target delineation for lung cancer

1. LUNG CANCER
CHALLENGES IN TARGET DELINEATION
AND
ROLE OF PET CT
DR KANHU CHARAN PATRO
1

2. MORNING - MAINTAINING EQUILIBRIUM
2
Hot and cold water management at
bath room

3. TARGET
DAY TIME- MAINTAINING EQUILIBRIUM
3

4. EVENING-MAINTAINING EQUILIBRIUM
4Sas bohu management

5. PUSHING BACKWARD AND FORWARD AT A TIME
DIFFICULT BUT NOT IMPOSSIBLE
OAR
TARGET
5

6. GTV:Primary and Nodal disease as per clinico-
radiological findings
CTV: GTV + margins for subclinical disease
ITV : CTV + margins for uncertainties in size/shape,
position of CTV
PTV: ITV+ Margins for Set up error
TARGET VOLUMES-ARE STRAIGHT FORWARD?
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7. 7
DEFINING THE EDGE?

8. Cahllenge-1- WHICH WINDOW?
Primary: Lung window
Node: Mediastinal window
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9. LEVEL AND WIDTH FOR DELINEATION
WIDTH
LEVEL
A. Brightness refers to the overall lightness or
darkness of the image.
B. Contrast is the difference
in brightness between objects in the image.
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10. Brightness- window level Contrast- window width
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11. WIDTH LEVEL
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12. 1. CT: standard imaging modality
2. Complementary information by MRI and PET scanning
3. MRI used for imaging apical primary tumours (Pancoast) and
chest wall tumors
4. PET scanning in suspicious conditions
Cahllenge-2- WHICH image?
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13. Proposed margin: 5-10mm
Microscopic extension Adeno Squamous
Mean value 2.69mm 1.48mm
5mm margin covers: 80% 91%
Margin to cover95% 8mm 6mm
Histopathologic quantification of subclinical cancer around the grossly
visible primary Giraud P et al, IJROBP 2000
Cahllenge-3- HOW MUCH CTV?
In the absence of radiographic proof of invasion, the CTV of the
primary lesion should not extend into the chest wall or mediastinum.
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14. Proposed margin: 5-10mm
Cahllenge-4- HANDLING PLEURAL TAG?
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15. 15

16. Cahllenge-5- HANDLING SPICULES?
Tae 11 Han et al ,Journal of the Korean Radiological Society, 1994 : 31 ( 1) : 63 - 67 16
Contour coarse spicules but do not do the contouring
fine spicules

17. Proposed margin: 5-10mm
Challenge 6 - HANDLING THE CAVITY?
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18. Challenge-7
HANDLING TUMOR ATELECTESIS INTERFACE?
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19. Soft tissue
Width-60
Level-40
lung
Width-1400
Level-300
liver
Width-150
Level-50
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20. Challenge-8
HANDLING TUMOR CHEST WALL INTERFACE?
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21. 21

22. Challenge-9- HANDLING THE NODE.
1. Lymph nodes with a short axis diameter of ≥1cm
are generally consideredpathological.
2.Any nodes with abnormal findings detected on
bronchoscopy and/or mediastinoscopy.
3. Any visible nodes that are growing or with
abnormal structures;
4. Two or more nodes clustered in the high risk
nodal stations.
5. any visible nodes at the 1st echelon or within
1cm proximity to the primary tumor.
6. Any node PET active
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23. Challenge-10 - CTV FOR NODE?
1. 8 mm expansions of involved nodes of the CTV is recommended,
but not extend into the major airways or lung, chest wall, or
vertebral body without evidence of invasion.
2. Giraud P et al, Cancer Radiotherapie 2016
Around involved nodes, CTV not recommended!
3. The relevance of ENI is in doubt:
1. Complete tumor control -within the GTV is often
not possible at conventional doses.
2. Isolated nodal failures rare – systemic failures and
death comorbidities far more common
3. prevents dose escalation ENI increases doses to
normal structures –lowers local control
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24. GTV N 24

25. PTV node = GTV+5-7mm
Giraud P et al, Cancer Radiotherapie 2016 25

26. Challenge-11-HOW MUCH PTV
1. Created by adding margin to CTV
1. Based on institutional experience
2. Defining the PTV
1. Set up uncertainties
2. ITV[Internal organ motion]
 Respiration
 Cardiac motion
 Tumor location in lung
 Fixation to adjacent structures
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27. 1. Not all tumors move equally
(affected by tumor location and
fixity)
2. Chest wall, diaphragm, heart –
all affect motion
Shirato et al. 2004
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28. 1. In free breathing Non-ITV approach:
1. PTV = CTV+10mm for upper & middle
lobe tumors
2. PTV = CTV+20mm for lower lobe tumors
1. In free breathing & measuring ITV:
PTV = ITV+2mm
Giraud P, Cancer Radiotherapie 2016
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29. Challenge-12- POST OP SETTINGS
1. Post op bed
2. Bronchial stump
3. Surgical clips
4. rCTV
5. Pathological positive nodal station
6. Ipsilateral hilar region
7. Possible extensions of peritumoral mediastinal pleura
8. Adjacnet lymph node if skip mets
9. Frequent involvement of sub-carinal (LN7) and homolateral
paratracheal nodes (LN4) on surgical series, these stations will
always be systematically included in the CTV.
10. As for the left-located tumors, LNS 5 should also be included in
the CTV.
LUNG ART STUDY PROTOCOL
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30. Challenge-13-POST CHEMO SETTINGS
1. Pre chemo or Post chemotherapy tumor ?
I. Pre chemo GTV: Higher dose to OARs
II. Post chemo GTV: Underdosing the tumor
2. Targeting post chemotherapy volume –
I. Reduces mean GTV and PTV by upto 37%
II. Reduces mean V20 by 3%
Jonathan D Grant/radiation oncology/2015
RIND
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31. Challenge-13-POST CHEMO SETTINGS
 Usually planned for pre-op chemo but latter realized not suitable
for sx.
 Some large tumors not good for CT RT as OAR constraints not
achievable.
 Discretion-Volume preCT vs postCT depends upon oncologist and
response.
 As per guideline prechemo volume should be.
 If OAR is constraints achievable plan with preCT volume
otherwise postCT volume
 Can plan with two phase with lesser dose to rind.
 PostCT volume-risk of increasing the marginal recurrence rate, it
should be used with caution.
 PreCT volume- insignificant response and blurred margin
 In the absence of significant lung collapse or consolidation, we
recommend treating the preCT GTV for the majority of patients 31

32. 32

33. Challenge-14-DELINEATING OAR
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34. Challenge-15
INCORPORATING PET SCAN FOR TARGET DELINEATION
1. Visual interpretation of PET images
1. Arbitrarily windowing, may lead significantly different
apparent tumour volumes
2. Automatic Image segmentation methods based on SUV
either
As an absolute SUV.
1. SUVmax of 2.5 is often used as a threshold for the
distinct
Threshold value (a percentage of SUV max)
1. 40% to 50% of the maximum uptake
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35. 35

36. 36

37. SUSPICIOUS CONDITIONS
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38. Nodule in other lobe/satellite
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39. Atlectesis /Consolidation/tumor
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40. Intra and inter observer variation
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41. Rib and chest wall invasion
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42. Suspicious node
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43. 43

44. WHEN IT IS UNCLEAR
THINK OF NUCLEAR
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45. 45

46. 46

47. HENCE PET
1. Morphological and functional
characterization of pulmonary nodules or
masses;
2. Differentiation tumor vs atelectasis
3. For tumor-node-metastasis (TNM) staging of
the mediastinum
4. Screening for metastases that might not be
detected by CT alone
5. For radiotherapy planning
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48. Suspicious satellite nodule
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49. Differentiating atelectesis and mass
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50. Suspicious chest wall invasion
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51. Suspicious node
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52. Suspicious prevertebral node
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53. 53

54. WHEN THINGS ARE SUSPICIOUS
PET CT IS AUSPICIOUS
PARAMETER VOLUME
CHANNGE
TREATMENT CHANGE
T STAGE
UPSTAGING
1. PREVENTS GEOGRAPHICAL MISSING
2. MAY CHANGES TT FROM CURATIVE TO PALLLIATIVE
DOWN STAGING 1. PREVENTS EXTRA DOSE TO NORMAL TISSUE
2. MAY CHANGES TT. FROM PALLIATIVE TO CURATIVE
3. DOSE ESCALATION IS POSSIBLE
N STAGE UPSTAGING 1. PREVENTS GEOGRAPHICAL MISSING
2. MAY CHANGES TT FROM CURATIVE TO PALLLIATIVE
DOWN STAGING 1. PREVENTS EXTRA DOSE TO NORMAL TISSUE
2. MAY CHANGES TT. FROM PALLIATIVE TO CURATIVE
3. DOSE ESCALATION IS POSSIBLE
M STAGE UPSTAGING MAY CHANGES TT. FROM PALLIATIVE TO BSC
DOWN STAGING MAY CHANGES TT. FROM PALLIATIVE TO CURATIVE
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55. Bird’s eye view Eagle’s eye view
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56. PET CT is not money making
It brings
wow moment to the patient
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