From new systems, to emerging best practices and increasing impact from artificial intelligence, presented in chronological order, here are the ten biggest CT stories of the year from our Daily News online.

Is proton CT superior to conventional CT for planning proton therapy?

Research in January showed that using proton CT instead of X-ray CT for proton therapy planning could spare patients from overexposure to radiation when undergoing multiple scans and may improve the accuracy of the treatment.

Proton therapy manufacturer ProtonVDA and researchers at Loyola University Stritch School of Medicine, Northern Illinois University and Loma Linda University found that proton CT reduced range uncertainties, which could allow radiation oncologists to potentially use smaller margins around tumors and more precisely deliver proton radiation to cancer sites.

The reason for this is because using X-ray CT requires the CT Hounsfield units to be converted into proton relative stopping power (RSP) to calculate proton range in the patient and generate a plan. This leads to uncertainties, which necessitates the need for wider margins. Proton CT directly measures RSP, which decreases uncertainties and may allow for smaller margins.

While small reductions in dose associated with a single scan are not likely to cause harm, the 10- to 100-fold decrease brought on by proton CT could enable scans to be repeated regularly, according to senior author James Welsh, a professor of radiation oncology at Loyola University Stritch School of Medicine.

The findings were published in Medical Physics.


MR-guided radiotherapy cuts side effects in half compared to CT for prostate

Scientists at the University of California, Los Angeles showed in February that using MR instead of CT to guide radiotherapy may result in fewer side effects for prostate cancer patients.

The findings are part of an interim analysis conducted during an ongoing Phase III randomized trial known as MIRAGE. Men undergoing SBRT for localized prostate cancer were randomly assigned to either CT-guidance or MR-guidance. Investigators assessed serious side effects or toxicities in both groups for 90 days following treatment and found those who underwent MR-guidance half as likely to experience treatment side effects.

When used with techniques such as high-dose stereotactic body radiotherapy, MR offers several theoretical advantages, including significantly reducing the need for planning margins in radiation. This is because the prostate and critical structures are more visible on MR than CT and because MR can perform real-time tracking to monitor the motion of the prostate

“This MRgRT platform obtains an MR four times a second and will 'turn off' the beam when the prostate moves outside of a preset boundary or margin. Because of these two features, we were able to significantly reduce the volume of tissue being targeted with radiation using MR-guidance. We hypothesized that this would in turn lead to less side effects,” Dr. Amar Kishan, vice chair of clinical and translational research in the departments of radiation oncology and urology at UCLA Health Jonsson Comprehensive Cancer Center, told HCB News.


Researchers in Germany develop dark-field CT prototype

Researchers at the Technical University of Munich showed in February they could derive more insight about human tissue for diagnosis through a combination of CT scanning and dark-field X-ray imaging.

Dark-field imaging provides information that conventional X-rays cannot on fine tissue structures, especially the lung. In conventional X-ray imaging, X-rays are attenuated by intervening tissue as they travel to the source of the detector. This creates images with varying degrees of attenuation that are based on tissue type and structures. When the X-rays interact with materials of different densities, such as an interface, they scatter. Dark-field imaging assesses this scattering effect to obtain more information on very fine tissue structures.

Technical challenges have made it hard to develop a dark-field CT device to the scale needed to assess human beings. But through their work, TUM researchers have developed a prototype that combines both technologies to produce 3D dark-field X-ray images. And it has already been used with a thorax phantom that depicts the upper human body and is large enough to repeat intended applications on real patients.

AI and CT combine to predict efficacy of immunotherapy for melanoma
Artificial intelligence has helped more accurately predict immunotherapy treatment outcomes for melanoma, according to Columbia University researchers in a March paper in JAMA Oncology.

The researchers created a machine learning algorithm that looked at patient CT scans and made a biomarker, called a radiomic signature, that correlated with “high accuracy” evaluating how well the melanoma would respond to immunotherapy.

“We hope to take a patient early on who looks like they are not doing well on a given therapy because of their signature and enhance, change, or add another drug to the therapy,” author Dr. Lawrence H. Schwartz of the Department of Radiology at Columbia University Vagelos College of Physicians and Surgeons said in a statement.

Plans now call for the project to broaden to other types of tumors — including lung, colon, prostate and renal, and to treatments other than immunotherapy.

At present, tumor size is the main way to determine therapy benefit. “Most of the current response criteria were developed several decades ago to assess the response to systemic treatments like chemotherapy,” noted first author Dr. Laurent Dercle of the Department of Radiology at the college. Since immunotherapy can lead to a transitory enlargement of tumors before a response, “we needed to create new tools in order to predict treatment success,” he added.


Seven ways to optimize CT dose: study

After consulting with over 26 radiology leaders worldwide, in March, a group of researchers compiled a list of seven strategies for optimizing CT dose and ensuring safe exposure to radiation during scans.

The authors spoke to radiologists, medical physicists, CT technologists and operational managers from healthcare systems in the U.S., Europe and Japan to compose their framework, and see it as a foundation for CT dose optimization.

Feedback included:
Engaging radiologists and technologists – Make discussing issues and proposing changes with a designated radiologist and CT technologist (typically the lead tech) a priority, and communicate changes to those working alongside them.
Creating a CT dose committee – Establish a structured, diverse and inclusive group to implement changes, set goals, develop protocols and manage reviews.
Manage organizational changes – Establish clear communication and keep everyone involved in talks. Educate staff.
Leadership and support – Provide resources and “man-hours” for completing necessary work. Aim for more than a “lukewarm leadership buy-in” to keep staff engaged and motivated.
Monitoring and benchmarking – Use dose information to make changes and set benchmarks. This can help show where one’s focus should be for creating and adjusting protocols.
Modifying CT protocols – “Harmonize” protocols to limit variation and avoid confusion. Several participants agreed that their protocols were locked until everyone agreed to modify them.
Equipment and work rule changes – Invest in newer technology to optimize CT doses. While expensive, it is considered a worthwhile investment, according to the authors. Participants also listed work rules pertaining to developing department procedures and protocols that can be communicated through manuals.

The list was published in the Journal of the American College of Radiology.


Deep learning reconstruction sufficient at reducing dose in pediatric CT scans

In April, using deep learning-based reconstruction, Japanese researchers reduced the dosage in pediatric CT exams while still maintaining the same or even improving on the image quality of those using interactive reconstruction algorithms.

Because children are more sensitive to ionizing radiation, clinicians use the lowest possible dose when scanning them. One way to do that is to decrease tube voltage with iterative reconstruction. But lowering voltage increases image noise and impairs detection of low-contrast objects, especially when using reduced slice thickness to assess a child’s small anatomic structures.

Hybrid iterative reconstruction (HIR) and model-based iterative reconstruction (MBIR) can reduce noise and artifacts but do not preserve noise texture, low-contrast spatial resolution and low-contrast object detectability as well when decreasing dose.

An emerging technique for CT image reconstruction, DLR uses a convolutional neural network to generate low-noise, high-quality images in short time frames, reports Physicsworld. The team applied the application to low-tube-voltage exams and reduced noise without degrading the noise texture and image sharpness.

The findings were published in the American Journal of Roentgenology.


FDA gives nod to Siemens' ARTIS icono ceiling CT angiography system

In July, Siemens Healthineers received FDA clearance for its ARTIS icono ceiling, a cone beam CT angiography system mounted to hospital ceilings for routine and advanced interventional radiology and cardiology procedures.

The solution scans the head in 2.5 seconds and the left and right sides of the body in four seconds. The short 3D spin reduces motion artifacts and makes scans dependent on less contrast media.

Its OPTIQ image chain increases image quality across C-arm angles and different patient weights, while reducing dose to levels that adhere to the As Low As Reasonably Achievable (ALARA) guiding principal for radiation safety.

"With the ARTIS icono ceiling, Siemens Healthineers combines excellent image quality and a previously unseen level of design flexibility to be the angiography system of choice for an unprecedented number of interventional radiology and cardiovascular procedures," said Kris McVey, vice president of interventional radiology and cardiology at Siemens Healthineers North America, in a statement.

OPTIQ sets exposure parameters based on desired image quality. New rotational capabilities and simplified cabling of the C-arm reduce scanning time. The system’s open architectural design enables vendor-neutral third-party applications to be integrated to keep it up-to-date, regardless of the vendor.

EHR guidelines decrease reliance on contrast-enhanced CT amid shortage
Implementing entry-based guidelines for EHR orders may enable large healthcare systems to significantly cut back the number of contrast-enhanced CT exams they perform while the global shortage of iodinated contrast media continues.

In a retrospective study published in August, researchers at Brigham and Women's Hospital looked at these exams performed at two large academic medical centers, seven community hospitals, three specialty hospitals and multiple affiliated ambulatory care centers. All used a single EHR System, Epic System’s Hyperspace.

Among 78,792 patients who underwent at least one CT exam in outpatient, inpatient and emergency department settings, the authors found that interventions in EHR orders led to a decrease in procedures using contrast media.

"The number of patients undergoing contrast-enhanced CT examinations per day decreased by 12%, and the number of orders for CT with contrast media decreased by 15.2% per day," they wrote in the study.

Brought on by the shutdown in March of GE Healthcare's Shanghai plant, the shortage has caused providers worldwide to ration nonurgent procedures and curb their use of contrast agents for those that require it the most. And while the plant has reopened, the impact still lingers.


EDs see jump in chest, abdominopelvic CT scans for trauma-related injuries

In August, researchers showed that chest and abdominopelvic CT scans rose among commercially insured patients for trauma-related ED visits between 2011 and 2018.

The largest gains were seen for single-encounter thoracabdominopelvic CT exams, which increased from 3.4 to 9.8 (1.16 per year) per 1,000 trauma-related ED encounters; and for minor injuries, which went from 1.1 to 4.6 (1.18).

This has raised concerns about higher costs and the detection of incidental findings. “Further investigation is warranted to explore the potential benefit of single-encounter thoracabdominopelvic CT examinations in patients with minor injuries, as well as strategies to optimize order appropriateness,” wrote first author Dr. Ninad Salastekar, from the department of radiology and imaging sciences at Emory University School of Medicine, in a statement.

Salastekar and his team studied trauma-related ED encounters recorded in national claims that they extracted from the IBM MarketScan Commercial Database. ED encounters were organized using the Injury Severity Score (minor, intermediate, major) through the International Classification of Diseases codes. They assessed chest CT, abdominopelvic CT and single-encounter thoracoabdominopelvic CT.

Intermediate and major injury CT scans also rose, from 6.4 to 16.4 (1.16); and 99.6 to 179.9 (1.08), respectively.

The study was published in the American Journal of Roentgenology.


Philips debuts world's first spectral detector angio CT suite

In September, Philips announced it had combined its Spectral CT 7500 system and its Azurion image-guided therapy system with FlexArm to form the world’s first spectral detector angio CT suite.

Designed to perform whole-body imaging in 2D and 3D, Azurion with FlexArm utilizes imaging systems, software and specialized diagnostic and therapeutic solutions to visualize critical anatomy so that clinicians can perform complex procedures.

Spectral CT improves detection, delineation and quantification of lesions to better plan minimally invasive operations. It also has shown more sensitivity in detecting malignant findings and improving readings of incidental findings.

Using Philips’ scanner allows clinicians to image patients only once to distinguish and quantify different tissues. Together, both solutions will allow clinicians to explore potential new treatments and improve minimally invasive procedures in oncology, stroke and trauma care.

"We cannot only visualize better but also quantify, for example, iodine uptake in the tumor with an embolization. Or using Spectral information to define treatment success before the patient leaves the room," Karim Boussebaa, general manager of image-guided therapy systems at Philips, told HCB News.


UW-Madison to begin scanning humans with GE Healthcare's silicon detector photon-counting CT

In November, researchers at the University of Wisconsin-Madison announced plans to begin scanning humans with GE Healthcare’s photon counting CT technology with deep silicon detectors in December 2022, making it the first U.S. clinical evaluation site for the scanner.

Photon-counting CT decreases pixel size and improves spatial resolution in images by converting individual X-ray photons into an electrical signal. It also has higher dose efficiency, allowing for ultrahigh-resolution images of large areas of the body to be captured. It offers the potential to visualize minute details in organ structures, improve tissue characterization, and provide more accurate material density measurements or quantification.

The solution’s silicon detectors are designed to enhance spatial and spectral resolution at the same time to improve imaging for oncology, cardiology, neurology, and other clinical CT applications.

Among the capabilities the researchers will examine are the scanner’s reconstruction methods, image presentation workflows, and clinical benefits for specific pathologies and disease types. They will use these insights to optimize photon counting CT with Deep Silicon detectors for better visualization and utilization.

Karolinska Institutet and MedTechLabs in Sweden performed the first clinical evaluation with the scanner in November 2021.

The new prototype at UW-Madison includes a larger detector that can possibly speed up scanning time and expand coverage; ECG-gated cardiac scan capabilities for coronary artery imaging; and faster acquisition speed for reducing the chance of blurred images due to motion.


CT scan rates increase in hotter weather, researchers say at RSNA

Using a decade of weather and CT imaging data, researchers have identified specific weather conditions that are associated with the number of whole-body CT scans performed on polytrauma patients, or patients with injuries to multiple body parts. The results of the study were presented in December at the RSNA meeting in Chicago.

“Trauma accounts for a large portion of hospital admissions, and since polytrauma is particularly time-consuming and unpredictable, we wanted to investigate the association between weather fluctuations and the number of polytrauma CTs performed at our hospital,” said study co-author Dr. Martin Segeroth, a radiology resident in the department of radiology and nuclear medicine at the University of Basel in Switzerland.

Patients who suffer polytrauma typically require a whole-body CT that includes at least the chest, abdomen and pelvis. The exam requires a radiologist to provide an immediate reading and possible follow-up imaging and interpretation.

The researchers’ data set included 4,613 polytrauma CT scans performed in the Emergency Department of the University of Basel between 2011 and 2020. The median age of patients was 57 years, and 66% were male. The team also collected daily weather data, including average temperature, total cloud cover, wind speed, sunshine duration and precipitation.

Statistical analysis of the weather and imaging data revealed that hotter weather with more sunshine and UV light, less wind and fewer clouds was associated with a higher volume of polytrauma CTs. Colder, windier, cloudier days with less sunshine and less UV light correlated with fewer polytrauma CTs. More polytrauma CTs were performed at the hospital in the summer months (April through September) compared to the winter months (October through March).

“Many hospital admission rates, most notably those for respiratory and cardiovascular disease, are linked to weather variations,” Segeroth said.

The researchers also set out to forecast daily polytrauma CT occurrence by employing multiple machine learning algorithms on the historical data. Their model predicted 73% of the days where polytrauma CT use was higher than average and 83% of days where polytrauma use was lower than average. While the amount of cloud cover and temperature were the most important parameters for predicting daily polytrauma CT occurrence, the exact relationship between hotter weather and the increase in trauma cases remains unclear.

“One speculation is that in the summer, people are engaging in more outdoor activities — for instance sports — whereas in winter people are less often outside,” Segeroth said. “Although we don't have an explanation for it, we’ve observed a strong association.”

Segeroth said the hospital is considering creating a dashboard on its intranet to alert staff when above-normal volumes of polytrauma CTs are expected.