentiated the wearing of thicker suits with better coverage. One such exoskeleton-based technology created by StemRad MD has applications for professionals ranging from health care workers to astronauts in orbit.
Furthermore, software solutions and integrations can continue to improve dose safety for patients and practitioners. “Image reconstruction algorithms, needle/embolization guidance software, and multimodality imaging integration can all result in reduced overall dose from ionizing radiation,” Tewari says. “One such example of ultrasound/MRI image correlation can allow for complex procedures to be performed without any ionizing radiation at all, using nonionizing real-time ultrasound imaging correlated to previously acquired nonionizing MRI images. Thus, such software advancements continue to decrease or even completely nullify dose from ionizing radiation for certain image-guided interventions.”
Fabrizio expects hospitals and equipment manufacturers to provide built-in tools for automating, tracking, and comparing low-dose protocols. “Various imaging systems generate Radiation Dose Structured Reporting data outputs, real-time feedback, and tracking of national exposure and deviation indexes used on individual exams, which can showcase how a provider compares to other hospitals across the nation,” he says. “We hope to see more vendors worldwide offering imaging technologies that offer low-dose capabilities and safety mechanisms to help contribute to the overall patient comfort and experience.”
— Keith Loria is a freelance writer based in Oakton, Virginia. He is a frequent contributor to Radiology Today.