6. Several adjustable features to allow for the manipulation of
patients arms, wrists, head and shoulders.
To make chest wall surface horizontal, brings arms out of the way
of lateral beams.
Arm abducted at 90⁰ & hand holds handle of arm rest.
Face turned towards opposite side.
Thermoplastic breast support can be added.
Constructed of carbon fiber which has lower attenuation levels
permitting maximum beam penetration.
10. FOR TANGENTIAL FIELDS
Upper border – 2nd ICS (angle of Louis) when supra
clavicular field used.
When SCF not irradiated – head of clavicle
Medial border – at or 1cm away from midline
Lateral border – 2-3cm beyond all palpable breast
tissue – mid axillary line
Lower border – 2cm below inframammary fold
Anterior -2cm margin of light, above the highest point of
breast.
11. A pectoralis major
muscle
B axillary lymph
nodes: levels I
C axillary lymph
nodes: levels II
D axillary lymph
nodes: levels III
E supraclavicular
lymph nodes
F internal
mammary lymph
nodes
12.
13. HOW TO IMPLEMENT IT?
Deciding angle of rotation of gantry for tangential
fields:
Lead wire placed on lateral border
Field opened at 0⁰ rotation on chest wall and
central axis placed along medial border of marked
field
Gantry rotated , until on fluoroscopy, central axis &
lead wire intersect – angle of gantry at that pt.
noted – medial tangent angle
14. CENTRAL LUNG DISTANCE
Perpendicular distance from post. tangential field
edge to post part of ant. chest wall at centre of field
Best predictor of %age of ipsilateral lung vol.
treated by tangential fields
CLD (cm) % of lung
irradiated
1.5 cm 6%
2.5 cm 16%
3.5 cm 26%
20. SCF
Single anterior field is used.
Field borders –
Upper border : thyrocricoid groove
Medial border : at or 1cm across midline extending
upward following medial border of SCM ms to
thyrocricoid groove
Lateral border: insertion of deltoid muscle
Lower border : matched with upper order of
tangential fields
21. A pectoralis major
muscle
B axillary lymph
nodes: levels I
C axillary lymph
nodes: levels II
D axillary lymph
nodes: levels III
E supraclavicular
lymph nodes
F internal
mammary lymph
nodes
SUPRACLAVICULAR-AXILLARY FIELD
22. Humeral head shielding:–
• If arm angled >90⁰: Ax nodes overlap head of
humerus anteriorly.
• Larger the angle – less the head of humerus
spared in s.c port
24. Angulation
By inferior angulation of the
tangential fields.
Half beam block technique
Blocking the supraclav field’s
inferior half, eliminating its
divergence inferiorly .
Hanging block technique
Superior edge of tangential beam
made vertical by vertical
hanging block.
25. Single isocentre technique:
• Isocentre placed at the junction
of tangential and supraclavicular
field
• Inferior portion of field blocked for
supraclavicular treatment and
superior portion blocked for
tangential field
27. 1. Extension of tangential fields– by extending medial
border – 3cm across midline or by using imaging
techniques
2. Separate field –
• Medial border – midline , matching with tangential
field border
• Lateral border – 5-6cm from midline
• Superior border – abuts inferior border of supraclav
field or at 1st ICS (superior border of head of clavicle)
if only IMNs are to be treated
• Inferior border – at xiphoid or higher if 1st three ICS
covered
28. More normal tissue is being irradaited. (lung, heart and
contralateral breast)
33. Medial border – To allow
1.5-2cm of lung on the
portal film
Inferior border –
at same level of inferior
border of s.c field
Lateral border – just blocks
fall off across post axillary fold
Superior border – splits the clavicle
Superolaterally – shields or splits humeral head
Centre – at acromial process of scapula
35. BOOST-ELECTRONS
Appropriate energy selected to allow 85 -90%
isodose line to encompass target volume &
decrease dose to the lung.
Clinical set up - post lumpectomy volume or scar
on skin +3 cm in all directions.
Energy – 9-16 MeV
Dose – 10-20Gy
40. •Useful for voluminous breast
•For patients who are heavy smoker and previous
history of lung or cardiac disease
•For deep seated tumor
Disadvantage – For nodal RT treatment position
has to be changed
45. Reduces the hotspots specially in the superior and
inframammary portions of the breast.
Increases homogenity
Manifests clinically into decrease in moist
desqumation in these areas.
46.
47. IMRT BREAST: WHY?
(1) Better dose homogeneity for whole breast RT
(2) Better coverage of tumor cavity
(3) Feasibility of SIB
(4) Decrease dose to the critical organs
(5) Left sided tumors- decrease heart dose
64. When the CTV extends deeper
than 28 mm under the epidermal
surface, implants have a higher
ballistic selectivity in terms of the
volume of the irradiated breast
tissue and dose to the skin blood
vessels than electron beam
boosts.
65. LOCALIZATION OF LUMPECTOMY CAVITY
Pre-op clinical finding , pictures
Imaging- mammogram,usg,MRI
Per-op finding
HPR
Surgical clips
Post op imaging with USG,CT or MRI
66. Use of marker clips to
localise the boost
target volume and
simulate entrance
points of guide needle
at the skin of the breast
67. Use of mammography in defining
the boost target localisation in
breast conserving treatment
68. A. Defining the implantation isocentre and definitive needle entrance
and exit points at the skin for a breast implant. Reconstruction boost
target isocentre from mammography, by simulator, or CT. The
indicated entrance points are too close to the target volume (A)
B. Inclination of the implantation equator plane away from the target to
avoid an overlap of the boost PTV and needle exit points at the skin
69. (C). Indication of new entrance and exit points, further away from
the boost CTV, to avoid skin teleangiectases .
(D)Occurrence of severe teleangiectasic ‘stars’ at skin entrance or
exit points if rules for implementation are not followed
Why this planning so important.
With a delivered dose of 50 Gy , chances of late teleangiectases
may occur in 30% of cases
Vessels may have already received 20–40 Gy from the breast
irradiation.Therefore, there is usually only a small dose amount left
in skin vessel tolerance for teleangiectases
70. ANAESTHESIA
Breast implants can easily be carried out under L.A. and
premedication with 2.5–5 mg midazolam given 15–30
min before the implantation.(GA, <0.5%)
The patient is placed in supine position with the
homolateral arm in 90° abduction.
After the design of implant geometry and localisation of
entrance and exit points of the needles, the skin is
infiltrated at each point with 0.5–1 ml 1% lidocaine.
Retroareolar region is painful (1-5 ml extra infiltrate in
that area)
71. DESIGN OF THE IMPLANT GEOMETRY
Needles are implanted parallel and equidistance from
each other (Paris system).
In most cases inserted in a mediolateral direction.
In very medially or laterally located tumor sites, needles
should be implanted in a craniocaudal direction .to
enable separate target area from skin points.
In some rare cases, the upper outer quadrant has to be
implanted with needles orientated in a 45° angle to
avoid overlap of source positions and skin
72.
73. 2 planes of needles are usually needed to cover the
PTV.
A single plane may be sufficient in case of a target
thickness of less than 12 mm.
Three planes are required in a large breast where
the targeted breast tissue between pectoral fascia
and skin is thicker than 30 mm.
Five to nine needles spaced 15–20 mm are usually
required.
74. Reference needle is first implanted at the posterior
(deepest) side into the centre of the PTV.
For definitive positioning, the needle should pass about
5 mm behind the internal scar.
The other needles of the posterior plane are then
implanted parallel to the first one.
For definitive positioning, the needle should pass about
5 mm behind the internal scar.
The other needles of the posterior plane are then
implanted parallel to the first one.
