Techniques of breast brachytherapy

1. Brachytherapy in breast :
Techniques
Presenter Moderator
Dr Pallavi Kalbande Prof Dr N.R. Datta

2. Retreatment after a
relapsed patients
Indications
Boost after Whole
Breast
Irradiation
Accelerated Partial
Breast Irradiation
(APBI) after breast
conserving surgery
(BCS)

3. Patient Selection
 Age - ≥ 50 years
 Grade - 1–2 disease
 Tumour Size - ≤ 3 cm
 Hormone status – ER+ Her2-
 Nodes – Negative ( N0)
 margins - >1 mm
Boost
APBI
Age - < 50 years
> 50 years
 Grade III
 Extensive intraductal
component

4. Interstitial
Multicatheter
Intracavitary
Mammosite
Brachytherapy Techniques

5. Multicatheter interstitial brachytherapy
• This technique was initially developed to provide boost
radiation after whole breast radiation therapy
• Flexible after-loading catheters are placed through
the breast tissues surrounding the lumpectomy
• The catheters are inserted at 1 to 1.5 cm intervals
in several planes

6. Approaches
• Free-hand
• Template - guided
• LDR
• HDR

7. NEEDLES
INSERTION
CATHETERS
REPLACING
CATHETER IN-

8. Breast template

10. Prescription
• Dose : 34 Gy
3.4 Gy bid x 5 days
• <60% of the whole breast reference volume should
receive ≥50% of the prescribed dose
• Dose volume analysis of target will confirm that ≥90%
of the prescribed dose is covering ≥90% of the PTV

11. Dose constraints
• Dose Homogeneity:
150% (V150) of the prescribed dose ≤70 cc
200% (V200) of the prescribed dose ≤20 cc
Critical normal tissue DVHs within 5%

12. Multicatheter
• Advantages
• Highly conformal (possibly the most…)
• Can be used in non-spherical lumpectomy sites
• Less prone to patient setup variation
• Disadvantages
• Invasive
• Requires specialized equipment (HDR)

14. • The mammosite catheter consists of a silicone balloon
connected to a 15 cm double-lumen catheter that is 6
mm in diameter
• The catheter has both a small inflation channel and a
channel for the passage of an Ir-192 high dose rate
(HDR) brachytherapy source
Intracavitary Mammosite

16. Procedure
• The balloon is inflated with saline solution mixed with a small
amount of contrast material to aid visualization
• The balloon is inflated to a size that would completely fill the
lumpectomy cavity
 An Ir-192 radioactive source, connected to a computer-
controlled HDR remote after-loader, is inserted through the
 applicator can be placed into the lumpectomy cavity at the
time of surgery or in a separate procedure after
surgery(USG guided)

17. MammoSite Placement-
TIME OF LUMPECTOMY POST LUMPECTOMY USG
GUIDED

18. Mammosite applicator quality assessment
Implant quality
1. balloon conformance to the
lumpectomy cavity
2. distance from the surface of
the balloon to the skin
surface
3. symmetry of the balloon in
relationship to the central
catheter
1. Minimum balloon-to-skin
distance of 5 mm is required.
(threshold of at least 7 mm).
2. Adequate Conformance- less
than 10% of the
PTV is composed of fluid/ air
3. A symmetric implant in relation to
the source channel is also
essential for adequate
dosimetry.

19. Mammosite multilumen catheter
• The ML balloon is able to shift
radiation dosages away from
the skin
• Potentially reducing unwanted
toxicity to the healthy skin, ribs,
sternum and other
subcutaneous structures

20. • Dosimetric goals can be better
achieved
• when normal structures (skin
and ribs) are close to PTV
with a distance of <7 mm and
rib distance of <1 cm

21. CTV = Volume of the baloon
PTV_EVAL = CTV+ 1 cm
(Crop 5mm within skin and excludes chest wall)
Target volume definitions

23. Prescription
• 34 Gy in 10 fractions
(3.4 Gy per fraction, BID)
• The prescription point is 1 cm from the
balloon surface
• minimum of 6 hours between fractions
on the same day.

24. Prescription
• Tissue-balloon conformance
Measure trapped air
Minimal balloon surface-skin distance – ideally
≥7 m
if 5-7 mm then confirm skin dose <145%.
• <60% of the whole breast reference volume should
receive ≥50% of the prescribed dose
• Dose volume analysis of target will confirm that ≥90%
of the prescribed dose is covering ≥90% of the PTV

25. Dose constraints
• Dose Homogeneity:
150% (V150) of the prescribed dose ≤70 cc
200% (V200) of the prescribed dose ≤20 cc
Critical normal tissue DVHs within 5%

26. APBI RESULTS: MAMMOSITE BRACHYTHERAPY SERIES

27. Axxent Electronic Brachytherapy
• Modified form of balloon-based brachytherapy
• Similar to the MammoSite system, consists of a balloon
catheter that is inserted into the lumpectomy cavity by means
of a percutaneous approach
• The wall of the balloon is covered in radiolucent material
that is visible on a plain x-ray film or CT scan
• Electronic 50 kilo-voltage x-ray source rather than an iridium-
192

28. Axxent Electronic
Brachytherapy

29. Advantagesof AXXENT EB system
• a specifically shielded radiation room or an HDR afterloader unit
are not required
• Very portable, the number of setting in which the device can be
used increases
• Another potential contributing factor is the increase in Relative
biologic effectiveness related to the lower energy of the photons
emitted by the electronic brachytherapy source, because of the
dominance of photoelectric absorption at low energies.
-received FDA clearance for the treatment of breast cancer in Jan
2006.

30. Contura
• it has multiple lumens for
passage of an Ir-192 HDR
source
• In addition to a central
Lumen, the Contura balloon
has four surrounding
channels to accommodate
the HDR source
• The positions of the
surrounding channels have a
fixed 5-mm offset around the

31. Baloon catheter of CONTURA system
• Additional source positions and thus allow increased dose
flexibility compared with a single-catheter approach
• This approach has the potential to reduce the dose to normal
tissues (chest wall and skin) and organs at risk such as the
heart and lungs
• In addition, multiple catheters make it possible to account
for asymmetric balloon implant with respect to the central
channel
• Like the eB catheter, Contura has a port for a vacuum to
remove fluid or air around the lumpectomy cavity

32. Hybrid Brachytherapy Devices
Strut Adjusted Volume Implant
(SAVI)
• consists of a central strut
surrounded by 6,8,10
peripheral struts
 The peripheral struts can be
differentially loaded with a HDR
source
Strut Adjusted Volume Implant
(SAVI)

33. • Radio-opaque markers are present on three of the peripheral struts
(number 2, 4 and 6) for identification during the reconstruction
process
• The device is inserted in collapsed
form through a small incision
• Expanded to fit the lumpectomy cavity by clockwise rotation of a
knurled knob at the proximal end of the expansion device,
expanding the peripheral struts and providing a pressure fit
Strut Adjusted Volume Implant (SAVI)

34. Hybrid Brachytherapy Devices
Clear Path
• This was developed to combine the
advantage of balloon
brachytherapy and multicatheter
brachytherapy
• The CP device contains six outer
expandable plastic tubes to displace
the tissue
ClearPath

35. Clear Path
• In the center of the expandable tubes is a central catheter
surrounded by six additional catheters that allow the passage of
an HDR Iridium-192 source
• In contrast to the SAVI device, the radiation source is not in
direct contact with the breast tissue
• CP is a relatively new device and hence no clinical outcome
data have been reported.

36. Intra-OperativeRadiationTherapyTechniques
• Delivery of a single fractional dose of irradiation directly to the
tumor bed during surgery.
transportation of the patient from
the operating theatre to the
radiation therapy unit during
surgery
development of mobile
intraoperative radiation
therapy devices
• INTRABEAM (KV PHOTONS)
• MOBETRON (MV
ELECTRONS)
• NOVAC-7 (MV ELECTRONS)

37. Advantages of IORT
• Tissues under surgical intervention have a rich vascularization,
with aerobic metabolism, which makes them more sensitive to
the action of the radiation
• Minimize some potential side effects since skin and the
subcutaneous tissue can be displaced during the IORT to
decrease dose to these structures
• IORT eliminates the risk of patients not completing the
prescribed course of breast radiotherapy
• IORT has the potential for accurate dose delivery eliminates
the risk of geographical miss

38. Intrabeam
• Miniature, light-weight (1.6 kg) X-ray
source combined with a balanced
floor stand with six degrees of
freedom
• X-ray source has a probe of 10 cm
length and 3.2 mm Diameter
• Various spherical applicators with a
diameter ranging from 1.5 to 5 cm
are available to match the size of
the surgical cavity

39. Intrabeam
• The X-ray system produces low-energy
photons (30- 50 KVp) with a steep dose fall-
off in soft-tissue; no special shielding is
therefore required in the room
• Treatment time lasts for approximately 20 to
45 minutes
• Minimal exposure to the staff and patient;
rapid dose fall-off in the tissue around the
applicator guarantees minimal exposure
of the surrounding tissue such as the
lung and cardiac tissue

40. Mobetron
• Mobile electron beam
intraoperative treatment system.
• composed of three separate units:
the control console, the modulator
and the therapy module.
• produces electrons of nominal
energies of 4 MeV, 6 MeV, 9 MeV
and 12 MeV with therapeutic
ranges up to 4 cm.
• Single dose of 21 Gy is prescribed

41. Novac-7
• Delivers electrons with the
use of a mobile dedicated
linear accelerator
• its radiating head can be
moved by an articulated arm
that can work in an existing
operating room.
• It delivers electron beams at
four different nominal energies
(3, 5, 7 and 9 Mev).

42. Mick shielded HDR IORTapplicator
Available in broad range of sizes; 2-10
Channels
 Adjustable Tungsten Shields
provided
 Sizing Templates are provided
with the system for proper
applicator selection
• Compatible with all of today’s
Remote

44. TARGIT-Atrial
• Prospective, Randomised,
non- inferiority trial
• women aged 45 years or
older with invasive ductal
breast carcinoma undergoing
breast-conserving surgery
were enrolled from 28 centres.
• Targeted intraoperative
radiotherapy(1113) or whole
breast external beam
radiotherapy(1119)
 estimate of local recurrence in the
conserved breast at 4 years was
1.20% (95% CI 0.53-2.71) in the
targeted IORT and 0.95% (0.39-2.31)
in the external beam radiotherapy
group
The frequency of any complications
and major toxicity was similar in the
two groups (for major toxicity,
targeted intraoperative radiotherapy,
37 [3.3%] of 1113 vs external
beam radiotherapy, 44 [3.9%] of
1119; p=0.44)

45. Intraoperative radiotherapy versus external
radiotherapy for early breast cancer (ELIOT):a
randomised controlled equivalencetrial
• 1305 patients
• 654 to external radiotherapy and 651 to intraoperative
radiotherapy)
•
• The 5-year event rate for IBTR
4·4% (95% CI 2·7–6·1) in the IORT vs 0·4% (0·0–1·0) in
the external radiotherapy group (hazard ratio 9·3 [95%
CI 3·3–26·3]).
•
• 5-year overall survival

46. Limitations ofIORT
• Absence of final histopathological report at the time of
radiotherapy.
• Patient's longer stay at the operation theatre under
general anaesthesia.
• Potential risk of late complications related to the
administration of single high-dose radiation.