Brachytherapy (also referred to as Curie therapy) is defined as a short-distance treatment of malignant disease with radiation emanating from small sealed (encapsulated) Neutron capture therapy (NCT) is a nonsurgical therapeutic modality for treating locally invasive malignant tumors such as primary brain tumors, and recurrent head and neck cancer. Proton therapy, or proton radiotherapy, is a type of particle therapy that uses a beam of protons to irradiate diseased tissue, most often to treat cancer.

1. By Haider Ali Malik

2. Brachytherapy

3. • Brachytherapy (also referred to as Curie
therapy) is defined as a short-distance
treatment of malignant disease with radiation
emanating from small sealed (encapsulated)
sources.
• ‘Brachy’ is a Greek word for ‘short distance’
• It is a form of radiation in which radiation is
delivered by small sealed radioactive sources
arranged in a geographical fashion in and
around tumour
• The sources are placed directly into the
treatment volume or near the treatment
volume.

4. Evolution of Brachytherapy
• Radioactivity was described by Becqueral in 1896
• Marie Curie extracted radium from pitchblende ore in 1898.
• Danlos and Bloc performed first radium implant in 1901
• First ‘schools’ of brachytherapy were at Stockholm, Memorial
Salon Kettering and the Holt Radium Institute(Paris)
• Radon and Radium are the two radioactive sources used
extensively in the early years.
• Intracavitary systems of Brachytherapy including Stockholm
System(1914). Paris System(1926) and Manchester
System(1938) were made.
• Afterloading technique was first introduced by Henschke in
New York and Iridum-192 is used by him for the first time in
1953

5. Types of Brachytherapy
• According to method of source loading pattern:
o Preloading - Inserting needles containing radioactive material directly in tumour
o Afterloading – First non-radioactive tubes inserted into tumour
 Manual Afterloading - :- lr192 wires, sources manipulated into applicator by means of
forceps
 Remote Afterloading - consists of pneumatically or motor-driven source transport
system
• According to type of source placement:
o Contact - involves placement of the radiation source in a space next to the
target tissue.
o Interstitial - the sources are placed directly in the target tissue of the affected
site, such as the prostate or breast
 lntracavitary - Consists of positioning applicators bearing radioactive sources into the
body cavity in close proximity to target tissue eg :- Cervix
 lntraluminal - Consists of inserting single line source into a body lumen to treat its
surface &adjacent tissue.
 Surface Mould - (Plesiocurie/Mould therapy) Consists of an applicator containing array
of radioactive sources designed to deliver a uniform dose distribution to skin/mucosal
surface.
 lntravascular - Inserting a single line source to Blood vessels to treat the layers of
blood vessel

6. Emit radiation at a rate of 0.4-2 Gy/hour.
o
o
Low-dose rate{LDR)-
Medium-dose rate {MDR)- characterized by a medium rate of dose
delivery, ranging between 2-12 Gy/hour.
High-dose rate {HDR)-when the rate of dose delivery exceeds
12 Gy/h.
o
o Pulsed-dose rate {PDR) - involves short pulses of radiation, typically
once an hour, to simulate the overall rate and effectiveness of LOR
treatment. (1ci)
Ultra low dose rate - Dose range 0.03 to 0.3 Gy/Hr
o
Types of Brachytherapy
According to dosage rate, it is divided into:

7. • Esophageal Brachytherapy Applicator@ BBCI

8. lntracavitary Applicators @ BBCI

10. Brachytherapy Sources
Sour
ce
T1/2 γ (MeV)
HVL
(mm Pb)
Forms
222Rn 3.83 d 0.047 - 2.45 (0.83 avg)
8.0
Seeds
60Co 5.26 y 1.17, 1.33 11.0 Tubes, needles, pellets
137Cs 30 y 0.662 5.5 Tubes, needles, pellets
192Ir 74.2 d 0.136 - 1.06 (0.38 avg) 2.5 Wires, ribbon etc.
198Au 2.7 d 0.412 2.5 Seeds
125I 60.2 d 0.028 avg 0.025 Seeds
103Pd 17 d 0.021 avg 0.008 Seeds
226Ra 1600 y 0.047 - 2.45 (0.83 avg) 8.0 Tubes, needles
90Sr 28 y 2.25 (beta) Curved applicator

11. Choice of Nuclide and Implant
• Ra-226 was used for many decades but is almost never used
anymore due to risk of radon
• leakage.
• Permanent LDR implants generally use 1-125, Pd-103, or less
commonly Au-198.
• Temporary LDR implants may use Au-198, lr-192, Cs-137, Co-60
or others.
• HDR implants almost always use lr-192.

12. Why use sealed sources?
• Brachytherapy Sources are commonly used as sealed sources, usually
doubly encapsulated in order to:
• Provide adequate shielding against alpha and beta radiation produced
through source decay
• Contain radioactive material
• Prevent leakage of the radioactive material
• Provides rigidity of the source

13. The ideal brachytherapy source would be:
• a pure gamma emitter with an energy suitable for the
intended treatment site;
 with a high specific activity; and
 suitable for high dose rate applications.
• Physically small;
 for temporary implants, a long half life; to allow
economical re-use of sources
 for permanent implants, a medium half life.

14. Advantages of Brachytherapy
• Improved localized dose delivery to the target
• Sharp dose fall-off outside the target
• Better conformal therapy
• Shorter treatment time
• Acute reactions appear when treatment is over;
so no treatment breaks.
• Therapeutic ratio is high
• Normal tissue spared due to rapid dose fall off
• Better tumor control

15. Disadvantages of Brachytherapy
• Only good for well localized tumors
• Only good for small lesions
• Very labor intense
• Needs expertise and experience
• Time consuming
• Difficult to maintain uniformity across various centres
• Invasive procedure
• Radiation hazard due to radioisotopes (in olden days due to
preloading techniques, now risk decreased)
• General anesthesia required

16. 16
Brachytherapy Applicators

17. • Afterloading techniques are those in which non-
radioactive applicators or guide tubes are initially
placed in the patient and the radioactive sources are
later loaded into these applicators.
17
Afterloading devices (HDR and LDR)
• Depending on the manufacturer and model, remote
afterloaders typically employ 192Ir, 60Co or 137Cs sources.
HDR – high dose rate / LDR – low dose rate

18. • HDR units typically have a single source with activities
ranging from ~180 GBq to ~740 GBq.
18
HDR and LDR devices
• LDR units may have single or multiple sources with activities of
~370 MBq to ~550 MBq.
• Because of the higher activities involved, the shielding
requirements for HDR are greater than LDR units.
• HDR devices typically step the single source through a series of
dwell positions while a LDR device does not reposition its
multiple source string.
• HDR employs shorter irradiation time at higher dose rates than
LDR treatment.

19. • Treatments are usually fractionated (e.g. 6
fractions of 6 Gy each);
19
HDR brachytherapy
• Either the patient has a new implant each time or stays
in hospital for bi-daily treatments;
• The time between treatments should be >6 hours to
allow normal tissue to undertake some recovery.

20. Catheters are indexed to avoid mixing
them up.
20
Transfer catheters are locked into place
during treatment - green light indicates
the catheters that are in use.
HDR brachytherapy (cont)
Varian

21. Portable HDR Unit
21
HDR brachytherapy (cont)

22. LDR (137Cs) Cervix insertion
• 10 pellets each 550 MBq = 5.5 GBq total
• ~ 0.2 mSv/h at 1 m
• ~ 5 days for 1 mSv
HDR and LDR radiation levels near patients
HDR (192Ir)
• 370 GBq source
• ~ 47 mSv/h at 1 m
• ~1.3 minutes for 1 mSv
The treatment room door should be interlocked

23. • This technology uses radioactive catheters, pellets, and
stents to treat coronary and peripheral vascular
problems.
23
Intravascular brachytherapy
• The radioactive source can be ion implanted, plated, or
encapsulated in a sealed source device attached to a guide
wire used in the angioplasty procedure.
• The radioactive device can be
either permanently implanted or
removed via the guide wire
following treatment of the
affected vessel wall.

24. • After opening of a blocked blood
vessel by angioplasty there is a high
likelihood (60%+) that the vessel will
again block. i.e. restenosis will occur.
Intravascular brachytherapy (cont)
Purpose of treatment
• Gamma sources – 192Ir; Beta sources - 32P, 90Sr/Y, 188Re
• Radiation is a proven agent to
prevent growth of cells and has been
shown to be effective in preventing
restenosis

25. • have a finite range in tissue;
• have fewer radiation safety
issues
• physically smaller size
Intravascular brachytherapy (cont)
Beta sources
Beta-Cath™ System (Novoste)
Delivery catheter
Hydraulic delivery
Source train (90Sr)

26. Pre-PTCA
Post-PTCA
6 Months later
Intravascular brachytherapy (cont)
During treatment

29. Neutron capture therapy

30. Introduction
• Neutron capture therapy (NCT) is a nonsurgical therapeutic
modality for treating locally invasive malignant tumors such as
primary brain tumors, and recurrent head and neck cancer.
• The cross section of the 10B (3,837 barns) is many times greater
than that of the other elements present in tissues such as
hydrogen, oxygen, and nitrogen
• It is a two-step procedure: first, the patient is injected with a
tumor-localizing drug containing the non-radioactive isotope
boron-10 (10B), which has a high propensity to capture thermal
neutrons.
• In the second step, the patient is radiated with epithermal
neutrons, the source of which is either a nuclear reactor or an
accelerator. After losing energy as they penetrate tissue, the
neutrons are captured by the 10B, which subsequently emits high-
energy alpha particles that kill adjacent cells that have taken up
sufficient quantities of 10B.

31. • All of the clinical experience to date with NCT is with the
non-radioactive isotope boron-10, and this is known as
boron neutron capture therapy (BNCT).
• The use of other non-radioactive isotopes, such as
gadolinium, has been limited to experimental studies and
has not been used clinically.
• BNCT has been evaluated clinically as an alternative to
conventional radiation therapy for the treatment of high-
grade gliomas, meningiomas, and recurrent, locally
advanced cancers of the head and neck region and
superficial cutaneous and extracutaneous melanomas.

32. Boron neutron capture therapy
• Conceptually, BNCT is a “magic bullet” approach to treating
tumors.
• Pure beams of very low energy neutrons do not directly deposit
much energy in tissue via collisions but rather interact via
nuclear transmutation reactions.
• The basic idea is to selectively attach to the cancer cells a
nuclide having a large cross section for capturing a thermal
neutron. The nuclide then undergoes a nuclear reaction with
the localized release of a substantial amount of energy. In
principle, this kills the “tagged” cell but does not damage the
surrounding “untagged” normal cells.
• Although there is ongoing work in developing high-current
particle accelerators to produce low-energy thermal or
epithermal beams for BNCT, at the present time, all clinical
work is being done using moderated neutron beams from
nuclear reactors.

33. History of BNCT
• After the initial discovery of the neutron in 1932 by Sir James Chadwick, H.
J. Taylor in 1935 showed that boron-10 nuclei had a propensity to capture
thermal neutrons. This results in nuclear fission of the boron-11 nuclei into
stripped down helium-4 nuclei (alpha particles) and lithium-7 ions.
• The first study of charged particles from slow neutron irradiation of Boron
was completed at Cambridge University in December 1934
10B + 1n → 7Li + 4He
• In 1936, G.L. Locher, a scientist at the Franklin Institute in Philadelphia,
Pennsylvania, recognized the therapeutic potential of this discovery and
suggested that neutron capture could be used to treat cancer.
• In 1938, first radiobiological study was carried out by using neutron-10B
reaction at the University of Illinois.
• W. H. Sweet, from Massachusetts General Hospital, first suggested the
technique for treating malignant brain tumors and a trial of BNCT against
the most malignant of all brain tumors, glioblastoma multiforme, using
borax as the boron delivery agent in 1951.

34. • A clinical trial was initiated in a collaboration with Brookhaven
National Laboratory in Long Island, New York, U.S.A. and the
Massachusetts General Hospital in Boston in 1954.
• In 1960, Hatanaka in Japan confirmed that BNCT has
advantages for patient’s treatment of certain cancers by
comparing between BNCT and conventional chemo-immuno –
radiotherapy
• In 1980, a clinical trial was started which concentrated on
glioblastoma multiforme
• In 2001, an experiment using BNCT irradiated an explanted
liver suffering from diffuse metastases took place in Italy
• In 2003, BNCT used to treat skin melanoma (Nievaart 2007).
Boron Neutron Capture
Therapy - History

35. Boron Neutron Capture Therapy
6% 1.78 MeV – 94% 1.47 MeV
6% 1.01 MeV – 94% 0.84 MeV

36. Principle
 Neutron capture therapy is a binary system
that consists of two separate components to
achieve its therapeutic effect.
 Boron compound (b) is selectively absorbed by
cancer cell(s).
 Neutron beam (n) is aimed at cancer site.
 Boron absorbs neutron.
 Boron disintegrates emitting cancer-killing
radiation.
 BNCT is based on the nuclear capture and
fission reactions that occur when non-
radioactive boron-10, which makes up
approximately 20% of natural elemental boron,
is irradiated with neutrons of the appropriate
energy to yield excited boron-11 (11B*).

37.  This undergoes instantaneous nuclear fission to produce
high-energy alpha particles(4He nuclei) and high-energy
lithium-7(7Li) nuclei.
 The nuclear reaction is:
10B + nth → [11B] *→ α + 7Li + 2.31 MeV
 Both the alpha particles and the lithium nuclei produce
closely spaced ionizations in the immediate vicinity of the
reaction, with a range of 5–9 µm, which is approximately the
diameter of the target cell.
• The lethality of the capture reaction is limited to boron
containing cells. BNCT, therefore, can be regarded as both a
biologically and a physically targeted type of radiation
therapy.
• The success of BNCT is dependent upon the selective
delivery of sufficient amounts of 10B to the tumor with only
small amounts localized in the surrounding normal tissues.

38. • A wide variety of boron delivery agents have been synthesized.
E.g a polyhedral borane anion, sodium borocaptate or BSH
(Na2B12H11SH), and the second is a dihydroxyboryl derivative of
phenylalanine, referred to as boronophenylalanine or BPA.
• Following administration of either BPA or BSH by intravenous
infusion, the tumor site is irradiated with neutrons, the source
of which has been specially designed nuclear reactors. Specially
designed accelerators are being used as well.
• In theory BNCT is a highly selective type of radiation therapy
that can target tumor cells without causing radiation damage to
the adjacent normal cells and tissues.
• Doses up to 60–70 grays (Gy) can be delivered to the tumor cells
in one or two applications compared to 6–7 weeks for
conventional fractionated external beam photon irradiation.

40. BNCT: radiotherapy selective at cell level
Accumulate the boron in the tumour cells:
10B
then
Irradiate with neutrons:
Principle of BNCT

41. Boron delivery agents
• The development of boron delivery agents for BNCT began in the early
1960s and is an ongoing and difficult task.
• The most important requirements for a successful boron delivery agent
are:
 low systemic toxicity and normal tissue uptake with high tumor uptake and
concomitantly high tumor: to brain (T:Br) and tumor: to blood (T:Bl) concentration
ratios (> 3–4:1);
o tumor concentrations in the range of ~20 µg 10B/g tumor;
o rapid clearance from blood and normal tissues and persistence in
tumor during BNCT.
• However, as of 2019 no single boron delivery agent fulfills all of these
criteria.
• With the development of new chemical synthetic techniques and increased
knowledge of the biological and biochemical requirements needed for an
effective agent and their modes of delivery, a wide variety of new boron
agents has emerged but only two of these, boronophenylalanine (BPA) and
sodium borocaptate (BSH) have been used clinically.

42. Table 1. Examples of new low- and high-molecular-weight boron
delivery agents,
Boric acid Boronated unnatural amino acids
Boron nitride nanotubes Boronated VEGF
Boron-containing
immunoliposomes and liposomes
Carboranyl nucleosides
Boron-containing Lipiodol Carboranyl porphyrazines
Boron-containing nanoparticles Carboranyl thymidine analogues
Boronated co-polymers Decaborone (GB10)
Boronated cyclic peptides
Dodecaborate cluster lipids and
cholesterol derivatives
Boronated DNAc intercalators
Dodecahydro-closo-dodecaborate
clusters
Boronated EGF and anti-EGFR
MoAbs
Linear and cyclic peptides
Boronated polyamines Polyanionic polymers
Boronated porphyrins
Transferrin-polyethylene glycol
liposomes
Boronated sugars

43. .

44. • Thermal neutron absorbed by H atom of normal tissue
Low LET
𝜸 radiation
•
•
Thermal neutron absorbed by N atom
14N + 1n →14C + 1H
High LET
proton
•
•
Thermal neutron capture and fission reaction with boron
10B + 1n → 7Li + 4He
High LET 𝛼
particle
Types of Radiation Delivered

45. Working
• Boron Neutron Capture Therapy (BNCT) is a noninvasive therapeutic
modality for treating locally invasive malignant tumors such as
primary brain tumors and recurrent head and neck cancer.
• It is a two-step procedure: first, the patient is injected with a tumor
localizing, non-radioactive boron-10 containing drug that has a high
propensity to capture slow neutrons.
• In the second step, the patient is radiated with epithermal neutrons,
which after losing energy as they penetrate tissue, are absorbed by
the boron-10, and the resulting nuclear capture and fission reactions
yield high-energy alpha particles, thereby killing the cancer cells.
• It has been used to treat two of the most therapeutically refractory
human cancers, high grade gliomas and recurrent cancers of the head
and neck region. In theory, it is an ideal type of radiation therapy
since it is both physically and biologically targeted.

46. Reactions relevant for neutron
dosimetry
Fast neutrons
(elastic collisions)
Gamma emission
(capture on hydrogen)
1H(n,γ) 2H
Thermal neutrons
(capture on nitrogen) Boron capture
1H(n,n’)p
14N(n,p) 14C 10B(n,α) 7Li
𝐷𝑓
𝐷𝑡 𝐷𝐵
𝐷𝛾

47. Accelerator-based BNCT system under construction, showing
electrostatic proton accelerator (on the left) and beam transport line
towards neutron production target (on the right). (Photo: Nagoya
University)

49. BSH : The first clinically
effective boron compound
• In 1968, a team led by Hiroshi Hatanaka began
administering BNCT to patients with malignant
brain tumors using a new boron compound
(Na2B12H11SH, commonly known as BSH).
• The HTR and the Musashi Institute of Technology
Reactor (MuITR), which was modified for medical
use, were used as neutron sources, and a high-purity
thermal neutron irradiation field developed at the
heavy-water facility of the Kyoto University
Research Reactor (KUR) was also used in 1974.
• The compound BSH, of which each molecule has 12
10B atoms, is easy to use since it excels in its ability
to transport 10B and offers high water solubility.
• Whereas BSH is prevented from penetrating brain
tissue by the blood-brain barrier in normal brains,
the failure of this barrier function allows it to
penetrate, and accumulate in malignant brain
tumors, resulting in a large concentration difference.
However, the compound’s properties are not such
that cancer cells actively accumulate it.

51. The ILL Reactor
51018 neutrons/s
generated at 57 MW

52. Gadolinium neutron capture
therapy (Gd NCT)
• There also has been interest in the possible use of gadolinium-157 (157Gd) as a
capture agent for NCT for the following reasons:
• First, and foremost, has been its very high neutron capture cross section of
254,000 barns.
• Second, gadolinium compounds, such as Gd-DTPA (gadopentetate dimeglumine
Magnevist®), have been used routinely as contrast agents for magnetic
resonance imaging (MRI) of brain tumors and have shown high uptake by brain
tumor cells in tissue culture (in vitro).
• Third, gamma rays and internal conversion and Auger electrons are products of
the 157Gd (n,γ)158Gd capture reaction (157Gd + nth (0.025eV) → [158Gd] → 158Gd + γ
+ 7.94 MeV).
• It would be highly advantageous for the production of DNA damage if the 157Gd
were localized within the cell nucleus. However, the possibility of incorporating
gadolinium into biologically active molecules is very limited and only a small
number of potential delivery agents for Gd NCT have been evaluated.

53. Advantages and Disadvantages
• Clinical interest in BNCT has focused primarily on the
treatment of high-grade gliomas and melanoma, most recently,
head and neck and liver cancer
• There are no boron compounds which have a sufficiently high
tumor to healthy tissue ratio, to ensure that healthy tissues will
not be affected by BNCT treatment
• Undesirable dose components produced as an unavoidable side-
effect (like gamma rays)
• Well trained surgeon (Barth et al., 2009)

54. Applications
• Malignant brain tumors
• Head and neck cancers
• Malignant pleural
mesothelioma (MPM)
• Malignant melanoma of the
skin
Head and neck cancers

55. Malignant melanoma of the skin
Malignant brain tumor

56. Proton Therapy

57. Introduction
• Proton therapy, or proton radiotherapy, is a type of particle
therapy that uses a beam of protons to irradiate diseased
tissue, most often to treat cancer.
• The chief advantage of proton therapy over other types of
external beam radiotherapy (e.g., radiation therapy, or
photon therapy) is that the dose of protons is deposited over
a narrow range of depth, which results in minimal entry,
exit, or scattered radiation dose to healthy nearby tissues.
• The American Society for Radiation Oncology Model Policy
for Proton Beam therapy states that proton therapy is
considered reasonable in instances where sparing the
surrounding normal tissue “cannot be adequately achieved
with photon-based radiotherapy” and can benefit the
patient.
• Like photon radiation therapy, proton therapy is often used
in conjunction with surgery and/or chemotherapy to most
effectively treat cancer.

58. -1946 Harvard physicist Robert Wilson :
• Protons can be used clinically
• Maximum radiation dose can be placed
into the tumor.
• Proton therapy provides sparing of
healthy tissues
• Early proton: for research only
• 1990: First hospital based proton therapy
facility was opened at the Loma Linda
University Medical Center LLUMC in
California.
cyclotron
Robert Wilson
HISTORY

59. 1954: First treatment of pituitary
tumors
1958:First use of proton s a
neurosurgical tool
1990: First hospital based proton
therapy facility was opened at the
Loma Linda University Medical
Center(LLUMC) in California
HISTORY

60. Equipments
• Most installed proton therapy systems utilise
isochronous cyclotrons and synchrotrons alongwith
High gradient Eletrostatic Accelerator, Laser Plasma
particle Accelerator
• Cyclotrons are a short metallic cylinder divided
into two sections called dees
• Dees are highly evacuated and subjected to a constant
strength magnetic field applied perpendicular to the
plane of the dees
• Linear accelerators, as used for photon radiation
therapy, are becoming commercially available as
limitations of size and cost are resolved

61. SYNCHROTONS
• In the synchrotron, a proton beam of 3 to 7 MeV, typically from a linear
accelerator, is injected and circulated in a narrow vacuum tube ring by the
action of magnets located along the circular path of the beam.
• It produce proton beams of selectable energy, thereby eliminating the need for the
energy degrader and energy selection devices
• Beam currents are typically much lower than with cyclotrons, thus limiting the
maximum dose rates that can be used for patient treatment, especially for larger
• The proton beam is accelerated repeatedly through the Radiofrequency cavity
powered by a sinusoidal voltage with a frequency that matches the frequency of
the circulating protons.
• Protons are kept within the tube ring by the bending action of the magnets.
• The strength of the magnetic field and the RF frequency are increased in
synchrony with the increase in beam energy, hence the name synchrotron.
• When th e b ea m reaches the desired en ergy, it is ext ract ed.
• The maximum dose rate available from a commercially available synchrotron
based proton delivery system for 25x25 cm2 field has been specified at 0.8Gy per
minute

62. cyclotrons

64. Types of proton therapy
Passive
scattering
Therapy
Pencil beam
Therapy

65. Passive scattering beam
delivery
• The first commercially available proton delivery
systems used a scattering process, also known as
passive scattering, to deliver the therapy.
• With scattering proton therapy the proton beam is
spread out by scattering devices, and the beam is
then shaped by placing items such as collimators
and compensators into the path of the protons.
• Passive scattering delivers homogenous dose along
the target volume.
• Consequently, passive scattering provides more
limited control over dose distributions proximal to
the target.

67. Pencil beam scanning beam
delivery
• Pencil beam proton therapy, delivers a single, narrower proton
beam that is magnetically swept across the tumor, without the need
for a beam-shaping device.
• This technology provides an even more precise three-dimensional
beam that conforms to the shape and depth of the tumor.
• Multiple beams are delivered from different directions, and
magnets in the treatment nozzle steer the proton beam to conform
to the target volume layer as the dose is painted layer by layer.
• This type of scanning delivery provides greater flexibility and
control, allowing the proton dose to conform more precisely to the
shape of the tumor
• It further diminishes the risk of impacting surrounding healthy
brain tissue and adjacent, critical organs, lowering the risk for side
effects.
• Pencil beam proton therapy often is recommended for tumors with
complex shapes located in close proximity to critical organs..

68. Physics of Proton Therapy
Brag Peak
• LET is defined as dE/dx, where dE is the mean
energy deposited over a distance dx in media
• The average rate of energy loss of a particle per
unit path length in a medium is called the
stopping power. The linear stopping power is
measured in units of MeV/cm.
• Stopping power and LET, are closely related to
dose deposition in a medium and with the
biologic effectiveness of radiation.
• The rate of energy loss due to ionization and
excitation caused by a charged particle
traveling in a medium is proportional to the
square of the particle charge and inversely
proportional to the square of its velocity.
• As the the rate of energy loss per unit path
length increases. As the particle velocity
approaches zero near the end of its range, the
rate of energy loss becomes maximum.
• The sharp increase or peak in dose deposition at
the end of particle range is called the Bragg
p eak

69. Spread out bragg peak
• T
o provide wider depth coverage, the
Bragg peak can be spread out by
superposition of several beams of
different energies .These beams are
called the spread-out Bragg peak
(SOBP) beams.
• The SOBP beams are generated by
employing a monoenergetic beam of
sufficiently high energy and range to
cover the distal end of the target volume
and adding beams of decreasing
energy and intensity to cover the
proximal portion.

70. HOW PROTON THERAPY
WORKS
• Through proton therapy, highly energized protons are delivered from
a synchrotron or cyclotron through a precisely controlled conformal
beam to a patient’s tumor.
• Energy of the delivered protons is adjusted based on the tumor
location, size and shape in the brain.
• Each patient treatment room includes a robotic bed which serves as a
stable platform that positions the patient during the procedure.
• Newer room designs will include CT equipment to help determine
the shape of the tumor and to guide the direction of the proton beam.
• Patients typically attend a pre-treatment imaging session known as a
simulation, during which they are fitted with a positioning device
that will help to precisely direct the proton beam during the actual
procedure.
• Pre-treatment imaging may occur a week or two in advance of the
first proton therapy session to allow for planning and calculation of
the treatment.

71. • During the proton therapy session, the medical attendant leaves the
room.
• The patient’s treatment table is then directed into the gantry, a
donut-shaped, rotating steel device which is approximately 35 feet
in diameter.
• The gantry rotates around the table, directing the accelerated
protons to the patient’s tumor through the beam delivery system,
called an aperture.
• The duration of each treatment session is about 30–90 minutes,
and the patient neither hears nor feels the procedure
HOW PROTON THERAPY
WORKS

73. Applications
Two prominent examples are pediatric neoplasms(such as
medulloblastoma) and prostate cancer
Brain tumors that may be suitable for proton therapy
include:
 Some brain tumors that have previously received
radiation
 Benign tumors: Vestibular schwannomas/acoustic
neuromas, Meningiomas, Pituitary adenomas,
Arteriovenous malformations
 Certain low- and high-grade gliomas
 Chordomas
 Chondrosarcomas
 Pediatric brain tumors, including: Juvenile pilocytic,
astrocytomas (JPA), Ependymomas, Medulloblastomas,
Germ cell tumors, Pineal tumors

74. Pediatric treatments

75. Eye tumors

76. Base of skull cancer

77. Head and neck tumors

78. Lymphoma (Tumors of lymphatic tissue)

79. Prostate cancer

80. Gastrointestinal malignancy

81. BENEFITS OF PROTON
THERAPY
• The greatest benefit proton therapy offers is the reduced
negative impact on the tissue and structures that are near
the tumor.
• Proton therapy results in a significantly smaller amount of
energy being deposited as the radiation travels to the tumor
site.
• The energy can be adjusted to stop the protons at the tumor
site. This is different from conventional radiation, which
irradiates healthy cells as it travels beyond the tumor site.
• Sparing healthy tissues and organs helps reduce the impact
of side effects common in conventional radiation therapy
and allows for treatment in difficult locations in the body.

82. SIDE EFFECTS AND DISADVANTAGES
• Proton therapy is not appropriate for every type of
cancer. It is best suited for cancers in sensitive
areas, where other treatments might damage
surrounding healthy cells.
• As with all radiation therapy, there is the potential
for side effects. Most people, however, report far
fewer side effects as a result of proton therapy.
• If they do occur, side effects are generally minor
and vary depending on the tumor location, general
health, other medical conditions, age and medical
history.
• Some people experience tiredness, skin irritation,
hair loss in the treated area, nausea and headache

83. REFERENCES
• Nedunchezhian K, Aswath N, Thiruppathy M, Thirugnanamurthy
S. Boron Neutron Capture Therapy - A Literature Review. J Clin
Diagn Res. 2016;10(12):ZE01-ZE04.
• Dorn RV 3rd. Boron neutron capture therapy (BNCT): a radiation
oncology perspective. Int J Radiat Oncol Biol Phys. 1994 Mar
30;28(5):1189-201. doi: 10.1016/0360-3016(94)90494-4. PMID:
8175405.
• H. Tanaka, et. al., Nuclear Instruments and Methods in Physics
Research B 267 (2009) 1970̽1977
• International Atomic Energy Agency, “Current status of neutron
capture therapy”, IAEA-TECDOC-1223, 2001
• http://www.jsnct.jp/e/about_nct/index.html
• https://www.youtube.com/watch?v=cQrbfBiQpfk
• https://www.biomedcentral.com/collections/BNCT

84. • Nakagawa, Y., H. Yoshihara, T. Kageji and R. Matsuoka. 2009. Cost
analysis of radiotherapy, carbon ion therapy, proton therapy and
BNCT. Applied radiation and isotopes, 67: 80-83.
• Nievaart, V.A. 2007. Spectral Tailoring for Boron Neutron Capture
Therapy. IOS Press, ISBN 978-1-58603-762-8
• Turiqi, A. A. 2009. Neutron activation boron therapy for cancer
treatments. University of Surrey Thesis.
• Tai-Ze Yuan (2019). "New frontiers in proton therapy: applications
in cancers“. Cancer Commun. 39 (61): 61. doi:10.1186/s40880-019-
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• https://www.abta.org/wp-content/uploads/2018/03/proton-
therapy.pdf
• https://www.mskcc.org/cancer-care/diagnosis-treatment/cancer-
treatments/radiation-therapy/what-proton-therapy

85. • Johns H E and Cunningham J R 1983 The Physics
of Radiology, 4th edition (Springfield: C Thomas).
• Khan F M 1994 The Physics of Radiation Therapy,
2nd edition (Williams & Wilkins, Baltimore).
• Williams J R and Thwaites D I 1993 Radiotherapy
Physics in Practice (Oxford: Oxford University
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• International Commission on Radiation Units and
Measurements ICRU 55, Bethesda. Prescribing,
recording, and reporting interstitial brachytherapy,
1993.
• https://www.hopkinsmedicine.org/health/treatment-
tests-and-therapies/brachytherapy