TOTAL PROCESS OLD ND NEW PROCEDURES ND TYPES OF IMD

1. IMMOBILIZATION DEVICES
P SHIVARAM REDDY
INTERN MEDICAL PHYSICIST ( 2019-2020 )
OMEGA HOSPITAL
MLA COLONY BANJARA HILLS

2. Framework of presentation
 Immobilization
 History of immobilization methods
 Desirable characteristics of immobilization
 Materials used for immobilization
 Types of immobilization
 Conclusion

3. Radiotherapy treatment process
• Diagnosis
• Patient immobilization ( Immobilization devices )
• Imaging( CT, MRI,PET-CT )
• Target delineation
• Treatment plan system
• Record and verifying system
• Treatment delivery

4. IMMOBILIZATION
• Positioning & Immobilization are most crucial parts of RT treatment for
accurate delivery of a prescribed radiation dose and sparing surrounding critical tissues
Primary goal :
 Reproducibility of position
 Reduce positioning errors
Other benefits :
 Can reduce time for daily set up
 Make patient feel more secure & less apprehensive
 Help to stabilize relationship between external skin marks & internal structures
Without proper immobilization ,the patient is at risk for improper treatment and unwanted
side effects
Immobilization such as moulds casts ,headrests and other devices are constructed to reduce
setup errors and patient movement during the treatment.

5. SET-UP ERROR
It is used to describe the discrepancy between intended and actual
Treatment position.
Normally calculated as a shift in treatment field position when a treatment
image is compared against it corresponding reference.
It may be determined relative to the isocentre, the field borders or both.
It comprises a systematic and random error

6. SYSTEMATIC ERROR
• Systematic component of any error is a deviation that occurs in the same direction
and similar magnitude for each total treatment course.
• Systematic errors may be introduced into patient treatment at the localization,
planning or treatment delivery phases.
• For this reasons these type of errors are referred to as treatment preparation
errors.
• Once frozen into the process, systematic error will occurs in each treatment fraction
EXAMPLES
• Patient movement during CT
• Interobserver variability in contouring
• Jaws / MLCs in wrong position
• Planning and treating the wrong site

7. RANDOM ERROR
• The random component of any error is a deviation that can vary in direction
and magnitude for each delivered treatment fraction.
• Random error occurs at the treatment delivery stage for this reason are often
referred to as treatment or daily execution errors.
EXAMPLES
• Daily variable movements – internal and external.
• Miss interpreting setup instructions.
• Poorly immobilized patients.

8. TO REDUCE TREATMENT ERRORS
 In the console the technologist should set the machine and patient as per the
plan by the help of reference image with MV / KV image
 If there is any machine setup error or patient set up error occurs that should be
with in the tolerance limit otherwise investigating and solve the problem before
treatment delivery
 To reduce the machine errors the quality assurance of the machine should be
verified by the medical physicist as per QA protocal

9. DESIRABLE CHARACTERITICS OF IMMOBILIZATION DEVICES.
• Should be transparent to allow visibility of beam light and optical distance indicator
• Should be light weight, strong and durable
• Ease to use
• Ease of making the device
• Comfort for the patient
• Minimal place requirement for the storage
• Resistance of bending and stretching
• Minimal perturbation of the beam so as not to produce any artifacts in the image
acquisitions.
• Device be useable on simulator, CT/MRI and other treatment planning imaging system
• Surface dose should not be altered
• Rigid & holds its shape over time.

10. HISTORY OF IMMOBILIZATION METHODS
Early days
• Standardized neck roll casts
• Marking tapes ( Skin markers )
• Breath hold technique

11. 1960-70s
POP ( CaSO4.1/2H20 )
• Skin markers
• Bite blocks
Card board,Icecream sticks,syringe

12. • Polyurethane foam

13. EARLY 1980 AND ONWARDS
Lasers AIO Base plate
Indexer
Head rests Plexiglass
Thermoplastic
mould

14. MATERIALS USED FOR IMMOBILIZATION
Variety of materials and methods are available for immobilization. Selection
of the immobilization depends on the comfort of the patient and preferred
by the Radiation Oncologist.
 Plaster of Paris.
 Thermoplastics.
 Vac-lok
 Bite blocks.

15. PLASTER OF PARIS ( POP )
It is prepared by heating GYPSUM to a temperature of 373K. when gypsum is heated to
a temperature of 373K, it loses three-fourths of its water of crystallization and forms
Plaster of paris
Advantages of Plaster of Paris 373k
 It is easily available >>>>>>>
 comfortable
 easy to mould
 strong and light
 easy to remove
 permeable to radiography
 permeable to air and hence underlying skin can breathe.
 non inflammable

16. PLASTIC MATERIALS
Plastic is subset of polymers
• Thermoplastic
• Thermosets
• Thermoplastic elastomers
• Polymer composites

17. DIFFERENT THERMOPLASTICS
• Acrylic, a polymer called poly(methyl methacrylate) (PMMA), is also known by trade
names such as Lucite, Perspex.
• Nylon
• PLA – Polylactic acid
• Polycarbonate
• Polyethylene
• Poly vinyl chloride ( PVC )
• Teflon etc.

18. THEMOPLASTICS
 It Consists of simple molecular structure
 All macro or monomers are chemical independent
 Intermolecular forces keeps them together

19. THERMOPLASTIC PRINCIPLE

20. VARIOUS CONFIGURATIONS OF THERMOPLASTIC

21. THERMOPLASTIC MOULD PREPARATION
 The most common immobilization device used to treat cancers is Thermoplastic.
 Available in different sizes and shapes.
 It is rigid in room temperature.
 When it heated in water( for temperature 60 to 65 degree)the material softens and
become malleable)
 The mask is first heated in a water bath. then the warm, pliable mask is pulled over the
patient
 The mask is then formed to the patient’s contours and left on the patient until is has
completely cooled
 PMMA (Poly methyl methacrylate)

22. ADVANTAGES
o Thermoplastic provide great reproducibility in daily treatment lightweight and
easy to use.
o Additionally modification can be made to mask if the patient experienced with
swelling or weight loss during the course of treatment.
DISADVANTAGES
o Windows cut can not be reused and when old it becomes very soft when
activated .

23. WHY WE ARE USING THERMOPLASTICS ?

24. IMPRESSIONS :
Head cast :- Ear impression & Nasal impression
Head & neck cast :- Ear impression, and sternal notch impression
Chest cast :- Sternal notch impression
Abdomen cast :- Sternal notch, umbilicus impression
Pelvic cast :- Umbilicus impression

25. VAC-LOK
• Radiolucent plastic cushions filled with tiny polystyrene ball
• Semi-deflated cushion moulded around the patient's gross body contours
• Using vacuum pump air is pumped out and the balls come together to form a firm solid
support
• The cushion becomes an entirely rigid and comfortable mould of the patient's body

26. VAC-LOK

27. The direct beam of radiation will pass through such mouth guard material, but will create a
space between the restoration and the cheek or tongue. ... Mouth guards can also be created
to prevent biting of irradiated tissues that might become swollen during
treatment
Patient supine with a straight spine
Custom made mouth bite ice cream sticks, card board etc.
Pushing the tongue inferiorly when irradiating the hard palate or upper alveolus
Separate the roof of the mouth from the inferior oral cavity when irradiating the tongue
MOUTH BITE

28. OTHER ACCESSORIES WE ARE USE IN MOULD ROOM
• HEAD RESTS
• INDEXING BAR
• KNEE REST & FOOT REST

30. SHOULDER RETRACTOR

31. TYPES OF IMMOBILIZATION
Head & neck immobilization
 Immobilization in Brain tumour
Thorax and Breast immobilization
 Pelvic and abdominal immobilization
 Immobilization for the Body extremities
SBRT solution with AIO Board

32. HEAD & NECK IMMOBILIZATION
• Head & neck immobilization Initial construction and selection of proper immobilization
for H&N cancer is one of the most important parts of confirming proper treatment of
the patient.
• Current methods for the H&N tumours include a variety of masks moulds, and frame
systems.
• In some instances, shoulder Retractors are used to pull the shoulders out of the
treatment field for the neck.

33. IMMOBILIZATION IN BRAIN
• For the General brain tumour and whole brain cases the mostly common
immobilization device is the 3 clamp & Uniframe ,Thermoplastic
• Immobilization becomes more complex for radiosurgery, Cyber knife and Gamma
Knife procedure because the requirements for positional and numerical accuracy for
the dose delivery are -+1mm.

34. THORAX AND BREAST IMMOBILIZATION
• There are 3 common immobilization Devices used when treating the tumours in
the chest cavity,
• VACLOK
• BREAST BOARD
• 2 CALMP OR 4 CLAMP THORACIKC MOULD.

35. BREAST BOARD

39. PELVIC IMMOBILIZATION
• There are two important aspects to be followed in the case of Pelvic Immobilization
• Properly maintain patients outer contour during treatment with respect to the isocenter
• Immobilization system such as vac lok ,belly board, and thermoplastic masks are
commonly used during treatment of pelvic region.

40. IMMOBILIZATION FOR EXTREMITIES
 Immobilization for the body Extremities is a quite challenge for us But with this special
thermoplastic solution we can perform it easily.
 The system consists of a low density carbon fiber
base plate with a leg support,
two comfort cushions and dedicated masks.
The base plate can be indexed to any couch top on 2-pin bars and has multiple holes to
offer a maximum of possibilities for positioning and immobilizing both upper and lower
extremities.

41. SRS / SRT
Stereotactic radiosurgery (SRS) is a non-surgical radiation therapy used to treat functional
abnormalities and small tumours of the brain.
It can deliver precisely-targeted radiation in fewer high-dose treatments than
external therapy, which can help preserve healthy tissue.
 Stereotactic radiosurgery (SRS) and Stereotactic radiotherapy (SRT) use precisely focused
radiation beams to treat tumours and other abnormal growths in the brain, spinal column and
other body sites.

42. SBRT IMMOBILIZATION:
• Stereotactic Body Radiation Therapy (SBRT) – SBRT is a treatment procedure similar to SRS,
except that it deals extra-cranial radiosurgery
• Simple to use, highly indexable, and easily adjustable.
• The carbon fiber baseplate is lightweight and has handgrip holes on either side for easier
placement and hanging options.
• The SBRT Baseplate indexes to the couch top in two places, and scalloped edges allow the
belly and knee bridge to be fixed in the best position for the patient.
• The height of the belly and knee bridges can be adjusted quickly, and the bridges lock and
unlock without fuss.
• The SBRT System is also equipped with an ergonomic belly compression paddle designed to
maximize patient comfort while providing necessary immobilization.

43. SBRT

44. Belly Bridge
• The Belly Bridge and is equipped with compression paddle for supressing the
abdominal regional.
• The bridge is easy to lock and unlock on the SBRT Baseplate and the bridge
height is easily adjustable.
• Additionally, the compression paddle can be adjusted laterally and offers
varying levels of compression for better customization and indexing.
• The SBRT System can be used with or without the belly compression bridge and
paddle.

45. RESPIRATORY BELT
Provides pneumatic compression and immobilization to the
abdominal region.
• The respiratory belt can be used for customized, comfortable belly suppression.
• it is secured with Velcro and comes with an easily readable pressure gauge.
• The SBRT System can be used with or without the respiratory belt.

46. BLUE BAGS
 Blue bags are stronger, more reliable
 A durable and non-permeable nylon shell prevents punctures and tears.
 All bags are completely air-tight and leak-proof, filled with low density polystyrene
mini-spheres. Metal-free valves are fully MR Safe.
 A corner grommet allows for easy storage.
 blue bags are designed for long-term multi-patient use.
 The nylon shell can be easily cleaned between patient use.
 The durable design means that bags need to be replaced less often.
 blue bags come with replaceable valves and can be equipped with valves to fit all
standard vacuum pumps.