Various instruments and applicators used in radiotherapy

1. SPOTTERS

2. COBALT-LINAC-SRS

3. 1- LEAD SHIELDING BLOCKS
• To reduce dose to normal tissues
surrounding the tumour
• Thickness of shielding block depends
on the energy of the radiation.
• HVL- Thickness of material that will
reduce the intensity of the primary
beam by 50.
• Shielding material – ideally should
attenuate beam intensity to <5% of
its original
• Placement : KV radiation – On the surface
MV radiation – 15-20 cm from surface on shadow tray – As thicker and heavier and reduced electron scatter

4. Custom Blocks - Cerrobend
Lead Cerrobend / Woods metal /
Lipowitz alloy/ Bendalloy/
Pewtalloy/ MCP158
Composition Lead 50% Bismuth 26.7% Lead
13.3% Tin 10% Cadmium
Density 11.3 g/cm3 9.4 g/cm3
Melting Point 3270 700
Thickness
(4MV)
6cm 7.5cm
Features Toxic Lead fumes Harder than Lead at Room
Temperature
As melting point is low easier to
shape the blocks

5. 2- STYROFOAM CUTTER
Used to prepare custom blocks

6. POSITIVE BLOCK vs NEGATIVE BLOCK

7. 3- 2D COMPENSATOR
• Beam modifying device which evens out the skin
surface contours while retaining the skin sparing
advantage.
• To compensate for dose irregularities arising
due to reduced scatter near the field edges
• Sheets of Lead, Lucite or Aluminium glued
together
• Thickness varies along single dimension only
• Placed at >= 20 cm distance from the patients
sking

9. 4 – BUILD UP BOLUS
• A tissue equivalent material used to reduce the depth of
Dmax dose – to bring the build up zone more superficial
towards the skin
• Superficial Tumours
• Thickness varies according to the energy
Co60 – 2-3mm
6 MV- 5-8mm
10 MV- 12-14mm
• IDEAL = Same Z , Same electron density , easily pliable
• MATERIAL USED : Superflab , Superstuff , Bolx Sheet
( Mix-D , Temex rubber , Lincolnshine Bolus , Spiers Bolus,
Paraffin wax , cotton)

10. 5- BEAM SPOILERS
• Lucite (Perspex) shadow trays are kept in the path of the beam , at a distance from the skin
• Principle – To increase surface dose : Relative surface dose increases when the surface to tray distance is reduced.
• Used in TBI to bring the surface dose to 90% of the prescribed dose.

11. 6 - WEDGE
• A beam modifying device that causes progressive
decrease in intensity across the beam resulting in
tilting of the isodose curves from the normal
position
• They are mounted on trays which are mounted
onto the gantry
• Parts – HEEL and TOE
• Mounted – 15 cms from the skin surface
• Material
Steel
Lead
Tungsten
Brass
Mounted
HEEL TOE

12. Principle
• With a perpendicular beam arrangement the
superficial region of the tumour receives higher
dose leading to a hot spot
• To get a uniform dose distribution wedges are
used , which are placed with thick ends adjacent
to each other.
• In some tumours open field
anteriorly and wedged lateral field is
used. As the dose contribution from
the anterior field reduced , it is
compensated by wedged lateral fields

13. WEDGES
PHYSICAL
Individual
Universal
Motorised
DYNAMIC PSEUDO

14. Wedge Angle (θ)
• Refers to “the angle through which an
isodose curve is tilted at the central ray
of a beam at a specified depth.”
• The ICRU recommended depth for
wedge angle specification is 10cm.

15. Hinge Angle (φ)
• It is the angle between the central axes of
two beams passing through the wedge
• Relation:
Θ = 90o - φ/2
• Based on the principle that for a given
hinge angle, the wedge angle should be
such that the isodose curve from each
field are PARALLEL TO THE BISECTOR OF
THE HINGE ANGLE.

16. 7 - BREAST BOARD
Used in treatment of breast cancer
with parallel opposed tangential
field
Chest wall – had a normal slope
Allows the patient to be positioned
with the chest wall horizontal
Provides arm support to bring the
arm above the shoulders and out of
the way of lateral field

17. 8 - BITE BLOCK / MOUTH BITE
• Used in treatment of floor of mouth , alveolus,
tongue , maxillary sinus etc
• Positioning of tissue - Daily reproducibility
• Separation of tongue from hard palate
• Opens the jaws and depressed the tongue
• Protects the opposing structures
• Eg:
Reduced dose to hard palate in Ca tongue treatment
Reduced dose to tongue in Ca Hard palate treatment
• Material used : Dental Impression compound
(Natural resin + Filler + Lubricant + Colouring agent)
• Couch mounted Bite block system

18. 9- THERMOPLASTICS
• Material : Poly-capro-lactone with a discontinuous short
length fiber
• Heated in water bath – 60 – 700c (working temperature)
and stretched over the patients treatment area and
allowed to cool
• Melting Point – 1500c
• Available as sheets or as Custom made for different
areas
• Shrinkage +

20. 10 - VACLOK VACUUM BAGS
• Radiolucent plastic cushions filled with
polystyrne balls
• Semi-Deflated cushion is moulded around
the patients gross body contour
• Using vacuum pump air is pumped out and
the balls come together to form a firm
solid support
• ADV: Shape maintained throughout ,
Reusable , Comfortable
• DISADV: Conforms less well to finer
details, Strict immobilization possible with
combination of other devices

21. 11- EPID – Electronic Portal Imaging Device
• Used in Daily imaging for treatment localization and verification
• Portal images – viewed instantaneously and can be stored for viewing
/archiving
• TYPES :
VIDEO BASED SYSTEMS
LIQUID ION MATRIX CHMABERS
SOLID DTATE DETECTORS – AMORPHOUS SILICON , SELENIUM

22. SILICON Flat panel image detector
• Matrix of 256x256 solid state detectors
consisiting of amorphous Silicon photodiodes
(High resisitance to damamge from radiation).
• Mounted on a retractable arm
• Within this unit a scintillator (P) converts the
radiation beam into visible photons
• The light is detected by the photodiodes.
• The photodiode connected to an external
amplifier records the amount light detected /
charge by the photodiodes and is converted
into image
Specifications
• Active Imaging Area – 40 x 30 cm2
• Energy Range – 4-25 MV
• Dose Rate Range – 50-600 MU/min

23. • FEATURES
• Easy to use
• Allows online verification
• Multiple images can be
taken during one treatment
• Images available in digital
format
• Better image quality than
video based and liquid ion
based system but lesser
than CBCT

24. 12- ELECTRON CONE APPLICATOR

25. • Normally the photon beam collimators in the LINAC are
too far from the patient to be effective for electron field
shaping.
• After passing through the scattering foil , further
scattering occurs with accelerator head , air – creating an
unacceptable penumbra
• Hence Electron cone applicators are used to collimate the
beam. It is attached to the treatment head such that the
electron field in defined at a distance of around 5cm from
the patient.
• Cones of Several field sizes – 5x5cm2 – 25x25cm2

26. 13 - SRS CONE
For LINAC based SRS
Each cone is uniquely recognized by a coding system
Sharp Penumbra
Varying sizes

27. 14- T BAR/ROD
• It is a equipment used in
case source accidently gets
stuck in the source head
and does not return to its
OFF position.
• 3 regions –
RED – YELLOW - GRAY
Towards
source head

28. • Steps to follow in case of source
getting stuck:
• Turn the gantry to 90/270 and ask the patient to
come out if he can move
• Wearing TLD enter the room with T Rod
• Get the patient out first
• The external T rod should be fitted with the
indicator rod on the source drawer and source is
pushed inside to OFF position.
• T rod should be inserted till the yellow zone
• In case unable to move the source , room is locked
and informed to the authorities.

29. MEASUREMENT OF RADIATION

30. 15 -TLD
• A type of personal radiation monitoring
device
• 3 types –
CHEST BADGE
WRIST BADGE
FINGER BADGE

31. ( COPPER TOWARDS
THE TLD CARD )

32. x
γ
α β
x
γ
α β
x
γ
α β x
γ
α β
x
γ
β
x
γ
BETA
ALPHA
FILTERED
ALPHA AND
SOFT BETA
FILTERED
NONE
FILTERED
XRAY
GAMMA
BETA
ALL

33. Dysprosium

34. Conduction band
Valence band
Trap 3
Trap 2
Trap 1
Forbidden
Band
“Due to the impurities in crystals “

35. • Glow Curve – Plot of thermoluminescence against temperature
• Area under curve is proportional to the radiation absorbed
• Individual glow curves are numbered and correspond to different trap
depths
• ANNEALING – To be done before using to remove any residual effects
• 400oC for 1 hour to reset trap structure and eliminate nay residual electron
in the traps followed by
• 80oC for 24 hours – eliminates peak 1 and 2 of the curve
GLOW CURVE

36. • Badge should be worn at chest level
• Should be worn below the lead apron if used
• Usually have to be changed once in 3 months
• Unique Number for every person
• Badges should nor be left in areas of continuous
radiation / heat
ADVANTAGES DISADVANTAGES
Able to measure a large range of doses
Small in size
Available in various forms
Re-usable (upto 100 times – 300months –
25 years)
Unaffected by visible light , moisture
Caliberation
Annealing everytime
Not a permanent record
Does not give instant results
Expensive Instrumentation for reading
False Readings if kept in vicinity of
continuous radiation/heat

37. APPLICATORS

38. 18 - ICRT APPLICATORS

39. • Based on
Manchester System
Stainless steel
Cylindrical Ovoids

41. HENSCHKE APPLICATOR
• Similar to Fletcher sytem
• Ovoid source length
along the direction of
handle facilitated
afterloading.
• Used with patients with
narrow anatomy as the
ovoids tube have a
straight design

42. HDR - MODIFIED FLETCHER SUIT APPLICATOR
• Commonly used ICRT applicator
• Ovoids of variable sizes – Large ,
Medium , Small , Split
• Intrauterine tandems of varying
degrees with centimeter markings
– 150 , 300, 450
• CT compatible
• No inbuilt Rectal or bladder
shielding

47. 19 - ISBT CERVIX - MUPIT applicator
Martinez Universal Perineal Interstitial Template
• Can be used for cervix , vulva , vagina ,
prostate and rectal ISBT – Hence “
UNIVERSAL”
• Needles – Straight and angled
• Angled – To cover parametrium
• Angled needles covers upto 7 cm of
parametrium
• Inner Template is sutured to the
perineum

50. Syed Neblett Template

51. VENEZIA APPLICATOR
• Can be used for Intracavitary,
Interstitial and Intravaginal
Brachytherapy
20 -HYBRID APPLICATORS

52. VIENNA RING APLICATOR

53. Kelowna Applicator
Benidorm Applicator Pamplona Applicator

54. 21 - HDR - VAGINAL CYCLINDER APPLICATOR

55. MIAMI APPLICATOR
Multichannel Vaginal Cylinder

56. • Used in treatment of carcinoma cervix , Endometrium , Vagina
• Depending on the indications , If only upper vaginal is to be treated
cylinder should not extend to introitus
• If whole vagina is to be treated , cylinder should extend beyond
introitus
• Single Channel – Lowe dose to mucosa
• Multi Channel – Risk of Higher doses to mucosa

57. 22- ISBT CATHETERS
FLEXIBLE IMPLANT TUBES
• Used for treatment that require a moldable source path
using a Free Hand Implantation
• Needles are inserted into the area of Implantation
• Tubes are passed through the inserted needles with the
help of “Leader”
• Types – Single Leader with button
Single Leader with Blind End
Double Leader
• Used in Brachytherapy of breast , STS , Tongue ,Oral Cavity,
Extremities

58. BUTTONS

59. 23- NASOPHARYNX APPLICATOR – ROTTERDAM APPLICATOR

60. 24- ESOPHAGUS - INTRALUMINAL BRACHYTHERAPY APPLICATOR
Esophagelal
End
Radio-opaque
Guide Wire
Mouth Bite with
locking mechanism for the tube
DIAMETER LENGTH
6MM / 8MM 100CM/ 150CM

61. • Dose is prescribed to 1 cm from the mid point of the
source axis
• Radical with EBRT 8-10 Gy in 2 #
• Palliative – 10-14 Gy in 1-2 #

62. 25 - STRONTIUM 90 - OPHTHALMIC APPLICATOR
• Used in Brachytherapy of Ocular conditions
– Pterygium , Conjunctival Melanoma, Wet
Macular degeneration, Neovascularisation
• Beta Emitter
• Energy –
• Avg- 0.3MeV
• Max- 2.2 MeV
• Decays Into Yttrium 90
• T1/2 – 28 Years
• Flat eye , Curved Eye Applicator

63. • Dose Rate (Perez)
• 100 Gy/ Hour
• DEPTH DOSE
• 100% at surface
• 4% at 4mm (ANTERIR SURFACE OF LENS)
• 1% at 6.5 mm (EQUATOR)
• 0.9% at 8mm (POSTERIOR SURFACE OF LENS)

64. RADIOLOGY

65. 26 - ICRT SIMULATION

66. 27 - XRAY SOFT TISSUE NECK- LATERAL

67. 28 - MULTIPLE MYELOMA
• Lateral Radiography of the skull showing
multiple “Punched Out” lesions
• Also known as Raindrop Skull
• PUNCHED OUT lesions – are Lytic lesions with
absent reactive sclerosis of the surrounding
bones
• Part of Skeletal Survey
• >30% of cortical bone loss should happen for
lytic lesions to be picked up on Radiograph

68. 29 - BONE SCINTIGRAPHY / BONE SCAN
• Is a diagnostic study to evaluate the distribution of
active bone formation in the body
• ACTIVE BONE FORMATION = OSTEOBLASTIC
ACTIVITY
INDICATIONS
NEOPLASTIC
Evaluation of secondaries
Primary tumours
Ewings , Osteosarcoma
Response to therapy and
follow up
Prior to initiation of
radiometabolic therapy
NON NEOPLASTIC
Fractures
Inflammation
Bone viability
Grafts , infarcts
Metabolic Bone diseases

69. TYPES
• LIMITED BONE SCINTIGRAPHY
• WHOLE BODY BONE SCINTIGRAPHY
• SPECT
• MULTIPHASE BONE SCINTIGRAPHY- Includes Blood Flow, Immediate And Delayed Images
PHYSIOLOGY
• Phosphate analogues - Good concentration in the bones and rapid clearance from soft tissues
• Hence Phosphate analogues are labelled with 99mTc
• 99mTc MDP (Medronate / Methylene diphophonate)
• 99mTc HMDP, 99mTc HDP

70. Properties
99m
T1/2 = 6.03 hours
141 KeV
99m Tc-MDP ADMINISTERED ACTIVITY
700-1000 MBq (20-30 mCi)

71. SKULL – UNEVEN
ACROMIUM AND CORACOID PROCESS
MEDIAL END CLAVICLE, MANUBRIUM
KIDNEYS - VISUALISED
MORE UPTAKE IN
AXIAL SKELETON
GROWTH CENTRES
DISTAL FEMUR-PROXIMAL TIBIA
PROXIMAL JUMERUS
COSTOCHONDRAL JUNCTIONS
NORMAL BONE SCAN ADULT NORMAL BONE SCAN PAEDIATRICS

72. BONE LESIONS SUPERSCAN MULTIPLE MYELOMA
DIFFUSE METASTATIC PROCESS
ALL RADIOTRACER GETS ACCUMULATED IN
THE BONES WITH NIL IN
SOFT TISSUE/URINARY TRACT
BONE SCAN = OSTEOBLASTIC
MULTIPLE MYELOMA = MOST OFTEN PURELY
OSTEOLYTIC UNLESS A FRACTURE IS PRESENT

74. 30 - PET-CT

76. SUV
• Standardized Uptake value / Dose uptake Ratio
• Malignant vs Benign ??
• Post therapy Response assessment
• Variations