Dose Inspection – a Reason to be Proud

Erika Claessens |  Feb 16, 2015

CHR La Citadelle in Liège, Belgium, is among the hospitals with the lowest radiation doses in the country.


For more than fifteen years, the imaging department of CHR La Citadelle has been focused on lowering patient exposure. It regularly receives questions from well-informed parents anxious about the level of radiation that will be used during the medical treatment of their child. CHR La Citadelle has two SOMATOM® Perspective CT scanners from Siemens – one for the emergency department and one in the general radiology department.

“Bringing down radiation doses has always been our focus, especially when it comes to children,” explains Laurent Collignon, MD, and Head of the Medical Imaging Centre at CHR La Citadelle in Liège, Belgium. “No wonder I was surprised, but also proud and truly satisfied that our hospital is among those with the lowest radiation doses in the country.”

Dose-Inspection_Collignon
"I was surprised, but also proud and truly satisfied that our hospital is among those with the lowest radiation doses in the country." Laurent Collignon, MD, Head of the Medical Imaging Centre at CHR La Citadelle in Liège, Belgium

Monitoring patient radiation dose

AV Controlatom is a certified independent, non-profit organization licensed by the Belgian Federal Agency for Nuclear Control (FANC). It performs annual dosimetric data controls in medical imaging for a number of Belgian hospitals. FANC is responsible for monitoring the patient radiation dose and medical image quality in the Belgian health sector.

Following several radiology roundtable discussions in 2008, FANC recommended regulating patient dosimetry. The first official guidelines for the registration of the dosimetric data within medical imaging departments in the healthcare sector were produced in 2011. The determination of radiation dose is an important issue for all stakeholders, and is critical in protecting patients from high radiation doses. Initially, the controls were performed every three years but now they take place annually.

Raising awareness

Laurent Collignon points out: “For more than fifteen years, the Imaging Department of CHR La Citadelle has been focused on lowering patient radiation doses. Even my predecessor, radiologist Leon Rausin, MD, always emphasized the importance of lowering radiation dose as much as possible. At the time, people were becoming increasingly concerned about the radiation from medical imaging equipment, and governments and environmental organizations felt the need to start prevention campaigns to raise awareness among citizens.”

Nevertheless, he will never refuse to use computed tomography, he explains, because it can be a life-saving tool. “I work in one of the busiest emergency rooms in Belgium. One child in eight visiting our department is affected by an injury or shows symptoms where medical imaging is advised by our clinicians. We do 40 pediatric CT scans per month and I regularly get questions from well-informed parents anxious about the level of radiation dose that will be used during the medical imaging of their child.”

In most cases, Collignon states, they can relieve their anxiety by taking CT images. As such, they are not taking less images, but they use technology that enables low radiation dose levels. “We consider ourselves lucky that contemporary technological innovations in medical imaging have rapidly enhanced over the years, too.”

 

Fig. 1A: Abdominal CT: In Belgium the recommended dose levels1 for adults abdominal CT are between 6.90 and 12.96 CTDIvol (mGy). The graph above shows the dose distribution for 2,644 patients scanned on the two installed SOMATOM Perspective CT systems at CHR La Citadelle in Liège, Belgium. The majority of the scans were performed far below 6.90 CTDIvol (mGy).

Fig. 1B: Example of an abdominal CT scan from CHR La Citadelle in Liège, Belgium. The image quality is excellent at a dose level, far below the given Belgium reference values. The dose level for this obese adult patient was 6.59 CTDIvol (mGy).

Fig. 2A: Pediatric head scans: In Belgium the recommended dose levels1 for pediatric head scans are between 27.25 and 52.80 CTDIvol (mGy). The graph above shows the dose distribution for 498 children scanned on the two installed SOMATOM Perspective CT systems at CHR La Citadelle in Liège, Belgium. All scans were performed far below the max. recommended dose level of 52.80 CTDIvol (mGy).

 Fig. 2B: Example of pediatric head scan from CHR La Citadelle in Liège, Belgium. The image quality is excellent at a dose level, far below the given Belgium reference values. The dose level for this patient was 18.37 CTDIvol (mGy).

Annual check of radiation dose values

Nathalie Gérardy is a certified medical physics expert in radiology and works for AV Controlatom. She calculates the local average and median values recorded in periodic studies of radiation dose, provided annually by the hospitals. These results are compared with the reference values determined by FANC and sent back to the head of the department at the hospital together with advice on how to optimize its systems to lower the radiation dose for patients without compromising image quality. She explains how radiation dose is defined: “In Belgium, the minimum defined percentile for radiation dose is at percentile 25, the maximum percentile 75. The 25 percentile is considered ‘best practice’ for the healthcare sector as defined in the guidelines from the European Comission1. The maximum percentile 75 is defined as the ‘limit of good practice’, which means that it is preferable for a hospital not to pass the percentile 75 during a routine control with a ‘standard’ patient.”

“When the obtained percentile of a scanner is above 75, I need to examine the conditions in which the results were achieved,” Gérardy states. “It also means that I will check if the working methods and the equipment used can be improved in one way or another. However, in the case of the CHR La Citadelle, in several instances we came across exceptionally low radiation doses, close to or sometimes even below the standard 25 percentile. In order to exclude any errors in reporting, a second check has been made and confirmed the 25 percentile, which became standard for La Citadelle.”

Working together towards lower radiation dose

Gérardy has been working for years in the health sector in Belgium and had already noticed herself that CHR La Citadelle was making huge efforts in lowering patient radiation doses. “Of course, I am happy to see that some hospitals achieve a low radiation dose with their SOMATOM Perspective CT scanner. This is due to the narrow collaboration between the company offering computed tomography, the medical team, and the local technologists. It’s always possible to get low radiation dose percentiles if all these actors work together and all go for the same goal.”

Gérardy has been working for years in the health sector in Belgium and had already noticed herself that CHR La Citadelle was making huge efforts in lowering patient radiation doses. “Of course, I am happy to see that some hospitals achieve a low radiation dose with their SOMATOM Perspective CT scanner. This is due to the narrow collaboration between the company offering computed tomography, the medical team, and the local technologists. It’s always possible to get low radiation dose percentiles if all these actors work together and all go for the same goal.”

Since the installation of a SOMATOM Perspective at CHR La Citadelle, the reduction in dose levels has been significant. New technologies such as iterative reconstruction with SAFIRE2 or drastic optimization of protocols with Siemens’ CT experts, and also the implementation of SILT techniques (small increments long term) have made this possible.

“The SOMATOM Perspective scanner at CHR La Citadelle runs 24 hours a day, seven days a week,” Collignon says. “Our annual reports are the result of analyzed data taken on a huge scale and from a large number of patients so we know that the low percentiles are not an exception and, more importantly, they are authenticated by the federal agency. Of course, there will come a time when it will become difficult to reduce the dose levels any further. While some radiation dose is necessary, if we can bring it down and also help our patients, then we feel satisfied. And it’s not just to promote new technologies. It’s because lowering radiation dose has been our hospital’s number one aim for more than fifteen years.”



About the Author

Erika Claessens has contributed as a journalist and editor to numerous print and online publications in both Belgium and the Netherlands. Her principal topics are entrepreneurial innovation and technology. She works from Antwerp, Belgium.


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1European Guidelines on Quality Criteria for Computed Tomography.

2In clinical practice, the use of SAFIRE may reduce CT patient dose depending on the clinical task, patient size, anatomical location, and clinical practice. A consultation with a radiologist and a physicist should be made to determine the appropriate dose to obtain diagnostic image quality for the particular clinical task. The following test method was used to determine a 54 to 60% dose reduction when using the SAFIRE reconstruction software. Noise, CT numbers, homogenity, low contrast resolution, and high contrast resolution were assessed in a Gammex 438 phantom. Low dose data reconstructed with SAFIRE showed the same image quality compared to full dose data based on this test. Data on file. The statements by Siemens’ customers described herein are based on results that were achieved in the customer’s unique setting. Since there is no “typical” hospital and many variables exist (e.g., hospital size, case mix, level of IT adoption) there can be no guarantee that other customers will achieve the same results.