of More Than 11,000 Scans with Weight Bearing CT: Impact on Costs, Radiation Exposure, and Procedure Time

, Francois Lintz2, Cesar de Cesar Netto3, Alexej Barg4, Arne Burssens5 and Scott Ellis6



(1)
Department for Foot and Ankle Surgery, Hospital Rummelsberg, Schwarzenbruck, Germany

(2)
Foot and Ankle Surgery Centre, Clinique de l’Union, Toulouse, France

(3)
Department of Orthopedics and Rehab, University of Iowa, Iowa City, IA, USA

(4)
University Orthopedic Center, University of Utah, Salt Lake City, UT, USA

(5)
Department of Orthopedics and Trauma, University Hospital of Ghent, Ghent, OVL, Belgium

(6)
Department of Orthopedic Surgery, Hospital for Special Surgery, New York, NY, USA

 



Keywords

Weight bearing CTWBCTRadiographsRadiation doseTime spent


Introduction


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) [18]. 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 [6]. Radiation dose (RD) for WBCT has also shown to be lower than for CT [6]. 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.


Methods


Study Design


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).


Control 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).


Data Acquisition


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 [6].


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 [10].


Cost-Effectiveness


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.


Statistics


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.


Results


11,009 WBCT scans were obtained from 4987 patients (WBCT group). 4987 (45%) scans were performed before treatment, and 6022 (55%) at follow-up between 3 months and 5 years after operative treatment. 1957 WBCT scans and 10.6 CTs (all before treatment) were obtained on average yearly. The mean age of the scanned patients was 52.4 years (range, 8–92), and 41% were male. Table 18.1 shows the pathology location. The most common single location was forefoot (19.8%). In 2012, 1850 Rs and 254 CTs were obtained from 885 patients (RCT group). The yearly average RD was 4.3 uSv for WBCT group and 4.8 uSv for RCT group (mean difference of 0.5 uSv; a 10% decrease for the WBCT group, p < 0.01) (Table 18.2). The mean yearly T was 114 hours in total (3.3 minutes per patient) for the WBCT group and 493 hours in total (16.0 minutes per patient) for the RCT group (mean difference of 379 hours; a 77% decrease for the WBCT group, p < 0.01) (Table 18.2). The mean yearly cost-effectiveness was a profit of 43,959/−723 Euros for WBCT/RCT groups, respectively, 50.3/−0.82 Euros per patient (Table 18.2). Consequently, there is an overall profit increase of 44,682 Euros (51.12 Euros per patient).


Table 18.1

Epidemiology and pathology location RCT and WBCT groups




































































 

RCT


WBCT


Test p


Age (mean, range)


52.4 (8–92)


53.8 (6–91)


t-test 0.7


Gender (male n, %)


2045 (49%)


779 (42%)


Chi2 0.9


Pathology location


n


%


n


%

 

Ankle


603


12.1


104


11.8


Chi2 0.8


Hindfoot


480


10.1


98


11.1

 

Midfoot


457


9.2


78


8.8

 

Forefoot


987


19.8


182


11.8

 

Multiple locations


2423


48.6


423


47.8

 


RCT group, group from 2012 with conventional radiographs and optional CT; WBCT group, group from July 1, 2013 until March 12, 2019 with WBCT and additional conventional radiographs and CT




Table 18.2

Imaging data RCT and WBCT groups

































































Parameter


RCT


WBCT


T-test p


Patient number


885


873.6 ± 53

 

Radiographs (series, n per year)


1850

   

WBCT (n per year)

 

1957 ± 87

 

CT (n per year)


254


10.6 ± 2.4

 

Radiation dose per patient (uSv)


4.8 ± 4.3


4.3 ± 1.5


<.01


Time spent radiology technician


(hours in total per year)


493


114 ± 14.5


<.01


Time spent radiology technician


(minutes.seconds per patient)


15.59 ± 8.04


3.29 ± 2.56


<.01


Private insurance/self-payers (%)


15.1


15.5

 

Profit (Euros in total per year)


−723


43,959 ± 6512


<.01


Profit (Euros per patient)


.82


50.3 ± 10.9


<.01



RCT group, group from 2012 with conventional radiographs and optional CT; WBCT group, group from July 1, 2013, until March 12, 2019, with WBCT and additional conventional radiographs and CT. Numbers for WBCT group are average yearly numbers

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Apr 25, 2020 | Posted by in MUSCULOSKELETAL MEDICINE | Comments Off on of More Than 11,000 Scans with Weight Bearing CT: Impact on Costs, Radiation Exposure, and Procedure Time
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