2. DEFINITION
Derives from the Greek word ‘BRACHY’ – meaning short-distance
Brachytherapy involves placing small radiation sources internally, either
into or immediately next to the tumor in a geometrical fashion , allowing
precise radiation dose delivery (1)
1) Stewart AJ & Jones B. In Devlin Brachytherapy: Applications and techniques. 2007.
3. HISTORY
1896 :- Radioactivity was described by Becquerel
1898 :- Marie curie extracted radium from pitchblende ore
1901 :- Danlos and Bloc performed first radium implant
1931 :- The term brachytherapy proposed first time by Forsell
1940-1950 :- Brachytherapy rules were developed and followed
1953 :- Aterloading technique first introduced by Henschke in New
York – removed hazard of radiation exposure. Also Ir-192 used first
time by Henschke
1953 :- LDR brachytherapy became the gold standard
1968 :- HDR brachytherapy was introduced
1970s :- Brachytherapy is established as a safe and effective
standard of care for many gynecological cancers
4. ADVANTAGES
High dose of radiation is delivered to tumor in short time.So
biologically very effective
Normal tissue spared due to rapid dose fall off
Better tumor control
Radiation morbidity minimal
Acute reactions appear when treatment is over; so no
treatment breaks. Also radiation reactions localized &
manageable
Treatment time short – reduces risk of tumor repopulation
5. DISADVANTAGES
Invasive procedure
Radiation hazard due to radioisotopes (in olden days due to
preloading techniques, now risk decreased )
General anesthesia required
Dose inhomogeneity is higher than EBRT (but acceptable if
rules followed)
Because of greater conformity, small errors in source
placement can lead to extreme changes from the intended
dose distribution
6. TYPES OF BRACHYTHERAPY
Classification
⚫ Based on Duration of implant
⚫ Based on Source position
⚫ Based on Source loading pattern
⚫ Based on Dose rate
7. TYPES OF BRACHYTHERAPY
Classification
⚫ Based on Duration of implant
⚫ Based on Source placement
⚫ Based on source loading pattern
⚫ Based on Dose rate
8. DURATION OF IMPLANT
Temporary- Dose is delivered over a short period of time
and the sources are removed after the prescribed dose has
been reached. The specific treatment duration will depend on
many different factors, including the required rate of dose
delivery and the type, size and location of the cancer. Eg :-
Cs137, Ir192
Permanent- also known as seed implantation, involves placing
small LDR radioactive seeds or pellets (about the size of a grain of rice) in
the tumor or treatment site and leaving them there permanently to
gradually decay. Eg :- I125 ,Pd103, Au198
12. TYPES OF BRACHYTHERAPY
Classification
⚫ Based on Duration of implant
⚫ Based on Source placement
⚫ Based on Source loading pattern
⚫ Based on Dose rate
13. Interstitial - the sources are placed directly in the target
tissue of the affected site, such as the prostate or breast.
Contact - involves placement of the radiation source in a
space next to the target tissue.
⚫ Intracavitary – Consists of positioning applicators bearing radioactive sources
into the body cavity in close proximity to target tissue eg :- Cervix
⚫ Intraluminal – Consists of inserting single line source into a body lumen to treat
its surface &adjacent tissue.
⚫ Surface (Mould) – (Plesiocurie/Mould therapy) Consists of an applicator
containing array of radioactive sources designed to deliver a uniform dose
distribution to skin/mucosal surface.
⚫ Intravascular – Inserting a single line source to Blood vessels to treat the
layers of blood vessel
18. TYPES OF BRACHYTHERAPY
Classification
⚫ Based on Duration of implant
⚫ Based on Source placement
⚫ Based on Source loading pattern
⚫ Based on Dose rate
19. Pre-loading
into the tumor
:- Inserting needles/tubes containing radioactive material directly
After-loading :- First, the non-radioactive tubes inserted into tumor
Manual After Loading :- Ir192 wires, sources manipulated into applicator by means of forceps
& hand-held tools
Remote After Loading :- consists of pneumatically or motor-driven source transport system
20. PRELOADING (PROS & CONS)
Advantage:
⚫ – Loose & flexible system(can be inserted even in distorted cervix)
⚫ – Excellent clinical result
⚫ – Cheap
⚫ – Long term results with least morbidity (due toLDR)
• Disadvantages:
⚫ – Hasty application -Improper geometry in dose distribution
⚫ – Loose system – high chance of slipping of applicators – improper geometry
⚫ – Application needed special instruments to maintain distance.
⚫ – Radiation hazard
⚫ – Optimization not possible
21. AFTER LOADING (MANUAL)
Advantages
⚫ Circumvents radiation protection problems of preloading
⚫ Allows better applicator placement and verification prior to source placement.
⚫ Radiation hazard can be minimized in the OT/bystanders as patient loaded
in ward.
⚫ Advantages of preloading remain as practised at LDR.
Disadvantages:
⚫ specialized applicators are required.
23. Advantages :
No radiation hazard
Accurate applicator placement
-ideal geometry maintained
-dose homogeneity achieved
-better dose distribution
Information on source positions available
Individualization & optimization of treatment possible
Higher precision , better control
Decreased treatment time- opd treatment possible
Chances of source loss nil .
Disadvantages :
Costly
AFTER LOADING (REMOTE)
26. Emergency
button
Hand cranks if
everything else fails
Safe, holding the active
source and a dummy source
Optopair to verify
source position
Indexer face
with 18
source
channels
Transfer
tube
connector
Stepper motor
with shaft encoder (additional
DC motor available for source
retraction in case of failure)
Indexer
Radiation monitor
28. TYPES OF BRACHYTHERAPY
Classification
⚫ Based on Duration of implant
⚫ Based on Source placement
⚫ Based on Source loading pattern
⚫ Based on Dose rate
29. Low-dose rate(LDR)- Emit radiation at a rate of 0.4–2 Gy/hour.
Medium-dose rate (MDR)- characterized by a medium rate of dose
delivery, ranging between 2-12 Gy/hour.
High-dose rate (HDR)-when the rate of dose delivery exceeds
12 Gy/h.
Pulsed-dose rate (PDR) - involves short pulses of radiation, typically
once an hour, to simulate the overall rate and effectiveness of LDR
treatment. (1ci)
Ultra low dose rate - Dose range 0.03 to 0.3 Gy/Hr
30. HDR V/S LDR
Advantages :-
⚫ Radiation protection
⚫ Allows shorter treatments times
⚫ HDR sources are of smaller diameter than the cesium sources that are
used for intracavitary LDR ,hence reduced need of Anaesthesia
⚫ HDR makes treatment dose distribution optimization possible
Disadvantage
Radiobiological
Limited experience
The economic disadvantage
Greater potential risks
32. KEY ELEMENT
Obsolete or historical
226Ra, 222Rn
• Currently used sealed sources
137 Cs, 192Ir, 60Co, 125I, 103Pd,198Au, 90Sr.
33. IDEAL ISOTOPE
Easily available & Cost effective
Gamma ray energy high enough to avoid increased energy deposition in bone & low
enough to minimise radiation protection requirements
Preferably monoenergetic: Optimum 300 KeV to 400 KeV(max=600 kev)
Absence of charged particle emission or it should be easily screened (Beta energy
as low as possible: filtration)
Half life such that correction for decay during treatment is minimal
⚫ – Moderate (few years) T1/2 for removable implants
⚫ – Shorter T1/2 for permanent implants
Moderate gamma ray constant (determines activity & output) &also determine
shielding required.
34. No daughter product; No gaseous disintegration product to prevent physical damage
to source and to avoid source contamination
High Specific Activity (Ci/gm) to allow fabrication of smaller sources & to achieve
higher output (adequate photon yield)
Material available is insoluble & non-toxic form
Sources can be made in different shapes & sizes: Tubes, needle, wire, rod, beads
etc.
Should withstand sterilization process
Disposable without radiation hazard to environment
Isotropic: same magnitude in all directions around the source
No self attenuation
38. PATIENT SELECTION
Small size tumors (3 – 5 cm)
Depth of penetration/thickness < 1.5 – 2 cm
Histology: moderately radiosensitive tumors (ca squamous cell) ; some
adenocarcinomas
Early stage (localized to organ)
No nodal/distant metastasis
Location : accessible site with relatively maintained anatomy
Absence of local infection & inflammation
39. RULES OF THE GAME
Interstitial
• Manchester
• Quimby
• Paris
• Memorial
Intracavitary
• Manchester
• Paris
• Stockholm
Surface/
Mould
• Manchester
Objectives:-
•To determine the distribution & type of radiation sources to provide optimum dose
distribution
•To provide complete dose distribution in irradiated volume
Components :-
•Distribution rules
•Dose specification and optimization
•Dose calculation aid
40. PARAMETERS MANCHESTER QUIMBY PARIS COMPUTER
Linear strength Variable Constant Constant Constant
Source
distribution
Planar implant:(periphery)
Area <25 cm- 2/3 Ra;
25-100 cm- ½ Ra; >100 cm-
1/3
Volume
implant::Cylinder:belt-4
parts,core-2,end-1
Sphere:shell-6,core-2
Cube :each side-1,core-2
Uniform Uniform Uniform
Uniform Line sources
parallel
planes
Line sources
Parallel or
cylinderic
volumes
Spacing line Constant approx. 1 cm apart Same as Constant, Constant
source from each other or from Manchester Selective Selective
crossing ends Separation 8-
15 mm
Crossing needles Required to enhance dose at Same Crossing Crossing
implant ends needles not needles not
used;active used;active
length 30- length 30-40%
40% longer longer
43. Breast
⚫Indications: Boost after BCS & EBRT
⚫Postoperative interstitial irradiation alone of
the primary tumor site after BCS in selected
low risk T1 and small T2N0 (PBI)
⚫Chest wall recurrences
As sole modality As Boost to EBRT
Patient choice: cannot come for 5-6 wks treatment :
Distance
Lack of time
Close, positive or unknown margins
Elderly, frail, poor health patient EIC
Large breasts: unacceptable toxicity Younger patients
Deep tumour in large breast
Irregularly thick target vol.
44. T.V.: Primary Tumor site + 2-3 cm margin
Dose: As Boost: 10-20 Gy LDR
AS PBI: 45-50 Gy in 4-5 days LDR (30-70 cGy/hour)
⚫ 34 Gy/10#, 2# per day HDR
Technique:
⚫ Localization of PTV: Surgical clips (at least 6)
USG, CT or MRI localization, Intraop USG
⚫ During primary surgery
⚫ Guide needle technique or
⚫ Plastic tube technique using Template
Double plane implant
Skin to source distance: Minimum 5 mm
