As the demand for CT examinations continue to increase, radiologists need to think more carefully about how to optimise CT protocols to reduce the risks of radiation exposure to patients. That’s the view of Prof. Mika Kortesniemi, chief physicist and adjunct professor at Helsinki University Hospital, Finland.

“CT protocol optimisation has a huge influence because it involves the majority of cumulative radiation exposure in radiology and its impact on patients,” he told ECR Today.

Prof. Mika Kortesniemi is chief physicist and adjunct professor at HUS Medical Imaging Center, University of Helsinki, Finland. His professional focus is on quality assurance, dosimetry, optimisation and radiation protection in x-ray modalities, especially evolving CT technology. He was Chair of the ECR 2020 Physics in Medical Imaging Subcommittee.

Kortesniemi, who will be chairing the second of two European Federation of Organisations for Medical Physics (EFOMP) workshops, emphasises that CT is changing rapidly, with new models of CT scanners being developed, as well as additional features. These include a wider variety of types of image reconstruction techniques, such as filtered back projection and iterative methods, which work differently in a range of devices. There have also been innovations in deep learning, with at least two vendors now offering artificial intelligence (AI)-based reconstruction for CT.

Combined with the steady growth in the number of CT exams, as hospitals shift increasingly from 2D to 3D imaging, this has generated a huge variety of CT protocols – even within the same hospital. He argues that harmonising and managing these protocols should now be a major priority for imaging professionals.

“CT optimisation should be a multi-professional effort involving medical physicists, radiologists, and radiographers,” noted Kortesniemi, who adds that because radiographers and technicians are closely involved in patient safety and workflow, they have an important role to play in optimising protocols.

Optimising workflow to reduce the rate of repeat examinations will form part of a talk to be given by Dr. Timothy Szczykutowicz, from the Department of Medical Physics, Radiology and Biomedical Engineering at the University of Wisconsin, U.S.

Dr. Timothy Szczykutowicz, from the Department of Medical Physics, Radiology and Biomedical Engineering at the University of Wisconsin, U.S., will speak about a general framework for monitoring CT acquisition workflow.

“It is too simple in our field to hit the ‘easy button’ and focus on fancy scanner options when it is workflow issues that are wasting time and dollars and increasing patient dose,” he noted.

A major issue is how to disseminate good practice. Szczykutowicz gives the example of how the exact instructions given to a patient as they walk to the scanner couch can change the likelihood that they will need a repeat examination. These instructions are often developed by a single technologist or radiologist and are not always consistent across the institution.

Another example is where previous scans are not kept or harmonised between scanners, meaning that if a patient returns for a second scan, it is not possible to directly compare the images. He explains that protocols often have to be transferred manually between CT scanners on a USB stick or flash drive. Even if the model of scanner is compatible between manufacturers, there is no guarantee that will happen – meaning protocols can vary a lot, even within the same institution.

“Major vendors are now coming out with protocol management tools so I can sit in my office and change protocols on a scanner at the other side of the city,” Szczykutowicz said. “That is a game changer for uniformity – it is almost like getting an ‘easy button’.”

As part of his talk, he will be presenting results from recent studies on analysing the workflow that leads to higher CT repeat rates. Pointing out that the U.S. federal government does not require data kept on repeat rates for CT, despite it being expensive to perform, he notes that repeat exams cause patient discomfort as well as increasing radiation exposure.

Repeat exams can be caused by poorly designed protocols, but also by poor staff training or malfunctioning scanners. In a study published in the September/October 2019 edition of Radiology Management, Szczykutowicz and a colleague outlined how they developed an algorithm to automatically calculate repeat/reject rates in CT, thus allowing for easier data collection and analysis.

Uniformity of image quality, contrast enhancement, and image presentation (i.e., reconstruction and reformatting) are important. Uniformity needs to be thought of in two ways: between tests performed on the same scanner but for different clinical indications, and between tests performed on different scanners for the same clinical indication. Many practice setting- and device-specific differences make these goals of uniformity challenging to realise (provided by Dr. Timothy Szczykutowicz. Adapted from a slide presented by Prof. Mika Kortesniemi at the Prague 2018 CT workshop hosted by EFOMP).

Other speakers at the sessions include Dr. Mannudeep Kalra, staff radiologist at Massachusetts General Hospital, Boston, U.S., who will be presenting tricks and tips for optimising radiation dose in cardiac CT – which he describes as the most involved diagnostic CT procedure. He plans to discuss how to optimise cardiac CT protocols to maximise the diagnostic information. Using a clinical scenario-based approach, he will highlight how imaging personnel can make best use of their clinical skills and available technologies to optimise radiation dose with cardiac CT.

Dr. Federica Zanca, founder of Palindromo Consulting in Leuven, Belgium, meanwhile, will be giving an overview of radiation dose management systems, and how they can be used to optimise radiation doses and improve the quality of clinical workflow.

Please note that for pre-recorded sessions published during the ECR Highlight Weeks, there will be no chairpersons. However, we still wanted to keep Professor Kortesniemi’s statement for the article as he initially gave it.

EFOMP Workshops

EF 11 CT protocol management and optimisation: management (part A)

  • Developing a CT protocol management system (CT-PMS)
    Johan Helmenkamp; Stockholm/SE
  • A general framework for monitoring CT acquisition workflow
    Timothy Szczykutowicz; Madison, WI/US
  • Dose tracking systems as a tool for CT-PMS
    Federica Zanca; Leuven/BE

EF 12 CT protocol management and optimisation: optimisation (part B)

  • Optimised acquisition and reconstruction protocols: chest CT
    Elly Castellano; London/UK
  • Optimised acquisition and reconstruction protocols: cardiac CT
    Mannudeep Kalra; Boston, MA/US
  • Optimised acquisition and reconstruction protocols: abdomen and CT angiography
    Nico Buls; Brussels/BE

These sessions are part of the EuroSafe Imaging campaign.

FURTHER READING

De Bondt T, Mulkens T, Zanca F, Pyfferoen L, Casselman JW, Parizel PM (2017) Benchmarking pediatric cranial CT protocols using a dose tracking software system: a multicenter study. Eur Radiol. 27(2):841-850: european-radiology.org/4385

Pyfferoen L, Mulkens TH, Zanca F, De Bondt T, Parizel PM, Casselman JW (2017) Benchmarking adult CT-dose levels to regional and national references using a dose-tracking software: a multicentre experience. Insights Imaging. 8(5):513-521: i3-journal.org/570

Onur MR, Idilman I, Akpinar E, Özmen MN, Akata D (2018) Optimisation of CT protocols in abdominal emergencies. EuroSafe Imaging 2018 / ESI-0052: myESR.org/1852

Balázs E, Dankó Z, Bágyi P, Balkay L, Urbán L (2019) Protocol optimisation in chest CT imaging – effect of continuous protocol revision on patient dose. EuroSafe Imaging 2019 / ESI-0107: myESR.org/19107

Leale G, Samman LY, Cerini P et al (2018) Optimised dose protocols in patients who underwent cardiac CT: a single centre experience. ECR 2018 / C-1919: myESR.org/181919