Teletherapy & Brachytherapy Techniques In Ca

2. INTRODUCTIONINTRODUCTION
Cervical cancer is the commonest gynecological
malignancy in India.
Squamous cell carcinoma - 80%
Adenocarcinomas - 20%

3. INTRODUCTIONINTRODUCTION
Carcinoma of the cervix metastasizes in predictable sequential manner
The cervix drains into the para cervical L.N. and subsequently to the internal
and external iliac nodes, including the obturator nodes.
The pelvic lymphatic drains into the common iliac and the para-aortic lymph
nodes.

4. INTRODUCTIONINTRODUCTION
Cervical cancers are clinically staged.
The FIGO staging system is the most widely used
The cornerstone of the system is a thorough careful pelvic
examination, often done under general anesthesia.
Adjuncts to the pelvic examination include either an IVP or CT scan
with IV contrast to determine whether there is ureteral obstruction
and hydronephrosis.
Additionally, a chest X-ray is usually part of the initial workup.

5. FIGO STAGINGFIGO STAGING
Carcinoma-in-situ0
Spread to bladder or rectum and/or extending beyond
true pelvis
IVA
Spread to lower third of the vaginaIIIA
Spread to pelvic side wallsIIIB
Spread to parametrium but not as far as lat. pelvic wallIIB
Spread to distant sites outside true pelvisIVB
Carcinoma involves upper 2/3
rd
of vaginaIIA
Clinically invasive carcinomaIB
Micro invasive carcinoma confined to cervixIA

6. PRINCIPLE OF MANAGEMENTPRINCIPLE OF MANAGEMENT
These are sq. cell ca. that are moderately sensitive to radn. Hence rad
n

plays an important role in management of carcinoma cervix.
Predictable pattern of spread helps in designing radn portals.
Since tolerance of Cx is very high hence high dose can be delivered.
Aim is to deliver curative dose of around
Early stage - 80 - 85Gy to point A
Advanced stage - 85-90Gy to point A
But this dose can’t be delivered by EBRT because of presence of dose
limiting structures like bladder & rectum in the beam path.
Hence to achieve tumor control rad
n
is delivered by combined technique
of EBRT & Brachytherapy.

7. PRINCIPLE OF MANAGEMENTPRINCIPLE OF MANAGEMENT
The cervical cancer has two components
Central component - Disease confined to cervix , vagina & medial
parametria- best treated by brachytherapy
Peripheral component - Disease involving lateral parametria & lymph
nodes-best treated by EBRT& brachytherapy as boost

8. PRINCIPLE OF MANAGEMENTPRINCIPLE OF MANAGEMENT
Patients with stage IA ca cx are managed by radical hysterectomy
alone.
If inoperable, then dose of approx.80 Gy is delivered by
brachytherapy alone
Patients with stage IB may be managed by a radical
hysterectomy alone if the tumor is <4 cm in size with no other
adverse features.
Stage IB with tumor > 4 cm, and all patients with stage IIA,
IIB, IIIA, IIIB, and IVA are managed with EBRT with
concurrent chemotherapy and Brachytherapy.

9. PRINCIPLE OF MANAGEMENTPRINCIPLE OF MANAGEMENT
The relative proportion of EBRT increases with increasing tumor
bulk and stage
Early stage - Brachytherapy is given simultaneously or as sandwich with
EBRT
Advanced stage – EBRT is given prior to Brachytherapy. This
allows
tumour shrinkage
leads to a technically superior Brachytherapy application and
radiobiological advantage with better tumour oxygenation and
therefore more radio sensitivity as the tumour involutes.
Indications for EBRT prior to brachytherapy
Bulky cervical lesions or tumors beyond stage IIA
Exophytic, bleeding tumors;
Tumors with necrosis or infection; or
Parametrial involvement.

10. INDICTIONS FOR POST-OP RTINDICTIONS FOR POST-OP RT
Two or more positive pelvic lymph nodes
Patients with negative nodes who have microscopic
positive or close (<3 mm) margins of resection
Deep stromal invasion
Vascular/lymphatic permeation.

11. EBRTEBRT
Parallel opposed AP/PA field i.e. two field technique.
Four field box technique
Parallel opposed portals with midline shield when more dose
is delivered by I/C BT
Parallel opposed portals AP/PA with pt. in Frog leg position
in case of vaginal involvment.
This position opens up skin folds in groin region which is otherwise
susceptible to skin reactions

12. TARGET VOLUMETARGET VOLUME
Principle is to treat primary tumour with the first echelon
group of lymph nodes to maximize tumour control
Includes
primary tumour
Pelvic lymph nodes upto common iliac L.N. ( paracervical,
parametrial, internal iliac, external iliac, presacral, sacral and the
obturator L.N.)
& adequate margin for microscopic spread and set up uncertainties

13. POSITIONING & IMMOBILIZATIONPOSITIONING & IMMOBILIZATION
Pt. is treated in supine position as it is most
comfortable & reproducible position.
Pt. may be positioned using knee wedge to relaxes
lower back making pt. more comfortable.

14. MANUAL MARKINGSMANUAL MARKINGS
Anterior field centre is 3 cm above the pubic tubercle
Post field center is 5 cm above tip of coccyx
field size is either a square field of 15 x 15cm or rectangle of 14x16cm
 lateral field centre is 8 cm above table top
field size is 15 x 10cm
Radiographs should be taken to verify the field

15. SIMULATIONSIMULATION
Pt. is given oral barium one hour prior to simulation procedure
to locate small bowel w.r.t. treatment portal.
Portals should be shaped to minimize small bowel within
irradiated vol.
Pt. is made to lie supine on simulator couch with arms folded
over chest.
A contrast enhanced vaginal cylinder is inserted in vagina & a
rectal tube is inserted in rectum for later insertion of rectal
contrast.
The ant. field is set while the position is viewed in fluoroscopy.

16. SIMULATIONSIMULATION
Isocentric treatment is preferred & isocenter is set at pt.’s
middepth or at the vaginal marker.
Without moving couch/pt. gantry is turned 90° on either side.
While viewing in fluoroscopy ant. & post. margins of lateral
fields are set by lowering or raising couch.
The superior & inferior margins remain same as that of ant.
Portal.
Orthogonal radiographs are taken for later comparison with
portal image/films.

17. RADIOLOGICAL MARKINGSRADIOLOGICAL MARKINGS
Superior border –
At the L
4-5 inter space to include external &
internal iliac L.N.
This margin must be extended to the L
3-4
inter
space if common iliac nodal coverage is
indicated.
Inferior border - at the inferior border of the
obturator foramen.
For vaginal involvement, lower border is 2cm
below the lower most extent of disease
tumours that involve lower third of vagina,
inguinal nodes should be included in the fields
 Lateral borders - 1.5 - 2cm margin on the widest
portion of pelvic brim

18. RADIOLOGICAL MARKINGSRADIOLOGICAL MARKINGS
Anterior margin - at the pubic
symphysis
Posterior margin – at S
2 – S
3
junction and it should extend to the
sacral hollow in patients with
advanced tumours
Superior & inferior margins -
same as that for AP/PA Fields

21. SSD Vs SADSSD Vs SAD
SSD setupSSD setup
Easy setup
Setup time as well as
treatment time is more
Treatment time
calculation done using
PDD charts
SAD setupSAD setup
Reproducible setup

setup time & treatment
time is less
TAR/TMR tables
required for t/t
calculation

22. TWO FIELD
Heterogenous dose
distribution
Parametrium under dosed
More skin reaction
Useful when lower part of
vagina involved
FOUR FIELD
Homogeneous box shaped
dose distribution
Whole target vol. including
parametrium gets adequate
dose
Skin reaction are decreased
Treatment time more

23. BEAM ENERGYBEAM ENERGY
Because of the thickness of the pelvis, high-
energy photon beams (10 MV or higher) are
especially suited for this treatment.
They decrease the dose of radiation delivered to the
peripheral normal tissues (particularly bladder and
rectum)
provide a more homogeneous dose distribution in
the central pelvis.
avoid subcutaneous fibrosis

24. Composite of 6MV beam
6MV color wash
Composite of 15MV beam
15MV color wash

25. TIME DOSE & FRACTIONATIONTIME DOSE & FRACTIONATION
50Gy/25#/5wks with 2Gy/#
In PGI
46Gy/23#/4.3wks ( 2Gy/#)
More dose is delivered by I/C to achieve better tumor control

26. MIDLINE SHIELDINGMIDLINE SHIELDING
When more dose is delivered by Brachytherapy then EBRT is
delivered with the parallel opposed AP/PA ports (two fields)
with midline shielding
Done to shield rectum & bladder.
Shielding should be designed carefully to try to achieve
matching with the intracavitary dosimetry
Midline shielding can be rectangular or wedge shaped block.

27. PARAAROTIC L.N. IRRADIATIONPARAAROTIC L.N. IRRADIATION
For Para-aortic node involvement, pelvis & para-arotic L.N.
should be treated as contiguous extended field with parallel
opposed AP/PA fields.
Or the para - aortic L.N. and the pelvis are irradiated through
separate portals
In this case, a gap calculation b/w the pelvic and para-aortic
portals must be done to avoid overlap and excessive dose to the
small intestines.
The upper margin of the field is at the T
12
- L
1
interspace and the
lower margin at L
4
– L
5 while width of field is set to include
transverse processes of spine.
An IVU should be done to delineate kidneys

28. PARAMETRIAL BOOSTPARAMETRIAL BOOST
If parametrial tumor persists after delivery of 50 -60Gy is
then boost dose of 10 Gy/5#s may be delivered with reduced
AP/PA portals with superior border at mid SI joint.
The central shield should be used to shield the bladder and
rectum.

29. ROLE OF 3-D CRT & IMRTROLE OF 3-D CRT & IMRT
Ensures better tumor control.
Lesser dose to normal tissue resulting in less late term
complications.
Potential reduction in acute toxicity & better
radiation tolerance.

30. PALLIATIVE RTPALLIATIVE RT
Pt . of stage 4B or recurrent carcinoma require palliation
Aim is to relieve pt. from pain & bleeding
For vaginal bleeding single I/C insertion is given delivering a
dose of 6000mgh( 55Gy to point A)
If pt. has previously received radn then prescribed dose is lower(4000
-5000mgh)
EBRT may be delivered by two field or four field technique
26Gy in 13#s
Or single dose of 8-10 Gy that can be repeated seeing
response at an interval of 3-4wks

31. BRACHYTHERAPYBRACHYTHERAPY
Brachytherapy is a type of radiation treatment in which small,
encapsulated radioactive sources are arranged in a geometric
fashion in & around tumour
ADV.
It delivers very high dose of radiation to tumor
Sparing normal tissue
Dose delivered in short duration.

32. TYPES OF BTTYPES OF BT
Depending on methods of source loading :
Pre loading : The applicator is preloaded and contains radioactive
sources at the time of placement into the patient
After loading : The applicator is placed first into the target
position and the radioactive sources are loaded later, either
manual after loading or
remote after loading

33. TYPES OF BTTYPES OF BT
Depending on dose rate there are four types of delivery modes of
I/C Brachytherapy
Low Dose Rate (LDR) : 0.4–2 Gy /hr
Medium Dose Rate (MDR) :2-12Gy/hr
High Dose Rate (HDR) : >12Gy/hr
Pulsed Dose Rate (PDR) : pulses of around 1Gy/hr

34. BRACHYTHERAPYBRACHYTHERAPY
Brachytherapy plays vital role in treatment of ca cx. & is
mainly applied as an intracavitary procedure in selected cases
complemented by interstitial implants.
It consists of positioning specially designed applicators bearing
sealed radioactive sources into a body cavity in close proximity
to the target tissue.
I/C applications are temporary that are left in the patient for a
specified time to deliver prescribed dose.

35. WHY I/C BRACHYTHERAPYWHY I/C BRACHYTHERAPY
Uterine cx. is ideally suited for I/C brachy therapy because
High tolerance of cervix ,uterus & vagina
It is accessible organ hence Brachytherapy can be practised with ease.
The endocervical canal & vaginal vault form a suitable vehicle to
carry rigid applicators with radioactive sources.
These applicators can be used with minor modifications in all pts.

36. ADV. OF I/C BRACHYTHERAPYADV. OF I/C BRACHYTHERAPY
High dose of radiation is delivered in shortest time.
Cervix receives 20,000 – 25000 cGys.
Uterus receives 20,000- 30000 cGys
Vagina receives 10,000 cGys.
such high doses can’t be delivered by any technique of EBRT.
Best long term control is achieved
Sharp Fall off of dose and hence less dose to the normal structure.
Less late radiation morbidity .
Preservation of normal anatomy.
Better sexual functional life.

37. HISTORYHISTORY
1898: Discovery of Radium by Marie Curie in Paris.
1903: Margaret Cleaves, a New York physician described
inserting Radium into the Uterine cavity of a patient with
Ca Cervix.
1908: I/C brachytherapy started in Vienna
1910 : I/C brachytherapy started in Stockholm
1912: I/C brachytherapy started at Paris.
1930: Todd & Meredith developed Manchester system in U.K.

38. DOSIMETRIC SYSTEMSDOSIMETRIC SYSTEMS
The historical dosimetric systems were developed when computer
treatment planning and dose computations were not available
Term ‘system’ specifies a set of rules for
Geometrical arrangement of a specific set of radio isotopes in a specialised
applicator
To obtain suitable dose distributions over the volume to be treated.
It specifies treatment in terms of the dose, time and administration
A specified set of tables to allow, reproducible and easy calculation in
most of the encountered clinical scenarios.
A system ensures safety and is based on clinical experience.

39. STOCKHOLM SYSTEMSTOCKHOLM SYSTEM
Fractionated (2-3 #s) course over a period of one month.
For a period of 22 hours each.
Separated by 1-3wks
This system used
Intravaginal boxes made up of silver or gold
The intrauterine tube made up of flexible rubber.
These were not fixed together
Unequal loading of Radium
30 to 90 mg of Radium was placed inside the uterus
While 60 - 80 mg were placed inside the vagina.
A total dose of 6500 -7100 mg -hrs was prescribed out of which
4500 mg Ra was contributed by the vaginal box. (dose rate-
110R/hr)

40. PARIS SYSTEMPARIS SYSTEM
Single application of Radium for 120hrs (5-6days)
In this system, almost an equal amount of Radium
was used in the uterus and the vagina.
The system incorporated
two cork colpostats (cylinder) with 13.3mg Radium in
each and
an intrauterine tube of silk rubber with 33.3mg
Radium
The intrauterine sources contained three radioactive
sources, with source strengths in the ratio of 1:1:0.5.
the colpostats contained sources with the same
strength as the topmost uterine source
Designed to deliver a dose of 7000 - 8000 mg hrs
over a period of 5days (45R/hr) (5500mg/hr)

41. DOSE SPECIFICATIONDOSE SPECIFICATION
Done in mg-hr i.e. simple mathematical product of mg of
Radium times the duration (in hours) of the implant.
It was easy to use.
The dose prescription was entirely empirical due to the lack of
knowledge about the biological effects of radiation on the normal
tissues and the tumor
understanding about the dose, dose distribution and the duration of
treatment.
Only applicable when both tandem & ovoids are used & sources
are loaded in a rigidly prescribed manner.

42. FALLACIESFALLACIES
Long treatment time, discomfort to the patient
Dose prescription method was empirical. Both systems specified dose in
mg-hour.
Does not give any information about dose distribution.
When used in conjunction with EBRT, overall radiation treatment can’t
be adequately defined
Dose specification method lacks the information on
Source arrangement
Position of tandem relative to the ovoids
Packing of the applicators
Tumour size, and
Patient anatomy.
With the use of this dose prescription method dose to important
anatomical targets could not be quantified adequately.
Ignored the importance of tolerance of different critical organs to
radiation.

43. MANCHESTER SYSTEMMANCHESTER SYSTEM
The Manchester system is one of the oldest & extensively used
systems in the world.
Developed by Todd & Meredith in 1930 & was in clinical use by
1932.
This system was initially developed for radium tubes, but was
easily adapted to different afterloading systems.

44. MANCHESTER SYSTEMMANCHESTER SYSTEM
Manchester system was based on following principles:
To define the treatment in terms of dose to a point. To be acceptable this
point should have following criteria :
It should be anatomically comparable from patient to patient.
Should be in a region where the dosage is not highly sensitive to small alteration in
applicator position.
Should be in position that allows correlation of dose with clinical effects
To design a set of applicators and their loading (with a given amount of
radium), which would give the same dose rate irrespective of the
combination of applicators used.
To formulate a set of rules regarding the activity, relationship & positioning
of the radium sources in the tandem & vaginal ovoids to achieve desired
dose rate.

45. POINT APOINT A
Todd & Meredith defined a point in
paracervical triangle where the uterine
vessels cross the ureter as point A.
Point A is defined as a point 2cm. lateral to
the center of the uterine canal and 2 cm.
superior to the mucosa of the lateral fornix,
in the plane of the uterus.
Now point A is defined as a point 2cm
above the distal end of lowest source in
cervical canal & 2cm lat. to centre of
tandem.
Dose at point A showed a correlation with
local control and the incidence of late
normal tissue toxicity in the pelvis

46. POINT APOINT A
Although point A is defined in relation to important
anatomic structures, these can’t be visualized on a
radiograph.
It is therefore necessary to develop some convention by which
position of point A can be determined on radiograph.
The keel is placed at the external os. It serves as important
reference point as it can be visualized on radiograph.

47. POINT BPOINT B
Point B is defined 2cm above external os & 5 cm laterally to
midline
Represents dose to the pelvic wall, obturator L.N.
 The dose at point B is approx. 25 -30% of the dose at point A.
Dose to point B, depends little on the geometric distribution of
radium, but on the total amount of radium used

48. DOSE LIMITING STRUCTURESDOSE LIMITING STRUCTURES
Bladder
Rectum
Vaginal mucosa
Rectovaginal septum
No more than 40% of total dose at point A could be delivered safely through
the vaginal mucosa.
The rectal dose should be 80% or less of the dose at point A; this rectal dose can
usually be achieved by careful packing.

49. MANCHESTER SYSTEMMANCHESTER SYSTEM
In this system, the dose distributions were not calculated for
individual patients.
Applications outside the standard variations were corrected for,
but the majority of patients had applicators in place for a
standard time.
The Manchester system was a time system based on the use of
standard applicators

50. APPICATOR IN MANCHESTER APPICATOR IN MANCHESTER
SYSTEMSYSTEM
Similar to that used in Paris system
It had a pair of ovoids & a intrauterine tube

51. INTRAUTERINE TUBEINTRAUTERINE TUBE
The intrauterine tube was made up of the thin rubber ( to prevent excessive
dilatation of the cervical canal)
These tubes were available in three separate lengths
2cm
4cm
6cm

in order to accommodate 1, 2 or three Radium tubes (2 cm long) in line.
I.U.tubes were closed at one end, and had a flange at the other end so that when
packed into position, the uterine tube did not slip out during the treatment.

52. OVOIDSOVOIDS
Used in pairs, one in each lateral fornix
The shape of ovoids mimics the shape of isodose curves around a
Radium tube having "active length" of 1.5 cm.
The ovoids were designed to be adaptable to the different
vaginal capacity, with diameter of
2 cm
2.5 cm
3 cm
The largest ovoid are placed in the roomiest vagina in order to
achieve the best lateral dose throw off

53. SPACERSSPACERS
Apart from ovoids & I.U.tubes spacers or washers were used
To maintain the distance between the ovoids
To help in their fixation
Spacer was used to give the largest possible separation b/w the ovoids so
that the dose could be carried out as far laterally as possible.
It maintained a distance of 1cm b/w the ovoids
The washer was only used when it was not possible to accommodate the
spacer.

54. PACKINGPACKING
Manchester applicators do not incorporate rectal shielding.
Hence gauze is packed firmly and carefully
behind the ovoids,
anteriorly b/w the ovoids and the base of the bladder,
and around the applicator tubes down to the level of the introitus
The amount of packing should be such that at least 1.5 cm
separation is achieved b/w ovoids and vaginal mucosa.
Packing helps to
keep the applicators in position
to reduce dose to bladder and anterior rectal wall.

55. RULESRULES
The point A should receive the same dose rate, irrespective of the
combination of applicators used.
Not more than one third of the total dose to point A should be delivered by
the vaginal ovoids. So that tolerance of vagina mucosa is not exceeded
Standard or ideal loading is 60-40 i.e. 60% of the dose to point A is
contributed by intrauterine sources while 40% is contributed by ovoids.
Total Dose to point A : 8000 R
Total number of applications : 2
Total time for each application : 72 hrs
Total time : 144 hrs
Dose rate desired : 55.5 R /hour to point A
Amount of radium to be used was defined in terms of units.
1 unit = 2.5 mg of radium filtered by 1 mm platinum.
The loadings were specified in terms of integral multiples of this unit.

56. LOADING PATTERNLOADING PATTERN
Tube Type
Length
Tubes
used
Mg Ra
loaded
Units loaded from
fundus to cervix
Tubes (mg)
used for
loading
Large 6 3 35 6-4-4 15-10-10
Medium 4 2 25 6-4 15-10
Small 2 1 20 8(10) 20
OvoidTubes used
Mg Ra loaded
Units loaded
Tubes (mg) used for
loading
Large 3 22.5 9 10-10-5 or 20/25*
Medium 2 20 8 20
Small 1 17.5 7 10-5-5 or 20/15**

57. LOADING PATTERNLOADING PATTERN
Total dose at point A using different combinations of I.U tube
& ovoids :
Large tube with large ovoid and washer : 57.5 R
Large tube with large ovoid and spacer: 56.9 R
Large tube with small ovoid and washer: 57.6 R
Medium tube with small ovoids and spacer: 57.3 R
The variations were thus within 1.5% range.

58. ICRU SYSTEMICRU SYSTEM
For reliable and relevant comparison of different methods and
their clinical results ICRU38 recommends a common
terminology for prescribing recording and reporting I/C
Brachytherapy applications.
The ICRU recommends a system of dose specification that
relates the dose distribution to the target volume, instead of the
dose to a specific point
The dose is prescribed as the value of an isodose surface that
just surrounds the target volume.

59. ICRU REPORTINGICRU REPORTING
Description of technique
Time dose pattern (application duration)
Description of reference volume
Dose at reference points

60. Description of the TechniqueDescription of the Technique
Minimum information should include the
orthogonal radiographs of the application.
Source used (radionuclide, reference air kerma rate, shape and size of
source, and filtration)
applicator type
Loading pattern
Simulation of linear source for point or moving sources
Applicator geometry (rigidity, tandem curvature, vaginal uterine
connection, source geometry, shielding material)
Total reference air Kerma - proposed to introduce international units into
the Brachytherapy reporting.

61. DOSE AT REFERENCE POINTSDOSE AT REFERENCE POINTS
The dose to bladder and rectum depends on the
distribution of sources in a given application.
 The maximum dose to bladder and rectum should be
less than 80% of the dose to point A
The localization of bladder and rectum can be
performed using radiographs taken with contrast
media in the bladder and rectum.

62. BLADDER POINTBLADDER POINT
ICRU recommends :
On a lat. radiograph reporting
dose at a point at posterior
surface of Foley balloon on AP
line through centre of balloon.
On AP radiograph, reference
point is taken at the centre of
the balloon

63. RECTAL POINTRECTAL POINT
The dose is calculated at a point 5
mm posterior to (opacified) vaginal
cavity along an AP line midway
between vaginal sources.
On the frontal radiograph, this
reference point is taken at the
intersection of (the lower end of) the
intrauterine source through the
plane of the vaginal sources.

64. LYMPHATIC TRAPEZOIDLYMPHATIC TRAPEZOID
Lymphatic trapezoid represents
dose at lower Para-aortic , common
and external iliac L.N.
A line is drawn from S1-S2
junction to top of symphysis, then a
line is drawn from middle of this
line to middle of ant. aspect of L4,
A trapezoid is constructed in a
plane passing through transverse
line in pelvic brim plane and
midpoint of ant. aspect of body of
L4

65. PELVIC WALL REFERENCE POINTSPELVIC WALL REFERENCE POINTS
The pelvic wall reference point, represents
absorbed dose at the distal part of the
parametrium and at the obturator L.N.
Reporting dose at reference points related to
well defined bony structures & L.N. areas is
particularly useful when I/C BT is combined
with EBRT
On a AP radiograph, pelvic-wall reference point is
located at intersection of following lines
a horizontal line tangential to the highest point
of the acetabulum,
a vertical line tangential to the inner aspect of
the acetabulum.
On a lat. radiograph, the highest points of the right
& left acetabulum, in cranio -caudal direction, are
joined & lateral projection of the pelvic-wall
reference point is located mid-way b/w these
points.

66. REFERENCE VOLUMEREFERENCE VOLUME
The reference volume is the volume
encompassed by the reference isodose,
selected and specified to compare
treatments performed in different
centres using different techniques.
ICRU (43) recommends reference
volume be taken as the 60-Gy isodose
surface, resulting from the addition of
dose contributions from any external-
beam whole-pelvis irradiation and all
I/C insertions.
Height h,
Width w, and
Thickness t.
and their product should be reported
separately

67. TREATED VOLUMETREATED VOLUME
The Treated Volume is the pear and banana shape
volume that received (at least) the dose selected and
specified by the radiation oncologist to achieve the
purpose of the treatment e.g. tumour eradication or
palliation, within the limits of acceptable
complications

68. IRRADIATED VOLUMEIRRADIATED VOLUME
The irradiated volume is the volume, surrounding the
treated volume, encompassed by a lower isodose to be
specified, e.g., 90 – 50% of the dose defining the
treated volume.
Reporting irradiated volumes is useful for
interpretation of side effects outside the treated
volume and for purpose of comparison.

69. APPLICATORSAPPLICATORS
Applicators are small-caliber tubes that are inserted into body
cavities to hold the brachytherapy sources in clinically defined
configurations, or loading patterns.
The applicators include
A tandem to be inserted into the uterus
with different lengths that allow for adaptation according to the
individual anatomy (with a fixed uterine flange)
and angled at varying degrees to the line of the vaginal
component (0°,15°,30°,45° )
The deliberate angle in the tube draws the uterus, in most patients, into
a central position in the pelvis away from the pouch of Douglas, the
sigmoid colon, and the anterior rectal wall.
Two ovoids, to be positioned in the vaginal vault abutting the cervix.

70. APPLICATORSAPPLICATORS
Applicators used to insert intracavitary sources in the
uterus and vagina included
Rubber catheters and ovoids developed by French
researchers,
Metallic tandems and plaques designed in Sweden
Thin rubber tandems and ovoids of the Manchester
system.
Fletcher (1953) designed a preloadable colpostat, which
Suit et al. (1963) modified and made after loading

71. APPLICATORSAPPLICATORS
IDEAL CHARACTERISTICS of applicators
It should have a fixed geometry.
It should be made of rigid material as fixed & rigid applicators attain and hold better
geometry of the insertions
Lightweight (ideally 50- 60gm but should not be more than 100gm) for the patient's
comfort
capable of easy sterilization.
Applicators should be of inert material that is not adversely affected by exposure to
gamma radiation.
There should be minimal attenuation of gamma rays by the walls of the applicators i.e.
it should not produce its own characteristic radiations
Vaginal ovoids should be perpendicular to the long axis of vagina to avoid more dose
to rectum and bladder.
I.U. tube should be angulated

72. FLATCHER APPICATORFLATCHER APPICATOR
Based on Manchester System
Stainless steel
Cylindrical ovoid
Bladder and rectal shields
Preloaded but modified by Suit for
afterloaing
Disadv.
Presence of shielding lead to
uncertainty in dosimetry.
Cylindrical caps lead to
nonuniform doses to vaginal
mucosa.
Fletcher - Suit- Delclos
applicator for afterloading with Ir-192

73. HENSCHKE APPLICATORHENSCHKE APPLICATOR
Ovoids are hemispherical in shape.
Three ovoid diameters & various
tandem lengths are available
The radioactive sources are placed
parallel to the long axis of the
bladder & rectum
Thus delivering a higher dose to
these organs

74. PGI APPLICATORPGI APPLICATOR
Fixed geometry applicator
Desired dose can be delivered around
area of interest
Easy & accurate dosimetry
Less rectal dose because of obtuse
angle.
Perineal plate which helps to
maintain fixed geometry of
application i.e. applicator remains in
fixed position
Disadv.
Bladder complications are more as it
receives higher dose due to more
angulation

75. MDR/HDR APPLICATORMDR/HDR APPLICATOR
Modern after loading applicator that
mimics classical Manchester based
applicator.
I.U. tube with different lengths
graduated in centimeters (4& 6cm) &
angled at 40° to the line on the vaginal
component of the tube.
The vaginal ovoids are of ellipsoid shape
(large, medium, small, half)
These tubes are held together and their
relative positions fixed by a clamp
ensuring an ideal physical arrangement.
Used for HDR( with small tube
diameter)

76. MOULDED APPLICATORMOULDED APPLICATOR
The molded applicators
represent the most
individualized approach of
treatment

77. RING APPLICATORRING APPLICATOR
Based on Stockholm technique
Intrauterine tubes are of different lengths
& angulations
Ring is available in different diameters
(26, 30, 34mm)
Acrylic caps cover the ring tube to reduce
dose to vaginal mucosa.
The ring and the intrauterine tube are
fixed to each other with a screw.
A rectal retractor helps in pushing rectum
so that it receives less dose.
Adv. of ring applicator:
Fixed geometry
Interrelationship b/w ovoids is maintained.
Customized planning can be done

78. IDEAL APPLICATIONIDEAL APPLICATION
Use longest tandem that the patient's
anatomy can accommodate.
Increasing the tandem length increases
the point B (lateral parametrium and
pelvic lymph nodes) contribution
relative to the uterine cavity surface
dose
The radioactivity near the ends of the
long tandem contributes little to the
surface dose (because of inverse-square
law), whereas each tandem segment
makes roughly equal contributions to
points remote from the applicator.

79. IDEAL APPLICATIONIDEAL APPLICATION
Colpostats /ovoids with largest clinically indicated dia. should
be used to deliver highest tumor dose at depth, for a given
mucosal dose.
As colpostat diameter increases from 2 to 3 cm, the vaginal
surface dose decreases by 35% relative to the dose 2 cm from the
applicator surface; This is simply a consequence of increasing the
source-to-surface distance.
The geometry of the insertion must prevent under dosing around
the cervix;
Sufficient dose must be delivered to the Para cervical areas; and
Tolerance of vaginal mucosa, bladder and rectum must be
respected.

80. IDEAL APPLICATIONIDEAL APPLICATION
Optimal placement of the applicators in the uterus and vagina.
Optimal placement of the radioactive sources in applicators
Pear-shaped dose distribution -high dose to the cervical and
paracervical tissues; reduced dose to the bladder and rectum

81. IDEAL APPLICATIONIDEAL APPLICATION
Tandem -1/3 of the way b/w S1 –S2
and the symphysis pubis
The tandem -midway b/w the
bladder and S1 -S2
Marker seeds should be placed in the
cervix
Ovoids should be against the cervix
(marker seeds)
Tandem should bisect the ovoids
The bladder and rectum should be
packed away from the implant

82. IDEAL APPLICATIONIDEAL APPLICATION
The tandem should be in the midline or
as nearly as possible equidistant from the
lateral pelvic wall
The vaginal colpostats should be
symmetrically positioned against the
cervix in relation to the tandem
The ovoids should fill the vaginal
fornices, add caps to increase the size of
the ovoids if necessary.
The ovoids should be separated by 0.5 –
1.0 cm, admitting the flange on the
tandem.
The axis of the tandem should be central
between the ovoids.
Computerized dose optimization cannot
make up for a poor applicator position.

83. PATIENT PREPARATIONPATIENT PREPARATION
Pt is anaesthesitized.Pt is anaesthesitized.
Patient is in lithotomy Patient is in lithotomy
positionposition
Perineal area is disinfectedPerineal area is disinfected

84. APPLICATOR CHECKAPPLICATOR CHECK
Applicator set is check for Applicator set is check for
integrity and completenessintegrity and completeness
Length of uterus is Length of uterus is
measuredmeasured
Dilatation of the cervix Dilatation of the cervix
with standard tooling.with standard tooling.

85. PROCEDUREPROCEDURE
Correct length of IU-tube &
ovoids are selected
Inserted one by one and attached
to fixing mechanism.
To determine the rectal wall on
CT or radiograph a radio opaque
marker is inserted
After insertion of applicator
gauze packing is done behind the
ovoids to push rectum and bladder
away reducing the dose to these
organs


86. After procedure orthogonal radiographs are taken to After procedure orthogonal radiographs are taken to
check applicator geometry.check applicator geometry.

87. IMAGINGIMAGING
For treatment planning purposes
orthogonal radiographs/CT
images are taken
Images are transferred to
Treatment planning system.
If radiographs are to be used for
planning then radiographs are
scanned to transfer images to
TPS.
Catheter reconstruction done on
TPS

88. DOSE PRESCRIPTIONDOSE PRESCRIPTION

89. DOSE EVALUATIONDOSE EVALUATION

90. DOSE RATE EFFECTDOSE RATE EFFECT
Dose rate is one of the important factor
that determines biological consequences
of a given absorbed dose
As the dose rate is lowered & exposure
time extended, the biological effect of a
given dose is generally reduced.
Continuous low dose-rate (CLDR)
irradiation may be considered to be an
infinite number of infinitely small dose
fractions
consequently, the survival curve for
continuous LDR becomes shallow &
shoulder tends to disappear i.e.
survival curve becomes exponential
function of dose .

91. RATIONALE FOR LDR BACHTHERAPYRATIONALE FOR LDR BACHTHERAPY
For any selected dose, increasing the
dose rate will increase late effects much
more than it will increase tumor
control.
Conversely, decreasing the dose rate
will decrease late effects much more
than it will decrease tumor control.
Thus the therapeutic ratio (ratio of
tumor control to complications)
increases as the dose rate decreases.
For higher dose rates, the dose
reduction needed to match the late
effects is larger than the dose reduction
needed to match tumor control.
Despite all these facts there is a trend
towards increased use of HDR BT

92. In I/C BT equivalent HDR regimens can be achieved
without loss of therapeutic ratio.
Because the rad
n
dose that produces unwanted late
effects is significantly less than treatment dose (75%
of prescribed dose)
As OAR( rectum & bladder) are some distance away
from Brachytherapy sources.
Corrections
LDR – MDR - 33% reduction
HDR – HDR - 50% reduction

93. LDR BRACHYTHERAPYLDR BRACHYTHERAPY
The only type of brachytherapy
possible with manual after loading.
Most clinical experience available
for LDR brachytherapy
Earlier Radium was used for Low
dose rate brachytherapy
Performed with remote after loaders
using
137
Cs or with manual after
loading source trains of
137
Cs
pallets.

94. ADV. OF LDRADV. OF LDR
Long history of use
Ability to predict rate of late complications
Radio biologically superior as
Improves chances of catching tumors in sensitive phase of
cell cycle
Favorable dose-rate effect on repair of normal tissues
Infrequent replacement and calibration of sources
because of long isotope half-life

95. MDRMDR
Used to have adv of both LDR & HDR
Since dose rate correction was not used so it
lead to lot of complication
However in PGI two consecutive studies led
to incorporation of a 33% dose rate
reduction-probably only reported clinical
data with use of MDR
Availability of microselectron HDR with
miniature Ir-192 source & resultant smaller
applicators with the attendant adv of better
packing lead to more wide spread adoption
of HDR.

96. HDR BRACHYTHERAPYHDR BRACHYTHERAPY
Practiced only with remote after loading.
Most modern brachytherapy is delivered
using HDR
Outpatient procedure
Optimization possible
In the past Co – 60 pellets were used
Today, virtually all HDR brachytherapy is
delivered using single miniature linear 192-
Ir stepping source
Source moves step by step through the
applicator
The dwell times in different locations
determine the dose distribution

97. HDRHDR
During a treatment, the source is driven out of the HDR unit,
remotely.
Source steps through pre-determined treatment/dwell positions
within each treatment catheter,
Stopping at each dwell position for a pre-calculated length of
time i.e. dwell time,
to deliver the planned treatment dose distribution.
This type of stepping source HDR unit helps to achieve
optimized dose distribution for the treatment.

98. ADV. OF HDRADV. OF HDR
Out patient procedure
Pt.is not confined to bed for hours or days during irradiation
No indwelling catheters or vaginal packing
Geometry easily maintained during treatment
Ability to treat greater patient loads (high output of patients
on each machine)
Optimization of dose distribution by altering the dwell times
of the source at different locations

99. PDR BRACHYTHERAPYPDR BRACHYTHERAPY
PDR technology was developed at the beginning of the 90's
Unit has a similar design as HDR, however the activity is
smaller (around 1Ci instead of 10Ci)
Stepping source operation - same optimization possible as in
HDR
Treatment over same time as LDR treatment
The biologic effect mimics LDR, and the dose
optimization mimics HDR.
In-patient treatment: hospitalization required
Source steps out for about 10 minutes per hour and then
retracts. Repeats this every hour to deliver mini fractions
(‘pulses’) of about 1Gy

100. PDRPDR
Advantages
Complication rate profile more similar to that of LDR
Between fractions, patient is not radioactive, allowing for
near continuous nursing care during treatment
Radiation protection
Disadvantages
Long term results not available

101. VAULT RTVAULT RT
Disease localized to upper part of the vault
measuring <0.5cm in thickness & no vaginal wall
involvement
Delivered with colpostats

102. VAGINAL CYLINDERSVAGINAL CYLINDERS
If there is vaginal wall involvement or if there is parametrial
invasion then after EBRT vaginal cylinders are used.
Now a days if lower 1/3
rd
of vagina is involved then vaginal
cylinders are not used as tolerance of lower vagina is less (60-70Gy)
Disadv. Of vaginal cylinders :
Only depth of 0.5cm can be treated safely.
Rectal & bladder doses are higher
Because of anisotropy there is reduced dose to vaginal cuff.

103. INTERSTITIAL IMPLANTATIONINTERSTITIAL IMPLANTATION
The aim of this technique is to tailor the dose of irradiation to the
anatomy of the patient with a better target volume coverage.
Originally, interstitial implants were performed with free-hand
placement of the radioactive needles.
The development of transperineal or transvaginal templates
resulted in a better needle positioning.

104. INTERSTITIAL IMPLANTATIONINTERSTITIAL IMPLANTATION
Indications :
Pt. of ca cx with
Distorted anatomy
Narrow vagina & obliterated fornices
When os / uterine canal can’t be identified.
Extensive paravaginal (>0.5cm) or distal vaginal involvement
when parametrial extent of the tumor cannot be encompassed by
standard intracavitary brachytherapy.
patients with a recurrence inside an area previously irradiated
restricting the use of further external irradiation
Post op vault recurrence

105. INTERSTITIAL IMPLANTATIONINTERSTITIAL IMPLANTATION
It is delivered with either
Along with ICA using ring
applicator that has provision
for implantation
using template e.g. MUPIT

106. SEQUELAESEQUELAE
Acute reactions:
Diarrhoea , Nausea , abdominal cramping, rectal discomfort, &
occasionally rectal bleeding Fatigue ,weakness ,
Dysuria, frequency, nocturia
Erythema and dry or moist desquamation may develop in the
perineum or intergluteal fold.
Late reactions:
Haemorrhage, rectal ulceration ,rectovaginal fistulae, rectal
strictures,proctitis
Small bowel obstruction or perforation
Vesicovaginal fistulae,cystitis

107. CONCLUSIONCONCLUSION
Radiation plays an important role in management of carcinoma
cervix both in the form of EBRT & Brachytherapy & is only
mode of treatment in advanced cases.
Both of the components are important; however, successful
outcome of treatment depends on skilled use of I/C
Brachytherapy
Traditional method of low dose rate I/C Brachytheapy is being
replaced by modern high dose rate Brachytherapy
Most of clinical experience is available with low dose rate
Brachytherapy
Comparison of modern Brachytherary is still done with clinical
results of low dose rate Brachytherapy.

108. This is easy to understand in terms of the repair of
chromosome damage.
The linear component of cell damage will be unaffected by
dose rate since the two chromosome breaks that interact to
form a lethal lesion are caused by a single electron track.
The quadratic component, however, is caused by two separate
electron tracks; if there is a long time interval b/w the
passage of two electron tracks, then the damage caused by the
first may be repaired before the second arrives.

109. Cell killing by radiation is due largely to aberrations caused
by breaks in two chromosomes.
The dose–response curve for HDR irradiation is linear-
quadratic i.e. the two breaks may be caused by the same
electron (dominant at low doses) or by two different electrons
(dominant at higher doses).
For LDR irradiation where radiation is delivered over a
protracted period, the principal mechanism of cell killing is by
the single electron. Consequently, the LDR survival curve is
an extension of the low-dose region of the HDR survival
curve