SRS PLAN METRICS BY DR KANHU CHARAN PATRO

SRS PLAN METRICS BY DR KANHU CHARAN PATRO

1. 8/8/2024 1 SRS PLAN METRICS Dr Kanhu Charan Patro MD,DNB(Radiation Oncology),MBA,FICRO,FAROI(USA),PDCR,CEPC Clinical Director, HOD (Radiation Oncology) ISRo - I nstitute of S tereotactic R adiation o ncology Mahatma Gandhi Cancer Hospital & Research Institute, Visakhapatnam [email protected] /M- [phone]/ www.drkanhupatro.com THE COSID INDEX

2. SRS - Stereotactic Radiosurgery Stereotactic radiosurgery is very précised focused radiation therapy for intracranial lesions Benign Malignant Functional There is no surgery traditionally as there is no incision

3. Strict immobilization Extreme high dose

4. Indications

5. Steps

6. Steps

7. Elekta VERSA HD

8. Elekta VERSA HD MONACO 6MV Noncoplanar Dynamic delivery Cones ,KVCT based

9. Varian true beam STx

10. TRUE BEAM STx ECLIPSE 6MV Noncoplanar Dynamic delivery KVCT based

11. Tomotherpy

12. Tomotherpy MV/KV based 6MV, 6mm MLC Precision Helical, only coplanar Dose rate 1000

13. ZAP-X

14. ZAP-X Real time beam dosimetry 3MV Noncoplanar , > 2pi steradian coverage Gyroscopic gantry ,260 beam angle Cones ,DRR based

15. Cyberknife

16. Cyberknife

17. Gamma knife

18. Gamma knife n COBALT GAMMA PLAN Single target with multiple iso Small collimators

19. Proton Radiosurgery

20. MR Linac

21. MANAGEMENT OF DIFFUSE GLIOMAS 8/8/2024 22 SRS – Immobilization –frame to frameless

22. MANAGEMENT OF DIFFUSE GLIOMAS 8/8/2024 23 MLC and CONE

23. MANAGEMENT OF DIFFUSE GLIOMAS 8/8/2024 24 Isocentric vs Nonisocentric

24. For setup Is localizer box is mandatory ?

25. 2D verification vs 3D verification 8/8/2024 26

26. MANAGEMENT OF DIFFUSE GLIOMAS 8/8/2024 27 Hexapod couch ROLL YAW PITCH

27. MANAGEMENT OF DIFFUSE GLIOMAS 8/8/2024 28 FFF vs no FFF

28. PUSHING BACKWARD AND FORWARD AT A TIME DIFFICULT BUT NOT IMPOSSIBLE OAR TARGET 29

29. MANAGEMENT OF DIFFUSE GLIOMAS 8/8/2024 30 Michael Goitein

30. MANAGEMENT OF DIFFUSE GLIOMAS 8/8/2024 31 Basics – DVH

31. PLAN CONFLICTS OAR

32. 8/8/2024 33 Misleading DVH

33. 8/8/2024 34 DVH pitfalls Insensitive to hot spot and cold spot Shape of DVH alone can be misleading DVH is the most direct and informative representation of a treatment plan available 3D dose distribution are large and cumbersome to analyze quantitatively User interactivity is essential to extract the most information from dose distribution. Clinical studies have shown that DVH metrics correlate with patient toxicity outcomes. A drawback of the DVH methodology is that it offers no spatial information ; i.e., a DVH does not show where within a structure a dose is received.

34. Spatial Distribution

35. Basics of plan evaluation – Serial vs Parallel

36. Homogenous vs heterogenous NON STEROTAXY HOMOGENOUS PLAN STEROTAXY HETEROGENOUS PLAN FOR EXAMPLE, MARGINAL DOSE IS 20 Gy AT 80% MEANS YOU CAN ACCEPT HOT SPOT INSIDE 125% i.e. 25Gy 80% = 18Gy 100%= 18/80 X 100 = 25Gy

37. 8/8/2024 38 Dose displaying Isodose Contours : Set of closed contours linking voxels of equal dose Color Wash : The coding of CT and Dose in the same voxel through the modulation of both intensity (CT) and color (Dose) Isodose Surfaces: The Shaded surface (pseudo 3D) representation of the dose level and selected VOI

38. 8/8/2024 39 Low dose bath

39. 8/8/2024 40 BEAM entry exit point

40. 8/8/2024 41 Bridge dose between targets

41. MANAGEMENT OF DIFFUSE GLIOMAS 8/8/2024 42 BEV vs REV

42. QA IS MANDATORY

43. MANAGEMENT OF DIFFUSE GLIOMAS 8/8/2024 44 Plan evaluation

44. MANAGEMENT OF DIFFUSE GLIOMAS 8/8/2024 45 Notes to physics

45. DOSE PRESCRIPTION

46. MANAGEMENT OF DIFFUSE GLIOMAS 8/8/2024 47 CBCHOP Mary Dean/Applied Radiation Oncology/2017

47. PALN EVALAUATION - COSID INDEX

48. 8/8/2024 49 COSID INDEX Patro K C/Journal of Current Oncology/2022

49. COSID INDEX STEPS

50. 8/8/2024 51 Coverage Index Patro K C/Journal of Current Oncology/2022 PTV/CTV/GTV V 100 /D 100 100% coverage Dmax

51. 8/8/2024 52 OAR INDEX Patro K C/Journal of Current Oncology/2022 Max dose in series organ Mean dose in parallel organ Volumetric analysis

52. 8/8/2024 53 Basics of plan evaluation – Spillage Index Patro K C/Journal of Current Oncology/2022 Conformity index Homogeneity index Gradient index

53. 8/8/2024 54 Basics of plan evaluation – Imaging Index Patro K C/Journal of Current Oncology/2022 Axial view Coronal view Sagittal View

54. 8/8/2024 55 Basics of plan evaluation – Delivery index Patro K C/Journal of Current Oncology/2022 Complexity of plan MU Complexity of Delivery FFF VS FF

55. EXAMPLE

56. PLANNING CT 1mm slice Contrast Vertex to neck With fraxion

57. PLANNING MRI 3D-FSPGR CONTRAST 1MM SLICE NO GAP MULTIPLANNAR NO TILT DICOM FORMAT 512x512 MATRIX

58. IMAGE FUSION CT AND MRI FUSION

59. TARGET DELINEATION GTV delineation Volume- 4.65cc Multiplannar Evaluation

60. PTV 1mm Volume-5.75 cc

61. SMOOTH YOUR CONTOUR Smooth

62. OAR DELINEATION

63. PLANNING VMAT DCARC 3DCRT IMRT

64. 8/8/2024 66 Coverage Index Patro K C/Journal of Current Oncology/2022 PTV/CTV/GTV V 100 /D 100 100% coverage Dmax

65. PTV COVERAGE-COVERAGE INDEX SL NO PARAMETER VALUE 1 D MAX 22.89CC 2 D 95% 18.82CC 3 D 100% 16.62 CC 4 V 95% 99.93 5 V 18Gy [V 100% ] 99.15 6 V 110% 81.01 7 V 120% 17.97 8 V 130% Prescription Isodose level is usually not 100% PD covering 100% PTV Often 95% PD covering 95% PTV or higher Or 100% PD covering 95% PTV or higher. Michael Torrens,/J Neurosurg ( Suppl 2)/2014

66. 8/8/2024 68 OAR INDEX Patro K C/Journal of Current Oncology/2022 Max dose in series organ Mean dose in parallel organ Volumetric analysis

67. 12Gy VOLUME

68. 12Gy VOLUME WHOLE BRAIN-GTV Plan-10.765cc Desirable -10cc We found that the risk of developing S-NEC, but not A-NEC after gamma knife radiosurgery for non-AVM tumors correlates with 12-GyV. The risk of S-NEC increased significantly for 12-GyV 10 cc, regardless of plan conformality . These observations add to the knowledge base of postradiosurgical toxicity and can be used when planning and optimizing gamma knife radiosurgical treatments TIMOTHY KORYTKO / IJROBP /2006

69. OAR COVERAGE SL NO ORGAN DESIRABLE ACHIEVED 1 RT. EYE MAX <8Gy <1Gy 2 LT. EYE MAX <8Gy <1Gy 3 RT. OPTIC NERVE MAX <8Gy <1Gy 4 LT. OPTIC NERVE MAX <8Gy <1Gy 5 OPTIC CHIASM MAX <8Gy 1.88Gy 6 RT. HIPPOCAMPUS 5Gy 7 LT. HIPPOCAMPUS 9Gy 8 BRAIN STEM MAX <8Gy 3.83Gy 9 RT. COCHLEA MEAN<9Gy <1Gy 10 LT. COCHLEA MEAN<9Gy <1Gy GG HANNA/CLINICAL ONCOLOGY/2016

70. 8/8/2024 73 Basics of plan evaluation – Spillage Index Patro K C/Journal of Current Oncology/2022 Conformity index Homogeneity index Gradient index

71. RTOG CONFORMITY INDEX FORMULA VOLUME OF PRESCRIPTION ISODOSE/PTV VOLUME 6.811/5.755=1.18 DESIRABLE=1-2 [Sonja Petkovska Proceedings of the Second Conference on Medical Physics and Biomedical Engineering] PTV 100%

72. PADDICK CONFORMITY INDEX FORMULA (VOLUME OF PRESCRIPTION ISODOSE IN AREA OF INTEREST) 2 PTV VOLUME X VOLUME OF PRESCRIPTION ISODOSE 5.706X5.706/5.755X6.811=0.82 IDEAL=  > 0.85. AND <1 Michael Torrens,/J Neurosurg ( Suppl 2)/2014

73. HOMOGENITY INDEX FORMULA MAXIMUM DOSE/PRESCRIPTION DOSE 22.89/18 = 1.27 DESIRABLE = 1.1-1.3 NON STEROTAXY HOMOGENOUS PLAN STEROTAXY HETEROGENOUS PLAN

74. 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 must calculate equivalent radius Dose fall off- Gradient index

75. EQUIVALENT RADIUS 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 π r 3 r= (3V/4 π ) 1/3 Online calculator

76. EQUIVALENT RADIUS SL NO PARAMETER VOLUME RADIUS 1 100% ISODOSE 6.811CC 1.18CM 2 80% ISODOSE 18.82CC 1.38CM 3 60% ISODOSE 16.62 CC 1.6CM 4 50% ISODOSE 99.93 1.74CM 5 40% ISODOSE 99.15 1.93MM r= (3V/4 π ) 1/3

77. GRADIENT INDEX FORMULA Difference of equivalent radius of prescription isodose and equivalent radius of 50% isodose 1.18cm AND 1.74cm 0.56cm It should be between 0.3 to 0.9

78. GRADIENT INDEX-OTHER Ratio of the volume enclosed by half of the prescription isodose, which is divided by the Prescription Isodose Volume 9Gy VOLUME/18Gy VOLUME 22.2/6.8=3.2 IDEAL <3 Michael Torrens,/J Neurosurg ( Suppl 2)/2014

79. DISTANCE BETWEEN VARIOUS ISODOSE LINES Between 80% and 60%- ideal-<2mm Here- [1.38 and 1.6 cm]-0.22cm Between 80% and 40%- ideal- <8mm Here- [1.38 and 1.93 cm]-0.55cm EORTC-22952-26001

80. 8/8/2024 83 Basics of plan evaluation – Imaging Index Patro K C/Journal of Current Oncology/2022 Axial view Coronal view Sagittal View

81. 8/8/2024 84 Slicoscopy

82. 8/8/2024 85 Basics of plan evaluation – Delivery index Patro K C/Journal of Current Oncology/2022 Complexity of plan MU Complexity of Delivery FFF VS FF BEAM ARRANGEMENTS

83. 8/8/2024 86 BEAM ARRANGEMENTS

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

85. DRY RUN

86. SET-UP VERIFICATION CBCT CORRECTIONS

87. SET-UP VERIFICATION HEXAPOD CORRECTIONS

88. AUTOMATED EXCEL SHEET

89. Basics of plan evaluation – Check list TARGET COVERAGE D2 D98 AXIAL SAGGITAL CORONAL GTVp GTVn CTV PTV OAR LIMIT PHASE 1 PHASE 2 TOTAL VARIATION OC-[0.03cc] RON [0.03cc] LON [0.03cc] EYE_R MEAN EYE_L MEAN PAROTID_R MEAN PAROTID_L MEAN SPINAL CORD [0.03cc] BRAIN STEM [0.03cc]

90. 8/8/2024 93 Basics of plan evaluation – Check list

91. SRS PLAN EVALUATION CHECK LIST SHEET

92. ROSE ARTICLE- BRAIN METS

93. ROSE ARTICLE- BRAIN MET CAVITY SRS

94. ROSE ARTICLE- Glomus Jugulare

95. ROSE ARTICLE- VESTIBULAR SCHWANNOMA

96. ROSE ARTICLE- MENINGIOMA

97. Stereotaxy class

98. SRS/SBRT

99. Dr Kanhu’s Oncoeducation

100. Kanhu 8/8/2024 103