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IGRT IN LUNG CANCER
(PART-I)
Bharti Devnani
Moderator- Dr Shaleen Kumar
ROADMAP
1. Indications of RT in lung cancers
2. Role of IGRT in lung cancer
3. IGRT (motion management) strategies
 Free ...
6. Objectives
 Hypofractionation schedules
 BED calculations
 Constrains
7. Outcomes and patterns of failure
8. Toxicit...
INDICATIONS OF RT IN LUNG
CANCERS
INDICATIONS OF RT IN NSCLC
Early stage (I) tumors
 SBRT (T1, T2a inoperable)
 PORT for margin + / upstage to N2
Locally ...
Locally advanced stage (II/III)
Operable disease
 NACT+RT
 NACT-Sx-Post op RT
 PORT
Advanced /Metastatic disease
 For ...
Lobectomy
 FEV1 >75% of predicted volume or >1 liter
 DLCO >60% of predicted capacity.
 For ambiguous cases that are ne...
INDICATIONS FOR SBRT
Indiana University Criteria (Pulmonary)
- Baseline FEV1 < 40%
- Likely post-op FEV1 < 30% predicted
-...
ROLE OF IGRT
WHY IGRT
“Normal” Treatment plan
The effect of motion
 Cranio-caudal movement 0-12 mm +3 mm
 Medio-lateral 2-3 mm+2 mm
 Dorso-ventral 2-3 mm+2 mm
 50% of tumors move > 5 mm...
ICRU-62
significantly
GOAL OF RADIATION THERAPY
WHEN TO DO IGRT
AAPM-76
MOTION MANAGEMENT SOLUTIONS
Breath hold methods
 Organ motion dampening – Abdominal
compression
 Automated breath coordi...
BREATH HOLD METHODS
ABDOMINAL COMPRESSION
Abdominal compression reduces diaphragmatic excursion with
inspiration.
Dampens tumor motion throu...
PNEUMATIC COMPRESSION BELT
 Air inflation bulb
 Pressure gauge
 Non-Rigid
 Recording of the pressure
 Easy to use!
 ...
Advantages
 Abdominal compression reduces diaphragmatic excursion
with inspiration.
 Dampens tumor motion throughout the...
AUTOMATED BREATH COORDINATOR (ABC)
Components
Nose clip
Mouth piece
Spirometer to
measure respiratory
trace
Balloon va...
 A baseline PFT is done to know the patient’s
inspiratory capacity
 Coaching of breath hold to achieve a steady
breathin...
 The threshold is then fixed at 75 % of the average
inspiratory capacity and value is documented.
 When the operator act...
Advantage
 V20 and the mean lung dose decreases with an
increase in lung volume
 Increases the distance between the tumo...
FREE BREATHING METHODS
ITV BASED TREATMENT
Generates a composite target
volume for lung tumors, taking into
account the different shape, size
and...
THE PRINCIPLE OF GATING
Beam delivery is coupled with the phase of
respiration
Treatment delivery is done in the phase of ...
RPM
Real time Position Management (RPM)
1. CCD camera with attached illuminator
2.Camera interfaced with PC
3. Infrared re...
EXT. FIDUCIAL SYSTEM (IR REFLECTORS)
Plastic block is placed on the chest of the patient.
 The system tracks the upper marker as the
indicator of the breathin...
Gating System by ANZAI
AZ-733
THE PRINCIPLE OF “TRACKING”
SYNCHRONY
Synchrony camera
Synchrony tracking markers
Fiber optic sensing technology
Tracks patient’s respiratory motion
IMAGE ACQUISITION
Motion artifacts in free breathing 3 D scan
 Severe geometrical distortion
 Center of the imaged targe...
SOLUTIONS
 Breath-hold CT scan
Voluntary breath hold
Active breathing control
Combine inhale and exhale GTVs to get ITV
...
SLOW CT
Patient breathes normally
Rotation time >> breathing period
CT images are an average over all
breathing phases
Bor...
3 D CT SCAN
3
2
14
5
6
7
8 9
10
A large amount of
data is generated!
(>800 slices)
X-ray on
Exhalation
Inhalation
1st couch
position
2nd couch
position
3rd couch
position
“Image acquired”
signal to RPM
sys...
CT Scan
Axial scan trigger,
1st couch position
Axial scan trigger,
2nd couch position
Exhalation
Inhalation
Scan Scan Scan...
CORRELATION MODELS
IGRT IN LUNG CANCER
(PART-II)
ROADMAP
1. Indications of RT in lung cancers
2. Role of IGRT in lung cancer
3. IGRT (motion management) strategies
 Free ...
6. Objectives
 Hypofractionation schedules
 BED calculations
 Constrains
7. Outcomes and patterns of failure
8. Toxicit...
SEGMENTATION OF TUMOR
GTV
 Contrast if tumor located near great vessels or
close bronchial tree
 CT pulmonary windows fo...
IMPACT OF WINDOW LEVEL
Role of PET-CT
 To differentiate tumor from atelectasis
 To differentiate chest wall
musculature from tumor
 Accurate t...
Generation of iGTV
 Combining the entire GTV from all resp phases
 Combining the GTV contours from two extreme
respirato...
CTV- controversy
 No CTV in RTOG trials
 CTV=GTV
 Some centres CTV=5-8 mm expansion of GTV
PTV
 Appropriate PTV margin...
Size of movement dependent on:
-tumour location in the lung
-fixation to adjacent structures
-lung capacity and oxygenatio...
PTV Plus 2 cm
 As part of the QA requirements for “intermediate
dose spillage” a maximum dose to any point 2 cm
away in a...
ORGANS AT RISK
Lung
Spinal cord
Esophagus
Trachea
bronchus
Brachial plexus
Serial –parallel
Heart
Chest wall??
SEGMENTATION OF OARS
Average intensity projection when using 4D CT data
Spinal cord
Based on the bony limits of the spinal...
Heart
Contoured along with the pericardial sac. Superiorly
from the level of the inferior aspect of the aortic
arch (aorto...
Brachial Plexus
RTOG guidelines
Great vessels
Rt sided tumors- IVC
Lt sided –Aorta
All musculer layer out of fatty adventi...
Trachea
 Proximal-10 cm sup to PTV or 5 cm proximal to
carina till 2 cm proximal to carina
 Distal 2 cm trachea-included...
D
Dose/toxicity
concerns for
•Bronchus/trachea
•Esophagus
•Great vessels
Skin
It is contoured as rind of uniform thickness (0.5 cm)
which envelopes the entire body in the axial planes.
Rib
 Ribs...
RADIOBIOLOGICAL CONSIDERATIONS IN SBRT
SCHEDULES
 Endothelial cell damage
 Lethal cell damage
 Immunological effects?
LQ MODEL: HYPO FRACTIONATED
TREATMENTS
 In vitro studies: LQ Model fits well between 0-16 Gy
*Garcia LM et al Phys Med Bi...
WHAT HAPPENS WHEN LQ EQUATION IS USED TO
CALCULATE DOSE EQUIVALENCE AT HIGH DOSE PER
FRACTION
DOSE FRACTIONATION SCHEDULES
Range BED (Gy) 3yr OS T1 3 Yr OS T2 Gr III –V
toxicity
Low <83.2 0.554 0.170 0.053
Medium 83.2-106 0.863 0.544 0.073
Mediu...
LC and OS rates in 5 years with a BED of 100 Gy or more were
superior
BED <180 Gy -safe for stage I NSCLC
J Thorac Oncol...
DOSE FRACTIONATION SCHEDULES
location #
Away from
chest wall
20X3
Close to chest
wall
12X 4
Central lesion 8x6
Avoid hot spots in hilum, chest wall,
m...
Structure RTOG 0915 RTOG 0236 RTOG 915 RTOG 813
34X1 20x3 12x4 10-12x5
Cord 14Gy 18(6) Gy 26Gy 30(6) Gy
Esophagus 15.4Gy 2...
Critical volume
lung
Critical volume
Dmax lung
End point
RTOG-0813 1000cc 13.5 Gy pnemonitis
RTOG-0915 1000cc 7.4 Gy
(sing...
Trial Dose # Min gap Total time note
RTOG-0236 20x3 40 hrs
Max-8 days
1.5 wks Not more
than 2# a wk
allowed
RTOG-0813 10-1...
PLANNING
Multiple , non opposing, non coplanar beams
Prescription isodose:
The prescription isodose surface must be ≥ 60% ...
High Dose Spillage
The cumulative volume of all tissue outside the
PTV receiving a dose > 105% of prescription dose
should...
SBRT in lung cancer
SBRT in lung cancer
SBRT in lung cancer
SBRT in lung cancer
SBRT in lung cancer
SBRT in lung cancer
SBRT in lung cancer
SBRT in lung cancer
SBRT in lung cancer
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SBRT in lung cancer

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role of sbrt in lung cancer

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SBRT in lung cancer

  1. 1. IGRT IN LUNG CANCER (PART-I) Bharti Devnani Moderator- Dr Shaleen Kumar
  2. 2. ROADMAP 1. Indications of RT in lung cancers 2. Role of IGRT in lung cancer 3. IGRT (motion management) strategies  Free breathing  Breath hold methods 4. Technological aspects  Acquiring CT  Appreciation of tumor motion 5. Segmentation  Tumor  Normal tissues
  3. 3. 6. Objectives  Hypofractionation schedules  BED calculations  Constrains 7. Outcomes and patterns of failure 8. Toxicities and challenges 9. Comparison with other competing modalities 10. Follow-up 11. Conclusions and future directions
  4. 4. INDICATIONS OF RT IN LUNG CANCERS
  5. 5. INDICATIONS OF RT IN NSCLC Early stage (I) tumors  SBRT (T1, T2a inoperable)  PORT for margin + / upstage to N2 Locally advanced stage (II/III) Inoperable disease  Concurrent CTRT  Sequential ChemoRT/ RT alone in frail patients  Accelarated RT
  6. 6. Locally advanced stage (II/III) Operable disease  NACT+RT  NACT-Sx-Post op RT  PORT Advanced /Metastatic disease  For palliation pain/ bleeding/obstruction
  7. 7. Lobectomy  FEV1 >75% of predicted volume or >1 liter  DLCO >60% of predicted capacity.  For ambiguous cases that are near these thresholds, a Xenon study is obtained to predict postoperative pulmonary function.  Predicted postop.FEV1 <35% there is an increased risk of death.  Predicted postop. DLCO <40% is associated with an increased surgical complication rate.
  8. 8. INDICATIONS FOR SBRT Indiana University Criteria (Pulmonary) - Baseline FEV1 < 40% - Likely post-op FEV1 < 30% predicted - DLCO < 40% predicted - Hypoxemia (pO2 < 70mm Hg) - Hypercapnea (pCO2 > 50 mm Hg) - Exercise oxygen consumption < 50% predicted Other Potential Factors - Cardiac (IHD, LVF, PAH) - Anesthesia - Post-operative recovery Timmerman, Nov 2003 Chest 124(5):1946-55
  9. 9. ROLE OF IGRT
  10. 10. WHY IGRT “Normal” Treatment plan
  11. 11. The effect of motion
  12. 12.  Cranio-caudal movement 0-12 mm +3 mm  Medio-lateral 2-3 mm+2 mm  Dorso-ventral 2-3 mm+2 mm  50% of tumors move > 5 mm and >11% move >1 cm (up to 4 cm), particularly those close to diaphagram Ekberg L et al Radiother Oncol 1998 Jul;48(1):71-7 Bissonette JP.IJROBP 2009;75:688-695
  13. 13. ICRU-62
  14. 14. significantly
  15. 15. GOAL OF RADIATION THERAPY
  16. 16. WHEN TO DO IGRT AAPM-76
  17. 17. MOTION MANAGEMENT SOLUTIONS Breath hold methods  Organ motion dampening – Abdominal compression  Automated breath coordinator (ABC) Free breathing methods  ITV based treatment  Respiratory gating Real time position managment(RPM)  Tumor tracking (Exac trac/ Cyberknife/VERO)
  18. 18. BREATH HOLD METHODS
  19. 19. ABDOMINAL COMPRESSION Abdominal compression reduces diaphragmatic excursion with inspiration. Dampens tumor motion throughout the respiratory cycle.
  20. 20. PNEUMATIC COMPRESSION BELT  Air inflation bulb  Pressure gauge  Non-Rigid  Recording of the pressure  Easy to use!  Less comfortable for patients  more compression compared to the paddle
  21. 21. Advantages  Abdominal compression reduces diaphragmatic excursion with inspiration.  Dampens tumor motion throughout the respiratory cycle.  Lower lobe tumors near diaphragm Disadvantage  Patient discomfort  Poor pulmonary function  Med. comorbidities precluding the use of abdominal compression  Placement of a percutaneous gastrostomy tube  large abdominal aortic aneurysm  significant abdominal pathology.
  22. 22. AUTOMATED BREATH COORDINATOR (ABC) Components Nose clip Mouth piece Spirometer to measure respiratory trace Balloon valve
  23. 23.  A baseline PFT is done to know the patient’s inspiratory capacity  Coaching of breath hold to achieve a steady breathing pattern  The mouth piece and the nasal clips are placed and patient is asked to breath normally.  Once the patient achieves normal respiration, three measurements of inspiratory capacity are made
  24. 24.  The threshold is then fixed at 75 % of the average inspiratory capacity and value is documented.  When the operator activates the system, the balloon valve closes.  The patient is then instructed to reach the specified lung volume. The breath hold starts.
  25. 25. Advantage  V20 and the mean lung dose decreases with an increase in lung volume  Increases the distance between the tumor and critical structures Disadvantage  Increase t/t time  Poor pulmonary reserve
  26. 26. FREE BREATHING METHODS
  27. 27. ITV BASED TREATMENT Generates a composite target volume for lung tumors, taking into account the different shape, size and position of the tumor in each phase of respiration
  28. 28. THE PRINCIPLE OF GATING Beam delivery is coupled with the phase of respiration Treatment delivery is done in the phase of respiration where the tumor motion & resulting tumor treatment volume is minimum, by coupling the beam delivery with the phase of respiration
  29. 29. RPM Real time Position Management (RPM) 1. CCD camera with attached illuminator 2.Camera interfaced with PC 3. Infrared reflective markers that are rigidly embedded in a lightweight plastic block
  30. 30. EXT. FIDUCIAL SYSTEM (IR REFLECTORS)
  31. 31. Plastic block is placed on the chest of the patient.  The system tracks the upper marker as the indicator of the breathing motion .The user selects the portion of the breathing cycle for the gate.
  32. 32. Gating System by ANZAI AZ-733
  33. 33. THE PRINCIPLE OF “TRACKING”
  34. 34. SYNCHRONY Synchrony camera Synchrony tracking markers Fiber optic sensing technology Tracks patient’s respiratory motion
  35. 35. IMAGE ACQUISITION Motion artifacts in free breathing 3 D scan  Severe geometrical distortion  Center of the imaged target can be displaced by as much as the amplitude of the motion
  36. 36. SOLUTIONS  Breath-hold CT scan Voluntary breath hold Active breathing control Combine inhale and exhale GTVs to get ITV  Slow CT san 4 seconds per slice in axial mode  Gated CT scan Images at only 1 phase, acquisition times 4-5x longer  4D CT scan 3D scans at multiple phases
  37. 37. SLOW CT Patient breathes normally Rotation time >> breathing period CT images are an average over all breathing phases Borders of organs tumor volumes can become diffuse Observe target movement under fluoroscopy
  38. 38. 3 D CT SCAN 3 2 14 5 6 7 8 9 10
  39. 39. A large amount of data is generated! (>800 slices)
  40. 40. X-ray on Exhalation Inhalation 1st couch position 2nd couch position 3rd couch position “Image acquired” signal to RPM system (Ford 2003, Vedam 2003) Retrospective 4D CT Image Acquisition
  41. 41. CT Scan Axial scan trigger, 1st couch position Axial scan trigger, 2nd couch position Exhalation Inhalation Scan Scan Scan Axial scan trigger, 3rd couch position Prospective CT Image Acquisition
  42. 42. CORRELATION MODELS
  43. 43. IGRT IN LUNG CANCER (PART-II)
  44. 44. ROADMAP 1. Indications of RT in lung cancers 2. Role of IGRT in lung cancer 3. IGRT (motion management) strategies  Free breathing  Breath hold methods 4. Technological aspects  Acquiring CT  Appreciation of tumor motion 5. Segmentation  Tumor  Normal tissues
  45. 45. 6. Objectives  Hypofractionation schedules  BED calculations  Constrains 7. Outcomes and patterns of failure 8. Toxicities and challenges 9. Comparison with other competing modalities 10. Follow-up 11. Conclusions and future directions
  46. 46. SEGMENTATION OF TUMOR GTV  Contrast if tumor located near great vessels or close bronchial tree  CT pulmonary windows for target segmentation  Soft tissue windows with contrast may be used to avoid inclusion of adjacent vessels, atelectasis, or mediastinal or chest wall structures within the GTV.
  47. 47. IMPACT OF WINDOW LEVEL
  48. 48. Role of PET-CT  To differentiate tumor from atelectasis  To differentiate chest wall musculature from tumor  Accurate target Delineation and Volume reduction
  49. 49. Generation of iGTV  Combining the entire GTV from all resp phases  Combining the GTV contours from two extreme respiratory phases (0% and 50%)  Defining the GTV contour as the maximum intensity projection (MIP) at each voxel during an entire respiratory cycle  Using MIP technique, modifying the contours as needed with visual verification in each individual respiratory phase
  50. 50. CTV- controversy  No CTV in RTOG trials  CTV=GTV  Some centres CTV=5-8 mm expansion of GTV PTV  Appropriate PTV margin(See set up, motion = 5mm)  1 cm craniocaudally and 5 mm axially in RTOG trials
  51. 51. Size of movement dependent on: -tumour location in the lung -fixation to adjacent structures -lung capacity and oxygenation -patient fixation and anxiety Average movement in normal breathing: -Upper lobe 0 -0.5cm -Lower lobe 1.5 -4.0cm -Middle lobe 0.5 -2.5cm -Hilum1.0 -1.5cm
  52. 52. PTV Plus 2 cm  As part of the QA requirements for “intermediate dose spillage” a maximum dose to any point 2 cm away in any direction is to be determined.  An artificial structure 2 cm larger in all directions from the PTV is contoured with automatic contouring .
  53. 53. ORGANS AT RISK Lung Spinal cord Esophagus Trachea bronchus Brachial plexus
  54. 54. Serial –parallel Heart Chest wall??
  55. 55. SEGMENTATION OF OARS Average intensity projection when using 4D CT data Spinal cord Based on the bony limits of the spinal canal. It should be contoured starting at least 10 cm above the superior extent of the PTV & continuing on every CT slice to at least 10 below the inferior extent of the PTV. Esophagus Mediastinal window on CT to correspond to the mucosal, submucosa, and all muscular layers out to the fatty adventitia. 10cm above and below
  56. 56. Heart Contoured along with the pericardial sac. Superiorly from the level of the inferior aspect of the aortic arch (aorto-pulmonary window) to extend inferiorly to the apex of the heart. Whole lung  Both the right and left lungs should be contoured as one structure. (common lung)  Pulmonary windows.  All inflated and collapsed lung should be contoured;  GTV & trachea/ipsilateral bronchus should be subtracted.
  57. 57. Brachial Plexus RTOG guidelines Great vessels Rt sided tumors- IVC Lt sided –Aorta All musculer layer out of fatty adventitia 10cm above below PTV
  58. 58. Trachea  Proximal-10 cm sup to PTV or 5 cm proximal to carina till 2 cm proximal to carina  Distal 2 cm trachea-included in proximal broncial tree Proximal bronchial tree 2 cm above carina up till segmental bifurcation Proximal broncial tree+ 2 cm margin
  59. 59. D Dose/toxicity concerns for •Bronchus/trachea •Esophagus •Great vessels
  60. 60. Skin It is contoured as rind of uniform thickness (0.5 cm) which envelopes the entire body in the axial planes. Rib  Ribs within 5 cm of the PTV should be contoured by outlining the bone and marrow.  Several portions of adjacent ribs can be contoured as one structure but not in a contiguous fashion (avoid ICS)
  61. 61. RADIOBIOLOGICAL CONSIDERATIONS IN SBRT SCHEDULES  Endothelial cell damage  Lethal cell damage  Immunological effects?
  62. 62. LQ MODEL: HYPO FRACTIONATED TREATMENTS  In vitro studies: LQ Model fits well between 0-16 Gy *Garcia LM et al Phys Med Biol 2006;51:2813–2823  In Vivo studies :Also shows that LQ model reliably predicts dose response between 2-20 Gy Barendsen GW et al. Int J Radiat Oncol Biol Phys 1982;8:1981–1997 Van der Kogel AJ. Radiat Res Suppl 1985;8:S208–S216 Peck JW, Gibbs FA. Radiat Res 1994;138:272–281
  63. 63. WHAT HAPPENS WHEN LQ EQUATION IS USED TO CALCULATE DOSE EQUIVALENCE AT HIGH DOSE PER FRACTION
  64. 64. DOSE FRACTIONATION SCHEDULES
  65. 65. Range BED (Gy) 3yr OS T1 3 Yr OS T2 Gr III –V toxicity Low <83.2 0.554 0.170 0.053 Medium 83.2-106 0.863 0.544 0.073 Medium to high 106-146 0.750 0.580 0.078 High >146 0.55 0.35 0.093 The OS for the medium or medium to high BED (range, 83.2–146 Gy) was higher than those for the low or high BED group Zhang,vol 81,305-16 IJROBP 2011
  66. 66. LC and OS rates in 5 years with a BED of 100 Gy or more were superior BED <180 Gy -safe for stage I NSCLC J Thorac Oncol. 2007;2: Suppl 3, S94–S100)
  67. 67. DOSE FRACTIONATION SCHEDULES
  68. 68. location # Away from chest wall 20X3 Close to chest wall 12X 4 Central lesion 8x6 Avoid hot spots in hilum, chest wall, mediastinum
  69. 69. Structure RTOG 0915 RTOG 0236 RTOG 915 RTOG 813 34X1 20x3 12x4 10-12x5 Cord 14Gy 18(6) Gy 26Gy 30(6) Gy Esophagus 15.4Gy 27(9) Gy 30Gy 105% PP I/L brachial plexus 17.5Gy 24(8) Gy 27.2Gy 32(6.4) Gy Heart 22Gy 30(10) Gy 34Gy 105% PP Trachea , brochus 20.2Gy 30(10) Gy 34.8Gy 105% PP Skin 26Gy - 36Gy 32(6.4) Gy Ribs 30Gy - 40Gy - Great vessels 37Gy - 49Gy 105% PP
  70. 70. Critical volume lung Critical volume Dmax lung End point RTOG-0813 1000cc 13.5 Gy pnemonitis RTOG-0915 1000cc 7.4 Gy (single #) 12.4 Gy (4#) pnemonitis
  71. 71. Trial Dose # Min gap Total time note RTOG-0236 20x3 40 hrs Max-8 days 1.5 wks Not more than 2# a wk allowed RTOG-0813 10-12x5 (Central) 40hrs 1.5-2 wks Upto 3 #/wk RTOG-0915 12x4 34x1 18hrs 4 days 4 consecutive days
  72. 72. PLANNING Multiple , non opposing, non coplanar beams Prescription isodose: The prescription isodose surface must be ≥ 60% and < 90% of the maximum dose  The prescription isodose surface should be chosen that 95% PTV is conformally covered by the prescription isodose surface & 99% of PTV receives a min. of 90% of the prescription dose ?
  73. 73. High Dose Spillage The cumulative volume of all tissue outside the PTV receiving a dose > 105% of prescription dose should be no more than 15% of the PTV volume. Intermediate Dose Spillage  To evaluate the falloff gradient beyond the PTV extending into normal tissue structures

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