194DOI: 10.7763/LNSE.2013.V1.44

Abstract—This paper mainly focuses on diagnosing the

osteoporosis using X-Ray images. Osteoporosis is a metabolic

bone disease which is characterized by compromised bone

strength predisposing a person in to an increased risk of

fracture. It is most common in women after menopause where

it is called post menopausal osteoporosis. The condition of

Osteoporosis are decrease in the bone density, decrease in the

bone strength resulting in fragile bones and susceptibility to

fracture. In clinical practice, dual energy X-ray

absorptiometry (DEXA) scanning is the most common way of

measuring BMD levels and it is the current gold standard for

diagnosing and monitoring the osteoporosis. In DEXA

scanning, the method of comparing individual BMD

measurements to the normal is called the ‘T-score’ system.

This project work presents an efficient method to diagnose the

osteoporosis by measuring the bone mineral density (BMD) of

segmented femur bone parts with the help of X-Rays images

and also compare the bone mineral density obtained from the

DEXA scan with the density obtained from the conventional X-

rays.

Index Terms—Bone mineral density (BMD), dual-energy X-

ray absorptiometry (DEXA), t-score, osteoporosis.

I. INTRODUCTION

Bone is a living material which helps to form the skeleton,

thereby enabling the locomotion and giving protection to the

organism [1]. Human body has increasing complex levels of

organization progressing from cells to tissues to organs to

organ systems and finally to the organism. The principal

functions of the skeletal bone are giving mechanical support

and maintain the calcium homeostasis and haematopoiesis in

the bone marrow of an organism.

This can be disturbed by various skeletal disorders.

Osteoporosis is one of the systemic skeletal disorders,

Characterized by low bone density and micro architectural

deterioration of bone tissue with a Consequent increase in

bone fragility [2]. It is three times more common in women

than in men because women have a lower peak femur bone

mass and the hormonal changes that occur at the menopause

stage [3].Femur or thigh bone is most proximal bone of the

leg in tetra pods vertebrates capable of walking and jumping.

It is the largest, longest and strongest bone in our body

extends from the hip to the knee. Four main parts of the

human femur bone having bone minerals are neck, ward,

trochanter and shaft. Dual -energy X-ray Absorptiometry

Manuscript received

January

31,

2013; revised April

25, 2013.

This

work was

supported

in

part

by

the

R.M.K

Engineering

College,

Chennai,

India.

The authors are with R.M.K

Engineering

College,

Chennai,

India

(e-

mail:

santhoshi.pandiyan@gmail.com, tamil_ct@rediffmail.com,

rsk.ece@rmkec.ac.in).

(DEXA) scans are one of the bone measuring techniques

which are used to diagnose the osteoporosis but it requires

high radiation dose to the patients. It is the current „gold

standard‟ for the diagnosis of osteoporosis [4] .In this

project work, normal x-ray image of femur bone is taken.

Four main parts in that femur bone image are automatically

segmented and measure the bone mineral content of each

part which helps to diagnose the Osteoporosis. The term

“bone mineral content” describes the amount of mineral in

the specific bone site is scanned, from which a value for

BMD can be derived by dividing the bone mineral content

by the area or volume. BMD values are expressed in relation

to the young adult mean called T-score or age-matched

controls called Z-score. . Finally, compare the normal X-ray

image bone mineral density and DEXA image bone mineral

density for their accuracy.

II. FEMUR BONE FEATURES

The femur or thigh bone is the largest, longest and

strongest bone in the human body. The upper end of femur

bone is a part of the hip joint (the largest joint in the body)

and the lower end of femur bone is a part of the knee joint. It

is almost perfectly cylindrical in the greater part. In the erect

posture, it is not look like a vertical cylinder. it is being

separated above from its fellow by a considerable interval,

which corresponds to the breadth of the pelvis but inclining

gradually downwards and medial wards, so its fellow is

approach towards its lower part for the purpose of bringing

the knee-joint near the line of gravity of the body. The

degree of this inclination varies from different persons and

is greater in the female than in the male because women

having pelvis of greater breadth. The femur bone is divisible

into a body, upper and lower extremities like other long

bones. The upper extremity consists of a head, a neck, a

greater and a lesser trochanter.

The Head: The head, which is globular in shape. Its

surface is coated with smooth cartilage in the fresh state

except the fovea captious femoris, which is situated a little

below and behind the center of the head .the head region is

partially embedded in pelvis region. In this project, Hough

filter is used to segment the head region in the femur bone

by detecting the spherical shape .The bone mineral density

of head part in normal femur bone must have 0.846994.

The Neck: The neck is a flattened pyramidal shape which

connects the head with the body and forms a wide angle in

the medial ward. The angle becomes lessened during

puberty. So it forms a gentle curve from the axis of the bone

body. In the adult stage, the neck forms an angle of about

125° with the body. It is inversely proportion to the

development of the pelvis region. For female, the femur

Automatic Segmentation of Femur Bone Features and

Analysis of Osteoporosis

P. Santhoshini, R. Tamilselvi, and R. Sivakumar, Member, IACSIT

Lecture Notes on Software Engineering, Vol. 1, No. 2, May 2013

195

neck forms more nearly a right angle with the body. The

angle decreases during the period of growth but after full

growth has been attained, it does not undergo any change,

even in old age. It varies in different persons who having

same age. In addition, the femur neck is also projecting 12°

to 14°upward and medial ward from the body. The bone

mineral density of neck part in normal femur bone must

have 0.59259.

The Trochanter: The greater Trochanter is a large,

irregular, quadrilateral eminence, situated at the junction of

the neck with the upper part of the body. It is directed a little

lateral ward and Backward. It has two surfaces and four

borders. The lesser Trochanter is a conical eminence which

varies in size. It projects from the lower and back part of the

base of the neck. The bone mineral density of trochanter part

in normal femur bone must have 0.7975.

The Body or Shaft: The body, almost cylindrical in

shape which is little broader than in the center. It is slightly

arched, the shaft part is convex in front and concave behind.

The shaft and the lower extremity is separated from one

another by a smooth shallow depression called the patellar

surface. The bone mineral density of shaft part in normal

femur bone must have 1.12771.The block diagram in Fig. 1,

clearly explains the various stages for measuring bone

mineral densities in femur bone.

Fig. 1. Block diagram.

In this work, Normal X-Ray image of pelvis femur bone

is taken. By using canny Edge-based image segmentation,

femur bone parts are automatically segmented and then

measure the T-score value of BMD of each femur bone parts

which is used to diagnose the Osteoporosis. Finally,

compare the accuracy between normal X-ray and DEXA

scan.

III. SEGMENTATION

Normal X-ray image of femur bone of a 75 aged women

is collected from CETIR centre medic, Barcelona, Spain

through E-mail. The Fig. 2 shows the X-Ray image of left

and right of the femur bone which is along with pelvis

region.

Before segmentation of femur bone x-ray image, the

threshold of each region is to be calculated. It is done by

thin plate spline Transformation (TPS).it has been widely

used for non-rigid Transformation model such as image

alignment and shape matching. The interpolation gets

smoothened with derivatives of any order for its energy

function [5]. Thin spline interpolation is done after the

initial estimation. It helps to calculate the area of each femur

bone parts. The area of each parts is not constant .It is varied

image to image. The rectangle box (red color) in Fig. 3

indicates the area of region wish to measure which is

selected by the user.After thresholding the selected

region,the image of femur bone becomes interpolated which

is shown .

Fig. 2. X-Ray image of femur bone.

Fig. 3. Thin plate spline interpolation.

Usually x-ray image having both strong and weak edges.

The Canny Edge detector is an optimal edge detection

algorithm that can be used to detect a wide range of strong

and weak edges in images .The canny algorithm contains a

number of adjustable parameters, which can reduce the

computation time. It gives good detection, good localization

and minimal response. It is very effective edge detecting

technique as it detects faint edges even when the image is

noisy. If the pixel value is less than the lower threshold then

it is set to 0 and if it is greater than the higher threshold then

it is set to 1. If a pixel falls in between the two thresholds

and is adjacent or diagonally adjacent to a high-value pixel

then it is set to 1, otherwise it is set to 0. The object to be

segmented is differs from the background image. It can be

detected by gradient operators of an image. The calculated

gradient image can be applied to create a binary mask

containing the segmented cell. The Fig. 4 shows the canny

edge detected output of femur bone which helps for

segmentation.

Fig. 4. Canny edge detection.

Segmenting the femur bone parts such as neck, ward,

trochanter and shaft regions. Initially measure the pixel

value inside the blue box for each part in the femur bone x-

ray image. The neck and ward region segmentation is shown

in Fig. 5. The Trochanter and shaft region segmentation is

shown in Fig. 6. It helps to make segmentation easier. After

Lecture Notes on Software Engineering, Vol. 1, No. 2, May 2013

196

segmenting out the regions, calculated the areas of each

femur bone part which is actually needed to measure the

BMD. As the edges are clear it is easier to measure the area.

The area obtained was in pixels, so we used pixel

conversion calculator to attain the area in centimeter square.

In x-ray images of femur bone, the areas defined for the

neck region is a rectangle, for the ward region it is a square

and for the shaft and the trochanter it is a triangle. This

geometrical shape makes comparison more flexible.

Fig. 5. Neck and ward region.

Fig. 6. Trochanter and shaft regions.

The area of region is obtained from the pixel conversion

calculation. The bone mineral content values of the normal

femur and the osteoporotic femur is collected from hospitals.

BMD is a measure of degree and heterogeneity of

mineralization in bone tissue [6]. which is calculated by

bone mineral content divided by area of each femur part.

IV. T-SCORE MEASUREMENT

The T-score is the number of standard deviations below

the average for a young adult at peak bone density [7]. The

prevalence of low bone density in the general population can

be assessed by means of the WHO diagnostic criteria.

According to these criteria, persons with bone density levels

of t-score more than 2.5 standard deviations and below the

young adult reference mean are considered to have

osteoporosis. Persons with bone density below this threshold

who also sustains a fracture meet the definition of

“established or severe osteoporosis” [8].

Fig. 7. BMD measurement.

Fig. 7 shows the boundary detection of femur bone x-ray

image. This boundary detection is not same for all images. It

will vary according to the osteoporotic affected bones [9].

Layout is created using the MATLAB GUIDE, Graphical

user interface development environment [10]. The Fig. 8

shows the first page of the program that can be created using

the GUI, listing down all the femur images.

Fig. 8. GUI layout.

Then we have placed the pushbutton named „Measure

BMD‟. First a particular femur image is selected, and then

clicking on the „Measure BMD‟ button gives the BMD

value of the particular femur. The Fig. 9 shows the GUI

layout page displaying the area, the BMC and the measured

BMD values of the osteoporotic femur. Fig. 10 shows the

GUI layout page displaying the area, the BMC and the

measured BMD values of the normal femur.

Fig. 9. GUI layout for osteoporotic bone.

Fig. 10. GUI layout for normal bone.

The head region is still manually removed by setting the

threshold value. But, in this work, it represents a method

which is potentially removed automatically by incorporating

a Hough filter for detecting spherical objects in head region

which is articulates in pelvis area [5]. Fig. 11 highlights the

head region of femur from pelvis which is done by matlab

using Hough filter.

Lecture Notes on Software Engineering, Vol. 1, No. 2, May 2013

197

Fig. 11. Hough filter output.

Then comparing the BMD values obtained from X ray

image and DEXA image. This is done for both normal

femur image and an osteoporotic femur image and estimates

their accuracy. The BMD values measured from X-ray

image is very close to the BMD values measured from

DEXA image. The BMD Measurement from X-ray image is

very much simpler compared to the DEXA method. This

makes the method much easier as well as efficient. The

Table I compares the BMD values.

TABLE I: BMD COMPARISON

NORMAL FEMUR

OSTEOPOROTIC

FEMUR

REGIONS

DEXA

IMAGE

X-RAY

IMAGE

DEXA

IMAGE

X-RAY

IMAGE

Neck 0.847 0.8469 0.8469 0.654917

Ward 0.593 0.5925 0.5925 0.479726

Trochanter 0.797 0.7975 0.7975 0.507397

Shaft 1.128 1.1277 1.1277 0.780815

The Fig. 12 shows the BMD values obtained from X ray

and DEXA images in chart, showing small variations for all

the regions namely, the neck, the ward, the trochanter and

the shaft of the osteoporotic femur. From the chart it can

conclude that, the BMD measured from X-ray image by this

method does not vary to a great extent for the osteoporotic

femur.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

neck ward troch shaft

DEXA

X ray

Fig. 12. BMD comparison chart.

V. CONCLUSION

Thin Spline Interpolation is mainly used for an intensity

based registration process using thin plate Spline registration

where the landmarks on the reference volume are defined by

the corresponding surface mesh. The WHO defines

osteoporosis as a BMD of 2.5 or more standard deviations

below that of a normal young healthy female (a T score of

≤ .2.5 SD) for postmenopausal women and men over 50

years as measured by DEXA at the femoral neck. Low BMD

is a major risk factor for fragility fracture and other risk

factors may act via their effect on bone mineral density. The

automatic segmentation of femur bone parts include neck,

ward, trochanter and shaft region and then measure the

BMD of proximal femur from X ray images. It is much

simpler than the DEXA method. The results show some

promising correlations with the DEXA scan results both for

normal and osteoporotic femur. The values of BMD from X

ray and DEXA images show very less variations. The

measurement is cost effective. As measurement of BMD is

possible with the conventional X ray image, hospitals need

not replace their X ray machines with high cost DEXA

equipment to diagnose osteoporosis, especially to measure

BMD. Moreover special training to personnel to handle the

DEXA equipment is also not needed. So, it is mainly helpful

for economically weaker people to diagnose the

osteoporosis.

REFERENCES

[1] C. Matsumoto, K. Kushida, K. Yamazaki, K. Imose, and T. Inoue,

“Metacarpal bone mass in normal and osteoporotic Japanese women

using computed X-ray densitometry,” Calcified Tissue International,

vol. 55, no. 5, pp. 324-329, 1994.

[2] WHO, Prevention and management of osteoporosis World Health

Organization Technical Rep., 921, 2003.

[3] The sex and age distributions of population. The 1994 revision of the

United Nations global population estimates and projections, New

York, NY, United Nations, 1995.

[4] Peripheral X-ray absorptiometry in the management of osteoporosis

edited by Dr Rajesh Patel, Head of Academic Bone Densitometry and

Clinical Studies, Imperial College London.

[5] A. Malich, “Early results of the comparison of bone mineral density

values assessed with digital X ray based radiogrammetry and double

energy x ray absorptiometry on patients suffering from rheumatoid

arthritis,” The Internet Journal of Radiology, vol. 5, no. 1, 2003.

[6] T. Whitmarsh, L. Humbert, M. De Craene, L. M. Del R. Barquero,

and A. F. Frangi, “Reconstructing the 3D Shape and Bone Mineral

Density Distribution of the Proximal Femur from Dual-Energy X-Ray

Absorptiometry,” IEEE Transactions on medical imaging, vol. 30, no.

12, December 2011.

[7] R. McKinney et al., Author affiliations appear on, pp. 2288–2289.

[8] E. Shane et al., Atypical Subtrochanteric and Diaphyseal Femoral

Fractures: Report of a Task Force of the American Society for Bone

and Mineral Research.

[9] J. A. Kanis et al., “Assessment of fracture risk and its application to

screening for postmenopausal osteoporosis,” Synopsis of a WHO

Report. Osteoporosis International, 1994, vol. 4, pp. 368–381.

[10] S. Simakov, “Introduction to MATLAB Graphical User Interfaces,”

Maritime Operations Division Defence Science and Technology

Organization DSTO–GD–044.

P. Santhoshini is pursuing M.E. Applied Electronics

Final Year, having 9.1 CGPA in R.M.K Engineering

College, Chennai, India .In 2011 she graduated in

Electronic and communication Engineering at C.Abdul

Hakeem College of Engineering and Technology,

Vellore, India with Distinction. During her College

days, She Won Third Prize for Presented a Paper

named as “A VLSI Architecture of an Invisible

Watermarking Unit for a Biometric Based Security System in a Digital

Camera” at the Student‟s National Level Technical Symposium

(IMPETUS‟10) in Mount Zion College of Engineering And Technology.

She attended two day workshop on “Signal and Image Processing” in VIT

University, Vellore. She Underwent Project Work Training on

“Development of Analog Data Acquisition for Controlling ESP Using AVR

Micro Controller” in BHEL, Ranipet

R. Tamilselvi is an Assistant Professor in the

Department of Electronics and Communication

Engineering at R.M.K Engineering College,

Tamilnadu, India. She has been teaching in the

Electronics and Communication field since 2004.

She is pursuing her PhD in College of Engineering

Guindy, Anna University Chennai. She obtained her

Master‟s degree from sastra university, Thanjavur.

Her research interests include Medical Image

Lecture Notes on Software Engineering, Vol. 1, No. 2, May 2013

198

Processing and wireless communication. She has published over 3 journal

and 8 international conference papers over the last few years. Tamilselvi is

a life member of Biomedical Engineering Society of India.

R. Sivakumar is a Professor and Head of

Department of Electronics and Communication

Engineering at R.M.K Engineering College,

Tamilnadu, India. He has been teaching in the

Electronics and Communication field since 1997. He

obtained his Master‟s degree and PhD from College

of Engineering Guindy, Anna University Chennai.

His research interests include Bio Signal Processing,

Medical Image Processing, wireless body sensor networks and VLSI. He

has published over 22 journal and 35 conference papers over the last

several years. He has taught a wide variety of Electronics courses including

Digital Image Processing, Multimedia Compression Techniques, VLSI

Design, Medical Electronics and Electronic Circuits. Dr. Siva is a life

member of the Indian Society of Technical Education, Senior Member of

IACSIT and a member of IEEE. Dr. Siva has been invited to Chair and

speak at various conferences; more recently, he was Conference Chair at

the ICCTS 2012 in Delhi & ICIAE 2012 in Bangalore.

Lecture Notes on Software Engineering, Vol. 1, No. 2, May 2013