particle therapy is advanced external beam therapy used to treat cancer , which uses beams of protons or other charged particles such as helium, carbon or other ions instead of photons. charged particles have different depth-dose distributions compared to photons. They deposit most of their energy in the last final millimeters of their trajectory (when their speed slows). This results in a sharp and localized peak of dose, known as the Bragg peak.

1. PARTICLE BEAM –
PROTON,NEUTRON &
HEAVY ION THERAPY
ASWATHI C P
M.SC RADIATION PHYSICS
CALICUT UNIVERSITY

2. INTRODUCTION
• Particle therapy is a form of external beam
radiotherapy using beams of energetic protons,
neutrons, or positive ions for cancer treatment .
- neutrons produced by neutron generators and
cyclotrons,
- protons produced by cyclotrons and
synchrotrons ,and
- heavy ions ( helium,carbon,nitrogen,argon,neon)
produced by synchro -cyclotrons and
synchrotons

3. • The most common type of particle therapy as of
2012 is proton therapy.
• Although a photon, used in x-ray or gamma ray
therapy, can also be considered a particle, photon
therapy is not considered here. Additionally,
electron therapy is generally put into its own
category. Because of this, particle therapy is
sometimes referred to, more correctly, as hadron
therapy (that is, therapy with particles that are
made of quarks)

4. 1. HISTORY OF HADRON THERAPY
A TIME LINE OF HADRON THERAPY
1938 Neutron therapy by John Lawrence and R.S. Stone
(Berkeley)
1946 Robert Wilson suggests protons
1948 Extensive studies at Berkeley confirm Wilson
1954 Protons used on patients in Berkeley
1957 Uppsala duplicates Berkeley results on patients
1961 First treatment at Harvard (By the time the facility closed
in 2002, 9,111patients had been treated.)
1968 Dubna proton facility opens
1969 Moscow proton facility opens
1972 Neutron therapy initiated at MD Anderson (Soon 6 places in
USA.)
1974 Patient treated with pi meson beam at Los Alamos
(Terminated in 1981) (Starts and stops also at PSI and
TRIUMF)

5. 1. HISTORY OF HADRON THERAPY (CONT)
A TIME LINE OF HADRON THERAPY
1975 St. Petersburg proton therapy facility opens
1975 Harvard team pioneers eye cancer treatment with protons
1976 Neutron therapy initiated at Fermilab. (By the time the
facility closed in 2003, 3,100 patients had been treated)
1977 Bevalac starts ion treatment of patients. (By the time the
facility closed in 1992, 223 patients had been treated.)
1979 Chiba opens with proton therapy
1988 Proton therapy approved by FDA
1989 Proton therapy at Clatterbridge
1990 Medicare covers proton therapy and Particle Therapy
Cooperative Group (PTCOG) is formed:
1990 First hospital-based facility at Loma Linda (California)
1991 Protons at Nice and Orsay

6. 1. HISTORY OF HADRON THERAPY
(CONT)
A TIME LINE OF HADRON THERAPY
1992 Berkeley cyclotron closed after treating more than
2,500 patients
1993 Protons at Cape Town
1993 Indiana treats first patient with protons
1994 Ion (carbon) therapy started at HIMAC (By 20088
more than 3,000patients treated.)
1996 PSI proton facility
1998 Berlin proton facility
2001 Massachusetts General opens proton therapy center
2006 MD Anderson opens
2007 Jacksonville, Florida opens
2008 Neutron therapy re-stated at Fermilab (due to an ear mark).

7. PHYSICAL BASIS OF PARTICLE
THERAPY
• In particle therapy (Proton therapy), energetic
ionizing particles (protons or carbon ions) are
directed at the target tumor.
• The dose increases while the particle penetrates
the tissue, up to a maximum (the Bragg peak) that
occurs near the end of the particle's range, and it
then drops to (almost) zero.
• The advantage of this energy deposition profile is
that less energy is deposited into the healthy tissue
surrounding the target tissue.

9. LINEAR ENERGY TRANSFER
• It is defined as the average energy deposited
per unit length of track of radiation and the unit
is keV/μm.
• The energy loss per unit distance increases as the
particle slow down in the medium, such that
there is a peak of energy deposition at the end
of the track of a charged particle, called Braggs
peak.
• Charged particles generally have higher LET
than X and γ rays because of their greater
energy deposition along the track.
• biological effect of a radiation (its relative
biological effectiveness, RBE) depends on its
average LET

10. DOSE DISTRIBUTIONS OF DIFFERENT BEAM
QUALITIES IN TISSUE

11. WHERE IS THE ENERGY
DEPOSITED?
100
80
60
40
20
0
0 5 10 15 20 25 30 35
)Depth in Phantom (cm
Dose, Normalized to Dmax (%)
SAD = 190 cm
SSD = 180 cm
Photons
Neutrons
Protons

12. PROTON THERAPY
Proton therapy (also called proton beam
therapy) is a type of radiation treatment
that uses protons rather than x-rays to treat
cancer.
A proton is a positively charged particle
that is part of an atom, the basic unit of all
chemical elements, such as hydrogen or
oxygen. At high energy, protons can destroy
cancer cells.

13. HISTORY
• In 1946 Harvard physicist
Robert Wilson (1914-2000)
suggested*:
• Protons can be used
clinically
• Accelerators are available
• Maximum radiation dose can
be placed into the tumor
• Proton therapy provides
sparing of normal tissues
• Modulator wheels can
spread narrow Bragg peak
*Wilson, R.R. (1946), “Radiological use of fast protons,” Radiology 47, 487.

14. SHORT HISTORY OF PROTON BEAM
THERAPY
• 1946R. Wilson suggests use of protons
• 1954First treatment of pituitary glands in Berkeley, USA
• 1956Treatment of pituitary tumors in Berkeley, USA
• 1958 First use of protons as a neurosurgical tool in
Sweden
• 1967First large-field proton treatments in Sweden
• 1974Large-field fractionated proton treatments
program begins at HCL, Cambridge, MA
• 1990First hospital-based proton treatment center
opens at Loma Linda University Medical
Center

15. DESCRIPTION
• Proton therapy is a type of external beam radiotherapy
using ionizing radiation.
• During treatment, a particle accelerator is used to
target the tumor with a beam of protons. These charged
particles damage the DNA of cells, ultimately causing
their death or interfering with their ability to proliferate.
• Due to their relatively large mass, protons have little
lateral side scatter in the tissue; the beam does not
broaden much, stays focused on the tumor shape and
delivers only low-dose side-effects to surrounding tissue.

16. DESCRIPTION (CONT)
• All protons of a given energy have a certain range; very
few protons penetrate beyond that distance.
Furthermore, the dose delivered to tissue is maximum just
over the last few millimeters of the particle’s range; this
maximum is called the Bragg peak.
• The accelerators used for proton therapy typically
produce protons with energies in the range of 70 to 250
MeV
• By adjusting the energy of the protons during application
of treatment, the cell damage due to the proton beam
is maximized within the tumor itself.

17. In most treatments, protons of different energies with Bragg peaks
at different depths are applied to treat the entire tumor

18. SPREAD OUT BRAGG PEAK (SOBP)
• In a typical treatment plan for proton therapy, the
Spread Out Bragg Peak (SOBP, dashed blue line), is the
therapeutic radiation distribution. The SOBP is the sum of
several individual Bragg peaks (thin blue lines) at
staggered depths.
• The depth-dose plot of an x-ray beam (red line) is
provided for comparison. The pink area represents the
additional dose delivered by x-ray radiotherapy which
can be the source of damage to normal tissues and of
secondary cancers, especially of the skin.

19. APPLICATION
• Proton therapy goes to a specific area of the patient's
body, so this therapy can best shrink tumors that have
not spread to other parts of the body
• proton therapy alone, or they may combine with
standard radiation therapy, surgery, and/or
chemotherapy are used clinically .
• Proton therapy is particularly useful for treating cancer in
children because it lessens the chance of harming
healthy, developing tissue.

20. PROTON THERAPY MAY BE USED TO TREAT THESE
CANCERS:
• Central nervous system cancers (including chordoma,
chondrosarcoma, and malignant meningioma)
• Eye cancer (including uveal melanoma or choroidal
melanoma)
• Head and neck cancers (including nasal cavity and
paranasal sinus cancer and some nasopharyngeal cancers)
• Lung cancer
• Liver cancer
• Prostate cancer
• Spinal and pelvic sarcomas (cancers that occur in the soft-tissue
and bone)
• Some noncancerous tumors of the brain may also benefit from
proton therapy.

21. WHY PROTONS ARE
ADVANTAGEOUS
• Relatively low entrance dose
(plateau)
• Maximum dose at depth
(Bragg peak)
• Rapid distal dose fall-off
• Energy modulation
(Spread-out Bragg peak)

23. ADVANTAGES
When compared to standard x-ray radiation:
1.Fewer short –and long-term side effects
2.Improved quality of life during and after treatment
3.Proven to be effective in adults and children
4.Reduces the likelihood of secondary tumors caused
by treatment
5.Can be used to treat recurrent tumors even in
patients who have already received radiation
6.Targets tumors and cancer cells with precision,
reducing the risk of damage to surrounding healthy
tissues and organs

24. DRAWBACKS
• Limited availability- This treatment requires highly
specialized, expensive equipment. As a result,
proton therapy is available at just a few medical
centers in the United States
• Higher expense- Proton therapy costs more than
conventional radiation therapy. equipment for
production of protons, neutrons and heavy ions is
considerably more expensive than standard
radiotherapy equipment, both in capital costs and
in maintenance and servicing costs.

25. HEAVY ION THERAPY
• Heavy-ion therapy is the use of particles more
massive than protons or neutrons, such as carbon
ions
• They are produced in ion sources and accelerated
up to 50% of the speed of light in order to reach the
necessary depth in the patient.
• A typical therapy beam consists of 1 million to 10
million carbon ions per second .

26. PHYSICAL BASIS OF
HEAVY ION THERAPY

28. ADVANTAGES
As compared to conventional radiotherapy, heavy ion
radiotherapy has the following advantages:
• Higher tumor dose and improved sparing of normal
tissue in the entrance channel
• More precise concentration of the dose in the target
volume with steeper gradients to the normal tissue
• Higher radiobiological effectiveness for tumors which are
radio-resistant during conventional

29. APPLICATION CARBON
ION THERAPY
• Prostate cancer
• Lung cancer
• Specific bone and soft-tissue sarcomas

30. DISADVANTAGE
Compared to protons, carbon ions have the
disadvantage that beyond the Bragg peak,
the dose does not decrease to zero, since
nuclear reactions between the carbon ions
and the atoms of the tissue lead to
production of lighter ions which have a
higher range. Therefore, some damage
occurs also beyond the Bragg peak.

31. NEUTRON RADIOTHERAPY
• Fast Neutron Therapy Beams
• Boron Neutron Capture Therapy

32. FAST NEUTRONS
METHODS OF PRODUCTION
• Neutrons can be produced in a cyclotron by
accelerating deuterons or protons and impinging them
on a beryllium target.
• Protons or deuterons must be accelerated to ≥50 MeV to
produce neutron beams with penetration comparable
to megavoltage x-rays.

33. FAST NEUTRONS
METHODS OF PRODUCTION
• Accelerating deuterons to
≥50MeV
• Requires very large
cyclotron, too large for
hospital.
• Accelerating protons to
≥50MeV
• Much smaller cyclotron b/c
proton has ½ the mass of
deuteron.

34. P+
n
FAST NEUTRONS
FROM DEUTERON BOMBARDMENT
OF BE
• Stripping Process –
• Proton is stripped from the deuteron.
• Recoil neutron retains some of the incident kinetic
energy of the accelerated deuteron.
• For each neutron produced, one atom of Be is
converted to B.
B 10
5
Be 9
4 n
+ g

35. FAST NEUTRONS
FROM PROTON BOMBARDMENT OF
BE
• Knock-out Process
• Protons impinge target of beryllium, where they
knock-out neutrons.
• For each neutron “knocked-out”, one atom of Be is
converted to B.
B 9
5
Be 9
P 4 n +
+ g

36. Why are Neutrons Needed?
LARGE RADIORESISTANT TUMORS ARE NOT
WELL CONTROLLED BY PHOTON (OR
PROTON) THERAPY
• Resting cells are radioresistant
• Hypoxic (low oxygen) cells are
radioresistant
Neutron therapy is less affected by cell
cycle or oxygen content

37. RADIOBIOLOGICAL ASPECTS
OF NEUTRON THERAPY
• Neutrons are more effective per unit dose than x-rays
• Cell survival curves for neutrons are more nearly
exponential than those of x-rays
• The modifying effect of hypoxia is smaller for neutrons
than for photons
• Cell sensitivity to neutrons is much less dependent on
cell growth stage than cell sensitivity to photons

38. APPLICATION
Neutrons have effective for patients with slower growing
tumors such as
• adenoidcystic carcinoma (cancer of
parotid glands)
• locally advanced prostate cancer
• locally advanced head and neck tumors
• inoperable sarcomas
• cancer of the salivary glands

39. ADVANTAGES
• LET
comparisons of low LET electrons and high LET electrons
electrons produced from X-rays have high energy and low
LET cause only few ionizations , when they interact with a cell ,
and so single strand breaks of the DNA molecule are possible ,
which can be readily repaired.
The high LET charged particles produced from neutron
irradiation cause many ionizations as they traverse a cell, and
so double-strand breaks of the DNA molecule are possible.
DNA repair of double-strand breaks are much more difficult for
a cell to repair, and more likely to lead to cell death.

40. ADVANTAGES(CONT)
• Oxygen effect
Neutron irradiation overcomes the effect of tumor
hypoxia

41. BORON NEUTRON CAPTURE
THERAPY (BNCT)
• Neutron capture therapy might be considered a type of
particle therapy, as the damage it does to tumors is
mostly from energetic ions produced by the secondary
nuclear reaction after the neutrons in the external beam
are absorbed into boron-10 (or occasionally some other
nuclide), and not due primarily to the neutrons
themselves. It is therefore a type of secondary particle
therapy.

42. BNCT-PRINCIPLES
42/18
BNCT is a form of cancer therapy which uses a boron-containing
compound that preferentially concentrates in
tumor sites. The neutrons irradiated interact with the boron in
the tumor to cause the boron atom to split into an alpha
particle and lithium nucleus. Both of these particles have a
very short range (about one cellular diameter) and cause
significant damage to the cell in which it is contained.
Incident
epithermal
neutrons
Air Tissue
10B 11*B
α
t =10-12 sec 7Li
E7
Li=0,84 MeV
Eα=1,47 MeV
γ
Eγ=0,48 MeV
Thermal
neutrons

43. WHY BORON???
1. it is non-radioactive and readily available,
comprising approximately 20% of naturally
occurring boron;
2. Emitted particles (a and 7Li) have high LET
3. Chemistry of boron is well understood and allows it
to be readily incorporated into a multitude of
different chemical structures.

44. DOOR DESIGN FOR NEUTRON
SHIELDING DETAILS
1. Boronated polyethylene:
 The polyethylene (high H content)
slows (moderates) the fast and
intermediate energy neutrons to
thermal energies.
 The 5% Boron absorbs the low
energy neutrons (high cross section
for thermal neutron absorption).
2. Lead absorbs the 0.48 MeV
photon that results from the (n,a)
and capture gammas ( from
Polyethylene 5% maze ceiling, and floor).
Boron
Steel
Casing
Lead
Maze

46. NEUTRON SOURCES
 nuclear research reactors
 accelerators
 radioisotopes (in particular 252Cf)
Neutron beam requirements
 epithermal neutron flux  109 neutrons/cm2s
(at the therapy position)
 neutron energy ~ 1 eV to ~ 10.0 keV
 gamma dose rate  2х10-13 Gy/cm2
 fast neutron dose rate  2х10-13 Gy/cm2
 current:flux (J/) ratio > 0.8

47. APPLICATION
• Brain tumors
• head and neck cancers
• Melanoma
• Colon cancer

48. REFERENCE
• PROTON THERAPY PHYSICS - Edited by Harald Paganetti
• RADIATION ONCOLOGY PHYSICS (A handbook for
• teachers and students)
• WIKIPEDIA

49. THANK YOU