Role of Interstitial Brachytherapy in Head and Neck cancers

1. INTERSTITIAL
BRACHYTHERAPY
in HEAD and NECK
CANCERS
Dr. Sayan

2. Brachytherapy - Placement of sealed radioactive
sources into or immediately adjacent to the target
tissue is called as brachytherapy.
Interstitial Brachytherapy – refers to surgically
implanting radioactive sources directly into the
target tissues

3. Radiotherapy actually started in the form of Brachytherapy
1898: Marie & Pierre Curie isolated Radium
1904: Robert Abbe (American surgeon) - First
one to use Radium for treatment of cancer.
1909: 1st text-book of Radium therapy
(Wickham & Degrais)
1938: Manchester System by Paterson-Parker
1950-60s: Advent of mega voltage type tele-
therapy machines - noninvasive

4. Use of brachytherapy declined in the middle of the twentieth century
due to the problem of radiation exposure to operators from the
manual application of the radioactive sources
1964: Bernard Pierquin et al. used Ir192 after-loading
interstitial implant
1978: Paris System – Pierquin and Dutreix
1980-90s: remote after-loading , computer planning
& optimization
New possibilities in Interstitial Brachytherapy with advantages of
remote after-loading & computer optimization

5. Ideal Brachytherapy Source
• Pure γ emitter – less α/β emission
• Medium γ energy – high enough to target tumor with
homogenous dose & low enough to avoid normal
tissues & reduce shielding needs
• High specific activity – small size & suitability for HDR
• Stable ( not liquid/gaseous) daughter product
• Long/medium t ½ for permanent/temporary implant
• Should be available in a form which does not powder or
disperse if source is damaged or dispensed

6. Types of sources

8. Brachytherapy in Head & Neck Cancers
• They are easily accessible for placement of needles and after-
loading catheters
• Better dose fall off profile
 higher dose to be delivered to tumor
 sparing of normal tissues
• Reduction in overall treatment time by allowing higher doses
To be preferred as an alternative for EBRT in well selected cases.
Ultimate conformal therapy

9. Intent of treatment
1. Radical : Brachytherapy alone as treatment
2. Boost: EBRT  Brachytherapy to boost dose to the
primary
3. As salvage therapy in recurrent cases who have been
irradiated before or who are unfit for surgery

10. Important Facts to be Noted in H&N
Brachytherapy
CLINICAL:
– Accurate assessment of tumor dimensions
– Pre-treatment imaging
– Submucosal spread to be examined clinically or in EUA.
– Extension to adjacent tissue may lead to misinterpretation of
exact dimension: prone to failure.
– Assessment of neck node involvement
– Rule out other lesions in the upper aero-digestive tract
(synchronous 2nd primary)

11. Imaging for GTV/CTV delineation for different
sites of Brachytherapy
Bragg DG, Rubin P. Oncologic Imaging, 2nd edition,
W.B.Saunders Comp. Philadelphia, Pensylvania 2002
SITE 1st CHOICE 2nd CHOICE
Tongue MRI CT
Floor of Mouth MRI CT, US
Buccal Mucosa MRI, CT, US
Lip MRI, CT
Oropharynx MRI CT
• CT scan is more sensitive than MRI for evaluating lymph nodes
• MRI is more sensitive for detecting muscle invasion and for depicting invasion of
the medullary space of the mandible and tumour spread along the inferior
alveolar nerve

12. Important Facts to be Noted in H&N
Brachytherapy
CLINICAL:
– Feasibility for Brachytherapy: Mouth opening, dental status,
proximity of bones to implant site and requirement of dental
shields/spacers
– Requirement of tracheostomy
– Fitness for anesthesia

13. PHYSICAL:
– Dose distribution even in a good implant is likely to be non-
homogenous (due to complex geometry)
– Even minor displacement may produce significant hot/cold
spots; increased morbidity/recurrence
– Peripheral fall off- may cause under-dosage of a site
– Under-dosage at borders where placement of additional
radio-active line may not be possible (dorsum and lateral
border tongue)
Important Facts to be Noted in H&N
Brachytherapy

14. • PHYSICAL:
– Interstitial edema may produce alteration in dose distribution
calculated to an extent of 10-15%.
– Narrow loops may prevent Rx with after-loading technique.
– Dose prescription volume and dose points should be clearly
specified.
– Method of optimization should be noted.
– Optimization is not to be used as a substitute for good
catheter placement
Important Facts to be Noted in H&N
Brachytherapy

15. BIOLOGICAL:
– Type of lesion: proliferative/infiltrative
– Ulcerative/proliferative lesions respond better
• Sensitivity
• Well defined and hence better delineation
• Minimal potential margin
– Infiltrative lesions are less preferred
– Larger lesion to be avoided for same reasons
Important Facts to be Noted in H&N
Brachytherapy

16. BIOLOGICAL:
– Total duration of EBRT + Brachytherapy should be kept as short
as possible (<8 weeks) to minimize tumor cell repopulation
– Interval between EBRT and Brachytherapy should be as short as
possible (<1–2 weeks) depending on degree of recovery from
mucositis
– Interval between twice daily HDR fractions should be as long as
possible (minimum of 6 hours)
– Previous irradiation history for dose calculation
Important Facts to be Noted in H&N
Brachytherapy

17. • BIOLOGICAL:
– In case of brachytherapy boost, placement of radio-opaque
markers before starting EBRT can help delineate the target
volume, before any shrinkage occurs
– No definite evidence on use of concomitant chemotherapy; risk
of increased mucosal toxicity compromising treatment –
however, appears to be useful for the treatment of recurrences
Important Facts to be Noted in H&N
Brachytherapy
Strnad V, Geiger M, Lotter M, Sauer R. Role of brachytherapy
for head and neck cancer: retreatment in previously irradiated
area. Brachytherapy 2003;2:158–63

18. Dental Preparation
• Teeth with caries should be restored. Teeth with deep caries or
poor periodontal support must be removed and complete healing
obtained before starting RT.
• A prosthesis (made of acrylic resin) including lead shielding (2mm
thick) should be made for brachytherapy of the lips, tongue, and
floor of mouth, to reduce dose to the mandible and prevent
osteoradionecrosis.
• The shielding is worn by the patient during whole duration of
irradiation, to protect teeth, gum, and mandible as it reduces the
transmitted dose by about 50%

19. Brachytherapy Procedure
• Explain Procedure to patient
• Obtain informed consent
• Admit a day prior to
procedure
• Anxiolytics and sedatives
Before Implant During Implant
• NGT insertion
• Positioning - Head rest ;
Shoulder support ; Neck
extension
• EUA / Gentle handling
• Target Volume ( Marker Seed)
• Plan/mark entry and exit points

20. Implant Technique
• Brachytherapy sources should always be implanted in an
operating room equipped for anesthesia, with adequate lighting
and suction facilities and the means to deal with extensive
bleeding
• Although arterial hemorrhage is rare it should be anticipated
• The brachytherapy technique should be based on a classic
system for interstitial brachytherapy (like those designed in
Paris, Manchester or New York)

21. Implant Technique
• Most LDR implant techniques can be used for HDR or PDR
treatments.
• However, some of them, such as the loop technique, are more
complicated because it is difficult for the source ‘‘to negotiate
the bridge”
• Loops can be replaced by two parallel tubes and dose
distribution can be optimized by increasing dwell times at the
blind end of the catheter

23. Cancer of the Lip
Indications:
•T1-2 N0 M0 tumors – Radical Brachytherapy alone
•Larger tumours (>5 cm in their major axis) are treated by EBRT
followed by brachytherapy boost, or surgical excision followed by
reconstruction.
•Tumours invading adjacent bone usually require surgery if feasible.
Brachytherapy when chosen offers better functional and cosmetic results
than surgery or EBRT alone
Mazeron JJ, Richaud P. Lip cancer, report of the 18th annual meeting of the
European Curietherapy Group, May 1981. J Eur Radiother 1984;5:50–6.

24. Hypodermic Needles
•Hollow, bevelled needles with outer diameter of
0.8mm and variable length (4 to 8 cm), open at
both ends.
• Cause little trauma - can be directly inserted in
the tissues
•The rigid steel and template system avoids
displacement of the sources due to the elasticity of
the soft tissues
•Can be used in lip tumours of ≤3cm in largest
diameter, not involving the lateral commissure.

25. Classic plastic tubes
•They have a diameter larger (1.6 to
1.9mm) than hypodermic needles.
•More flexible, allowing a better adaptation
to round surfaces
•More difficult to keep good parallelism
between tubes over the whole length of the
treated volume
•Indicated for larger masses, or when
commissure is involved.
•Loading is delayed for regression of the
post brachytherapy trauma and edema.

26. •They are seldom used for lip cancer,
unless it is a very small lesion preferentially
in the upper lip
•Can be used in combination with plastic-
tube implant or hypodermic needles
•When a part of the tumour bulges out of
the implanted area and a sub-optimal
dosage is achieved, this can be corrected
by an additional silk thread that can “warm
up” the under-dosed area
Silk Threads

27. Complications
•Superficial necroses occur in 3 - 10%. They heal spontaneously
in 70% cases before 6 months and require surgery in less then
5% of cases. Lip ulceration depends strongly on total dose and
dose rate.
•Depigmentation (2.5 – 15%)
•Teleangiectasia (10-15%)
•Edema (4-5%)
•Dyskeratosis (4-6)%
•Fibrosis (6-10%)
•Lip deformation and retraction (5-6%)
Van Limbergen E, Ding W, Haustermans K, et al. Lip
cancer: local control results of low dose rate
brachytherapy. The GEC-ESTRO 1993 survey on 2800 cases

28. ORAL TONGUE
• Brachytherapy alone is recommended for T1N0 and T2N0
tumors <4 cm.
• For larger lesions, a combination of external beam and implant
is usually preferred.
• For tumors >3–4cm or N1 lesions, although surgery is often
preferred, brachytherapy can be delivered as a boost after 40–
45 Gy of EBRT to the neck and oral cavity.

29. • These implants are done under GA.
• Catheters are looped through the oral tongue via entry sites in
the submental and submandibular areas.
• Care is taken to avoid placing catheters adjacent to the mandible.
• The spacing between loops is approximately 1 cm, and the
spacing between the limbs of each individual loop is the same.
• If the lesion approaches the base-of-tongue, some patients will
require a temporary tracheostomy as part of the procedure to
allow for maximal protection of the airway in case there is tongue
swelling as a result of the implant.

30. • Iridium hairpins with a fixed separation of 12 mm are used
• This limits width of volume which can be treated to
approximately 15 mm and the technique can therefore
only be used for smaller tumours (≤30 mm in length).
• The guide gutter is first inserted angled towards the mid
line of the tongue but once within the muscle it is
straightened out so that the lateral limb of the hairpin runs
3 to 4 mms below the mucosa of the lateral border of
tongue
• When the guide gutters are in position, the radioactive
hairpins can be cut to the desired length
• The pre-prepared suture is then tied over the bridge of the
hairpin to secure it within the tongue
Guide-gutter technique:

31. LOOPS/HAIRPINS
• Straight branches of the loops are parallel
and not spaced too wide.
• Ht. of curved portion of loop < half of
spacing.
• Loop to form a regular semi-circle or flatter.
• Ellipse  loss of parallelism of branches
and isodose variations.
• Branches of loop to be parallel for atleast the
distance equal to the spacing between them.
• BDR calculated at a point perpendicular to
the center of parallel branches and not at
midlength of loop.
b
b/2
L/2 x

32. Advantages:
• This allows a wider separation between the sources -
can be used to treat larger volumes.
• Remote after-loading that reduces the risk of
exposure
• In case of local oedema inducing the risk of
displacement of the plastic tubes, one can wait for an
acceptable local status before loading the iridium wire.
• Self retaining assembly, no suturing required
• No tubes protruding outside mouth (only threads) -
patient comfort
• Beads create a space with palate reducing dose
delivered to palate (spare minor salivary glands)
Plastic-Tube Loop Technique:

33. • A nylon cord is passed up the stainless steel needle
where it exits into the oral cavity and is then passed
down the other needle to form a loop. The stainless
steel needles are then removed.
• A length of plastic tubing with a 1.6 mm outer diameter
is threaded over the nylon cord and clamped over the
cord at its end.
• Three or four loops are inserted into the tongue
depending on the volume to be treated with a
separation between each loop between 15 to 18 mm.
• The distance between the “legs” of each loop is the
same as the distance between the different loops.
• A nylon bead and a steel button are passed over the
ends of the plastic tube in preparation for fixing the
implant once it is loaded.

35. • Loops are technically difficult
• Cable-driven after-loading sources may
not negotiate the sharp curve of the loop
• Non-looping functional loop after-loading
technique developed whereby transverse
catheter is eliminated
• Button-ended catheters tied together to
form an apex of functioning loop
• Structurally, the paired catheters are
separate semi-loops with no sharp
curves; however, functionally, they are a
loop
NON-LOOP TECHNIQUE

36. Complications
• The two main complications are soft tissue necrosis and
osteonecrosis.
• Soft tissue necrosis is usually a self-limiting process, and heals with
time.
• Osteonecrosis can be quite severe. In a minority of cases, it can lead
to the need for mandibular resection.
• However, as the oral tongue is situated away from the mandible, the
risk of osteonecrosis is small.

37. FLOOR OF MOUTH IMPLANT
• Radical Implant: recommended for T1N0 and T2N0 tumors <30 mm and
>5 mm from the mandible
• Tumors >30 mm and <40 mm and >5 mm from the mandible may be
treated either with brachytherapy or by surgery.
• Postop brachytherapy may be used in case of close or positive margins or
lymphatic invasion or tumour infiltration > 5 mm in the absence of positive
lymph nodes.
• Involvement of the mandible is an absolute contraindication to
brachytherapy.
• Both guide-gutter and plastic tube techniques are applicable. In order to
decrease the dose to the mandible, contact between the mandible and
high dose areas should be minimized (no more than two lines).

38. Buccal Mucosa
• Indication: lesions <4 cm in diameter and <1.5 cm in thickness
involving the anterior and central part of the buccal mucosa.
• If there is deep involvement of the GBS, brachytherapy is
contraindicated because of risk of osteoradionecrosis of mandible.
• For the posterior third of the buccal mucosa it is usually very
difficult to evaluate tumour extension to the RMT and
intermaxillary commisure accurately
• For tumours larger than 40 mm or tumours involving the posterior
third of the buccal mucosa (without involvement of the
intermaxillary commissure), a combination of EBRT and
brachytherapy boost is indicated.

39. • Can be performed under LA.
• The guide gutters are implanted parallel to the buccal
mucosa in the antero-posterior direction.
• An intraoral finger of the operator checks the position of the
guide gutter. In general, one double-guide gutter is
sufficient, sometimes completed by an extra single-guide
gutter.
• After the replacement of the gutters by iridium hairpins, the
relative position of the suture around the bridge to the lip
commissure is crucial to maintain the source in position.
Guide-gutter technique:

40. There are 2 ways of implanting a buccal mucosa carcinoma,
taking into account the thickness of the tumour and the anatomical
characteristics of the cheek, whose thickness increases from the
lip commissure to the intermaxillary commissure.
1) needles are implanted through the skin: first parallel to each other,
parallel to the oral mucosa and parallel to the horizontal branch of the
mandible.
• The lines are placed 3-5 mm deep, under the buccal mucosa.
• They should cover 10 mm of normal mucosa behind or in front of the
lesion with a recommended spacing of 12 to 15 mm.
• 2-3 plastic tubes are usually required to cover the target volume if
the thickness of the tumour does not exceed 5 mm
Plastic-tube Technique

41. • If the lesion is thicker than 5 mm, a
second plane of tubes is implanted
between the first one and the skin, with an
interplane spacing equal to the
intersource spacing in each plane.
• With a single plane, the thickness of the
target volume equals about 50% of the
space between the lines (i.e. distance 18
mm, treated thickness 9 mm).
• If the thickness to be treated is greater, 2
planes are necessary or the second
technique should be chosen

42. PERNOT technique : posterior loop made ( to be
kept atleast 0.5 cm anterior to ramus of mandible)
When the lesion is posterior, near the intermaxillary commissure, there is a
risk of geographic miss at the back with the parallel tubes. So, a posterior
loop is recommended whose top is as close as possible to the intermaxillary
commissure.

43. 2) Gerbaulet technique: used for very bulky infiltrating tumour;
Needles are inserted perpendicularly to the skin of the cheek organized in
several loops to cover the target volume .
• Whereas for other interstitial implants in head-and-neck carcinoma,
radioactive sources are perpendicular to the surface of the tumour, for buccal
mucosa they are (except for the Gerbaulet technique) parallel to it as also in
lip lesions
• For all these different implants, the position of the lines must be checked not
only when the mouth is open but also closed, with the shielding device in
place inside the oral cavity.
• The shielding system may reduce the thickness of the target volume by
stretching the cheek and squeezing the tumour so irradiation is better
adapted

44. Oropharynx
Indications
Tumors less than 5 cm as combination modality
Brachytherapy alone: 1) purely exophytic tumours ≤ 10 mm in
diameter
2) recurrent cancers
3) new tumour arising in previously
irradiated territory
Contra-indications
Tumour extends to the RMT, NPX, larynx, HPX
If the lesion is fixed to the underlying structures or invades bone.
Tumour is associated with bulky cervical lymph nodes

45. Base of tongue
• Patients who do not have palpable LN
metastasis receive elective irradiation to the
neck along with EBRT to the primary site.
• Treatment is completed with an implant to the
base-of-tongue, performed approximately 2-3
wks after the completion of EBRT.
• This type of implant usually consists of
three sagittal planes, each containing a
'looping' catheter running over the dorsum
of the base of tongue and two or three
blind ending catheters with buttons sutured to
the looping catheter.

46. • The implants are done under GA with nasal intubation.
• A temporary tracheostomy might be necessary if the vallecular region is invaded
by a large tumor.
• Supine position with the neck in hyperextension
• 3 or 4 sagitally oriented parallel loops, spaced 15 - 20 mm, are implanted.
• The posterior branch of the central loop is first implanted. A guide needle is
inserted perpendicularly to the skin above the hyoid bone. The needle is guided
into the pharynx, in most cases into the vallecula, with the index fingertip. A nylon
filament is introduced into the needle. Then the needle is removed. A nylon tube is
advanced along the nylon filament, and the two are clamped together. Then the
tube is pulled into oropharyngeal cavity. The filament is removed.
• A second needle is implanted anteriorly into the base of tongue, and a filament is
advanced into the needle. The needle is removed and the filament inserted into
the first plastic tube. The two are clamped together and pulled through tongue and
skin, so completing the loop. The filament is removed.

47. RAYNAL LOOP SUBSTITUTION TECHNIQUE

48. Vallecular region
• The loop technique can be modified for
implanting vallecular tumours.
• The posterior inferior branches of the loops are
implanted between the hyoid bone and the
thyroid cartilage through the epiglottis, and the
superior branches into the base of tongue.
• When the loops are formed, the free portion of
the epiglottis is pulled forward and held against
the base of tongue
• Straight, blind-ended plastic tubes may replace
loops if a stepping source afterloader is used.

49. Soft Palate
The procedure is carried out under general anaesthesia
with nasal intubation
Two parallel frontal loops 15 -20 mm apart are
implanted to cover the whole or two thirds of the faucial
arch
Classical Plastic Loop Technique

50. Poseidon Technique
• This technique permits to treat lesions of
the uvula and small central tumours of
the soft palate
• Three curved needles are implanted in a
sagittal direction into the soft palate.
• They are inserted into the mucosa at the
junction of the hard and soft palate and
sort at the free border laterally and
through the uvula for the central line.
Then a loop is made joining the two
lateral lines.

51. Tonsil
• For tumours of the tonsillar region, the implant
covers only the ipsilateral tonsillar region and a part
of the soft palate.
• The two pillars and the soft palate are implanted
using Pernot technique, but the tubes exit in the
oropharyngeal cavity at the opposite side of the soft
palate.
• A plastic spacer secures spacing between the
oropharyngeal extremities of the tubes. These
extremities are fixed with buttons.
• For tumours limited to the lower half of the tonsillar
region, the two tubes can be replaced by a loop
covering only the tonsillar region (Baillet technique)

53. •For tumours involving the tonsillar region as
well as the adjacent tongue, an additional
loop may be implanted into the tongue, in
order to irradiate the glosso-tonsilar sulcus
and the adjacent tongue
•However, it is advised to use this technique
only when there is limited (< 1 cm) invasion in
the adjacent tongue.
•Parallelism between this loop and the tubes
implanted into the faucial arch can be
optimised using fluoroscopy

54. Imaging for Treatment Planning
• The main issue in imaging for brachytherapy is always to display the
tumour in relation to the applicator as accurately and reproducibly as
possible.
• The best fit to the topographical and dosimetric situation with the
applicator in place can be achieved if sectional images are taken, in
three dimensions parallel and perpendicular to the (projected) axis of
the needles or tubes.
• By this technique, the image section represents the plane along or
perpendicular to which irradiation will be performed.
• The highest accuracy can be achieved in estimating tumour
dimensions related to the projected applicator geometry and dose
distribution by using such image orientation.
• E.g. sagittal (parallel), paratransverse (90°) and paracoronal
(parallel) images (MRI) related to the axes of the tubes in tumours at
the base of the tongue
Pötter R, Kovacs G, Lenzen B, et al. Technique of MRI
assisted Brachytherapy Treatment Planning. Activity.
Selectr Brachyther J 1991; 5(3): 145-48

55. Target Definition
• GTV is the primary tumour volume as defined by the clinical
examination and imaging techniques.
• CTV is the GTV plus a safety margin taking into account
possible microscopic extension, which depends on the tumor
situation but should never be less than 5 mm, and is in most
cases 0.5–1 cm.
• The skin should not be included in the CTV unless it is invaded
by tumor, and the skin dose should be minimized as much as
possible. Markers placed on the skin surface or CT/MRI
planning can help identify it and calculate the dose

56. • In sectional image assisted treatment planning The GTV and
the CTV are delineated slice by slice as accurately as possible,
independent of the position of the applicator.
• The same procedure is followed for the organs at risk.
• Image based dose distributions are calculated orientated to the
different slice positions or even in 3D with display in systematic
or arbitrary planes.
• For the target and for the different organs at risk dose volume
histograms are generated.
Target Delineation

57. Planning method
Forward planning
• physicist wants to achieve a dose distribution which meets
certain criteria by adjusting iteratively the dwell times.
• It does not use information about the anatomy of the patient: the
presence of critical organs and normal tissue is not taken into
account during the optimization process.
• This method aims to give a homogeneous dose to the target
volume and is based on the location of the catheters.
• This leads to a mere approximation of the actual target
volume

58. Forward Planning
• Such a geometric representation of the target volume
cannot guarantee that the actual target volume receives
sufficient, and the normal tissue no excess radiation.
• Hence the dwell times always need manual adjustments.
After the physicist has changed the dwell times, the
computer will recalculate the dose distribution.
• Then the physicist evaluates the resulting dose distribution.
The whole process is repeated until he is satisfied with the
resulting treatment plan.
• Such a method of trial and error makes the whole procedure
very time-consuming and dependent on the experience of
the physicist

59. Inverse Planning
• Here the physicist defines what the objectives are by
defining restrictions on target volume and critical organs
before optimization.
• During the optimization process, one almost always uses the
images of the target volume and critical organs.
• So this model do take the anatomy of the patient into
account.
• The system determines how the objectives of the physicist are
realized: the result is an optimal set of dwell times.
• The physicist therefore does not anymore need to do the
manual adjustments. The resulting plan will be used
immediately for treatment.

60. Planning Objectives
• The first type of objectives is related to the dwell time of the
source in the dwell locations. This objective aims at reducing
disparities between the dwell times in each catheter and
avoiding solutions with very high dwell times in some dwell
locations.
• A second set of objectives is directly related to the radiation
dose. These objectives aim at a minimum underdose and/or
maximum overdose of the target volume, critical organs
and normal tissue.

61. • The objectives of the dose points in a given tissue type,
are related to dose homogeneity.
• A homogeneous dose distribution is a dose distribution that is
very evenly spread over the volume.
• The objectives of the dose points on the surface of a
particular tissue type are related to the dose conformity.
• A conformal dose distribution is a dose distribution that
ensures that the entire volume receives the optimal dose.
Planning Objectives

62. Planning Objectives
• Objectives based on dose-volume histograms (DVH) are a
third class of objectives.
• The DVH objectives consist of
a) the percentage of the target volume with a dose value smaller
than the prescribed dose (underdose)
b) the percentage of the target volume with a dose value
exceeding a critical dose value
c) the percentage of the critical organs with a dose value
exceeding a critical dose value (overdose)

63. Optimization Techniques
• In Dose-point optimization, the desired dose at a number of
dose points at a certain distance from the catheter are defined.
• In Geometric optimization, the dwell locations themselves act as
dose points.
• Graphical optimization: the isodose curves of the radiation plan
the computer displays are changed manually with the mouse.
After manual adjustment, the algorithm calculates the exact
corresponding dwell times.

64. After geometric optimization, the overdosed region receiving at least
200% of the reference dose is reduced, especially at the intersection of the
blind-ended catheters and the looping catheter.
Un-optimized Optimized

65. Evaluation Criteria
• The most frequently used methods are the visual evaluation
of the isodose distribution and dose-volume histograms of all
tissue types.
• Isodose distribution is seen in all three planes: Axial, Coronal and
Sagittal.
• To look for Maximum isodose percent covering intended target
volume well in all appropriate planes.
• To look for volume and location of hot-spots

66. Evaluation Criteria
• Other methods include dosimetric parameters derived from the
dose-volume histograms for evaluating the quality of a plan.
• The target volume-oriented parameters include:
a) a dose that covers 90% of the target volume (D90),
b) the percentage of the target volume that receives at least the
prescribed dose (V100)
c) the percentage of the target volume that receives one and a
half times the prescribed dose (V150)

67. Evaluation Criteria
• Conformality Index (COIN): This index is a measure of the
conformity of the plan, taking into account both the target
volume, critical organs and normal tissue.
• Dose homogeneity index (DHI): It gives the fraction of the target
volume that receives a dose between V100and V150.
• External volume index (EI): This is a fraction of the normal
tissue receiving a dose at least equal to the prescribed dose of
the target volume.
• Sum index (SI): This index is equal to the weighted sum of
V100, V200, DHI and EI.

94. Dose and Dose Rate Prescription
• In LDR brachytherapy, delivering a high total dose is
recommended to secure local control, and to maintain the dose
rate between 0.3 and 0.6 Gy/h to minimize late side effects.
• With HDR brachytherapy, doses between 3 and 4 Gy/# have
been recommended.
• The optimum time-dose pattern for PDR brachytherapy remains
under debate. Some recommend the same total dose as that
used for LDR brachytherapy, delivered in the same total time in
24 hourly fractions per day.
Mazeron JJ, Simon JM, Le Péchoux C, et al. Effect of dose rate on local control and
complications in definitive irradiation of T1-2 squamous cell carcinoma of mobile tongue
and floor of mouth with interstitial iridium 192. Radiother Oncol 1991;21:39–47.
Nag S, Cano ER, Demanes DJ, et al. The ABS recommendations for HDR brachytherapy for
head and neck carcinoma. Int J Radiat Oncol Biol Phys 2001;50:1190–8

95. Dose for Brachytherapy– here in TMH
• Radical Brachytherapy:
T1-2 N0 tumors - low dose rate 60-70Gy
high dose rate 49 Gy/14# (2#/day)
• Boost Brachytherapy: (after External RT: 56 -60Gy/28-30#/6wks)
low dose rate : 15-20 Gy or
high Dose rate: 14Gy/4#/2 days(4-3-3-4 Gy)

96. PLAN IMPLEMENTATION
• Patient shifted to treatment room.
• Appropriate positioning.
• Catheters connected in order as per initial labelling.
• Final plan transfer confirmed
• Patient counselled and monitored while on treatment using
CCTV.
• Post treatment local dressing done and pt. shifted to ward.

97. Monitoring
• Patients should receive adequate analgesics.
• Steroids, antibiotics and a feeding tube may be indicated.
• The implantation site is inspected at least twice daily
• Implant catheters should be removed in the operating room,
where management of haemorrhage and airway protection are
achieved more effectively.
• An intravenous access is recommended and the presence of
two persons is mandatory.
• In case of bleeding, bimanual compression for ten minutes is
usually effective for stopping arterial bleeding.
Catheter Removal

98. Post-treatment Patient Care and Follow-up
• GEC-ESTRO recommends that patients should be seen 1 month
after treatment, every 3 months during years 1 to 3, then every 6
months during years 4 and 5, then yearly.
• Patient should be counselled regarding mucositis that develops 1
- 2 weeks after brachytherapy.
• The reaction is maximal after 3 - 4 weeks, and heals
progressively in 5 - 8 weeks