Patients' T-shirt size an accurate measurement for CT dose reference levels
Can a patient’s computed tomography dose be decided by the size of their T-shirts? New research says yes.
A study published in the European Journal of Radiology that analyzed CT exams from 256 facilities in the United States found that using T-shirt sizes for dose reference levels is actually a simple and effective way to optimize radiation exposure. Experts suggest that their findings indicate dose reference levels could be shirt size specific in the not so distant future.
“While we have several ways to represent radiation dose, there is lack of a simple method to represent body habitus for correlating with dose by the clinical staff,” corresponding author Madan M. Rehani, from the Radiology Department at Massachusetts General Hospital, and co-authors discussed. “The study indicates that the concept of expressing body habitus in term of T-shirt size is not only simple and intuitive for healthcare professionals, but also provides a tool to have perception of differences in dose metrices among patients of different body build.”
In CT exams, patients with higher body mass require higher doses to obtain optimal imaging. Dose adjustments take a number of factors into account, including age, weight and body mass index. For adult patients, measurements such as BMI may not correlate with a patient’s body habitus or the specific area of interest (neck, abdomen, extremities, etc.). Size-specific dose equivalent (SSDE) measurements were developed for this reason. However, SSDE is a dose metric, not a size metric, and can therefore be difficult for technologists and other staff members to make size-based dose decisions from.
In this study, researchers presented a simpler concept that optimizes CT doses based on patients’ T-shirt sizes. Thousands of CT scans were used to calculate effective diameter for various acquisitions, which researchers combined with a range of circumferences to determine accurate sizing information. Patient size was divided into seven categories: XXS, XS, S, M, L, XL and XXL. After choosing a shirt size for each acquisition, dose measurements were correlated for each size and each exam type.
Using size medium as a reference, researchers calculated that very small patients (XS, XXS) received a dose reduced by 60%. Conversely, larger patients (XXL) required a dose that was double that of the reference. The experts also noted a 40% to 220% variation in SSDE across the range of shirt sizes.
“Stating that a patient with XXL size typically may need twice the dose as compared to a patient with M size provides a simple and meaningful message that does not come easily otherwise using a variety of dose and size metrices,” the authors noted. “Perhaps the beauty of T-shirt size is that it is discrete and stepwise rather than being on continuous scale making perception of size easy.”
The authors concluded by suggesting that the developing technology is anticipated for use, possibly in the near future.
More on CT dose optimization:
Deep learning-based reconstruction reduces pediatric CT dose by 54%, maintains image quality
World imaging leaders share 7 strategies to optimize CT dosage
Deep learning decreases CT radiation dose by 65% in patients with liver metastases
In addition to her background in journalism, Hannah also has patient-facing experience in clinical settings, having spent more than 12 years working as a registered rad tech. She began covering the medical imaging industry for Innovate Healthcare in 2021.