This document provides an overview of cryosurgery. It discusses the history and development of cryosurgery using extreme cold, particularly liquid nitrogen, to destroy diseased tissue. The document outlines the cryosurgery procedure for conditions like prostate cancer, which involves inserting cryoprobes under ultrasound guidance to create ice balls to destroy the tumor. It explains how cryosurgery works through immediate and delayed cell destruction caused by rapid freezing and slow thawing. The document emphasizes the importance of using the lowest possible temperatures, rapid cooling and slow thawing to maximize the effectiveness of cryosurgery.

1. CRYOSURGERY
PREPARED BY: -
KETAN GOJ IYA

2. Table of Contents
 Introduction
 History of Cryosurgery
Procedure
Scientific Background
 Patient Selection
In what situations can cryosurgery be used to treat Prostate Cancer?
 Summary
 Reference

3. INTRODUCTION
o Cryosurgery (cryotherapy) is the application of extreme cold to
destroy abnormal or diseased tissue. The term comes from the
Greek words cryo ("icy cold") and surgery meaning "hand
work" or "handiwork".
o Cryosurgery is the use of extreme cold produced by liquid
nitrogen (or argon gas) to destroy abnormal tissue.

4. HISTORY OF CRYOSURGERY
oJames Arnott, in 19th century, stated that a very low temperature
will arrest every inflammation which is near enough to the surface.
oThe first cryogens were liquid air and compressed carbon dioxide
snow.
oIn 1961, Cooper and Lee developed the first cryotherapy probe
system, involving the circulation of liquid nitrogen through a closed
metal tube placed in direct contact with the target tissue.

5. PROPERTY OF LIQUID NITROGEN (LN2)
oLiquid nitrogen, which boils at −195.6°C (77.4 K), is the most
effective cryogen for clinical use. It is particularly useful in the
treatment of malignant lesions.
o Temperatures of −25°C to −50°C can be achieved within 30
seconds if a sufficient amount of liquid nitrogen is applied by
spray or probe.
o Generally, destruction of benign lesions requires
temperatures of −20°C to −30°C. Effective removal of
malignant tissue often requires temperatures of −40°C to
−50°C

6. Cryogens - Boiling point
o Liquid nitrogen (most commonly used) : -196°C
o Nitrous oxide : - 89°C
o Solidified CO 2 (dry ice, CO2 snow) : -78°C
o Chlorodifluoromethane : -41°C
o Dimethyl ether and propane : -24°C, -42°C

7. Mechanism of cryosurgery
o The destructive effect of freezing tissue has been categorized
into two major mechanisms
1. Immediate cell destruction
2. Delayed cell destruction

9. Controlling parameters during cryosurgery
o cooling rate
o Temperature
o Thawing rate
o Freeze duration
o Repetitive freeze- thaw cycle

10. .
Cooling rate
• In cryosurgery, rapid cooling rate i.e. more than 500C/min
produces intracellular ice- crystals which ismore destructive
• Such higher rates of cooling can only be achieved close to
the cryoprobe
Temperature
• Mazur stated that the lethal temperature range is between
-50C to -500C.
• The treatment of tumor requires a tissue temperature at
which all the abnormal cells are certainly dead.

11. oFrom the review of all experimental studies the end point
temperature below -40 0C has been considered prime factor
for tissue destruction

12. Thawing rate
• Thawing rate should be slow and continued for longer
time period; rapid thaw rates allow cell survival.
Repetitive freeze- thaw cycle
• Rapid freezing and slow thawing do not guarantee effective
cell destruction.
• Use of repeated freeze-thaw cycle is also beneficial in
treatment of cancerous tumor

14. Bio-heat Equation
oSeveral heat transfer mechanisms occur during cryosurgery,
including conduction, convection, metabolism and phase change.
o Heat transfer by conduction has been assumed to be the primary
heat transfer process during cryosurgery since the cryoprobe
operates at an extremely low temperature.
o Bio-heat transfer is the study of heat transfer in biological system.
oThe fundamental heat transfer equation in biological tissue was
firstly suggested by Pennes.

15. Pennes suggested that the rate of heat transfer between blood and tissue is proportional to the product of the
volumetric perfusion rate and the difference between the arterial blood temperature and the local tissue temperature.
He expressed that relationship as follows
Where,
hb is the rate of heat transfer per unit volume of tissue,
V is the perfusion rate per unit volume of tissue,
ρb is the density of blood,
cb is the specific heat of blood,
K is a factor that accounts for incomplete thermal equilibrium between blood and tissue
(0<K<1, for some cases K = 0)
Ta is the temperature of arterial blood, and
T is the local tissue temperature.

16. PROCEDURE
oWarts, moles, skin tags, solar keratoses, and small skin cancers are
candidates for cryosurgical treatment.
oSeveral internal disorders are also treated with cryosurgery,
including liver cancer, prostate cancer, cervical disorders and, more
commonly in the past, hemorrhoids.
oCryosurgery works by taking advantage of the destructive force of
freezing temperatures on cells. At low temperatures, ice crystals
form inside the cells, which can tear them apart. More damage
occurs when blood vessels supplying the diseased tissue freeze.

17. oIn this approach, several hollow probes (needles) are placed in
direct contact with target tissue.
oThe doctor guides them into the gland(tumor) using Trans-Rectal
Ultra-Sound (TRUS).
oThis type of procedure requires spinal or epidural anesthesia (where
the lower half of your body is numbed) or general anesthesia (where
you are asleep).

19. oVery cold gases are then passed through the needles, creating ice
balls that destroy the gland(tumor).
oTo be sure the prostate is destroyed without too much damage to
nearby tissues, the doctor carefully watches the ultrasound images
during the procedure

20. oAfter the procedure, there will be some bruising and soreness in
the area where the probes were inserted. Patients might need to
stay in the hospital overnight, but many patients leave the same
day.
oThe most common method of freezing lesions is using liquid
nitrogen as the cooling solution. The super-cooled liquid may be
sprayed on the diseased tissue, circulated through a tube called a
cryoprobe.

21. HOW CRYOSURGERY WORKS

22. Cryoprobe
Manufacturers have devised various metal attachments to serve as heat-conducting
probes for cryotherapy. Copper, because of its high conductivity, is
typically used.

23. oThe effect of cryoprobe diameter, cryoprobe temperature and heat
generation due to metabolism and blood perfusion on phase change heat
transfer process during cryosurgery in lung tumor has been analyzed
numerically.
oResults show that (i) increase in cryoprobe diameter (ii) decrease in
cryoprobe freezing temperature, lead to increase in minimum temperature,
freezing rate, freezing area in tissue and decrease in tumor freezing time
oIn summary, to maximise the effectiveness of cryosurgery, it is important to
use as low a temperature as possible, cool the tissue as rapidly as possible,
Thaw as slowly as possible , use more than one freeze thaw cycle,.

24. Advantages of cryosurgery
1. Minimal invasion of tissue
2. Less bleeding
3. Local application
4. Less time taking
5. Anesthetic capabilities
6. Repetition of procedure
7. Minimal hospitalization
8. Less expensive

25.  In summary, to maximise the effectiveness of cryosurgery, it is important to use
as low a temperature as possible,
cool the tissue as rapidly as possible,
Thaw as slowly as possible
use more than one freeze thaw cycle,.

27. REFERENCE
o History of cryosurgery. Semin Surg Oncol 1998
o Guideline for the management of clinically localized prostate cancer: 2007
o Longitudinal comparative study of early health-related quality-of-life outcomes
in patients undergoing surgical treatment for localized prostate cancer: a short-term
evaluation of five approaches from a single institution. J Endourol 2006
o Cryosurgical ablation of the prostate: high risk patient outcomes. Cancer 2005
o Cryosurgery of the prostate: techniques and indications. Rev Urol 2004
o www.wikipedia.org/cryosurgery_for_prostate _cancer.htm