Different Radiotherapy Modalities in treatment of brain tumors. @D

1. ROLE OF RADIOTHERAPY IN
BRAIN TUMORS
Dr. Abhilash G
JR-3

2. SEER STATISTICS
 Brain tumors account for 1.4% of all cancers
 Median age of diagnosis is 58 years.
 Incidence is 6.4 per 100,000 men and
women per year
 The 5-year survival for localized brain and
other nervous system cancer is 36.3%.
 Brain tumors account for 2.6% of all cancer
deaths

3. INTRODUCTION
 Sixty percent of all primary brain tumours are
glial tumours, and two-thirds of these are
clinically aggressive, high-grade tumours.

4. COBALT 60 LINAC

5. INDICATIONS OF RADIOTHERAPY
 High Grade Gliomas
 Residual Disease
 Recurrent Disease
 Benign Tumors
 Brachytherapy (selected cases)

7. BENIGN BRAIN TUMORS
 Meningioma
 Pituitary tumors
 Craniopharyngioma
 Arteriovenous Malformations
 Hemangioblastoma and Hemangiopericytoma
 Glomus Jugulare Tumor
 Pineocytoma
 Chordoma
 Vestibular Schwannoma
 Ganglioglioma
 Central Neurocytoma

8. TYPES OF
RADIOTHERAPY
TECHNIQUES

9.  Conventional 2D approach
 3 dimensional conformal radiotherapy
(3DCRT)
 Stereotactic Radiosurgery and Stereotactic
Radiotherapy
 Brachytherapy
 Proton Beam Therapy

10. Two Dimensional planning
for Brain Tumors

11. CONTOUR TARGET
OUTLINE

12. PLACE A FIELD

13. Immobilization
• Head Rest
• Thermoplastic mask
• Base plate

14. 2-D BEAM ARRANGEMENTS

15. CONVENTIONAL PLANNING
 Disadvantages
 Irradiation of large volumes of brain with
normal tissue also
 Higher toxicity and side effects
 Lack of 3D visualization of tumor
 2D planning of 3D tumor

16. 3D CRT

17. Immobilization
Delineation of
Target & critical organs
Beam
Shaping
Block , MLC
Steps of 3DCRT

18. TAKING PLANNING CT SLICES IN
NEUROONCOLOGY
 Different from diagnostic imaging
 Use appropriate immobilization device
 Image the patient in treatment position

19. Planning MRI
• Position
Ideally in treatment position with
orfit & base plate.
• Transfer images to planning system

20. Imaging
• CT
• CT-MR Fusion
• PET Scan – limited but
emerging role

21. TARGET DELIENATION

22. BEAM SHAPING

23. Multileaf collimators (MLC)
Tumor
OAR
OAR

24. PLAN EVALUATION

25. 3-D PLANNING
 Advantages
 Ideal for all cases
 Conformal
 Maximum sparing of normal tissue
 Lower toxicity

26. Stereotactic Radiosurgery
and Stereotactic
Radiotherapy

27.  “Stereo”: Greek: Solid or 3 dimensional “tact” Latin: To
touch: Greek “taxic” an arrangement
 Stereotactic: 3 dimensional arrangement to touch
 Stereotactic Radiosurgery (SRS): Stereotactically
directed conformal radiation in a single fraction
 Stereotactic Radiation Therapy (SRT): Stereotactically
directed conformal radiation in multiple fractions
 Fractionated Stereotactic Radiosurgery (FSR):
Stereotactically directed conformal radiation in 2-5
fractions

28.  Advantages of SRS and SRT over 3DCRT
High conformity
To treat small lesions not amenable to 3D
CRT
Higher tumor dose
Save larger amount of normal tissue

29. STEREOTACTIC
RADIOSURGERY
STEREOTACTIC
RADIOTHERAPY
Dose per Fraction High Low
Number of Fractions 1 Multiple
Targeting accuracy <1 mm 3-20 mm

30. INDICATIONS
SRS
 Benign and malignant brain tumors
 Arteriovenous malformations
 Well circumscribed targets < 4 cm diameter
SRT
 Lesions > 4cm
 Lesions located near critical structures

31. Leksell Frame
Brain Lab Non invasive head ring for SRT

33. GAMMA KNIFE (SRS & SRT)

34. ADVANTAGES
• Over 30 years of clinical use and a large clinical
experience
• Very high targeting precision
• Multiple targets treated during a single treatment
session
DISADVANTAGES
• Use in the brain only
• Painful stereotactic head frame
• Difficult to treat lesions located in the periphery of the
brain
• Co sources decay, increasing treatment time and cost
to replace after 5 years

35. LINAC BASED (SRS & SRT)

36. ADVANTAGES
• More commonplace technology in hospitals
• No invasive stereotactic frame
• Can be used for extracranial tumors also
DISADVANTAGES
• Painful head frame
• Less targeting accuracy and treatment accuracy when treating
extracranial tumors

37. TRUE BEAM

38. Linear
Accelerator
Manipulator
Image
Detectors
X-ray Sources
IMAGING
SYSTEM
ROBOTIC
DELIVERY
SYSTEM
TARGETING SOFTWARE
Cyber knife

39. Gamma Knife Cyber Knife
Immobilization Invasive Frame Frameless
Patient Comfort Moderate Very Good
Issue of radioactivity Replacement & Disposal None

40. BRACHYTHERAPY
 bis-Chloronitrosourea (BCNU)-impregnated
biodegradable polymer (GLIADEL wafer)
may be considered for intraoperative
placement if frozen section reveals high
grade glioma.
 I-125 liquid soaked wafers also used

42. FUTURISTIC
RADIOTHERAPY IN
BRAIN TUMORS

43. PROTON BEAM THERAPY

44.  Low entrance dose
(plateau)
 Maximum dose at depth
(Bragg peak)
 Rapid distal dose fall-off
Photons Protons

45. PROTONS IN CNS TRIALS
• Low grade & High grade glioma
• Benign brain tumors:
– Vestibular Schwannomas/Acoustic Neuromas
– Meningioma
– Pituitary adenoma
– AVM
• Skull base tumors: Chordoma/Chondrosarcomas
• Pediatric brain tumors: Medulloblastoma,
Ependymoma, Pilocytic astrocytoma, Germ cell
tumors

46. EXAMPLE – CASE OF
PITUITARY ADENOMA

47. TWO DIMENSIONAL PLAN

48. THREE DIMENSIONAL PLAN

49. CYBER KNIFE PLAN

50. SUMMARY
 Multiple options and techniques available for
treating brain tumors.
 Need to use the optimum technique
 Decision to be based on need of patient and
available technique.

51. THANK YOU