KeywordsWeight bearing CTWBCTRadiographsRadiation doseTime spent
Weight bearing CT (WBCT) has been proven to more precisely measure bone position than conventional sequencing including systematic weight bearing radiograph series (R) and optional conventional CT without weight bearing (CT) [1–8]. These improvements are attributed to the absence of superimposition and the possibility to account for rotational errors after the image process [6, 9]. Time spent on image acquisition (T) has shown to be lower for WBCT than for R and CT . Radiation dose (RD) for WBCT has also shown to be lower than for CT . The cost-effectiveness of using WBCT clinical settings is questionable. As far as we know, T, RD, and especially cost-effectiveness have not been investigated in a high number of patients so far. The purpose of this study was to assess the potential benefits of using WBCT instead of R and/or CT in a foot and ankle department, regarding RD, T, and cost-effectiveness.
A WBCT device (PedCAT, CurveBeam, Warrington, PA, USA) was put into operation from July 1, 2013, in the first author’s foot and ankle department. All patients who obtained WBCT (bilateral scan) and/or CT from July 1, 2013 until March 15, 2019 were included in the study (WBCT group).
All patients who obtained radiographs and/or CT from January 1 to December 31, 2012 were included in the control group (R/CT group).
No exclusion criteria for patients were defined (both groups). Initial radiographs in trauma patients and early postoperative (1–4 days) radiographs were excluded from the study (both groups).
Age, gender, primary pathology location, and additional CT (bilateral feet and ankles) were registered. Pathology location was differentiated in the ankle, hindfoot, midfoot, forefoot, and multiple other locations based on anatomy as follows: the hindfoot between the ankle and the Chopart joint, the midfoot between the Chopart and Lisfranc joints, and the forefoot distal to the Lisfranc joint. Involvement of the joints were defined relative to the main neighboring location or, when unclear, as multiple location.
Imaging Time (T)
T was calculated based on an analysis of previous studies as follows: R (bilateral feet dorsoplantar and lateral, metatarsal head skyline view), 902 seconds; CT (bilateral feet and ankle), 415 seconds; and WBCT (bilateral), 207 seconds .
Radiation Dose (RD)
RD per patient was calculated based on previous phantom measurements as part of obligatory standard periodic quality assurance protocols: R, 1.4 uSv; CT, 25 uSv; and WBCT 4.2 uSv .
For the analysis of cost-effectiveness, device cost, working time cost of radiology technicians (similar to T), and reimbursement in the local setting were taken into consideration for the WBCT group. The total device cost was calculated at a 200,000 Euro acquisition cost with a 5-year asset depreciation range (40,000 Euro yearly) and an annual 5000 Euro maintenance cost, i.e., 45,000 Euro yearly cost for the WBCT group. No device costs were included for the RCT group since the R and CT devices were already installed. Staff costs were calculated by multiplication of T with 20 Euro per hour (based on local practice fares). The only reimbursement that could be considered was the one generated by privately insured patients or self-payers which corresponded to 15.5/15.1% of WBCT/RCT groups at a rate of 30 Euro for each R series and 300 Euro for each CT/WBCT. Vice versa, no reimbursement was achieved and considered for the study for all other patients (with public insurance). The potential profit was then considered in total and per patient.
Data Analysis/Control Group
All parameters were compared between WBCT and R/CT group.
Either a Student’s t-test or Chi-square test was used for comparison between groups with normal distributed and binomial data, respectively. P-values were considered significant when lower than .05. SPSS (20.0.0, SPSS, Inc., Chicago, IL, USA) was used.
Epidemiology and pathology location RCT and WBCT groups
Age (mean, range)
Gender (male n, %)
Imaging data RCT and WBCT groups
873.6 ± 53
Radiographs (series, n per year)
WBCT (n per year)
1957 ± 87
CT (n per year)
10.6 ± 2.4
Radiation dose per patient (uSv)
4.8 ± 4.3
4.3 ± 1.5
Time spent radiology technician
(hours in total per year)
114 ± 14.5
Time spent radiology technician
(minutes.seconds per patient)
15.59 ± 8.04
3.29 ± 2.56
Private insurance/self-payers (%)
Profit (Euros in total per year)
43,959 ± 6512
Profit (Euros per patient)
50.3 ± 10.9