This document discusses brachytherapy techniques for head and neck cancers. It describes different types of brachytherapy based on positioning of the radionuclide (interstitial, intracavitary, surface moulds), dose rate (LDR, MDR, HDR, PDR), and technique (temporary, permanent). It also discusses dosimetry systems like Patterson-Parker, Quimby, Paris and computerized planning. Key aspects of treatment planning, delivery, and post-treatment care are summarized. Advantages include localized high dose with rapid falloff and organ preservation, while limitations include inaccessibility and quality dependence on implant. American Brachytherapy Society guidelines emphasize accurate assessment and dental

1. BRACHYTHERAPY IN HEAD AND
NECK
DR AKHILESH
DEPARTMENT OF RADIATION
ONCOLOGY
REGIONAL CANCER CENTRE ,
TRIVANDRUM

2. BRACHYTHERAPY –
 Method of radiaton therapy in which an encapsulated
source or group of such sources is utilized to deliver
gamma or beta radiation at a distance of up to a few
centimetres, either by surface, intracavitary or
interstitial application.

3. Head and Neck

4. TYPES OF BRACHYTHERAPY
BASED ON POSITIONING OF RADIONUCLIDE
o INTERSTITIAL - Sources are implanted surgically
within tumour volume.
o INTRACAVITARY – Sources are placed into body
cavity close to tumour volume.
o SURFACE MOULDS – Sources are placed over
tissues to be treated.

5. TYPES OF HEAD AND NECK
BRACHYTHERAPY
INTERSTITIAL SURFACE MOULD INTRACAVITARY
Lip, Buccal
Mucosa,
Tongue, Tonsil
Soft palate
Neck, PNS
Hard palate,
Nose,
Face, Pinna,
Ext.auditory canal
Nasopharynx

6. BASED ON DOSE RATE
o Low Dose Rate (LDR) - 0.4-2Gy/hr
o Medium Dose Rate (MDR) – 2-12Gy/hr
o High Dose Rate (HDR) - >12Gy/hr
o Pulsed Dose Rate (PDR) – involves short pulses of
radiation, typically once an hour, to simulate overall rate
and effectiveness of LDR treatment.

7. BASED ON TECHNIQUE
 TEMPORARY – Dose is delivered over a short period
of time and the sources are removed after the
prescribed dose has been reached (Ir-192)
Eg:- Buccal mucosa, Tongue etc
 PERMANENT – Dose is delivered over the lifetime
of source until complete decay ( I-125 seeds, Au-198)
Eg:- Parotid , Nasopharynx

8. BASED ON METHOD OF SOURCE LOADING
 PRE LOADING – The applicator is preloaded and
contain radioactive sources at the time of placement
into the patient.
 AFTER LOADING – Applicator is placed first into
the target position and the radioactive sources are
loaded later, either by hand (manual afterloading) or by
a machine (automatic remote afterloading).

9. RATIONALE
 Highly conformal treatment.

10. INTENT OF TREATMENT
 RADICAL : Brachytherapy alone as treatment.
 BOOST : EBRT  Brachytherapy to boost dose to the
primary.
 SALVAGE THERAPY : Recurrent cases who have
been irradiated before or who are unfit for surgery.

11. SELECTION CRITERIA
 Easily accessible lesions
 Early stage diseases (Ideal implant ≤ 5 cm)
 Well localized tumor to organ of origin
 No nodal or distant metastases
 No local infections or inflammation
 Proliferative/ ulcerative lesions preferred.
 Favorable histology

12.  Brachytherapy alone contraindicated –
 Non accessible tumour location
 Tumour limits are ill-defined
 Tumor is abutting or has invaded bone

13. No randomized trials
Recommendations by experts
 American Brachytherapy Society (ABS)
recommendations
 GEC-ESTRO recommendations
For head and neck
brachytherapy

14. PRE TREATMENT WORKUP
 Detailed CLINICAL EXAMINATION of the head and
neck region
 Examination under general anesthesia preferably in
combination with panendoscopy – Posterior lesion
 Computerized tomography (CT) and magnetic resonance
imaging (MRI) - Optional
 Dental preparation.

15. Prerequisites for brachytherapy
treatment
TARGET VOLUME :-
 Brachytherapy catheters should be placed about 1 to
1.5 cm apart as equidistant and parallel as possible, to
encompass the CTV with a margin determined on the
basis of the clinical parameters.
Pre-planning :-
 Measure the tumour carefully.
 Plan the exact number of radiation sources to be used
with their length and separation.

16. Treatment Delivery
 High Dose Rate Brachytherapy
 Two fractions given every day
 6 hours apart
 Dose: 300-400cGy per fraction

17.  RADICAL :- Equivalent of 60-66Gy of low dose
rate brachytherapy, 400cGy per fraction bid X 12
 BOOST :- Equivalent of 20-30Gy of low dose rate
brachytherapy, 400cGy per fraction bid X 8-10
TOTAL DOSE

18. The most common technique is afterloading
with Ir192
Eg:- Lip, Buccal Mucosa,
Tongue, Tonsil
Soft palate
Neck, PNS
INTERSTITIAL
BRACHYTHERAPY

19. RULES OF IMPLANTATION

20. DOSIMETRY IN INTERSTITIAL
IMPLANT
Paterson-parker system
Quimby system
Paris system
Computer system or No system

21. PATERSON PARKER SYSTEM
 Deliver uniform dose(+/- 10%) to a plane or volume.
 Row of parallel needles with ends crossed by needles at
right angles.
 Needles should be in parallel rows at spacing not greater
than 1 cm
 Crossing needles should ideally cross the active needle
ends, but should not be more than 1 cm from the active
ends.

22.  Depending on the size of the lesion a single plane, double
plane, or volume implant can be used to cover the tumor
with a 1-cm margin.
 For tumors :-
• <1 cm in thickness - single plane implant
• 1-2.5 cm thickness - double plane implant
• > 2.5 cm thickness - volume implant

23.  Areas covered by
implants with
1. Two crossed
ends
2. One crossed end
3.No crossed ends

24. Paterson Parker tables
 The P-P tables are designed to
give milligram hours / 1000
roentgens for various implant sizes
both for planar and volume
implants depending on the surface
area of implant.
 CORRECTIONS
(Total correction factor = 0.90)
 Gamma-factor originally 8.4
Rcm2/mg-h,now 8.25 Rcm2/mg-h.
 R to cGy factor = 0.957
 Oblique filtration
 Correction for tissue attenuation and
scattering

25. Rules for planar implant
Area of plane
(cm2)
% Activity in
periphery
% Activity in
the center
<25 2/3 1/3
25-100 ½ ½
>100 1/3 2/3
Deduct 10% of the area for each uncrossed end

26. For volume implants
 Sources on each surface must
be spaced as evenly and not
more than 1.0 to 1.5 cm
apart.
 The belt should contain not
less than 8 needles and the
core not less than 4 needles.
 For each Uncrossed ends :
7.5% reduction in volume.

27.  P-P tables give cumulated source strength per unit dose
(in mgh per 1000cGy) for given implant or volume.
 To obtain the total dose strength, the table value is
multiplied by the desired dose rate.
 Dose derived from the table value – STATED DOSE
 Stated dose is 10% larger than minimum dose and 10%
lesser than maximum dose ( Uniformity Criterion) in the
treatment region.

28. QUIMBY SYSTEM
 Uniform distribution of sources of equal linear activity of
Ra-226.
 surface applicators.
 No appropriate guidelines for multiple planar implants.
 Volume implants: the stated dose is the minimum dose
within the volume.
 Two plane implants hotter near center, cooler at edges
 Central minimum dose typically 25- 30% hotter than
prescription dose
 Corrections are the same as the Patterson-Parker system

29. PARIS SYSTEM
 Predictive Implant System
 Define a target volume
 Define its three dimensions. ie., length (L), width (W)
and thickness (T) . TV= L x W x T
 Number of source planes depends upon the thickness.
 If the thickness exceeds 12 mm, there must be 2 source
planes.
 the source pattern, the number of sources and the source
spacing are easily determined

30.  GENERAL RULES :-
 Sources must be straight, parallel and equidistant from each
other ( no crossing).
 Regular geometric pattern with equal separation( 5mm and
20mm
 The linear activity of the sources must be uniform along the
length of each line and identical for all the lines used.

31.  Central plane : plane
perpendicular to the sources ,
which is at right angles to the
long axis of the sources, and is
situated mid-way along their
length.

32.  Basal Dose Rate provides a measure of the dose rate in
the centre of the treated volume .
 Arithmetic mean of all the basal dose rates
 Single plane: midway
 Triangular plane: centroid of each triangle
 Square : centre of each square
 Calculated from the position of the sources in the central
plane and is at the points of minimum dose rate between
a pair or group of sources

33.  SINGLE PLANE
IMPLANTS
 IN SQUARES
 IN TRIANGLES

34.  Reference Dose Rate - dose which encompasses the
tumour volume.
 85% of the basal dose rate
 Dose rate used for calculating the total time of the implant.
 Treatment volume - volume enclosed by the 85%
reference isodose ( approx. 0.65 times the length of
sources)
 Sources should be 20-30% longer at each end than the
target volume.

35.  Hyperdose Sleeve - defined as the volume of the tissue
receiving twice the reference dose rate (170% of the basal
dose).

37.  Length (L) of the treatment
volume is defined as “the
smallest distance between the
invaginations of the treatment
isodose at either end of this
volume, between the active
lines and parallel to them”.
 It is measured in the same
plane as the lines if there is
only one plane or mid-way
between the planes if more
than one plane.

38.  Thickness (t) of the
treatment volume is
defined as “the smallest
distance between two
parallel planes which are
tangents to those
invaginations which give
the target volume its least
thickness”.

39.  Width (w) is defined as
“the maximum width of the
reference isodose in the
central plane” .
 It is equal to the distance
between the most lateral
sources plus 37% of the
separation between the
sources added on to each
side.

40.  Safety margin is defined as
“the minimum distance
measured between the
reference isodose and a line
joining the points where
any two sources intersect
the central plane”.

41. COMPUTER SYSTEM
 Single-stepping source High Dose Rate Remote After-
loading machine (Single miniature Ir-192 source)
 3D imaging for defining target volumes and for guiding
applicator insertion. (CT/MRI)
 Three dimensional isodose distributions.
 Optimization.( Dwell positions & Dwell times)
 Dose–Volume Histogram (DVH) indices for quantifying
dose delivery and implant quality

42.  1, 2, 3……… - Dwell positions
 T1, T2, T3…. - Dwell times

43.  Similar to Paris and Quimby, Implant that is hotter in the
centre than the periphery.
 This dose inhomogeniety accepted – more dose needed to
the centre to sterilize the tumour.
 No crossing sources – active length of line sources
should be suitably longer (=40% longer) than the length
of target volume.

44. Hard palate
Nose
Face
Pinna
Ext.auditory canal
MOULD BRACHYTHERAPY

45.  HDR brachytherapy using a mould, without need of
invasive needles.
 Surface mould is a custom made device, which attaches
to the patient and supports applicators or radioactive
sources at a fixed distance from the skin surface ( 5-
20mm).
 Dosimetry system – Paterson parker system or Paris
system

46.  Distance between source to skin surface – depend on
depth of treatment.
 Dose to the treated area varies by +10% due to the non-
uniform isodoses produced by the spaced, discrete
sources.

47. Nasopharynx
 Salvage therapy –
well circumscribed and
superficial local recurrences
limited to nasopharynx without
involvement of underlying
bone.
INTRACAVITARY
BRACHYTHERAPY

48.  Nucletron Rotterdam applicator
 Specialized form of surface mould
 Made of soft silicone
 Consists of 2 approximately parallel applicators and a
Paris system of basal points can be set up to give an
initial dose calculation.

49. Catheter removal in interstitial
brachytherapy
 Removed in the operating room
 An intravenous access is recommended
 Presence of two persons is mandatory
 In case of bleeding - bimanual compression for ten
minutes.

50. Post-treatment patient care and follow-
up
 Should be regularly followed up.
 Every monthly for atleast 1-2 years
 Every 3 monthly thereafter
 Most common complication – soft tissue necrosis

51. Advantage of Brachytherapy
 Delivers localized dose to the tumor
 Rapid dose fall off outside the target volume allows
excellent normal tissue sparing
 Less integral dose as compared to 3DCRT & IMRT
 High biological efficacy
 Decreased risk of tumor population
 Elimination of set up errors as the source maintains a
fixed relationship to target volume

52. Advantage of Brachytherapy
 High tolerance: Tolerable acute intense reaction
 High control rate
 Better cosmetics: May avoid disfigurement and
mutilating surgery
 Minimal radiation morbidity
 Day care procedure
 Organ preservation
 Reirradiation for localized recurrence

53. Limitation of brachytherapy
 Difficult for inaccessible regions
 Limited for small tumors (T1-T2)
 Nodal disease cannot be covered simultaneously
 Invasive procedures, require GA
 Greater conformation –small errors in placement of
sources lead to extreme changes from the intended dose
distribution
 Quality of implant is operator dependent

54. General concepts based on ABS
recommendation
 Use of brachytherapy as a component of the treatment of
head-and-neck tumors.
 No definite evidence on use of concomitant
chemotherapy; risk of increased mucosal toxicity
compromising treatment – appears to be useful for the
treatment of recurrences.

55.  Sequencing of EBRT and brachytherapy - obtain
shrinkage with EBRT before applying brachytherapy in
advanced tumors.
 Brachytherapy boost - placement of radio-opaque
markers before starting EBRT can help delineate the target
volume, before any shrinkage occurs.

56. Dental Preparation
 Teeth with deep caries or poor periodontal support -
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.

57. Important Facts to be Noted in H&N
Brachytherapy Based on ABS
recommendations
CLINICAL :-
 Accurate assessment of : tumor dimensions, neck node,
lesion type via clinical examination.
 Feasibility for Brachytherapy: Mouth opening, dental
status, proximity of bones to tumor.
 Requirement of dental shields/spacers.
 Requirement of tracheostomy.
 Fitness for anaesthesia

58. PHYSICAL :-
 Dose distribution :- non-homogenous (due to complex
geometry)
 Minor displacement - significant hot/cold spots;
increased morbidity/recurrence.
 Peripheral fall off- cause under-dosage of a site
especially at borders
 Interstitial edema - produce alteration in dose
distribution calculated to an extent of 10-15%.

59.  The isodose distribution should be computer optimized
to conform to the CTV.
 The dwell times can be adjusted to minimize dose
inhomogeneity.
 Optimization should not be used as a substitute for
good catheter placement.

60. Treatment Monitoring
 To detect potential displacement of radioactive sources
or catheters.
 Adequate antalgic and anti inflammatory coverage
 Mouthwashes and nutritional support through a
nasogastric tube
 Antibiotics may be useful
 patient must also be taught - watch out for
inflammatory reactions - occur after the removal of the
implants, start about 7 days later, increase until the
third week, are stable over one week, and then decrease
and finally disappear at the end of the sixth week.

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

62. ABS Recommendations -recurrent head &
neck cancer
 Strongly emphasizes on using brachytherapy for
recurrent tumors
 The extent of disease should be carefully studied with
CT, MRI, or PET scan as necessary.
 Complication risks are increased in patients with
previous surgery, skin or mucosal ulceration, deep soft
tissue necrosis, bone exposure, or severe fibrosis
 Meticulous implant technique and adequate doses are
necessary

63.  Generally larger margins are required for recurrent
tumors, especially if additional EBRT is not applied.
 Because of the paucity of data – No specific
recommendations for the indications for HDR
brachytherapy in recurrent head and neck tumors.

65. PARAMETER
SYSTEM
Manchester Quimby Paris
Dose 6000-8000 R 5000-6000 R 6000-7000 R
Dose Rate 40-60 R/hr 60-70 R/hr 25-90 cGy/hr
Prescription Point 10% above absolute
minimum dose
On bisector
(planar) or
periphery (volume)
85% of minimum
central dose
Linear Activity Variable :
0.66 & 0.33
mgRaEq/cm
Constant :
1.0 mgRaEq/cm
Constant
Activity Distribution
Single Plane Varies with area Uniform Uniform
Volume Implant Varies with shape Uniform Multiple Uniform
Planes
Source Spacing Constant at 1 cm Constant at 1-2 cm Constant at 0.5-2
cm
Crossing needles Yes No No

66. LDR HDR PDR
Predictable clinical
effects
Short treatment time Emulates LDR
Superior radiobiologic
role
Dose optimization Optimized dose
distribution
Less morbidity, control
is best
No radiation hazards Potential radiation
safety hazards
Well practiced since
long
Small applicator Superior radiobiologic
role
Minimum intersession
variability in dose
distribution.
Radiation hazards