PARTICLE BEAM RADIOTHERAPY

1. Particle beam
RT
Dr kanhu

2. RADIATION THERAPY

3. CONVENTIONAL
TECHNIQUE
CONFORMAL TECHNIQUE

4. X-ray
¥-ray

5. ARE THESE
everything

6. NO

7. • PIT FALLS OF
PHOTON BEAM
• LOW LET
• NO 100% TUMOR
CONTROL
• HIGHER OER
• MORE SIDE SCATTER
• NO MUCH SKIN
SPARING
• NO BETTER STOPPING
CHARACTERSTICS
• LESS EFFECT ON
HYPOXIC CELLS
• NOT EQUAL
SENSUTIVITY IN
CELL CYCLE PHASES
• BETTER
WORDS
• HIGH LET
• 100% TUMOR
CONTROL
• LOWER OER
• LESS SIDE SCATTER
• 100% SKIN SPARING
• BETTER STOPPING
CHARACTERSTICS
• EQUAL EFFECT ON
HYPOXIC CELLS
• EQUAL SENSUTIVITY
IN CELL CYCLE
PHASES

8. EM RADIATION
X-ray, Y-ray
Particle beam
p,n, , -, ß
heavy particle

9. LET
• It is the energy deposited in tissue by
a ionizing radiation along its path
• Depends upon
– mass of the particle,
– velocity,
– energy
• LET of photon beam2-20Kev/µ
• LET of proton beam20-100Kev/µ
• LET of neutron beam100-1000Kev/µ

10. RADIOBIOLOGY
• High LET
• High RBE
• Low OER
• Low SLDR
• Less variation in cell cycle sensitivity
• Less treatment time

11. High LET vs. low LET
• High LET
• Direct injury
• Low OER
• High RBE
• Small shoulder in
cell surv .curve
• Low SLDR
• Low LET
• indirect injury
• High OER
• low RBE
• large shoulder in
cell surv .curve
• Low SLDR

12. HIGH LET
LOW LET

13. OER
• Oxygen enhancement ratio
• It is a simple ratio between dose required in
anoxic or hypoxic condition to dose required
in aerobic condition to yield same biologic
effect.
OER of photon beam2.5-3
OER of proton, beam1.5—2
OER of neutron beam1 (NO OXY.
EFFECT)

14. RBE
• Relative Biologic Effectiveness
• It is a simple ratio between dose required of
known LET to that of testing LET to produce
same biologic effect
• More the LET=More RBE
• RBE of photon beam1
• RBE of proton, beam1.1—1.2
• RBE of neutron beam3—3.5

15. CONCLUSION
•HIGH LET
•HIGH RBE
•LOW OER

16. Increase
uniform dose distribution
P ,alpha particle
HEAVY ION
BNCT
PION
IORT
CONFORMAL RT
BRACHY
SETREOTAXY

17. INCREASE
RADIO SENSITIVITY
NUTRON
HEAVY ION
BNCT
PION
BRM
CT+RT
HYPOXIC CELL
SENSITIZERS
HYPERTHERMIA

18. PROTON BEAM

19. BRAGG PEAK EFFECT
• AS BEAM TRAVERSES through tissue the dose
deposited approx. constant with depth until near
end of range, dose peaks out to high value followed
by rapid fall off to zero. This high dose region at
end of particle is called Bragg peak effect. it is
seen in proton beam and charged particle.
• The Bragg peak is too narrow to treat any target.
For irradiation of larger targets the beam energy
is modulated to widen the Bragg peak which is
accomplished by super imposing of several beams of
closed spaced energy ranges to create a region of
uniform dose over a depth of target called spread
out Bragg peak or modulated Bragg peak

20. Dose distribution
Bragg peak Photon beam
Modulated Bragg peak

22. Proton beam
• Low LET
• RBE of 1.1 to 1.2
• Superior dose distribution
• Well defined dose in tissue
• Minimal scattering outside
• High dose to tumor region
• Low integral dose
• Non divergent
• Good skin sparing
• So energy of 250Mev penetrates approx
38cm in water that is sufficient for RT

23. SO IN SINGLE WORD PROTON
BEAM HAS SUPERIOR DOSE
DISTRIBUTION RATHER THAN
HIGH LET

24. PROTON MACHINES
• 19 centers in world wide.21 centers under
process
• Cyclotrons(higher energy)(100-200Mev)
• Synchrotron( simple energy variability)
• The Loma Linda proton facility in
California is the largest of its kind in world

25. Proton Radiosurgey
• According to Laskell defined
radiosurgey is a procedure involving
single# of ionizing RT focused on
intracranial target localized by
stereotactic method
• This was 1st led by Dr, Raymond at MGH
treating inoperable AVM & pit adenomas
• The 2nd one technique system capable of
stereotactic alignment(STAR)
developed because of inherent
restriction of fixed horizontal beam at
HCL

26.  particle
• for all particle
purpose the dose
localization
radiobiological
properties are
equivalent to proton

28. AUTH
OR
YEAR JOUR
NA
VS SIT
E
OS
(7)
COM
PLIC
FAIL
U
SHIP
LEY E
1995 RED PH
PR
PRO
STA
35%
85%
HGH
-PR
CASR
O
1985 RADN
REG
ALPH
A
SKU
LLB
ASE
LC-
5YR
82%
CASR
O
1991 RED ALPH
A
JSP
TU
LC-
52%
PROTON BEAM
ONE PHASE III TRIAL ON PROSTATE
SKULL BASE TUMOR,JUXTRA SPINAL CORD TUMOR
UVEAL MELANOMAS,BRAIN TUMORS

29. PION BEAM
• PION=  meson(-, + )
• Protons and neutrons are held together by
mutual exchange of pions.
• Protons of energy400-800 Mev
• Target material(Be)
• Various pions of with spectrum of energy
• Only –ve pions are only in use
• Pions of energy 100Mev are in use in RT
providing of range 24cm in water.

30. PION STAR FORMATION
• The Bragg peak effect produced by pions are more
pronounced than other particles,
• The nuclear disintegration of pion particle results
in release of several particles such as p,  ,n,
etc.having high LET properties& mixture of
LETs.this is known as star formation.
• Thus Bragg peak produced is naturally broader than
other.
• Because broader Bragg peak it has attractive
radiobiology than other particles.
• Disadv. Are high cost, beam
contamination,lowdose rate
•

31. pion
muon
electron
NEUTRON
STAR

32. AUT
HOR
YEAR JOUR
NA
VS SIT
E
RESULT
PICKL
E
ET.AL
1999 RED PH
PI
GLI
OM
A
QOL,SERIAL
KPS,TTP,MS,T
OX SAME
PICKL
E
ET.AL
1999 RED PH
PI
LA.P
ROS
ATE
LC,5YR S
SAME
PION BEAM

33. OTHER HEAVY
PARTICLES
• C.N,Ar,Ne,Si etc
• Produced in an Accelerator by stripping of
their electrons.These ions are then
injected into synchrotrons for
acceleration.
• High LET
• High RBE
• Broad Bragg peaK
• Adv. In deep seated tumors

34. Neutron Beam

35. Neutron Beam
• High-fast,medium,slow
• Slow---small range,no OER adv.
• Range between 6-15 Mev are suitable for
RT
• At present neutron beams are used only in
trials.
• D-T generators,cyclotrons,linear
accelerators
• Neutrons are produced by bombarding of
deuterons ,protons with target materials
like Usually Be &,Tritium.

36. Neutron BEAM
NEUTRON
PROTON
PROTON

37. Photon BEAM
PHOTON
e-
e-

39. Hypoxic gain FACTOR
OER of X-ray 2.6 1.6
OER of neutron 1.6
If a course of neutron therapy
causes normal damage is equal
to 66GY of x-ray the biologic
effect of neutron would be in
a completely hypoxic tumor is
1.6x66=105.6gy 0f x-ray
= =

40. RADIOBIOLOGY
• High LET
• High RBE
• Low OER
• Low SLDR
• Less variation in cell cycle sensitivity
• Less treatment time
POOR ABSORPTION IN BONE

41. •Poorly oxygenated
•Poorly redistributed
•X-ray resistant
•Rapidly growing
•High RBE

42. Limitations
• Poor depth dose
• Poor skin sparing
• Poor collimation
• Inadequate beam flatness
• Frequent equipment breakdown
• Fixed horizontal beam
• High absorption in fatty tissue-
poor cosmesis

43. So in single word neutron
beam have high
LET(RBE)
properties but poor
distribution

44. AUTHO
R
YEAR JOURN
A
VS SITE LRC P
RTOG&
MRC
1993 RED P
N
SALU
R
17%
56%
S
HUBER
et.al
2001 GREEN N+P
N
ACC 32%
75%
S
LARAM
RE et
1993 AJCO N+P
N
LA
PRO
58%
70%
S
LARAM
ORE
1989 AJCO P
N
CH.SA
RCOM
A
33%
49%
S
LARAM
ORE
1989 AJCO P
N
OS 38%
53%
S
NEUTRON BEAM

45. Neutron Brachytherapy
• Cf-252
• It is artificially produced isotope from Bk249 by ß
decay then it is steeped up to Cf252 by a series of
neutron capture reactions.
• Energy range of neutron is 2.3Mev,Y ray is 40-100
Kev.
• RBE of –6 for neutron component
• Various studies showed that the use of Cf252 is
feasible the results are equivalent to those
obtained using standard Y sources .
• The use of this in trials has indicated that there
may be faster tumor shrinkage than conv. Brachy
with normal tissue complication rate
NO PHASE III TRIAL
MARYMAL.E
T.AL
CA
CX,CAEND
O
CONV,
CF252
5YR,10YR
SURV SAME

46. BNCT
• Boron neutron capture therapy
• The fundamental concept is production of
high LET particles like He,Li when a tumor
having Boron compound captures slow or
thermal neutron ,goes to an excited state .
This excited B nucleus release energy which
drives heavy ion products over short
distance.
• So one could kill tumor cells containing Boron
while sparing adjacent normal tissue that
dose not contain Boron.

47. Boron carrying agents
• Should be non toxic
• High tumor to normal tissue ratio
• Agents are
– Dihydroxyborylphenylalanine
– SEVERAL CLINICAL PROTOCOLS UNDERWAY
ON GBM,MAL.MELANOMA,BRAIN METS, RA

48. B CARRYING AGENT

49. B
B
B
B
B
B
B
B
B
B
B
B
B

50. B
B
B
B
B
B
B
B
B
B
B
B
B
Li
He
SLOW NEUTRON

51. AUTH
OR
YEAR JOUR
NA
VS SITE RTOG PF L
R
C
F
A
I
L
U
LARA
MORE
ET.AL
1997 SEMI
IN
ONCO
BNCT
CONV
GBM NO DIFF
BNCT NO PHASE III TRIAL
JAPANESE TRIL SHOWED THAT IN
GBM SURVIVAL AS HIGH AS 58%

52. FOOT PRINTS
• Proton beam has only superior dose
distribution
• Neutron beam has only high LET properties
• Heavy charged particles having both superior
dose distribution& high LET properties
• BNCT superior tumor specific injury
• Limited availability
• Costly
• Yet to establish