Adobe Systems
Department of Biophysics, Medical Faculty, Masaryk University in Brno
1
Lectures on Medical Biophysics
Endoscopes, tissue ablation devices and lithotripters
shock%20shoulder schlinge

Adobe Systems
2
Lecture content
This lecture deals with the following biomedical devices:
̶Endoscopes
̶Lasers
̶Electrosurgery devices
̶Ultrasonic surgery devices
̶Cryosurgery devices
̶Water jet surgery devices
̶Plasma scalpel
̶Lithotripters
  Keep in mind that endoscopes are often equipped with surgical tools including lasers (for tissue
ablation). Lithotripsy is a minimally invasive method for removal of kidney stones and gallstones
(helps avoid major surgery).

Adobe Systems
3
Endoscopy
̶Endoscopes are devices for the visual examination of body cavities. They are based on the
reflection and refraction of light.
̶They are inserted into the body cavity to be examined either through natural body openings (nasal
and pharyngeal cavity, larynx, airways, urethra, uterus, rectum) or surgical incisions (abdomen,
thorax, joints).
̶Endoscopes can be categorized according to their complexity, method of illumination and method of
observation.
̶There are groups of endoscopes with different complexity:
•Endoscopic mirrors
•Endoscopes with rigid tubes
•Fiberscopes and videoendoscopes
•Endoscopic capsules
̶Endoscopes are used also for minor surgery as they can be equiped with small surgical tools.

Adobe Systems
4
Way of illumination and observation
̶Lighting can be:
̶Internal: source of light is part of the device
̶External: examined cavity is illuminated by an external source (Endoscopic mirrors are typical
representatives of the second group).
̶In endoscopes with internal lighting, the source is directly inside the body cavity (distal
lighting) or outside the cavity (light is guided into the cavity by an optical system, proximal
lighting).
̶The observation of the body cavity can be:
̶direct when the physician uses his/her own eyes aided by an optical system
̶indirect when the images are taken by a digital video camera and observed on a monitor

Adobe Systems
5
Endoscopic mirrors (specula)
̶Laryngoscope. Spoon-like mirror used for the examination of the larynx and posterior part of the
nasal cavity.
̶Otoscope. Funnel-like endoscope inserted into the auditory meatus to examine its distal part and
the ear drum.
̶Rhinoscope. Pliers-like instrument with concave reflecting jaws – examination of anterior part of
nasal cavity.
̶Ophtalmoscopic mirror. Planar or concave mirror with an central orifice. It serves for induction
of the so-called red reflex – reflection of light from the retina.
̶Retina is examined by direct ophtalmoscopy – an ophtalmoscope, a small see-through endoscope with
light source and correction of the doctor’s visual handicap.
̶Vaginal speculum (colposcope). Pliers-like instrument with concave reflecting jaws – examination
of vagina and cervix.

6
Ophthalmoscope
Endoscopic mirrors
ant%20rhino
laryngoscope
Rhino-scope
otoscope
grand2 http://www.physiologie-online.com/ana_media/Larynx-Laryngoskopie.jpg

7
Endoscopic mirrors
Oftalmoskop Riester Pen-scope Disposable Graves Vaginal Speculum
ophtalmoscope
vaginal speculum

Adobe Systems
8
Rigid tube endoscopes
̶Rigid metallic tubes with optical system and built-in light source (proximal or distal).
Disadvantages: relatively high light loss and the rigidity of tubes. The first gastroscopic
examination was done by Adolf Kussmaul in 1868.
̶Cystoscope – urinary bladder
̶Rectoscope – rectum and sigmoid colon
̶Endoscopes inserted surgically:
̶Laparoscope – abdominal cavity.
̶Arthroscope – joints (namely knee joint).
•

Adobe Systems
9
Rigid tube endoscope

Adobe Systems
10
Rektoskop cystoskop
rectoscope
cystoscope
Rigid tube endoscope

11
Fiberscopes
Fibre optics, total reflection, critical angle.
The lowest light loss is typical for two-layer optical fibres made of glass or plastics. The core
has higher index of refraction n1 than the coating n2. Total reflection occurs when sina < (n12 -
n22)1/2. The fibres form bundles serving for illumination and image transfer.
312
- trachea and bronchi (bronchoscopy)
- oesophageal mucosa(Oesophagoscopy)
- gastric mucosa (Gastroscopy)
- colon (colonoscopy)
Fiber Optic Diagram
In the image transferring bundle, the fibres are arranged in the same way both on input and the
output of the bundle. Light signal loss: 0.001 – 0.005 dB per 1 m of length.

Adobe Systems
12
Fiberscopes
̶The fiberscopes make possible to take tissue samples and to make minor surgery. The are flexible
so we can examine body parts which are not accessible by rigid endoscopes. Length 130 - 140 cm.
̶Inside the flexible cable we can see:
̶3 bundles of optical fibres (2 for illumination, 1 for image transfer),
̶a tube for air or water,
̶a channel for insertion of surgical tools and
̶control drawbars enabling movement of the distal end with objective giving a sharp image from the
distance of 3 - 100 mm.
̶The proximal end is equipped by an eyepiece mounted in the rigid part of the tube. There is also
the control device for distal end movement.
̶A powerful source of light, air and water pump and vacuum pump also belong to the device
accessories.

13
Fiberscopes
Frontal part of the colo(no)scope - www.endoscopy.ru/diler/ pentaxvideo.html.
schlinge

Adobe Systems
14
Fiberscopes
fiberscope

Adobe Systems
15
Videoendoscopy
http://www.bethesda.de/kliniken/medizinische-klinik-ii---gastroenterologie/endoskopien-spiegelungen
/index.php
Videoendoscopy – modern endoscopes with a video camera. The image is shown on a monitor.
http://www.bethesda.de/images/39drstier004ret_480.jpg

Adobe Systems
Endoscopic capsule
16
http://medicalartbank.com/wp-content/uploads/2013/10/Capsule_endoscopy_medical_illustration.jpg

Adobe Systems
17
Laser
̶Light Amplification by Stimulated Emission of Radiation.
̶The first ruby laser was constructed by T.H. Maimann in 1960. Main parts of a laser:
̶active medium
̶optical resonator
̶source of excitation energy
̶Principle of the laser: alternating excitation and deexcitation.
̶Electrons of the atoms of the active medium are excited (brought to a higher energy level) by the
source energy („optical pumping“).
̶Thereafter they are deexcited by a stimulating photon, new photons of the same energy arise, and
the effect is repeated – amplification occurs.
̶In the so-called three-level laser, the third energy level is broad, thus it is not necessary to
use monochromatic (i.e. monoenergetic) light for optical pumping. Because of small energy
difference between the second and third energy level, the electron transition to the second energy
level is spontaneous („thermal“) – electrons are waiting for the stimulating photon there.

18
Three-level laser
Scheme of the 1st ruby laser  http://www.llnl.gov/nif/library/aboutlasers/Ruby%20cutaway.GIF

Adobe Systems
19
laser1 laser2 laser3 laser4

Adobe Systems
20
Lasers
̶Solid l. (compact, semiconductor): ruby laser (694.3 nm), neodymium (1.06 µm),
̶Semiconductor l. – based on the principle of electroluminescence.
̶Liquid l. An organic dye solution is used as active medium. Advantage: can be tuned to different
wavelengths (from near IR, VIS to UV range).
̶Gaseous l.. Important for medicine. Helium-neon laser (1.06 µm) and ion lasers (argon and
krypton). CO2-N2-He-laser etc.
̶Plasma l. Active medium is plasma, fully ionised carbon – irradiates soft X-rays.
̶Lasers can operate in two modes: continuous and pulsed
̶Laser power ranges from 10-3 to 104 W. Low-power lasers (soft-lasers) are used mainly in physical
therapy. High-power lasers are used as surgical tools (laser scalpel).

Adobe Systems
21
Effects of laser radiation
̶Laser light is monochromatic and coherent. This allows us to concentrate the laser beam on a small
area and to reach a high output density, that makes this surgical instrument useful even in
microsurgery. The laser beam can be guided by mirrors, lenses, or optical fibres. Photons are
absorbed in the surface layers of tissues.
̶Thermal effects depend on the power density of light and its wavelength. They are exploited mainly
in surgery and microsurgery. Non-thermal effects are typical for soft-lasers, they depend little on
the wavelength – based perhaps on a molecular action mechanism (action on enzymes of the
respiratory chain, enhancement of mitochondrial DNA replication, enhancement of enzyme activity).
Membrane potentials are also affected, possibly due to changes in membrane permeability for  Na+,
K+ a Ca++ ions.
̶Laser light also has a photodynamic effect – chemical changes of inactive substances irradiated by
laser light of certain wavelength can lead to formation of biologically active (cytotoxic)
derivatives.

Adobe Systems
22
Laser therapy – Safety
̶In non-invasive phototherapy, powers below 500 mW are used. Classes of lasers used are:
̶II (power up to 1 mW),
̶IIIa (power up to 5 mW)
̶IIIb (power up to 500 mW).
̶Surgery: Power lasers IV are used
̶Safety:
̶Labels placed on lasers must state class,
̶from IIIb also warning on eye damage by focussed beam
̶Medical staff as well as the patient must wear goggles absorbing laser light of given wavelength.
Care and handling

Adobe Systems
23
Soft-laser therapy
̶Surface applications – short wavelength, deep applications – long wavelength (near IR).
̶laser pens are the simplest devices, based on laser diodes, fed by batteries, constant power
setting.
̶Small lasers (pocket) with exchangeable probe, different frequency modes are possible.
̶Tabletop lasers – user comfort, many functions and applications.

Adobe Systems
24
medius-laser mdlx_s
Laser pen
Table-top soft-laser

Adobe Systems
25
Soft-laser therapy
̶Analgesic effect: increase of O2 partial pressure, increase of resting potential ® lowering of its
excitability.
̶Anti-inflammatory effect should be caused by activation of monocytes and macrophages, increased
phagocytosis, increased proliferation of lymphocytes.
̶Biostimulating effect: referred increased synthesis of collagen, better blood supply, faster
regeneration of some tissues.
̶Indications: laryngology, dentistry, orthopaedics and gynaecology. Seldom used as monotherapy.
̶Opinion of biophysicists: mostly placebo effect, specific action is supported by little research
evidence.

26
laser1 Photo of Laser Surgeon
?
Surgical laser unit
[USEMAP]

Adobe Systems
27
High-power laser application
General surgery:
A laser can serve as an optical lancet cutting without contact. The blood vessels are coagulated
and the cut practically does not bleed. The cutting speed depends on intensity (output density) and
on the properties of the tissue. The most frequently used lasers are infrared, namely CO2 laser
(10.6 mm) or solid Nd:YAG laser (1.064 mm).
Ophthalmology:
Besides being the light source of many optical instruments used for examination, the main use is
photocoagulation of retina and photoablation of cornea to correct refraction defects.
Lasers used for photocoagulation are mostly Nd:YAG with green light 532 nm, adjustable output up to
1.5 W.
For corneal refraction defects removal – photoablation - ArF or KrF excimer (excited dimers) lasers
are used. They emit UV radiation with 193 nm wavelength. It causes photochemical ablation of the
collagen macromolecules in the cornea (every impulse removes 0.1 - 0.5 mm of the tissue). The aim
is to change the curvature of the cornea and its refraction, thus improving the patient's vision.

Adobe Systems
28
http://www.dekamela.com/lasertessuto/fig5.gif
The effect of laser beam depends on its energy!

Adobe Systems
29
High-power laser application
̶In dentistry, neodymium and erbium YAG lasers are used. The Nd:YAG laser (1.064 mm) is used in
oral surgery and endodontics. The Er:YAG laser (2.940 mm) is used for precise preparation of the
tooth enamel and dentine.
̶Dermatology uses ruby lasers (690 nm) or other laser types including Nd:YAG and alexandrite lasers
(adjustable from 720 to 830 nm, well absorbed by skin melanin). The main applications are
photocoagulation of varicose veins, wart removal, skin lifting, depilation and tattoo removal.

30
laser wart_laser
Laser applications
ph_resurf1_lg
caries removal
Face lifting
removal of warts

Adobe Systems
31
Electrosurgery
̶These methods use heating effects of high frequency electrical currents. An electrode with a point
or a sharp edge can develop a high density of current.
̶ Heat effects are so extensive that water evaporates in the cells, causing their destruction. The
high temperature causes coagulation of the tissues and blood, so no bleeding (haemorrhage) occurs.
The operating frequency of electrosurgical instruments is about 3 MHz, the output is adjustable up
to 500 W. The power differs according to the aim of the surgical intervention (50 W is used in eye
and teeth surgery, higher output in breast and abdominal surgery and traumatology).
̶Electrosurgery devices are equipped with electrodes for electrocoagulation, which closes bleeding
vessels by coagulation of proteins.

32
Electrosurgery
22330089[1]
•
51
 Electrosurgical unit
Point electrode for removal skin defects

Adobe Systems
33
Electrosurgery
F321446
Whipple procedure. Transection of the neck of the pancreas with electrocautery.

34
Endoscopic electrosurgery
eq-repro-3[1] shared_1210_GC-27[1]
Removal of the polypus from intestinal mucosa by hot wire loop
•
Removal of a small gastric tumour

Adobe Systems
35
Ultrasonic tools
̶Ultrasound of high intensities (50-1000 W·cm-2) can be used in surgery for selective tissue
destruction.
̶1. Focused ultrasound with high frequency (1-3 MHz) for selective destruction of soft tissue
structures. These systems are in clinical test for breast tumour ablation.
̶2. Low frequency ultrasound (20 - 50 kHz) has been developed for surgical use. Ultrasound produced
by piezoelectric or magnetostrictive generators is transmitted to the tissue by special
wave-guides, able to enhance the amplitude of ultrasound oscillations up to 10 times. A steel
lancet or removable tip is attached to the end of the wave-guide. The removable tip is used also as
an aspiration tube, so that the destroyed tissue can be sucked away (aspired).

36
Ultrasonic tools
Aspirator. The acoustic vibrator contracts and expands due to ultrasonic oscillations. The motion
of the tip (stroke) is approximately 200 μm. The end of the tip experiences high velocities and
accelerations that produce the effect of fragmenting contacted  tissues.
•
Figure3.jpg (17806 bytes) Figure1.jpg (5443 bytes)
Cavitational Ultrasonic Surgical Aspirator. This modified probe includes an extended flue and a
vibrating tip for laparoscopic surgery.

37
Ultrasonic tools
Low frequency intensive ultrasound source –phacoemulsifier - is an indispensable aid for eye
surgeons in the extraction of opaque eye lenses (cataracts). The emulsified lens is immediately
sucked away (aspired).
phaco[1] pic01[1]

Adobe Systems
38
Ultrasonic tools in dentistry
̶The main application field: tartar removal - scaling. Ultrasonic scalers are fast and efficient.
They consist of two main parts: the source of electric oscillations necessary to driving generator
of ultrasound, and a handpiece containing ultrasonic transducer, working at a frequency of about 40
kHz.  The transducer is linked to variously shaped working tips. Some devices are equipped with
water spray (rinsing and cooling).

̶Ultrasonic scaling mechanisms:
̶direct effect of ultrasonic oscillations of the working tip on the deposited tartar
̶ultrasonic cavitation
̶ultrasonic microstreaming

39
A schematic diagram of ultrasonic scaler (up with magnetostrictive, down with piezoelectric
transducer)
magetostrikční scaller piezoel scaller
Ultrasonic tools in dentistry

Adobe Systems
40
Cryosurgery
̶The temperature -25 °C down to -190 °C creates ice crystals inside cells and in intracellular
spaces. Cell lysis occurs when the ice thaws.
̶The advantage is the limitation of tissue destruction to the frozen area sparing nearby healthy
tissue. The freezing has an anaesthetic effect so that the cryosurgical intervention causes little
pain. The wound practically does not bleed. The frozen tissue sometimes is fixed to the tool, which
can be used to extract it (cryoextraction of the eye lens when the cataract is operated).
Applications in eye surgery, urology, oncology, gynaecology and plastic surgery.
̶Cryosurgical devices use liquid nitrogen (-196 °C) or other gases to reach low temperature. The
proper cryosurgical tool –- has a freezing part on its distant end. The end part of the cryocauter
is changeable and has a different shape according to the procedure performed. A digital thermometer
displays the temperature.

41
Cryosurgery
53 CO2-N2Oimage017l[1]
Cryosurgical equipment using nitrous oxide (N2O) and carbon dioxide (CO2)

42
Cryosurgery (using liquid nitrogen)
cry-ac_with_flyout[1]

43
Water jet dissector as a surgical tool
The device comprises a pressure pump, a high-pressure tube and a manipulation part with the thin
jet of 0.1 mm diameter on its end.
Pressures in the range from 1.5 to 5.0 MPa are usually used.
The cut borders are smooth.
The jet is a sterile isotonic solution, sometimes with medicaments added to limit bleeding or
resist infection.
It is said that it gives excellent control of the cut, which is especially significant at brain and
parenchyma-tous organs (liver, spleen).
expansionseffekt_e[1] http://www.thejgo.org/article/viewFile/297/html/2124

Plasma scalpel in fibroma removal
44
Výsledek obrázku pro plasma scalpel Výsledek obrázku pro plasma jet

Adobe Systems
45
Lithotripsy
̶In the early 80s, extracorporeal shock-wave lithotripsy (ESWL) was introduced in clinical
practice. Destruction of  stones (kidney, biliary) by the action of multiple shock waves – strong
impulses of acoustic pressure. The debris is removed from the body via natural efferent ways. It is
a minimally invasive method.
̶A rapid onset of pressure gradient arises on an interface of two media as a result of difference
in acoustic impedances. If the pressure force exceeds the mechanical resistance of a stone, its
progressive fragmentation occurs. Pressures of about 108  Pa are necessary. Many shock waves (50 to
4000, on average 1000) must be applied (synchronously with heart beats).
̶Main parts of the lithotripter: source of shock waves, focussing device, coupling medium, accurate
device for stone targeting (ultrasonograph or X-ray device).

46
Lithotripsy
time-course of a shock wave
time
•

Adobe Systems
47
Lithotripsy
production of shock waves and their focussing
emsepict Schematic Diagram of Electrohydraulic Lithotripter
Ellipsoidal metallic mirrors. Shock waves are produced in one focus and are reflected to the second
focus.

Adobe Systems
48
Lithotripsy
Destruction of a kidney stone
http://www.nlm.nih.gov/medlineplus/ency/imagepages/19246.htm
Lithotripsy procedure

Adobe Systems
49
Lithotripsy (beginnings – Munich - Germany)
sv3053052

Adobe Systems
50
www.uni-duesseldorf.de/.../Urologie/ Klinik/lithotry.htm.
Lithotripsy - lithotripter in clinical practice
ESWL

51
Lithotripsy - Czech lithotripter MEDILIT M8
http://www.medipo.cz/Obrazky/Lito/obr_1_stul_s_pristavky.jpg

Adobe Systems
52
ESWT – extracorporeal shock-wave therapy
Calcification of tendons in shoulder, calcaneal spur, stimulation of fracture healing
www.physio-chelsea.co.uk/ shockwave.htm.
shock%20shoulder heel%20shock
The shock waves of energy 1.2-40 mJ have energy density of 0.14 – 1.8 mJ/mm2 in focus. This energy
is sufficient to penetrate to max. 60mm in depth. The frequency can be changed from 1 to 4 Hz. The
focal pressure is 10 – 100-times lower that that produced by a lithotripter.

Adobe Systems
53
Last revision September 2024
Author:
Vojtěch Mornstein
Content collaboration and language revision:
Carmel J. Caruana