Medical uses of ionizing radiation include radiotherapy, medical imaging like CT scans and X-rays, and nuclear medicine. Radiotherapy uses radiation to treat cancer and can involve external beam techniques like 3D conformal radiation therapy (3D CRT), intensity modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT), stereotactic radiosurgery, and brachytherapy. Emerging techniques like proton beam therapy further improve radiation targeting and dose distribution. Precise imaging guidance and computer planning help deliver high radiation doses safely and effectively to tumors while avoiding nearby healthy tissues.

1. MEDICAL USES OF
IONISING RADIATION
Prof Amin E AAmin
Dean of the Higher Institute of Optics Technology
Prof of Medical Physics
Radiation Oncology Department
Faculty of Medicine
Ain Shams University

2. Medical Uses Of Ionising Radiation
Ionizing
Radiation
Radiotherapy
Medical and
Dental
Radiology
Nuclear
Medicine
Blood
Products
Irradiation

3. Radiotherapy

4. What Is Radiotherapy?
❖ The medical use of ionizing radiation in the
treatment of malignant cancers.
❖ Types:
❑ External Beam Radiotherapy (EBRT)
❑ Brachytherapy

5. Different Radiotherapy Modalities
Radiotherapy
Teletherapy
2D radiotherapy
Electron
beam
3DCRT
IMRT
VMAT
Tomotherapy
IGRT
Stereotactic
radiotherapy
IORT
Proton beam /
Heavey charged
particles
Neutron
therapy
Flash Radiotherapy
Brachytherapy

6. Aim of Radiotherapy
• The aim of radiotherapy is to kill tumor cells and
spare normal tissues
Patient
Tumor
Beam 3
Beam 2
Beam 1

7. 2D Radiotherapy

8. How Is 2D Radiotherapy Given?
❖ 2D beams using linear
accelerator or cobalt 60
machines from several angles.
❖ Aimed at tumour and
sometimes the draining
lymph node.
LINAC
COBALT 60

9. 2D Radiotherapy
❖ Simple field arrangements
➢ Single Beam
➢ Two parallel opposed beams
➢ Multiple beams (three or four)
❖ Uniformly radiate both the target
and the surrounding normal tissues.
❖ Includes the use of rectangular
blocks to shield normal structures.

10. 2-D BEAM
ARRANGEMENTS

11. Electron Beam Therapy

12. Introduction
❖ Photon radiation travels through the whole patient exposing the
distal normal tissue.
❖ Electron therapy is suitable for tumors within up to 5 cm of
the surface.
❖ H & N , Skin, Breast.

13.  Electron-beam therapy is advantageous
because it delivers a reasonably
uniform dose from the surface to a
specific depth, after which dose falls off
rapidly, eventually to a near-zero value.
 Using electron beams with energies up
to 20 MeV allows disease within
approximately 5 cm of the surface to
be treated effectively, sparing deeper
normal tissues.
Why Electron

14. Generation and Acceleration of Electron
Beam
• Linear accelerator
is used to generate
and accelerate
electron beam.

15. Characteristics Of Clinical Electron Beams
X-Ray
Contamination
Surface
Dose
Depth of
80% Dose
Depth of
50 %
dose
Depth of
90% Dose

16. Depth Dose Curve of Electron Beam
❖ A rapid dropoff of dose
❖ X-ray contamination
❖ 90%→E/4 cm 80%→E/3 cm
❖ The percent surface dose for
electrons increases with energy.

17. Electron Beam vs Photon Beam
Electron Beam Photon Beam

18. Electron Beam vs Photon Beam
Electron Beam Photon Beam

19. 6
Head and neck

20. Pediatric CNS

21. 17
ChestWall

22. Electron Arc Therapy
• For superficial tumors
along curved surfaces

23. 5
Skin

24. Total Skin Electron Therapy
❖ For superficial lesions covering large
areas like mycosis fungoides.
❖ Different methods are possible to expose
the whole body. Scatter place is closer to
body.
❖ Traditionally, patient on a stretcher.
Modified as standing or rotating.
❖ Modified Stanford technique.
❖ 2-9 MeV

25. The six-field Stanford technique

26. 3DCRT

27. 3D CRT
• 3D CRT, or three-dimensional conformal
radiation therapy, is an advanced technique that
incorporates the use of imaging technologies to
generate three-dimensional images of a patient’s
tumor and nearby organs and tissues.
• The use of three-dimensional images in the
treatment planning process distinguishes 3D
CRT from other forms of conventional radiation
therapy.

28. Conformal Therapy
It is described as radiotherapy
treatment that creates a high dose
volume that is shaped to closely “
Conform” to the desired target
volumes while minimizing the dose
to critical normal tissues.

29. Features of Conformal Radiotherapy
1. Target volumes are defined in three
dimensions using contours drawn on
many slices from a CT imaging study.
2. Multiple beam directions (2, 3, …, 7) are
used to crossfire on the targets.
3. Individual beams are shaped to create a
dose distribution that conforms to the
target volume and desired dose levels.

30. Automated 3-D Conformal
Radiation Therapy
❖ Radiation intensity is uniform
within each beam
❖ Modulation conferred only by
wedges.
❖ Beam shaping automated with
multileaf collimators (MLC)

31. IMRT

32. What is IMRT ?
• IMRT stands for Intensity Modulated Radiation Therapy.

33. IMRT
❖ IMRT is an advanced form of 3D
CRT
❖ IMRT refers to a radiation
therapy technique in which
nonuniform fluence is delivered
to the patient from any given
position of the treatment beam
using computer-aided
optimization to attain certain
specified dosimetric and clinical
objectives.

34. What is IMRT ?
• The purpose of IMRT is to shape isodose lines by varying the
incident beam intensity spatially in order to conform to clinical
requirement i.e. in order to generate a dose distribution that will
meet certain clinical specifications.
• These clinical specifications usually involves tight tolerances so
that the target organs receive high doses and the sensitive organ
receives an acceptable level.
• The intent of this clinical specification is usually to escalate the
normal dose levels to the target.

35. Different External Beam Radiotherapy
Modalities

36. IMRT vs Conformal RT
• Conformal radiotherapy is delivering a conformal dose distribution
to the shape of the tumour by using uniform beam intensities within
each beam portal.
• IMRT is delivering a conformal dose distribution to the shape of the
tumour by varying the beam intensities within each beam portal.
Treated
Volume
Tumor Tumor
Target
Volume
Treated
Volume
Critical
structure
Target Volume
Collimator
3DCRT
Critical
structure
IMRT

37. IMRT vs Conformal RT
• Conformal radiotherapy is
planned using manual
optimization techniques.
• IMRT is planned using
inverse treatment planning
techniques.

38. IMRT Plan

39. 40 38 40
40 38 40
Beam Intensity Map
3 MLC Segments
38 38 38
38 38 38
2
2
2
2
+ +

40. IMRT - MLC Delivery Methods
Converting Intensity Map to Leaf positions (‘Translator’)
• Static
• beam off during leaf/gantry/couch motion
• slower, simpler
• Dynamic
• beam on during leaf/gantry/couch motion
• faster, more versatile, more complicated

41. Forward Planning
• For 3D CRT forward planning is used.
• Beam arrangement is selected based on clinical experience.
• Using BEV, beam aperture is designed
• Dose is prescribed.
• 3D dose distribution is calculated.
• Then plan is evaluated.
• Plan is modified based on dose distribution evaluation, using various
combinations of
– Beam , collimator & couch angle,
– Beam weights &
– Beam modifying devices (wedges, compensators) to get desired dose
distribution.

42. Inverse Planning (IMRT Planning)
• IMRT planning is an inverse planning.
• It is so called because this approach starts with desired result (a uniform
target dose) & works backward toward incident beam intensities.
• Aftercontouring, treatment fields & their orientation dnuora )elgna maeb(
si tneitapdetceles.
• Next step is to select the parametersused to drive the optimization
algorithm to a particular solution.
• Optimization refers to mathematical technique of
– finding the best physical and technically possible treatmentplan
– to fulfill specified physical and clinical criteria,
– under certain constraints
– using sophisticated computer algorithm

43. Inverse Planning
1. Dose distribution specified
Forward Planning
2. Intensity map created
3. Beam Fluence
modulated to recreate
intensity map
Inverse Planning

44. VMAT

45. Volumetric Modulated Arc Therapy
(VMAT)
➢VMAT is a new type of IMRT technique.
➢VMAT stands for Volumetric Modulated Arc Therapy
➢The radiotherapy machine rotates around the patient during
treatment

46. Definition
Intensity Modulated Arc therapy
where the following three parameters
are modulated simultaneously
❖ Gantry rotation with variable speed
❖ Dose rate
❖ Leafe speed

47. Tomotherapy

48. Tomotherapy
• Tomotherapy is intensity-modulated rotational radiotherapy
utilizing a photon fan beam.
• Radiation therapy device designed on a CT scanner-based
platform.
• Tomotherapy means: slice therapy coined to describe IMRT
using fan beam.
• Tomo = slice, section (Gk)
• Therapy = treatment

49. Linac CT

50. It is a Ct machine in addition to the therapy machine

51. Intensity Modulation
• The linac output can be varied.
• The jaw opening can be changed.
• The gantry speed can be altered.
• The couch speed can be modified.
• The leaf states can be changed.

52. Helical Delivery
Can irradiate up to a 160 cm long field.

53. From Dr. An Liu
Total Marrow
Irradiation
Using
Tomotherapy

54. Stereotactic Irradiation

55. Stereotactic
• “Stereo” (Greek: “solid” or “3-dimensional”) “tact” (Latin:
“to touch” )
• Thus the literal meaning: “3-dimensional arrangement
to touch”

56. Stereotactic Irradiation
• Stereotactic irradiation is a highly precise form of radiation
therapy initially developed to treat small brain tumors and
functional abnormalities of the brain.
• However, attempts are under way to extend the technique to
other parts of the body (stereotactic body radiotherapy)
(SBRT).

57. Stereotactic Irradiation
• Stereotactic irradiation gives radiotherapy from many
different angles around the body. The beams meet at the
tumor.
• This means that the tumor receives a high dose of radiation
and the tissues around it receive a much lower dose.
• This lowers the risk of side effects.

58. Types of Stereotactic Irradiation
Stereotactic
Irradiation
Stereotactic
Radiosurgery
Stereotactic
radiotherapy

59. ❖ Stereotactic Radiotherapy
The delivery of multiple fractionated doses of radiation to a
definitive target volume sparing normal structure (both intra as
well as extracranial)
❖ Stereotactic Radiosurgery
The delivery of a single, high dose of irradiation to a small and
critically located intracranial volume, sparing normal structure
Types of Stereotactic Irradiation

60. The aim is to encompass the
target volume in the high dose
area and, by means of a steep
dose gradient, to spare the
surrounding normal tissue
Aim of Stereotactic Irradiation

61. Characteristics of Stereotactic Irradiation
The main characteristics of stereotactic irradiation are:
• The total prescribed doses are of the order of 10 Gy - 50 Gy.
• The planning targets are small, with typical volumes ranging from 1
cm3 to 35 cm3.
• The requirements for positional and numerical accuracy in dose
delivery are ±1 mm and ± 5%, respectively.
• Essentially any radiation beam that has been found useful for
external beam radiotherapy has also found use in radiosurgery
(cobalt-60 gamma rays, megavoltage x rays, proton and heavy
charged particle beams, neutron beams).

62. Equipment of Stereotactic Irradiation
Stereotactic
Irradiation
Gamma Knife
CyberKnife
NovalisTX
Linac
Tomotherapy
Proton Beam
Stereotactic
Radiosurgery
Stereotactic
Radiotherapy
All machines can be used in both SRT and SRS except
GammaKnife can only be used in SRS

63. Radiosurgical Techniques
Gamma Knife (Gamma unit)
• Gamma Knife (Gamma unit) is a radiosurgical device that has
been associated with, and dedicated to, radiosurgery for the
past four decades.

64. Gamma Knife
• Gamma unit incorporates 201
cobalt-60 sources, each source with
an activity of 1.1 TBq (30 Ci).
• Sources produce 201 circular
gamma ray beams directed to a
single focal spot at an SAD of 40
cm.

65. Gamma Knife
• Collimator aims the radiation
emitted by the Co-60 sources
to a common focal point.

66. Gamma Knife
• This is analogous to focusing the radiant
energy of the sun with a magnifying glass to
a hot focus.
• Near the glass there is not much heat, but the
energy is intense at the focal point.
• Optical lenses can not focus gamma rays,
rather individual beams are allowed to
summate by overlapping at the focal point of
the collimator, achieving the same effect.
Collimator allows the beam focus size to be
adjusted from 4 to 18 mm in size.

67. CyberKnife
Miniature linac on a robotic arm
(CyberKnife):
• This radiosurgical technique uses:
• A miniatute 6 MV linac instead of a
conventional isocentric linac. The miniature
linac operates in the X band and is mounted
on an industrial robotic manipulator.
• Non-invasive image guided target
localization, instead of the conventional
frame based stereotaxy.
• Image-guided frameless radiosurgery
system achieves the same level of
targeting precision as the frame-based
radiosurgery.

68. Treatment couch
Linear
accelerator
Manipulator
Image
detectors
X-ray sources
Synchrony™
camera
Targeting System
Robotic Delivery System
Cyberknife

69. NovalisTX
The Novalis Tx
platform
incorporates two
complementary
imaging systems that
work together to
enhance treatment
precision by enabling
doctors to target
areas being treated.

70. NovalisTX
• The ETX™(ExacTrac®)
room-based X-ray imaging
system provides real-time
imaging and fine-tuning of a
robotic couch that moves in
six dimensions to ensure that
the targeted lesion is aligned
with the treatment beam
during treatment.

71. Tomotherapy rapidly
rotates the beam around
the patient (and inside the
housing of the unit), thus
allowing the beam to enter
the patient from many
different angles in
succession. So it can be
used in SBRT
Tomotherapy

72.  The chief advantage of charged
proton radiosurgery is that the
beams stop at a depth related to
the beam's energy.
 The lack of an exit dose and the
sharp beam profile of protons
allow target irradiation with
lower integral doses than are
delivered with photon irradiation.
Proton Radiosurgery

73. LINAC
• The Linear Accelerator is
used to focus high energy
Xray onto the tumor site,
disrupting its DNA.
• High energy x-rays will be
directed to the patient’s
tumor and shaped as they
exit the machine to
conform to the shape of
the patient’s tumor.

74. Modifications to Standard Isocentric
Linacs for Radiosurgery
Modifications are relatively simple and consist of:
• Supplementary collimation
• Either in the form of a set of collimators to define small
diameter beams
• Or with a miniature MLC to define small area irregular fields
• Remotely controlled motorized table or treatment chair rotation.
• Table brackets or a floor stand for immobilizing the stereotactic
frame during treatment.
• Special brakes to immobilize the vertical, longitudinal and lateral
table motions during treatment.
• Interlocked readouts for angular and height position of the couch.

75. Multiple Non-coplanar Converging Arcs
Technique
• Target dose is delivered through a series of
gantry arcs, each arc with a different stationary
position of the treatment couch or chair.
• Arc angles are usually smaller than 180o to avoid
parallel-opposed beams in the plane of the arc.
• Typical number of arcs used ranges from 4 to 11.

76. Beam Entry Traces For Various Linac-
Based Techniques

77. Stereotactic Frame Immobilization In
Linac-based Radiosurgery
• Immobilization of the stereotactic frame during the treatment
is achieved with special brackets which attach the frame to
the linac couch, chair, or a special floor stand.
• Direct couch mounting of the stereotactic frame is less
expensive, safer for the patient, and more practical than
mounting onto a floor stand.

78. Stereotactic Frame

79. Stereotactic Collimators
 The stereotactic radiation is characterized bya very steep
dose fall-off on the margin of the target volume.
 The steep dose gradient is achieved by the use of appropriate
collimators and a multitude of radiation directions.

80. Collimation For Linac-Based
Radiosurgery
• Most linac based radiosurgical techniques use circular
radiation beams which are produced by special collimators
attached to the tray holder in the head of the linac.
• Circular beams are usually between 10 and 40 mm in
diameter at the linac isocentre and are produced by 10 cm
thick lead cylinders with appropriate circular holes drilled
along their axes.
• Use of the original rectangular linac collimators for defining
the small radiosurgical beams is not recommended.

81. Example Of Circular Collimator Attached
To The Linac Head

82. IORT

83. Intraoperative radiotherapy
• Intraoperative radiotherapy (IORT) is a special
radiotherapeutic technique that delivers in a single
session a radiation dose of the order of 10 - 20 Gy to a
surgically exposed internal organ, tumor or tumor bed.
• IORT combines two conventional modalities of cancer
treatment: surgery and radiotherapy.
• Usually used to “clean up” a surgical bed

84. Beam Modalities for IORT
Three beam modalities are used for IORT:
• Megavoltage electrons
• Orthovoltage X rays
• High dose rate brachytherapy with iridium-192 source.

85. Electron Beam for IORT
• The enengy of the electron beams
used is usually between 9-16 Mev.

86. Original Hard Docking Cox Ll
Standard Linear Accelerator

87. Mobile Beam IORT System-Mobetron
4-12 MeV

88. Electron Beam
for IORT

89. Mobile dedicated Linac

90. Conventional Linac

91. Control
Workstation
Arm stand with
x-ray source
X-ray
source
IORT with kV X-Ray

92. Solid Applicator And Balloon

93. Solid applicator size available:
1.5, 2.0, 2.5, 3.0, 3.5, 4.0,
4.5, 5.0 cm in diameter, labeled by
A, B, C, D, E, F, G, and H for the part
number. Reusable 100 times.
Balloon size available: 3.0, 3.5, 4.0, 4.5,
5.0 cm in diameter. Single use.
Applicator on the x-ray source
Solid Applicator And Balloon

94. Spatial Distribution Of X-ray Beam
0
+1.5 mm
-1.5 mm
7 6 5 4 3 2 1 Gy/min
50 kV, 40 µA

95. Carl Zeiss IORT IntraBeam System in OR
A solid applicator
with X-ray source
ready to insert
Radiation from
a mini-x-ray
source of 50kV
Drape
Applicator
Lead Shield

96. Step 1: The lumpectomy, immediately
following tumor removal.
Step 2: After the surgeon has removed the
tumor, the radiation oncologist positions
the INTRABEAM applicator in the area of
the breast where the tumor was located.
Step 3: Low energy radiation is delivered
locally to the targeted tissue in the tumor
bed, minimizing healthy tissue exposure to
radiation.
Step 4: After 20-30 minutes of
radiotherapy, the applicator is removed and
the surgeon then closes the incision.
IORT Procedure with Solid Applicator

97. Electrons Vs. Low Energy X Rays
Electrons 12 MeV applicator 
60 mm
X ray 50 KV
applicator  25 mm

98. Interstitial multi-
catheter MammoSite
Intraoperative Brachytherapy
Contura
SAVI

99. Interstitial Brachytherapy –
Multi-Entry/Multi-Catheter

100. MammoSite –
Single Entry/Single Catheter

101. Contura Applicator-
Single Entry/Multi-Catheter
MammoSiteBalloon

102. SAVI Applicator –
Single Entry/Multi-Catheter

103. Intraoperative Brachytherapy

104. Intraoperative Brachytherapy

105. Modified breast HAM
(Mick Radionuclear Instruments)
Tungsten shield
2-cm total thickness

106. Intraoperative Brachytherapy

107. Proton Beam Therapy

108. The Bragg peak
• The Bragg peak is a pronounced
peak on the Bragg curve which
plots the energy loss of ionizing
radiation during its travel through
matter.
• For protons and other ion rays,
the peak occurs immediately
before the particles come to rest.
• This is called Bragg peak
• Proton beam is accelerated by
Cyclotron.

109. 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.

110. Proton Beam Therapy

111. Conventional Radiotherapy And
Proton Therapy

112. Conventional Radiotherapy And
Proton Therapy
ROI
Beam
intensity
Profile
PatientTumor
Beam
intensity
Profile
ROI
Tumour
Beam
intensity
Profile
Beam
intensity
Profile
Beam
intensity
Profile
Beam
intensity
Profile

113. Fast Neutron Beam Therapy

114. Neutron Radiotherapy
Fast Neutron Therapy Beams
Boron Neutron Capture Therapy

115. 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.

116. 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.
9
Be4 n
+ 
10
B5

117. • 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.
99
Be4 nP+
+ 
5 B
Fast Neutrons From Proton
Bombardment Of Be

118. Fast Neutrons Methods Of Production

119. ❖ 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
Why are Neutrons Needed?

120. Flash Radiotherapy

121. About Flash Therapy
• Flash radiotherapy is a novel external non-invasive radiotherapy
technique that consists of delivering a high dose of radiation at
an ultra-high dose rate.
• When compared to radiotherapy delivered at conventional dose
rates (1 – 7 cGy/sec), the Flash phenomenon seems to appear
when irradiation is delivered with a dose superior to 8 Gy and at
a dose rate above 33 Gy/sec in a very short time (less than a
second).

122. About Flash Therapy
❖Researchers theorize that irradiation at very high dose rate
causes oxygen depletion in tissues which renders healthy tissue
radioresistant, enabling dose escalation to levels that destroy
tumor tissues even in high hypoxia.
❖In other words, healthy tissue seems to withstand this novel
method of irradiation better, while the tumor has the same level
of sensitivity to Flash irradiation as to conventional treatment.

123. Advantages of Flash Radiotherapy
• Why is radiotherapy with ultra-
high dose-rate (Flash) of
interest?
• Possible increase in differential
response between normal tissue
and tumors.
• Short treatment times (<1s)
• Motion management, i.e.
remove intra-fraction motion
• Patient comfort
• Improved treatment efficiency

124. IGRT

125. IGRT
• Image-guided radiation therapy (IGRT) is the use of x-ray
images taken immediately before, during or after your
radiation therapy treatment session to improve the accuracy
and precision of treatment.

126. Treatment Planning in Radiotherapy
position in the ct scan position in the treatment
In the treatment the prostate
position changes with respect
to the reference position.
Determines the reference
position of the prostate
throughout the treatment.

127. Why May The Target Be Elsewhere?
• Mispositioning (interfraction)
• Organ motion (intrafraction)
• Shape change (interfraction)
Sources of
uncertainties
May result in absorbed dose in the volumes of
interest and organs at risk that do not
correspond to the theoretical dose planned.

128. Immobilization Systems
In many cases it is not
enough.
Personalized cushions
Vacuum cushions

129. What is IGRT?
IGRT means several things;
• Use of images for online setup correction, before treatment
begins
• IGRT also may mean adaptive radiation therapy

130. What is IGRT?
• With adaptive radiation therapy, images of the tumor
size, shape and location are used to adapt the treatment plan
before it is delivered
Original treatment
plan and anatomy
Original treatment plan
and new anatomy
with tumor shrinkage
due to radiation
Adapted
treatment
plan
Critical structure
Target
Prescription
isodose

131. Will IGRT replace IMRT?
•No, the two are
complementary.
• IMRT allows the dose to
conform tightly to the PTV.
• IGRT allows the PTV to shrink
to the CTV.
• IG-IMRT then allows
simultaneously margin-reduction
and dose conformation.
Conventional RT
IMRT
IG-IMRT
CTV
PTV
Organ
at risk
High dose
isodose

132. Imaging Techniques For IGRT
Planar Imaging IGRT
Electronic Portal Imaging Devices (EPID
Cyberknife
Novalis
Real-Time Tumor Tracking (RTRT)
Gantry-Mounted Systems

133. Types of EPID
❖ Liquid Matrix Ion Chamber
❖ Camera based devices
❖ Amorphous silicon flat panel detectors
❖ Amorphous selenium flat panel detectors

134. Real-Time Tumor Tracking
(RTRT)CyberKnife
Imaging Techniques for IGRT

135. On Board Imaging
Intensifier
KV Xray
Room Mounted OBI
Gantry
mounted OBI

136. Imaging Techniques for IGRT
Volumetric X-ray imaging
❖ Kilovoltage fan-beam CT (kV CT)
❖ Kilovoltage cone-beam CT (kV CBCT)
❖ Megavoltage cone-beam CT (MV CBCT)
❖ Megavoltage fan-beam CT (MV CT)

137. Respiratory gating
• RPM Gating System
• Infrared camera
• External marker block
• Gating workstation

138. Brachytherapy

139. Brachytherapy
• Brachytherapy = dose delivered from sealed radioactive
sources implanted in the patient close to the target (brachys
= Greek for short distance)

140. Brachytherapy
the placement of the radiation sources in the target
treatment area
the rate or ‘intensity’ of the irradiation dose delivered to
the tumour
the duration of dose delivery
Different types of brachytherapy can be defined according to:

141. Source Placement
The two main types of brachytherapy treatment in terms of the
placement of the radioactive source are;
Interstitial implant brachytherapy and
Contact brachytherapy.

142. Interstitial Brachytherapy
• In the case of interstitial
brachytherapy, the sources are
placed directly in the target
tissue of the affected site,
such as the prostate or breast
Interstitial implant for breast
radiotherapy

143. Contact Brachytherapy
• Contact brachytherapy involves placement of the radiation source
in a space next to the target tissue. This space may be;
• A body cavity (intracavitary brachytherapy) such as the cervix,
uterus or vagina;
• A body lumen (intraluminal brachytherapy) such as the trachea or
oesophagus;
• A radiation source can also be placed in blood vessels
(intravascular brachytherapy) for the treatment of coronary in-
stent restenosis.

144. Contact Brachytherapy
Intracavitary
gynecological implant

145. Dose rate
• The dose rate of brachytherapy refers to the level or ‘intensity’
with which the radiation is delivered to the surrounding medium
and is expressed in Grays per hour (Gy/h).
Low-dose rate(LDR)
Medium-dose rate (MDR)
High-dose rate (HDR)
Pulsed-dose rate (PDR)

146. Low-Dose Rate(LDR)
• LDR brachytherapy involves implanting radiation sources
that emit radiation at a rate of up to 2 Gy/h. LDR
brachytherapy is commonly used for cancers of the oral
cavity, oropharynx, sarcomas and prostate cancer.

147. Medium-dose rate (MDR)
• MDR brachytherapy is characterized by a medium rate of
dose delivery, ranging between 2 Gy/h to 12 Gy/h.

148. High-Dose Rate (HDR)
• HDR brachytherapy is when the rate of dose delivery exceeds
12 Gy/h.The most common applications of HDR
brachytherapy are in tumours of the cervix, esophagus, lungs,
breasts and prostate.
• Most HDR treatments are performed on an outpatient basis,
but this is dependent on the treatment site.

149. Example for HDR Brachytherapy
A tongue implant treated using a Nucletron High
Dose Rate (HDR) remote afterloading unit

150. Pulsed-Dose Rate (PDR)
• PDR brachytherapy involves short pulses of radiation, typically
once an hour, to simulate the overall rate and effectiveness of
LDR treatment. Typical tumour sites treated by PDR
brachytherapy are gynaecological and head and neck cancers.

151. Radiation Sources
Half-lifeEnergyTypeRadionuclide
30.17 years0.662 MeVγ-rayCaesium-137 (137Cs)
5.26 years
1.17, 1.33
MeV
γ-raysCobalt-60 (60Co)
73.8 days
0.38 MeV
(mean)
γ-raysIridium-192 (192Ir)
59.6 days
27.4, 31.4 and
35.5 keV
γ-raysIodine-125 (125I)
17.0 days21 keV (mean)γ-ray
Palladium-103
(103Pd)
1.02 years3.54 MeV
β--
particles
Ruthenium-106
(106Ru)

152. Duration of Dose Delivery
The placement of radiation sources in the target area can be:
temporary
permanent

153. Temporary Brachytherapy
• Temporary brachytherapy involves placement of radiation sources
for a set duration (usually a number of minutes or hours) before
being withdrawn.

154. Permanent Brachytherapy
• Permanent brachytherapy, also known as seed implantation,
involves placing small LDR radioactive seeds or pellets (about
the size of a grain of rice) in the tumour or treatment site and
leaving them there permanently to gradually decay.
• Over a period of weeks or months, the level of radiation emitted
by the sources will decline to almost zero.
• The inactive seeds then remain in the treatment site with no
lasting effect.
• Permanent brachytherapy is most commonly used in the treatment
of prostate cancer.

155. Permanent Brachytherapy
"seeds" used for brachytherapy of prostate cancer

156. Electronic Brachytherapy
Customized Ballon
Applicator
KV Xray Tube
AXXENT
X ray Source Assembly

157. Radiology

158. Radiology
• Radiology is the medical discipline that uses medical imaging
to diagnose and treat diseases within the bodies of both
humans and animals.

159. Radiology
Radiology
X-Ray
Radiography
Fluoroscopy Mammography CT MRI Ultrasound

160. X-Ray Radiography
• X-ray machine
provide a static
image on
radiograph.

161. Fluoroscopy
❖ Fluoroscopy is based
on x-rays.
❖ X-ray tube is installed
❖ The radiation dose is
higher than
Radiography.
❖ Provide both static and
dynamic images.

162. Computerized Tomography (CT)
• A computerized
tomography (CT) scan
combines a series of X-ray
images taken from different
angles and uses computer
processing to create cross-
sectional images, or slices,
of the bones, blood vessels
and soft tissues inside your
body.

163. Magnetic Resonance Imaging (MRI)
• Magnetic resonance
imaging (MRI) is a
type of scan that uses
strong magnetic fields
and radio waves to
produce detailed images
of the inside of the body.

164. Ultrasound
• Ultrasound is a type of
imaging. It uses high-
frequency sound waves to
look at organs and structures
inside the body.

165. Nuclear Medicine

166. What is Nuclear Medicine
• Nuclear medicine is a medical specialty that uses radioactive
tracers (radiopharmaceuticals) to assess bodily functions and
to diagnose and treat disease.

167. Nuclear Medicine
Nuclear
Medicine
Diagnostic N M Therapeutic N M

168. Therapeutic Nuclear Medicine
• Therapy using unsealed radioactive
sources includes treatment of the
thyroid (hyperthyroidism and thyroid
cancer) using radioactive iodine, pain
palliation of bone metastasis using
radioactive bone seeking agents and
others.

169. Diagnostic Nuclear Medicine
Diagnostic
Nuclear Medicine
Gamma Camera PET Scan

170. Gamma Camera

171. Gamma Camera
Gamma Camera
Single Head
Gamma Camera
Double Head
Gamma Camera
Trible Head
Gamma Camera

172. Single Head Gamma Camera

173. Double Head Gamma Camera

174. Trible Head Gamma Camera

175. Scan Method
Scan
Method
Static
Whole-
Body
Dynamic SPECT
CT-SPECT
Fusion

176. Static
• Single image of a particular structure
• Demonstrates radiopharmaceutical distribution
• Ex: lung scans, spot bone scans images, thyroid images
• Obtained in various orientations, anterior, posterior, and oblique
• Low activity levels
• Generally 30 seconds to five minutes

177. Whole Body
• Entire body or a large section of body
• Primarily used for
• Bone scans
• Tumor scans
• Abscess imaging
• Clinical and research applications

178. Dynamic
• Timed record of distribution of
radiopharmaceutical
• Commonly used for
• Cardiac studies
• Hepatobiliary studies
• Gastric emptying studies
Dynamic Renogram

179. 179
SPECT
• SPECT means Single
Photon Emission
Computed Tomography
• Images similar to CT & MRI
• thin slices through a particular
organ
• 360 degree rotatator heads
allows for:
• Coronal, planar and 3D
imaging
• Ex: cardiac perfusion, brain,
liver and bone studies

180. 180
SPECT and CT Combination
• Merges SPECT functional testing with CT anatomic
landmark images
• Statistics show
• 25-30% change of treatment options from what would have been
done with SPECT alone

181. PET

182. Positron Emission Tomography (PET)
• Positron Emission Tomography (PET) is a nuclear imaging
technique that produces a 3-D image of functional processes
in the body by detecting the radiation emitted by photons .
• The system detects pairs of gamma rays emitted indirectly
by positron emitting radionuclide (tracer), which was
previously injected in body on a biologically active
molecule,
• 3-D images of tracer concentration within the body are
then constructed by computer analysis.

183. Positron Emission Tomography (PET)

184. Positron Emission Tomography (PET)

185. PET-CT Scanner
Flat couch top insert
CT Scanner
PET scanner
❖Allows hardware based registration as the patient is scanned
in the treatment position
❖CT images can be used to provide attenuation correction factors
for the PET scan image reducing scanning time by upto 40%
60cm

186. PET-CT
CT only PET only
PET/ CT

187. PET-MRI

188. PET-MRI

189. Blood Products Irradiation

190. Blood Products Irradiation
• Irradiation of blood components
for the prevention of transfusion-
associated graft versus host
disease (TA-GvHD) in
immunosuppressed or otherwise
at-risk patients is a long-
established practice.
• Blood and blood components may
be treated with gamma rays from
137Cs or 60Co sources