1. TEC , OYOOR

2.  WIRELESS CAPSULE ENDOSCOPY (WCE)
 LOCALIZATION METHODS
BASED ON MAGNETIC FIELD STRENGTH
MAGNETIC LOCALIZATION FOR PASSIVE CAPSULE ENDOSCOPE
UTILIZATION OF A PERMANENT MAGNET
UTILIZATION OF A SECONDARY COIL
UTILIZATION OF A MAGNETO-RESISTIVE SENSOR
MAGNETIC LOCALIZATION FOR ACTIVE ACTUATION SYSTEM
BASED ON HIGH-FREQUENCY ALTERNATING MAGNETIC FIELD
LOCALIZATION BASED ON INERTIAL SENSING
MEASURING A ROTATIONAL MAGNETIC FIELD
BASED ON ELECTROMAGNETIC WAVES
RADIO WAVES
RECEIVED SIGNAL STRENGTH INDICATOR(RSSI)
RADIO FREQUENCY IDENTIFICATION(RFID)
VISIBLE WAVES
X-RAY
GAMMA RAY
CONTENTS

3. • Endoscopy ?
• Conventional techniques
• WCE is an ingestible pill-like device contains a tiny camera and an illuminating system
• WCE offers patient friendly and painless investigation
• A reliable and precise localization system plays an important role in enhancing the
benefits of WCE.
• Methods for determining the capsule locations are categorized into two,
- magnetic field strength based
- electro magnetic wave based
INTRODUCTION

4. DATA
RECORDER
COMPUTER
Data Acquisition & Storage
Of Data On Computer
Produces two images per
second, approximately 2,600
high quality images.
Movement Of Capsule Through The
Digestive System

5. OPTICAL DOME
LENS HOLDER
LENS
ILLUMINATING LED CMOS IMAGE
SENSOR BATTERY
ASIC
TRANSMITTER
ANTENNA
INSIDE A CAPSULE CAMERA

6. LOCALIZATION METHODS BASED ON MAGNETIC FIELD STRENGTH
• This method is used because of 2 main reasons
* static and low frequency magnetic signals can pass through human tissue without
attenuation.
* magnetic tracking is a non line of sight method .
• The negligible interaction between magnetic field and human body
• The problem is the conflict between 2 systems due to interference of 2 applied magnetic
fields.
* Magnetic localization for passive capsule endoscope
* Magnetic localization for active actuation system

7. UTILIZATION OF A PERMANENT MAGNET ENCLOSED INSIDE A
CAPSULE
 Why a permanent magnet ?
 The majority of magnetic tracking systems generate magnetic field through integrating
a permanent magnet inside the capsule.
 Magnetic flux intensities originating from the magnet vary their magnitudes and direction
depending on the magnets location and orientation.
 Magnetic sensors are placed outside of a patients body to measure these persistent
magnetic signals.

8. UTILIZATION OF A SECONDARY COIL EMBEDDED IN A CAPSULE
 The spatial information of the capsule can be obtained through utilizing a coil enclosed
inside a capsule.
 The field seen by the receiving coil is,
UTILIZATION OF A 3-AXIS MAGNETO-RESISTIVE SENSOR
 A 3-axis magneto-resistive sensor used to measure the intensity of the external magnetic
field generated by 3 energized coils fixed on the patients body.
 The 3 coils are excited in turn by square waves with the same period of 0.03s,and at the
end of every cycle, there is a break period of 0.1s when the coils are not activated to
estimate earth’s magnetic field magnitudes.

9. MAGNETIC LOCALIZATION FOR ACTIVE ACTUATION SYSTEM
• These systems were designed to work effectively with their own magnetic actuation
mechanisms.
* localization based on high frequency alternating magnetic field
* localization method based on inertial sensing
* based on measuring a rotational magnetic field by rotating an external permanent
magnet.
LOCALIZATION BASED ON HIGH FREQUENCY ALTERNATING MAGNETIC FIELD
• It uses a spiral structure on the surface of a capsule in which a permanent magnet is integrated
• 3 pairs of coils were placed in three perpendicular axial directions to generate an external
rotating magnetic field around the patient’s body.
• The spiral structure rotate the capsule by applying this magnetic field on the magnet can propel
it forward and backward.
• The frequency of rotating magnetic field should not be higher than 10Hz

10. LOCALIZATION METHOD BASED ON INERTIAL SENSING
• Magnetic steering , utilized a 6 degree-of-freedom robotic arm to carry a permanent magnet
at the end.
• 4 cylindrical magnets were mounted uniformly on the body of a capsule in order to create a
magnetic link between body and the external permanent magnet.
• By this design , the capsule can be dragged and steered effectively with the assistance of the
magnetic interaction.
• For the localization function , a 3-axis accelerometer was inserted into the capsule.
.

11. LOCALIZATION BASED ON MEASURING A ROTATIONAL MAGNETIC FIELD
GENERATED BY ROTATING AN EXTERNAL PERMANENT MAGNET
• It uses an endoscopic capsule with a helical architecture , created an external rotational
magnetic field to rotate 2 permanent magnets embedded in the endoscopic device.
• instead of utilizing 6 bulky coils around the patients body , here rotates a big parallel piped
permanent magnet made by 7 smaller rectangular magnets to generate a rotational mag.field.
• The magnetic field generator was driven by an electrical motor mounted on a manipulator , so
that it could spin and its position can be changed during the control process of capsule.
• When the external permanent magnet is spinning , field strength changes periodically and its
highest or lowest value occurs at XZ/XY plane.

12. LOCALIZATION METHODS BASED ON ELECTROMAGNETIC WAVES
• These methods are not influenced by magnetic field generated for the actuation purpose.
• Radio frequency has been widely used for locating an object in both outdoor and indoor
environments.
- Received Signal Strength Indicator(RSSI)
- Radio Frequency Identification(RFID)

13. 1. RECEIVED SIGNAL STRENGTH INDICATOR(RSSI)
 The transmitter built inside the capsule wirelessly sends endoscopic images ,which
are captured during its travel along the inner parts ,to 8 receivers placed uniformly
on the exterior of the patient abdomen.
 The low accuracy achieved by this localization system can make it impossible to
provide feedback for actuation systems.
2. RADIO FREQUENCY IDENTIFICATION(RFID)
 RFID is also investigated in radio frequency based localization systems for WCE.
 A cubic antenna array is built surrounding a patient’s body to track a RFID tag
integrated inside a capsule.

14. VISIBLE WAVES
 Visible waves cannot penetrate human body , it has still been exploited for the aim
of capsule localization through computer vision.
 Inside the WCE ,white light emitting diodes(LED) illumination sources are used in
conjunction with a miniature camera for capturing images .
X-RAY
 Beside the application of medical imaging , X-rays can also be exploited to track an
object
 Fluoroscopy
GAMMA RAY
 A gamma ray has not been employed in the localization approaches for WCE , was
exploited in gamma scintigraphy technique .

15. OTHER LOCALIZATION METHODS
1) MRI (MAGNETIC RESONANCE IMAGING)
Diagnostic imaging technique used widely in medical clinics.
1) ULTRA SOUND
A potential method for localization in soft tissue.

16. Localization methods extra extra accuracy interference real health
space power time effects
passive permanent magnet Yes No High Yes Yes No
WCE secondary coil Yes Yes Mdm Yes -- No
magneto-resistive
sensor Yes Yes Mdm Yes No No
Active HF alternating m.f Yes No High No Yes --
WCE Inertial sensing Yes Yes Low No -- No
Rotating external
permanent magnet Yes Yes Mdm No -- No
EM Visible No No Low No --
Waves X-ray No No -- No Yes Yes
Gamma Yes No -- No Yes Yes
Others MRI Yes Yes High -- Yes Little
Ultra sound Yes Yes -- No Yes Little
COMPARISON OF LOCALIZATION METHODS

17. ADVANTAGES
 Painless, no side effects or complications
 Miniature size , so can move easily through digestive tract.
 Accurate , precise and effective
 Images taken are of high quality which are sent almost instantaneously to the data recorder for
storage.
 Made of bio-compatible material , doesn’t cause any harm to the body.
DRAWBACKS
 Patients with gastrointestinal structures or narrowing are not good candidates for this procedure.
 The pill will get stucked , if there is a partial obstruction in the small intestine.
Impossible to control camera behavior.

18. CONCLUSION
 WCE with the capability of moving automatically in the digestive tract under an
external control will be introduced in the near future.
 Such an active system requires a sufficiently accurate localization system
 None of the existing methods could offer a complete solution to address the challenging
capsule localization problem.
 A future WCE is expected to have fully robotic capabilities such that it will be able to
accomplish both diagnosis and disease treatment
 In order to achieve such an autonomous WCE , building a complete localization system
which is ,
- acceptably accurate in real-time
- minimally invasive
- work with different actuation mechanisms
- easily implementable

19. A FUTURE CAPSULE