determination of the accuracy of semi-automatic and fully automatic 2d lateral cephalometric ...

119 Pages·2013·3.87 MB·English

DETERMINATION OF THE ACCURACY OF SEMI-AUTOMATIC AND
FULLY AUTOMATIC 2D LATERAL CEPHALOMETRIC ANALYSIS
PROGRAMS

by

Dr. Nicholas Grant Playfair

A Thesis submitted to the Faculty of Graduate Studies of

The University of Manitoba

in partial fulfilment of the requirements of the degree of

MASTER OF SCIENCE

Department of Preventive Dental Science

University of Manitoba

Winnipeg

Copyright © 2013 by Nicholas Grant Playfair

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Acknowledgments
I would like to thank the following people for their help and support.

My committee members
• Dr. William Wiltshire, for making the Orthodontic Program at the University of
Manitoba one of the best in the world through his continuing dedication and
sacrifice.
• Dr. Frank Hechter, for constantly inspiring me with his wealth of orthodontic
knowledge.
• Dr. Stephen Ahing, for his time spent both teaching and helping me with my
thesis.

Dr. Charles Lekic, and his family, for their continual support and friendship that they
provided to me during my time at the University of Manitoba. Without them, I would not
be where I am today.

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Abstract

DETERMINATION OF THE ACCURACY OF SEMI-AUTOMATIC AND FULLY
AUTOMATIC 2D LATERAL CEPHALOMETRIC ANALYSIS PROGRAMS
Nicholas G. Playfaira, William A.Wiltshireb Frank Hechterc, Stephen Ahingd,
a Graduate Resident, Division of Orthodontics, University of Manitoba

b Professor, Program Director and Department Head, Division of Orthodontics, University of Manitoba

c Part-time Professor, Division of Orthodontics, University of Manitoba

d Associate Professor, Division Head, Oral Diagnosis and Radiology, University of Manitoba

AIM: To evaluate the accuracy of current semi-automatic and fully automatic 2D lateral
cephalometric analysis programs.
MATERIAL AND METHODS: 60 lateral cephalometric radiographs were randomly
selected and grouped based their skeletal malocclusions to form 3 equal groups of 20
Class I, 20 Class II and 20 Class III. These radiographs were then analyzed via traditional
hand-based analysis. The values obtained from this method of analysis were compared to
4 subsequent methods of analysis. These consisted of semi-automatic analysis using
Dolphin Imaging software, semi-automatic analysis using Kodak Orthodontic Imaging
software, fully automatic analysis using Kodak Orthodontic Imaging software and fully
automatic analysis combined with limited landmark changes using Kodak Orthodontic
Imaging software.

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RESULTS: ICC tests were completed to compare the gold standard hand-based analysis
to the 4 subsequent methods. The values obtained from semi-automatic Dolphin and
Kodak Orthodontic Imaging software were found to be comparable to hand-based
analysis. Whereas, the values obtained from the fully automatic mode of Kodak
Orthodontic Imaging software were not found to be comparable to hand-based analysis.
CONCLUSIONS: Digital cephalometric programs can be used as an accurate method
when performing lateral cephalometric analyses. The fully automatic mode of these
programs should only be used as a support to diagnosis and not as a diagnostic tool.

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Contents

Introduction.............................................................................7
Literature Review…………………………………………....8
Purpose……………………………………………………...21
Null Hypotheses…………………………………………….21
Materials and Methods………………………………………22
Results………………………………………………………38
Statistical Analysis………………………………………….47
Discussion…………………………………………………..48
Conclusions…………………………………………………55
Raw Data……………………………………………………56
References…………………………………………………..97
Article………………………………………………………101
Appendices…………………………………………………119

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List of Tables and Figures
Table 5.1: Cephalometric Landmarks…………………………………………………22
Table 5.2: Measured Values…………………………………………………………..28
Table 5.3: Methods of Analysis……………………………………………………….33
Figure 5.1: Hand-based analysis of radiograph……………………………………….34
Figure 5.2: Semi-automatic analysis of radiograph using Dolphin
Imaging Software……………………………………………………………………..35
Figure 5.3: Semi-automatic analysis of radiograph using Kodak
Orthodontic Imaging Software……………………………………………………….36
Figure 5.4: Fully-automatic analysis of radiograph using Kodak
Orthodontic Imaging Software……………………………………………………….37
Table 6.1: Descriptive data for Dolphin semi-automatic (Interclass Correlation)…...39
Table 6.2: Descriptive data for Kodak semi-automatic (interclass correlation)……...41
Table 6.3: Descriptive data for Kodak fully automatic (interclass correlation)………43
Table 6.4: Descriptive data for Kodak fully automatic with limited landmark
changes (interclass correlation)……………………………………………………….44
Table 10.1: Calibration, Operator 1, T1 (Hand Tracing)……………………….….....57
Table 10.2: Calibration, Operator 1, T1 (Dolphin Semi-Automatic)…………………59
Table 10.3: Calibration, Operator 1, T1 (Kodak)……………………………………..61
Table 10.4: Calibration, Operator 2, (Hand Tracing)…………………………………63
Table 10.5: Calibration, Operator 2, (Dolphin)……………………………………….64
Table 10.6: Calibration, Operator 2, (Kodak)………………………………………..65
Table 10.7: Calibration, Operator 1, T2 (Hand Tracing)……………………………..66
Table 10.8: Calibration, Operator 1, T2 (Dolphin)…………………………………...67
Table 10.9: Calibration, Operator 1, T2 (Kodak)……………………………………68
Table 10.10: Method 1 (Hand Tracing)………………………………………………69
Table 10.11: Method 2 (Dolphin Semi-Automatic)…………………………………..74
Table 10.12: Method 3 (Kodak Semi-Automatic)……………………………………80
Table 10.13: Method 4 (Kodak Fully Automatic)……………………………………86
Table 10.14: Method 5 (Kodak Fully Automatic with Landmark Changes)…………92

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Introduction
Radiographic cephalometry was first introduced in 1931 by Hofrath and Broadbent
(Damstraa et al, 2010). Lateral cephalometric analysis is a major tool used in
orthodontics to diagnose, treatment plan and evaluate treatment results (Proffit et al,
2007). Traditionally, lateral cephalometric analysis has been completed by way of a
hand-based analysis.

As radiographs have become progressively digital in nature, computer programs
have been developed to perform these analyses digitally. These programs have replaced
the traditional form of hand-based analysis in many orthodontic offices.

More recently, some of these computer programs have introduced a fully
automatic mode. This mode allows for automatic identification and location of the
landmarks used in these analyses.

The accuracy of these programs have been analyzed in a small number of studies
(Forsyth et al, 1996; Li et al, 2002; Leonardi et al, 2008). There remains speculation in
the profession about the accuracy of these programs.

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Literature Review

Cephalometric radiography was developed simultaneously in two countries in 1931. It
was developed in the USA by B. H. Broadbent and in Germany by H. Hofrath. These
pioneers produced cephalometric radiographs by positioning the patient’s skull in a
cephalometer and taking radiographs from the lateral aspect. (Leonardi et al, 2008)

This same technique is still used today when taking cephalometric radiographs.
The American standard positions the patient’s midsagittal plane 60 inches (152.4 cm)
from the x-ray source and 15 cm from the film. This positioning used by the American
standard enables standardized and comparable craniofacial images to be produced on
radiographic films. (Cohen et al, 2005)

Cephalometric radiography has many uses. It is an essential tool in the diagnosis
and treatment of dental malocclusions and underlying skeletal discrepancies. Serial
cephalometric radiographs can be taken and used to study and predict growth,
orthodontic treatment progress and surgical outcomes of dentofacial deformity treatment
(AlBarakati et al, 2012). Cephalometric radiographs can be used to evaluate changes
between pre- and post-treatment measurements and are used to help in treatment
evaluation (Brodie et al, 1941; Baumrind et al, 1971; Ricketts et al, 1981; Celik et al,
2009).

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Analyses and numeric norms for various facial types and ethnic groups have been
established with the use of cephalometric radiographs. These analyses are created by
plotting a set of landmarks and anatomical planes on each radiograph. The angular
measurements are made by measuring the angles between specific planes. The linear
measurements are made by measuring the distances between landmarks. (Roden-Johnson
et al, 2008)

These analyses can be used to compare individual patients to standard norms.
These values generate classifications based on the patient’s soft tissue drape (e.g nasio-
labial angle, lower-lip to S-line); their skeletal pattern (e.g ANB, Wits) and also their
dental pattern (e.g. UI to NA, LI to APog). These classifications can then be used as an
aid in determining the relevant treatment for the patient. (Singh et al, 2011)

Cephalometric radiographs were initially analogue. Analogue films are produced
when X-rays from the cephalostat source pass through the skull onto radiographic film
housed in a cassette. These radiographs are traditionally analyzed by placing them on a
light box and placing acetate paper over the top of them. Landmarks are then marked on
these acetate overlays with a pencil. Construction lines are then drawn onto this paper.
The lengths of these construction lines and the angles between these construction lines
are then measured. (AlBarakati et al, 2012)

Despite its widespread use in orthodontics, this technique of manual tracing is
time-consuming and has the disadvantage of being subject to random and systematic

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error. The main sources of errors include technical measurements, radiographic
acquisition and identifying landmarks. Most errors occur in landmark identification and
are influenced by clinician experience, landmark definition, image density and sharpness.
(AlBarakati et al, 2012)

With the rapid evolution of computer radiography, digital tracing has slowly
replaced the manual tracing methods (AlBarakati et al, 2012). The use of computerized
or computer-aided, cephalometric analysis eliminates the mechanical errors produced
when drawing lines between landmarks as well as those made when taking measurements
(Chien et al, 2009).

It is also possible to manually trace digital cephalometric radiographs. This is
accomplished by printing hard copies of digital cephalometric radiographs. These are
then traced on overlying acetates. Although slight enlargements have been observed in
hard-copy printouts of digital cephalograms, it has been shown that the differences are
minimal and are regarded as clinically acceptable (Bruntz et al, 2006; Celik et al, 2009;
Polat-Ozsoy et al, 2009).

Recently, technological advances have made it possible to perform cephalometric
tracing using computers. Two techniques are commonly reported: the first uses digitizer
pads for tracing analogue cephalometric films and software programs to compute the
measurements; the second uses scanners or digital cameras to export cephalometric
images to measurement programs. The use of computers in treatment planning helps not

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