Camera in laparoscope

Prof, MEDHAT M.IBRAHIM

Bozzini’s “Lichtleiter”

The “Lichtleiter” was made from an aluminum tube. The tube was illuminated by a wax candle and had mirrors fitted to it in order to reflect the images.

Bozzini published his invention in 1806 in the Hufeland’s Journal of Practical Medicine, Volume 24, under the title “Light Conductor, An Invention for the Viewing of Internal Parts and Diseases with Illustration.”

Incidentally, Bozzini was censured for “undue curiosity” by the Medical Faculty of Vienna for this invention. (Courtesy of Olympus Austria,

Antoine Jean Desormeaux

Antoine Jean Desormeaux (1815–1894), a French Surgeon, was the first to introduce the Bozzini’s “Lichtleiter” into a patient. In 1853, he further developed the Lichtleiter and termed his device the “Endoscope.” It was the first time this term was used in history.

Desormeaux presented the endoscope in 1865 to the Academy in Paris. He even used his endoscope to examine the stomach; but due to an insufficient light source he was not quite successful.

(Copyright Verger-Kuhnke AB. The life of Philipp Bozzini (1773-1809), an idealist of endoscopy. Actas Urol Esp. 2007;31:437-444)

Desormeaux’s “Endoscope”

Desormeaux’s endoscope used as a light source a kerosene lamp Berning alcohol and turpentine, with a chimney to enhance the flame and a lens to condense the beam to a narrower area to achieve a brighter spot.

He used this instrument to examine the urethra and bladder.

As might have been expected, burns were the major complication of these procedures. Interestingly, he thought of using electricity but felt it unsafe. (Courtesy of Olympus Austria, Vienna, Austria)

Johannes Freiherr

surgeon of Polish-Lithuanian descent born in Bukowina, Romania, constructed the first rigid endoscope in 1880 and was the first to use Edison’s light bulb for his gastroscope in practice. He modified the instrument so that it could be angled by 30Åã near to its lower third to achieve better visualization. He added a separate channel for air insufflation. In one of the first interventional endoscopic procedures, he pushed a large swallowed bone from the esophagus into the stomach, thus avoiding surgery. (Copyright: surgeon in the evolution of flexible endoscopy. SurgEndosc 2007: 21; 838-853 Springer Verlag)

Georg Kelling (1866–1945), a German physician

from Dresden, was introduced to endoscopy and gastrointestinal surgery when he worked with Professor Mikulicz-Radecki at the Royal Surgical Clinic in Breslau, Germany. In with the help of Nitze’s cystoscope, and coined this laparoscopic examination “celioscopy.”

He used air filtered through sterile cotton to create pneumoperitoneum in dogs. For insufflation he used a trocar Developed by Alfred Fiedler, an internist from Dresden.(Copyright: Hatzinger M: Georg Kelling (1866–1945) Der Erfinder der modernen Laparoskopie. Urologe A 2006; 45 (7):868-71 Springer Verlag)

Harold Horace Hopkins

Hopkins (1918–1994) obtained a degree in physics and mathematics at Leicester University in 1939. After the war, in 1947, Hopkins became a research fellow at Imperial College, London, UK.

Hopkins invented the rigid rod-lens system for scopes, which allows double light transmission, requires short and thin spacer tubes, and gives a larger and clearer aperture.

He filed a patent for the rod-lens system in 1959.

However, the English and American companies to whom he offered the system displayed little interest. The situation changed however in 1965 when Professor George Berci, who recognized the potential of this invention, introduced Hopkins to Karl Storz to manufacture the scopes. (Courtesy of William P. Didusch Center for Urologic History, American Urological Association, MD, USA)

Kurt Karl Stephan Semm

Kurt Karl Stephan Semm (1927–2003) was born in Munich, Germany, where he also studied medicine at the Ludwigs-Maximillian University. In 1958, he wrote his medical thesis under the guidance of Nobelmlaureate Adolf Butenandt. Semm began his career in gynecology under Professor Fikentscher in Munich. In 1970s, as the Head of Gynecology in Kiel, introduced an;

1- Automatic insufflation device capable of

monitoring intra-abdominal pressures,

2- Endoscopic loop sutures,

3-Extra- and intracorporeal suturing techniques.

4-Created the pelvi- trainer. He performed the

first laparoscopic appendectomy

in 1982. (Courtesy of Monika Bals-Pratsch MD,

Zentrum fur Gyn.kologie, Universit.t

Regensburg,

Germany)

Anatomy of a Rigid Scope

Central to the instrumentation is the scope. Its backbone is the rod lens system designed by Hopkins.

The shaft of scopes houses both light fibers

and viewing optics. The viewing optic consist of three

distinct parts: o The objective lens,o Rod lenses, o ocular lens.

Field of View

The field of view (also field

of vision) is the angular

extent of the observable

area that is seen at any

given moment. The field of

view in scopes for

endoscopic surgery can

vary from 600 to 820

depending up on the type

of instrument. Wider angles

of view provide a greater

depth of field in the image

with better utilization of

illumination. A smaller field

of view allows the scope to

be farther from the tissue,

for the same to be

observed.

Angle of View

The angle of view in scopes can vary with respect to the central axis view are designated as 00 and provide a straight view of the structure in question. Scopes are also available with a 50, 250, 300, 450, and even 700 angle of view, allowing utilization of the scopes much as a periscope. The off-axis scopes enable one to observedown into the gutters and up the anterior abdominal wall as well as sideways. Off-axis scopes are difficult to work with; however, they provide an excellent means of obtaining close inspection of tissuesat difficult angles and positions.

Scope Size and Screen Image

The decrease in the size of scopes was an

important factor in the advancement of

minimally invasive surgery in the pediatric

age group. Although scopes are available in

sizes from 1.9 mm to 12 mm in diameter,

the majority of the procedures are

performed using 5- or 10-mm scopes.

When compared to the reduced view

obtained in the previous generation of

scopes (left), modern5-mm, full-screen

scopes provide a bright, distortion- free, full-

screen image (right). In addition, the image

size in modern 5-mm scope is equivalent to

that obtained by the previous-generation

10-mm scope. (Courtesy of Richard Wolf,

Knittlingen,

Germany)

Charge Coupled Device (CCD)Video Cameras Scope cameras are available in either single-chip three-chip versions (one chip offers 300,000 pixels/cm2). In single-chip CCD cameras, all the three primary colors (red, blue and green) are sensed by a single chip. In three-chip CCD cameras, there are three chips for separate capture and processing of the primary colors.Single-chip CCD cameras produce images of 450 lines/inch resolution and are ideal for outpatient surgery. On the other hand, three-chip CCD cameras have high fidelity with unprecedented color reproduction to produce images of 750 lines/ inch resolution that can be viewed optimally on flat-panel screens and are best suited for endoscopic surgery. (Courtesy of Richard Wolf, Knittlingen , Germany) Light source:Light-Source Generators and Transmission Pathways There are two commonly utilized light sources: halogen and xenon. A schematic overview of light transmission is outlined12

The Concept of White Balancing

White balancing should be performed before inserting the camera inside the abdominal cavity. This is necessary before commencing surgery to diminishthe added impurities of color that may be introduced due to a variety of reasons such as: (1)voltage difference, (2)staining of the tip by cleaners,(3)scratches and wear of the eyepiece.White balancing is achieved by keeping a whiteobject in front of the scope and activating the appropriate button on the video system or camera.The camera senses the white object as its referenceto adjust all of the primary colors (red, blueand green). (Courtesy of Richard Wolf, Knittlingen,Germany)

A three-CCD camera is a camera whose imaging system uses three separate charge-coupled devices (CCDs),

each one taking a separate measurement of the primary colors, red, green, or blue light.

Light coming into the lens is split by a trichroic prism assembly, which directs the appropriate wavelength ranges of light to their respective CCDs.

The system is employed by still cameras, telecine systems, professional video cameras and some prosumer video cameras.

Rods and ConesThe retina contains two types of photoreceptors, Rods cones. The rods are more numerous, some 120 million, and are more sensitive than the conesthey are not sensitive to color. The 6 to 7 million cones provide the eye's color sensitivity and they are much more concentrated in the central yellow spot known as the macula. In the center of that region is the " fovea centralis ", a 0.3 mm diameter rod-free area with very thin, densely packed cones.

The experimental evidence suggests that among the cones there are three different types of color reception. Response curves for the three types of cones have been determined. Since the perception of color depends on the firing of these three types of nerve cells, it follows that

visible color can be mapped in terms of three numbers called tristimulus values.

Color perception has been successfully modeled in terms of tristimulus values and mapped on the CIE chromaticity diagram.

Rods Do Not See Red!

The light response of the rods peaks sharply in the blue; they respond very little to red light. This leads to some interesting phenomena:

Red rose at twilight: In bright light, the color-sensitive cones are predominant and we see a brilliant red rose with somewhat more subdued green leaves. But at twilight, the less-sensitive cones begin to shut down for the night, and most of the vision comes from the rods. The rods pick up the green from the leaves much more strongly than the red from the petals, so the green leaves become brighter than the red petals!

The ship captain has red instrument lights. Since the rods do not respond to red, the captain can gain full dark-adapted vision with the rods with which to watch for icebergs and other obstacles outside. It would be undesirable to examine anything with white light even for a moment, because the attainment of optimum night-vision may take up to a half-hour. Red lights do not spoil it.

These phenomena arise from the nature of the rod-dominated dark-adapted vision, called scotopic vision.

Cone Details

Current understanding is that the 6 to 7 million cones can be divided into "red" cones (64%), "green" cones (32%), and "blue" cones (2%) based on measured response curves. They provide the eye's color sensitivity. The green and red cones are concentrated in the fovea centralis . The "blue" cones have the highest sensitivity and are mostly found outside the fovea, leading to some distinctions in the eye's blue perception.

The cones are less sensitive to light than the rods, as shown a typical day-night comparison. The daylight vision (cone vision) adapts much more rapidly to changing light levels, adjusting to a change like coming indoors out of sunlight in a few seconds. Like all neurons, the cones fire to produce an electrical impulse on the nerve fiber and then must reset to fire again. The light adaption is thought to occur by adjusting this reset time.

The cones are responsible for all high resolution vision. The eye moves continually to keep the light from the object of interest falling on the fovea centralis where the bulk of the cones reside.

The combination of the three sensors can be done in the following ways:

Composite sampling, where the three sensors are perfectly aligned to avoid any color artifact when recombining the information from the three color planes

Pixel shifting, where the three sensors are shifted by a fraction of a pixel. After recombining the information from the three sensors, higher spatial resolution can be achieved.

Pixel shifting can be horizontal only to provide higher horizontal resolution in standard resolution camera, or horizontal and vertical to provide high resolution image using standard resolution imager for example. The alignment of the three sensors can be achieved by micro mechanical movements of the sensors relative to each other.

Arbitrary alignment, where the random alignment errors due to the optics are comparable to or larger than the pixel size.

Compared to cameras with only one CCD, three-CCD cameras generally provide superior image quality through enhanced resolution and lower noise.

By taking separate readings of red, green, and blue values for each pixel,

three-CCD cameras achieve much better precision than single-CCD cameras.

By contrast, almost all single-CCD cameras use a Bayer filter, which allows them to detect only one-third of the color information for each pixel.

The other two-thirds must be interpolated with a demosaicing algorithm to 'fill in the gaps', resulting in a much lower effective resolution

Video and Data StorageEquipment2.21.1 Digital Video RecordersModern endoscopic surgery towers are generallyequipped with digital video disc (DVD) recorders(DVRs), which enable recording of a procedurein digital quality. The procedures are recorded oncommercially available DVDs, which can later beviewed on normal DVD players or edited on personalcomputers.DVRs have evolved into devices that are featurerich and provide services that exceed the simplerecording of video images that was previouslyachieved using video cassette recorders (VCRs).DVR systems provide a multitude of advanced functions,including video searches by event and time.

Digital Video PrintersA variety of printers from small print format tolarge A5 print format are available. These printersoffer high-resolution prints, quick, 20-s print time,and high-quality, curl-free prints at 400 dpi resolution.Most modern printers come with a four-framememory. The new compact design of printers allowsfor easy integration with other video equipment.Small, compact printers are ideal for the officesetting, but large-print format printers are preferablein the operating room.

Digital Video ManagersThese are computer-based systems that display intuitivepatient information screens that allow forquick and easy input of vital data. The data is storedon hard drives and can be viewed as images orvideos, and may be stored or deleted. The editingscreen enables viewing and editing procedures.Current systems allow storage of up to 50 patientarchives for multiple procedures. These systemsare compatible with personal computers andhospital network software. (Courtesy of RichardWolf, Knittlingen, Germany)

Place colored marker on instrumentConvert RGB to HSV spaceHue value of a pixel is much less susceptible to lighting changesRecord hue value of marker to be trackedSearch entire image for hue values within epsilon rangeCentroid of matched pixels gives position of tracker in the imageIf target is detected, localize search to a smaller neighborhoodTracking performed in real-time at 25 fps

Tracking Instruments using Color

Markers

Allows shared autonomy with surgeon

The feedback from the tracker can be used to drive motors to keep the tool in the center of the image

PD controller used

( Ex , Ey ): off set error of tracker from center of image

Pan speed ( x * Ex ) – ( x * dEx/dt )

Tilt speed ( y * Ey ) – ( y * dEy/dt )

Stereo image

3D Trajectory Reconstruction

The Flock of Birds (FoB) sensor can transmit the position of its sensor w.r.t. its base Accuracy within 1.8mm Refresh rate up to 144HzBy placing an optical marker on the FoB sensor we can track its position in the image By tracking the sensor using stereo cameras we can compute its 3D trajectory

Stereo Camera

eMagin Z800 Head-Mounted VR Display- Uncomfortable

- Single User

RealD Crystal Eyes shutter glasses- Uncomfortable over longer periods

- Need to maintain Line Of Sight with

synchronizing emitter

True Vision back projected 3D display- Low incremental cost for additional users

- Bigger display size

-Passive polarization, lightweight glasses

3D Displays

THAN

K YO

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