Calibration Markers for Digital Templating in Total Hip Arthroplasty

Boese, Christoph Kolja; Lechler, Philipp; Rose, Leonard; Dargel, Jens; Oppermann, Johannes; Eysel, Peer; Geiges, Hansjoerg; Bredow, Jan

doi:10.1371/journal.pone.0128529

Cited by 36 publications

(73 citation statements)

References 10 publications

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“…Our study supplements previous studies by showing that magnification of hip radiographs depends not only on marker and patient-specific factors [ 7 , 9 , 10 ], but also on clinical workplace or more precisely on radiographic device. It indicates potential limits in generalizability of results of studies dealing with preoperative planning accuracy to other institutions.…”

Section: Discussionsupporting

confidence: 86%

“…distance between the femoral head and the table ( Fig 1 ). These effects could be related to individual body habitus that causes vertical shift [ 7 ] or lateral shift of the hip in the projected beam [ 5 ].…”

Section: Discussionmentioning

confidence: 99%

“…The accuracy of templating has been evaluated with respect to the marker type and position [ 4 , 7 , 8 ], template type (acetate vs. digital) [ 3 ], sex, age, body mass index and Harris Hip Score [ 9 – 11 ]. However, there is limited information whether results from one workplace dealing with certain radiological setup could be quantitatively transferred to another workplace.…”

Section: Introductionmentioning

confidence: 99%

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Magnification of digital hip radiographs differs between clinical workplaces

et al. 2017

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Preoperative planning for total hip arthroplasty includes templating on anteroposterior radiographs. It is necessary to consider radiographic magnification in order to scale templates accurately. Studies dealing with hip templating report different values of radiographic magnification. It is not clear if the observed difference in magnification between the studies is caused by variability in studied groups, methodology or instrumentation. We hypothesize that there is a difference in magnification between clinical workplaces. Within this study, radiographic magnification was estimated on 337 radiographs of patients after total hip surgery from five orthopaedic departments in the Czech Republic. Magnification was determined for each patient as a ratio between diameter of implanted femoral head measured on radiogram and its true size. One-way ANOVA revealed significant differences in magnification between workplaces (F(4,332) = 132, p≤0.001). These results suggest that radiographic magnification depends on the workplace where it is taken or more precisely on radiographic device. It indicates potential limits in generalizability of results of studies dealing with preoperative planning accuracy to other institutions.

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Section: Discussionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Magnification of digital hip radiographs differs between clinical workplaces

et al. 2017

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“…For image with distinct gray levels, the algorithm assumes that the pixels are divided by a threshold into classes and . The related class mean levels are: | | (5) and the inter-class variance is defined as: (6) where denotes pixel intensity, is normalized histogram value for intensity , is probability operator while and are occurrence probabilities of classes and , respectively.…”

Section: B Approach Based On Edge Detectionmentioning

confidence: 99%

“…As it is impractical to measure all the relevant positions in the system for every patient examination, calibration markers are used [4]. Markers are usually made from a radiopaque material [5] and are positioned near the anatomy of interest so that the magnification of their projection is approximately the same as of the anatomy. An example of radiography image with a calibration marker is shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Radiography calibration marker detection using Hough transformation

Novović¹,

Ostojić²,

Starčević³

et al. 2019

Telfor J

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In this paper we analyse the possibility of simple detection of circular radiography markers. To detect the marker, we utilised the Hough transform. Two approaches were analysed: with detecting image edges and without image edge detection where pixel gradient was used in the Hough voting process, i.e. to increase the accumulator values. Approaches were evaluated on 13 clinical radiography images. It was shown that the approach that detects image edges spatially matches the reference circles only 0.22 % less than manual annotation values, whereas the approach that uses just the gradient magnitudes spatially matches the reference circles 3.2 % less than manual annotations.

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Pre‐operative templating for total hip arthroplasty: How does radiographic technique and calibration marker placement affect image magnification?

Holliday

Steward

2021

J of Medical Radiation Sci

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Introduction: Pre-operative templating using digital radiography is an effective method of planning for total hip arthroplasty (THA) and requires a generalised fixed magnification factor (MF) or external calibration markers (ECM). The effect on image magnification when changing source-to-image distance (SID), object-to-image distance (OID) and different imaging conditions is not well described. This study aims to quantify the range of effects manipulation of radiographic parameters can have on image magnification across different body habitus and imaging conditions. Methods: A simple phantom study was performed. A 25 mm ECM was placed at eight different OID values along the anterior-posterior phantom plane at three different SID values and imaging conditions, and X-rays were obtained. On each radiograph, the ECM was measured using a line calliper tool by three radiographers and recorded. The MF was calculated and recorded. Results: The smallest observed image MF was 1.16, for an 8 cm OID, 120 cm SID with the ECM placed within the central ray and the X-ray detector in bucky underneath the X-ray table. The largest image MF was 1.40 for a 15 cm OID, 100 cm SID with the X-ray detector placed underneath an emergency department imaging trolley. Conclusions: Digital pre-operative templating for THA relies on accurate radiographic positioning and is dependent of the patient body habitus, radiographic parameters and imaging conditions selected by the radiographer. The use of appropriately positioned ECMsplaced medially between the patient's internally rotated legs at the level of the greater trochanter, lowers the potential for magnification inaccuracies.

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Calibration Markers for Digital Templating in Total Hip Arthroplasty

Cited by 36 publications

References 10 publications

Magnification of digital hip radiographs differs between clinical workplaces

Magnification of digital hip radiographs differs between clinical workplaces

Radiography calibration marker detection using Hough transformation

Pre‐operative templating for total hip arthroplasty: How does radiographic technique and calibration marker placement affect image magnification?

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