This document discusses intensity modulated radiation therapy (IMRT) and image guided radiation therapy (IGRT) for head and neck cancers. It provides details on contouring targets and organs at risk for treatment planning. It summarizes evidence from trials on reducing xerostomia with IMRT. It also discusses the benefits of daily imaging with IGRT for accurate treatment delivery and potentially reducing planning target volume margins. Adaptive planning is mentioned as an area that continues to be explored to account for anatomical changes over the course of radiation treatment.

1. IMRT & IGRT for Head Neck Cancers
Dr Sapna Nangia
Chief Radiation Oncologist
International Oncology Centre
Fortis Hospital
Noida

3. PARSPORT trial : Category I Evidence in support of
efficacy of IMRT in reducing xerostomia
Nutting et al Lancet Oncol 2011 12 (2) 127

4. PARSPORT trial : Numbers not enough to establish non-
inferiority.
Conventional IMRT
radiotherapy
2 yr LR PFS 80% 78%
Estimated 2 yr 76% 78%
OS

5. Contouring the CTV – Learning New Skills
Anatomical Boundary
Cranial Caudal edge of lateral
process of C1
Caudal Caudal edge of the body
of hyoid bone
Anterior Post. edge of sub-mandibular
gland, ant. edge of int. carotid
artery, post. edge
of post. belly of digastric m.
Posterior Post. border of the
sternocleidomastoid m
Medial Medial edge of int. carotid
artery, paraspinal (levator
scapulae) m.
Lateral Medial edge of
Cranial Boundary sternocleidomastoid

6. Contouring the CTV – Patterns of spread & failure
 Buccal Mucosa lesions involve the
buccinator muscle and buccal fat pad
 Alveolar and retromolar trigone lesions
involve bone early;
 Mandibular canal and inferior alveolar
nerve / maxillary antrum and floor of
nose – potential routes & sites of
spread, respectively.
 Bone Involvement : Absence of fixation
to bone / small size of a mandibular
lesion, does not rule our bone
involvement.
 INTRATEMPORAL FOSSA

7. Contouring the CTV – Patterns of spread & failure
 Buccal Mucosa lesions involve the
buccinator muscle and buccal fat pad
 Alveolar and retromolar trigone lesions
involve bone early;
 Mandibular canal and inferior alveolar
nerve / maxillary antrum and floor of
nose – potential routes & sites of
spread, respectively.
 Bone Involvement : Absence of fixation
to bone / small size of a mandibular
lesion, does not rule our bone
involvement. Yao et al IJROBP 2007
 INTRATEMPORAL FOSSA
55 pts, oral cancer alone. Mostly
postoperative IMRT
2/9 locoregional failures in the
infratemporal fossa

8. Contouring the CTV – Lymph Node Involvement
in N0 neck
Level I Level II Level III Level IV Level V
Buccal 44 11 0 0 0
Mucosa
Alveolus 27 21 6 4 2
Retro Molar 19 12 6 6 0
Trigone
Gregoire, R O 2000, 56, 135

9. Contouring the CTV – Lymph Node Involvement
in N+ neck
Level I Level II Level III Level IV Level V
Buccal 82 42 65 65 0
Mucosa
Alveolus 54 46 19 17 4
Retro Molar 50 60 40 20 0
Trigone
Gregoire, R O 2000, 56, 135

10. The Node Positive Neck
 What is a positive neck node ( Consensus at the 43rd
meeting of ASTRO, San Fransisco,2001)
 >1 cm in size ( 1.5 cm if jugulodigastric)
 Shape spherical rather than ellipsoidal
 Necrotic center, irrespective of size
 Cluster of 3 or more borderline nodes
 Our departmental protocol: Delineate ALL clinically &
radiologicaly apparent nodes, irrespective of above
criteria.
Eisbruch et al, Seminars in Rad Onco 12 238- 249

11. Impact Of Patterns Of Failure On Target
Delineation Strategy
Results Impact on Practice
Dawson et al & Eisbruch et al
2/58 failure & 21/133failures ,all in field Safe to omit contralat high level II if c/l neck
negative
3 RP node failures, all superior to CI vert Superior extent of RP nodes is base of skull
Ipsilat high Level II failure in OC & OP Consider treating ipsilateral high Level II in case
Primaries of OP primaries, even if N0
Bussels et al
2/72 failures at matchline . Consider including supraclavicular fossa in a
single IMRT plan.
Gregoire et al R & O 56 (2000) 135±150

12. Impact Of Patterns Of Failure On Target
Delineation Strategy
Results Impact on Practice
Cannon et al ? Do not disregard any nodules in a node
Noted 3 periparotid failures, two in positive neck, even if radiologicaly / PET
patients with bilateral disease. insignificant
Retrospectively, insignificant nodules
noted in periparotid region
One dermal failure in periparotid region in ?Consider sparing only the contralateral neck
ipsilateral neck
Nangia et al Investigation into dose ecscalation , hypoxia
30/83 locoregional failures , 28 of which sensitisation
were within the high dose volume
No failure in the area outlined as low risk
volume, using RTOG guidelines for Nodal delineation criteria validated
delineation of levels and using the 5 % cut
off for deciding which nodal levels to
include
Cannon et alIJROBP 70, (2008)660–665,
Nangia et al, IJROBP In press

14. Results
 Eighty three patients  WDSCC 36
 Larynx 35  MDCC 27
 Hypopharynx 13  PDCC 16
 Base tongue 17
 Oral tongue 06
 N0:N1:N2:N3 = 36:10:32:5
 Oral cavity 02
 TX:T2:T3:T4 = 3:29:37:14
 MUO 03
LRFS at 3 years 60.8%
OS at 3 years 81.7%

15. Treatment Related Factors Affecting
Outcome
Total Treatment Time < 53 Days/ > 53 days; Volume of 70Gy PTV <177cc/>177cc

16. Treatment Related Factors Affecting
Outcome
Coverage of 70Gy PTV by Prescription dose >91% /<91%; Minimum Dose to 70Gy PTV >54Gy /<54
Gy

17. Model For Predicting Locoregional Relapse
 Hazard of Locoregional Relapse
[100 –( 1.07x X 100)] + [100 –( 0.91y X 100)]
x = change in total treatment time
y = change in coverage for V 100% for 70Gy PTV

18. Prescription for Head Neck IMRT
60Gy
equivalent
GTV + Margin*
70Gy / 35 #
N
o
d
e
70Gy/ 35# 50Gy Equivalent

19. Prescription for Head Neck IMRT
 95% prescription dose to cover 98% of high dose PTV
 Prescription dose to cover at least 91% of high dose PTV
 95% dose to cover at least 95% of low risk PTV
 Avoid hotspots >107%
 Parotid
 PRV Spine
 Mandible

20. Image Guided Radiotherapy
“Image-guided radiation therapy
(IGRT) is the process of frequent
two and three-dimensional
imaging, during a course of
radiation treatment, used to
direct radiation therapy utilizing
the imaging coordinates of the
actual radiation treatment plan.”
 EPID
 kV-kV
 CBCT
 CT on rails
 Fluoroscopy

21. The questions being asked today -
IMRT IGRT
 OAR besides the parotid  Are we ensuring accurate
 Improving results treatment
 Imaging for target  Can PTV margins be
delineation trimmed below 5 mm
 Hypoxia targeting  What are the serial
 Dose escalation changes that take place
 Is SIB better than sequential during RT
boost  Are we ready for adaptive
planning

22. OARs besides the Parotid : Brachial Plexus
 Three distinct syndromes
 Transient neuropathy
 Classic, delayed, progressive
fibrosis - unlikely to occur <60
Gy
 Acute ischemic plexopathy
 Dose constraints
 RTOG 0412 (RT+CT):
60 Gy/30 #
 RTOG 0615 (RT+CT):
66Gy/303#

23. OARs besides the Parotid : TM Joint
 Trismus related to Pre RT Post RT
 Post radiotherapy fibrosis MID MID
 Scarring of muscles and
ligaments around TM
joint
Conventional RT 44.68 cm 32.7 cm
 Fibrosis and scarring of ( Wang et al (73.1%)
the pterygoid muscles Laryngoscope,
2005, 115. )
 Can be measured by
Maximal Interincisor IMRT 46.2cm 45.4
distance ( MID) ( Hsiung et al BJR , ( 98.1)%
2008, 809)
 Especially important for
nasopharyngeal cancer

24. OARs besides the Parotid : Thyroid
Proposed constraints : 20% volume <20 Gy;
10% volume <30 Gy;
5%volume <40 Gy
Maximum dose 50 Gy.
Diaz, IJROBP 2010, 77,2, 468

25. OARs besides Parotid : DARS
 Post-therapy abnormalities  Aspiration
contributing to a high rate of  PC Mean dose >60 Gy
aspiration:
 PC V65 Gy > 50%
 weakness of the posterior
motion of base tongue  SGL V50 Gy >50%
 prolonged pharyngeal transit  Stricture
time  PC V70 Gy >50%
 lack of coordination between
the swallowing phases
 reduced elevation of the larynx
 reduced laryngeal closure and
epiglottic inversion
Eisbruch IJROBP 2007 69 s 42

26. Other OARs besides Parotid : Miscellaneous
Constraints
Cochlea < 45 - 50 Gy Sensorineural deafness starts at 45Gy. Significantly
increased at 60 Gy. Starts at 10 Gy if cisplatin used,
especially for higher frequencies
Optic Retina < 45 Gy Optic chiasm dose > 60 Gy, optic neuropathy 11% -
apparatus Optic nerves & 47 %depending on fraction size, cut off 1.9 Gy
chiasm <54 Gy
Temporal
lobes

27. Other OARs besides Parotid : Miscellaneous
Constraints
Lacrimal Same as Severe dry eye syndrome, 100% at 57%. Can result
Gland parotid in visual loss secondary to ulceration, opacification
and neovascularisation.
Carotid Narrowing in 50 % vessels after 40Gy.Post RT 79%
patients likely to have significant stenosis.
Mandible Max dose Dental Extractions; occur more often if max
mandible < 70 mandibular dose > 70Gy, mean mandibular dose
Gy/ 75Gy. >40 Gy. Incidence of ORN < 1%
Mean dose <
40Gy

28. Can PTV margins be trimmed to < 5 mm
Margin : 5 mm in 95 pts
Margin : 3 mm in 130 pts
No difference in marginal
failures
Margins can only be
reduced with daily image
guidance
Shift > 3mm
ML 10%
SI 26%
AP 18%
Chen et al Head Neck 2011
July
Chen, IJROBP Article in press

29. IGRT : Calculating PTV margins pertinent to
a setup ( patient & departmental)
 van Herk’s recipe for Wk2Lat Wk2Longi Wk2Vert
PTV :
-1.00 0.00 -2.00
-3.00 3.00 -1.00
3.00 0.00 4.00
1.00 0.00 -3.00
-4.00 1.00 -6.00
0.00 0.00 0.00
-3.00 -1.00 1.00
3.00 0.00 0.00
2.5 Σ + 0.7 σ 0.00
2.00
0.00
-1.00
-2.00
0.00
0.00 1.00 1.00
-4.00 2.00 7.00
2.00 1.00 -2.00
-2.00 -1.00 2.00
-2.00 -3.00 2.00
Σ: SD of mean of all means 2.00
0.00
1.00
1.00
1.00
0.00
σ:
-2.00 -2.00 0.00
sum of all SDs ( actually -1.00 -2.00 1.00
RMS) 0.00
0.00
-3.00
-1.00
-3.00
3.00
4.00 3.00 0.00
-4.00 -1.00 2.00
-1.00 0.00 -1.00
-2.00 -4.00 -1.00

30. SIB or Sequential Boost ?
SIB: Ease of planning
Radio-biologically sound
Clinical results vouch for efficacy
SEQ: Standard fractionation
Cone down fields allow better
sparing of normal tissues
E. Lamers-Kuijper R O 2011 98 51

31. Are we ready for adaptive planning

32. Weekly Volumetric Changes
• Greatest reduction in CTV 1,
3.2 % between week 0 & 2 (
significant)
• Statistically significant
reduction in volume of CTV 2 ,
10.5% and 5.5% between wk 0
& 2 and 2 &4 respectively
• Parotid shrinks 14 % and 16% ,
wk 0&2, wk 2& 4 respectively
• Significant reduction in
minimum dose to CTV and
increase in mean dose to
parotid

33. Weekly Volumetric Changes
• Greatest reduction in CTV 1,
3.2 % between week 0 & 2 (
significant)
• Statistically significant
reduction in volume of CTV 2 ,
10.5% and 5.5% between wk 0
& 2 and 2 &4 respectively
• Parotid shrinks 14 % and 16% ,
wk 0&2, wk 2& 4 respevtively
• Significant reduction in
minimum dose to CTV and
increase in mean dose to
parotid

34. Weekly Volumetric Changes
• Greatest reduction in CTV 1,
3.2 % between week 0 & 2 (
significant)
• Statistically significant
reduction in volume of CTV 2 ,
10.5% and 5 5 between wk 0
& 2 and 2 &4 respectively
• Parotid shrinks 14 % and 16% ,
wk 0&2, wk 2& 4 respectively
• Significant reduction in
minimum dose to CTV and
increase in mean dose to
parotid
•

35. Adaptive Planning - Before

36. Adaptive Planning - After
Improved coverage / better sparing of OAR in 65% of cases of 23 patients who underwent
repeat scans at 11th, 22nd and 33rd fraction.
Ahn et al IJROBP2011 80 3 677

37. Indications for implementing adaptive
planning – Ahn etal

38. Indications for implementing adaptive
planning – Ahn etal
D max cord > 45 Gy
PTV-tumor or PTV-node D95% below 95% of prescription
Parotid D50% increased significantly above 26 Gy
Mandible V60 Gy above 10%,
Brainstem V54 Gy above 20%

39. Work In Progress
 Hypoxia targeting
 Dose escalation
Change in hypoxic area ( and therefore boost target volume) 3 days apart in 4/7 patients
Lin et al IJROBP 2008 70,4, 1219