This document summarizes the case of a 47-year-old male patient with brain metastases from lung cancer. He underwent surgery to remove a left occipital lobe tumor. Following surgery, the patient was planned for stereotactic radiosurgery to treat a residual cavity. The treatment plan delivered 30Gy over 5 fractions to the planning target volume surrounding the cavity. Dosimetry parameters and organ-at-risk constraints were evaluated to ensure safe and accurate delivery of the prescribed dose.

1. ROSE CASE
BRAIN METASTASIS CAVITY SRS
RADIATION ONCOLOGY
SIMULATION TO EXECUTION
DR KANHU CHARAN PATRO

2. HISTORY
• 47year male
• Nonsmoker
• ECOG-1
• One episode of GTCS in the month of march 12 2020.
• Duration of the episode is for 3 to 4 min, followed by aura.
• Post ictal confusion for a duration of 15 to 20 min
• No headache and vomiting
• No history of involuntary urination or defecation.
• Another episode of GTCS in the month of June 15th 2020.
• Duration of the episode is for 2 to 3 min, followed by aura.
• Post ictal confusion for a duration of 25 to 30 min
• No headache and vomiting’s.
• No history of involuntary urination or defecation

3. • Left occipital lobe and inferior
temporal lobe.
• Lesion of size 3.2*3.2 cm
• Hypointense on T1 .
• Heterogenous on T2 .
• Brilliantly heterogenous
enhancement
• Perilesional edema present
• Occipital horn of left lateral
ventricle dilated.
• MR spectroscopy shows
increased choline and
decreased NAA.
• Possibilities :? Ganglioglioma
PRE OP MRI

4. Preop image MRI
Adjacent to
dura
Sinus
involvement

5. • Left Prieto occipital
craniotomy
• Gross total excision
• Very vascular
• Clear plane of cleavage
SURGERY

6. • pT- 4cm x 3.5cm x 1.5cm
• Metastatic papillary
Adeno carcinoma
• CK7 positive
• TTF1 positive
• ALK- Awaited
• ROS- Awaited
• EGFR- Awaited
Histopathology and IHC

7. • Left temporo-occipital region
lesion
• Post surgical defect of size
3.2*3.0cm
• Thick walled minimal irregular
outline cavity
• Central cystic
• Hypointense on T1
• Hyperintense on T2
• Bloom on wall cavity s/o
hemorrhagic products
• No perilesional edema is seen.
• Hyperintense on diffusion images
along the peripheral wall of
lesion.
POST OP MRI

8. • Brain : surgical defect in the
left parieto-occipital region
• Size 3.2*2.4cm
• Lung : spiculated lesion in the
upper lobe of right lung .
• Size 2.6*2.1 (SUV max 3.5)
• Innumerable sub centimeter
nodules in both the lungs. s/o
met
• Right paratracheal lymph node
size 1.1*1.6 (SUV max 3).
• Hypermetabolic lymph nodes
in the right paratracheal and
subcarinal region.
PET SCAN WHOLE BODY

9. • CA Right lung with brain
metastasis
• Post operative case of
the brain metastasis
• TNM staging :
cT4N2M1b
Final Diagnosis

10. Tumor board decision
• After group discussion with neurosurgeon,
radiation oncologist and medical oncologist
board decided to plan for stereotactic
radiotherapy followed by chemotherapy
• Patient was explained about complications
and outcome of the procedure

11. STEREOTACTIC RADIOSURGERY
FOLLOWED BY CHEMOTHERAPY
PLAN of treatment

12. Patient discussion
• Discussed about the procedure
• Discussed about imaging and follow up
• Discussed about tumor response
• Discussed about need of radiotherapy in
future[WBRT/SRS]
• Discussed about post radiotherapy raised ICT

13. TUMOR CONTROL
APPERANCE OF NEW LESION IN FUTURE
RADIONECROSIS
Patient discussion

14. • Planned for FSRT
• Plan multiple fraction
• 30Gy/5# - marginal dose
Radiation tumor board

15. Immobilization and set up

16. Time interval to address cavity dynamics
Caution must be taken when treating cavities in the early(<21 days) interval after
surgery as it may lead to irradiating more normal tissue especially in small tumors

17. Time interval to address cavity dynamics

18. Give adequate DREAM protocol before
planning image to decrease edema
Drug Dosage
D Inj. /tab DEXA 8mg Thrice a day after food 5days
R Inj. /tab Ranitidine Twice a day before food 5days
E Inj. /tab Emset 8mg Thrice a day before food 5days
A ANTIEPILEPTICS SOS
M Inj. Mannitol
Syp. Glycerol
Thrice a day infusion over 20 min
20 ml Thrice a day in apple juice

19. • Surgery date -23rd JUNE 2020
• MRI planning 17th JULY 2020 - 24th day post op
• CT planning – 21st JULY 2020 - 28th day post op
Time interval to address cavity dynamics

20. • 1mm slice
• Contrast
• Vertex to neck
• With Fraxion
• CT plan done at end
of 28th day of surgery
keeping the cavity
remodeling in mind
Planning CT

21. MRI protocol
• T1/T2/FLAIR sequence- Usual
sequence
• 3D FSPGR contrast- Normal
anatomy
• 512x 512 matrix
• 1mm slice
• No gap
• No tilt
• Neutral neck
• FOV should include
• body contour nose, eye and skull

22. Pattern of recurrence in cavity
• Cavity
• LMD-leptomeningeal spread
– Nodular pattern
– Sugarcoat pattern
• Surgical tract
• Based on histology

24. • Breast cancer histology,
• Piecemeal resection of BM
• Posterior fossa location
• Multiple BM
• And hemorrhagic or cystic features
• It is thought that this increased risk is due to
tumor spillage into the cerebrospinal fluid
(CSF) at the time of surgical resection
Risk factors for LMD

25. • Nodular LMD (nLMD) was defined as new focal
extra-axial distinct nodular enhancing lesions
located on the leptomeninges or ependyma.
• Classical LMD (cLMD) was akin to “sugarcoating”
enhancement and was defined as new linear or
curvilinear enhancement of the leptomeninges
involving the sulci of the cerebral hemispheres,
cranial nerves, brainstem, cerebellar folia, or
ependyma
Types of recurrence

26. Consensus guidelines

27. Basics of target delineation
• ADJACENT DURA and
SURGICAL TRACT
• BONE FLAP INNER PART
• CAVITY PROPER
• DURAL SINUS
• ENHANCING COMPONENT

28. A-Contour of Adjacent Dura

29. B-Contour of Bony flap and tract

30. C-Contour of Cavity

31. D-Contour of Dural sinus

32. E-Contour of Enhancing component

33. • A+B+C+D+E
• CTV delineation
• VOLUME- cc
• Multiplanar evaluation
Target delineation total CTV

34. • 1mm
• VOLUME-37.491CC
PTV

35. • VOLUME- 1598CC
Brain-CTV

36. Multiplanar CTV and PTV

37. Smooth your contour

38. OAR DELINEATIONOAR delineation

39. Image fusion

40. • VMAT
• DCARC
• 3DCRT
• IMRT
Planning

41. The dose selection

42. The dose selection

43. Wait for Alliance A071801 trial

44. SL NO PARAMETER VALUE
1 D MAX 36.43Gy
2 D95% 31.01Gy
3 D100% 28.23Gy
4 V95% 99.99%
5 V30 Gy[V100%] 99.56%
6 V110% 44.45%
7 V120% 0.03%
8 V130% 0%
1. Prescription Isodose level is usually not 100% PD covering 100% PTV
2. Often 95% PD covering 95% PTV or higher
3. Or 100% PD covering 95% PTV or higher.
Michael Torrens,/J Neurosurg (Suppl 2)/2014
PTV coverage index

45. • FORMULA
• VOLUME OF PRESCRIPTION ISODOSE/PTV VOLUME
• 43.798/37.491=1.17
• DESIRABLE=1
[Sonja Petkovska
Proceedings of the Second
Conference on Medical Physics and
Biomedical Engineering]
RTOG conformity index

46. • FORMULA
(VOLUME OF PRESCRIPTION ISODOSE IN AREA OF INTEREST)2
PTV VOLUME X VOLUME OF PRESCRIPTION ISODOSE
• =39.764 x 39.764 /37.494 x43.798 =0.96
• IDEAL= > 0.85. AND <1
Michael Torrens,/J Neurosurg (Suppl 2)/2014
Paddick conformity index

47. • FORMULA
• MAXIMUM DOSE/PRESCRIPTION DOSE
• 36.43Gy/30Gy=1.21
• DESIRABLE = 1.1-1.3
HOMOGENITY index

48. • Dose fall off observation is very much needed in this
evaluation under headings
• Gradient index
• Difference between various isodose lines
• e.g between 80% and 60%- ideal- <2mm
• Between 80% and 40%- ideal- < 8mm
• For that reason we have to calculate equivalent
radius
Dose fall off

49. • To evaluate dose gradient we have to find out
difference between radius of various isodose line
• But none is iso spherical
• We have to find out equivalent radius from formula
• First find out the specified isodose volume
• Then calculate the radius
• V=4/3 πr3
• r= (3V/4π)1/3
Equivalent radius

50. SL NO PARAMETER VOLUME RADIUS
1 100% ISODOSE 43.79CC 2.19mm
2 80% ISODOSE 64.45CC 2.49mm
3 60% ISODOSE 101.19CC 2.89mm
4 50% ISODOSE 130.84CC 3.15mm
5 40% ISODOSE 177.96CC 3.49mm
r= (3V/4π)1/3
Equivalent radius

51. • FORMULA
– Difference of equivalent radius of prescription
isodose and equivalent radius of 50% isodose
• 2.19mm-3.15mm=0.96mm
• It should be between 0.3 to 0.9
Gradient index

52. • BETWEEN 80% AND 60%- IDEAL-<2mm
– HERE- 0. 4mm
• BETWEEN 80% AND 40%- IDEAL- <8mm
– HERE- 1mm
EORTC-22952-26001
Distance between various isodose lines

53. BMC - BRAIN MINUS CAVITY

54. • Requirement V30Gy = 10.5cc
• Achieved =10.30cc
BMC - BRAIN MINUS CAVITY
Salman Faruqi/ IJROBP/ 2019

55. BMC - BRAIN MINUS CAVITY

56. Isodose line
COLOUR ISODOSE LINE
Dark green 100%
Light green 80%
Sky green 60%
Pink 50%
Blue 40%
ISODOSE LINES

57. CONSTRAINTS

58. SL NO ORGAN DESIRABLE ACHIEVED
1 RT. EYE MAX <22.5Gy 1.97Gy
2 LT. EYE MAX <22.5Gy 4.4Gy
3 RT. OPTIC NERVE MAX <22.5Gy 2.3Gy
4 LT. OPTIC NERVE MAX <22.5Gy 5.5Gy
5 OPTIC CHIASM MAX <22.5Gy 7.5Gy
8 BRAIN STEM MAX 23-31Gy 10.01Gy
9 RT. COCHLEA MEAN <25Gy <1Gy
10 LT. COCHLEA MEAN <25Gy <1Gy
GG HANNA/CLINICAL ONCOLOGY/2016
OAR coverage

59. • MECHANICAL ISOCENTER CHECK
– WINSTON LUTZ TEST
• POINT DOSE VERIFICATION
• TOLERANCE-1MM
Travis R. Denton/JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS/2015
QA part

60. Dry run

61. • CBCT CORRECTIONS
Set-up verification

62. • HEXAPOD CORRECTIONS
Set-up verification

63. PREMEDICATION
• TAB. DEXAMETHASONE 8MG THRICE DAILY
STARTING DAY BEFORE
• TAB. ONDANSETRON 8MG THRICE DAILY
STARTING DAY BEFORE
• TAB. PAN 4O ONCE DAILY STARTING DAY
BEFORE
• DIABETES CARE IF
Pre medication-optional

64. • TAPER THE STEROID OVER A WEEK
• ANTI EMETICS
• PPI
Post medication-optional

65. • Imaging after 3 months
Advised

66. DOCTORS
• DR P S BHATTACHARYA
• DR C R KUNDU
• DR V K REDDY
• DR P MADHURI
PHYSICISTS
• MR A C PRABU
• MR A SRINU
• MR Prasad
• DR ANIL KUMAR
TECHNOLOGIST TEAM
Acknowledgments