Radiotherapy Planning for Pituitary Adenoma

RADIOTHERAPY PLANNING
PITUITARY ADENOMA
DR KANHU CHARAN PATRO
RADIATION ONCOLOGIST
3/30/2019 1

SLOW MY FLOW
• INTRODUCTION
• CASE SELECTION AND INDICATION
• PRE RADIOTHERAPY EVALUATION
• IMMOBILIZATION
• IMAGING
• FUSION
• TARGET DELINEATION [GTV, CTV, PTV]
• DOSE PRESCRIPTION[TARGET, OAR]
• PLANNING
• EVALUATION
• EXECUTION
• MONITORING
• FOLLOW UP
• OUTCOME
3/30/2019 2

INTRODUCTION
• Pituitary adenomas are mostly benign tumours
and comprise about 10% of all intracranial
tumours
• Radiotherapy has an important and long-
established role as part of the multi-disciplinary
management of both non-functioning and
functioning adenomas.
3/30/2019 3

SLOW MY FLOW
• INTRODUCTION
• IMMOBILIZATION
• IMAGING
• FUSION
• PLANNING
• EVALUATION
• EXECUTION
• MONITORING
• FOLLOW UP
• OUTCOME
3/30/2019 5

INDICATION
• Functioning/secretory adenoma
– When medical therapy fails
• Macro-adenomas
– Causing vision problems
– Compressing symptoms
3/30/2019 6
Radiation therapy should be considered in the management
of patients with pituitary adenomas, particularly when
medical and surgical options have been exhausted

INDICATIONS
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1. Significant residual (consider redo TSS first)
2. Very large silent corticotroph (increased risk of
recurrence post-operatively)
3. Atypical histology o Recurrent (ie following a
second TSS or within the cavernous sinuses)
4. Hormone secreting (not cured biochemically
surgically)
5. Medically unfit patients: Long-term control
rates are around 70-80% with radiotherapy
alone

RADIATION IN PITUITARY ADENOMA
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1. It works slowly, so it can take months or even years before
the tumor growth and/or excess hormone production is fully
controlled.
2. It can damage the remaining normal pituitary.
3. In many cases, normal pituitary function will be lost over
time, so treatment with hormones will be needed.
4. It may damage some normal brain tissue, particularly near
the pituitary gland, which could affect mental function years
later.
5. The optic apparatus may be damaged, causing vision
changes.
6. The radiation may increase the risk of developing a brain
tumor later in life, but this risk is low in adults.

SLOW MY FLOW
• INTRODUCTION
• IMMOBILIZATION
• IMAGING
• FUSION
• PLANNING
• EVALUATION
• EXECUTION
• MONITORING
• FOLLOW UP
• OUTCOME
3/30/2019 9

ENDOCRINE EVALUATION
3/30/2019 10

HORMONAL TREATMENT DETAILS
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SLOW MY FLOW
• INTRODUCTION
• IMMOBILIZATION
• IMAGING
• FUSION
• PLANNING
• EVALUATION
• EXECUTION
• MONITORING
• FOLLOW UP
• OUTCOME
3/30/2019 16

SIMULATION
POSITIONING SUPINE/NEUTRAL POSITION
HANDS LATERAL
MASK 3 CLAMP HEAD AND NECK
HEAD REST FLEX /NEUTRAL
INVASIVE STEREOTAXY MASK
NON INVASIVE STEREOTAXY MASK
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NON INVASIVE STEREOTACTIC MASK
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INVASIVE STEREOTACTIC MASK
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CHOOSING THE HEAD REST
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NECK SUPPORT WITH FLEXION (NRF)
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ERRORS WITH FLEXON NECK SUPPORT
Neck support with flexion leads with significantly
higher setup errors in the ML and AP directions.
Differential PTV margin for the ML and AP
directions may be considered for patients
undergoing treatment with flexion supports
3/30/2019 24

SLOW MY FLOW
• INTRODUCTION
• IMMOBILIZATION
• IMAGING
• FUSION
• PLANNING
• EVALUATION
• EXECUTION
• MONITORING
• FOLLOW UP
• OUTCOME
3/30/2019 25

IMAGING PREFERENCES PITUITARY ADENOMA
CT SCAN 1. CONTRAST CT BRAIN
2. 3MM OR LESS
MRI 1. CONTRAST MRI BRAIN
2. 3mm OR LESS
GENERALLY
T1 AND CONTRAST
PACKING MATERIAL
FATSAT SEQUENCE
OPTIC CHIASM
IDENTIFICATION
CISS/IR SEQUENCE
CAVERNOUS SINUS
DIFFERENTIATION
T2 AND FLAIR
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GENERAL PRINCIPLE
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1.The coronal plane offers the best single view for
assessing the sella and allows the pituitary gland
to be distinguished from the surrounding
structures
2.Sagittal views are particularly helpful for
evaluating midline structures. Because the
pituitary gland is small, high spatial resolution
images are required
3.Fat-saturation techniques are useful for
postoperative evaluations

CAVERNOUS SINUS
CAROTID ARTERY
OPTI C CHIASMA
INFUNDIBULUM
PITUITARY3/30/2019 30

INFUNDIBULAR RECESS
SUPRA OPTIC RECESS
OPTI C CHIASMA
INFUNDIBULUM
PITUITARY3/30/2019 31

NORMAL PITUITARY- MRI PICTURES
The adenohypophysis is isointense & the
neurohypophysis is hyperintense- T1 PLANE
Sagittal postcontrast T1shows normal
diffuse enhancement of the gland
3/30/2019 35

PITUITARY MICROADENOMA- MRI PICTURES
LEFT PART PITUITARY GLAND. WITHIN THE GLAND, A
FOCAL AREA OF HYPOINTENSITY IS SEEN IN T1 PLANE
Microadenoma remains hypointense while the
remainder of the gland enhances IN T1 CONT
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DELAYED IMAGE
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1. Imaging more than 30 minutes after intravenous contrast also
may help detect Microadenomas, which then appear as focal
hyperintense lesions relative to the surrounding gland.
2. Encasement of the intercavernous internal carotid artery by
adenoma greater than or equal to 67% was concluded to be a
specific sign of a cavernous sinus invasion in one study.
3. Fat packed in the surgical defect appears hyperintense on T1-
weighted sequences and requires the use of fat-saturated
sequences to distinguish contrast enhancement from packing
material

PITUITARY MACROADENOMA- MRI PICTURES
There is a well defined round lesion noted in
the pituitary fossa, the lesion is homogeneous
and isodense on T1
There is a well defined homogeneously
enhancing lesion in the pituitary fossa on
Sagittal T1 C+ suggestive of pituitary adenoma
3/30/2019 38

CONVEX UPPER MARGIN IN PUBERTY
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LOCATION OF THE TUMOR
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1. Tumors secreting ACTH, thyroid stimulating hormone,
luteinizing hormone, and follicle stimulating hormone
are found centrally within the pituitary gland
2. While prolactin and growth hormone adenomas occur
at the periphery

WITH PARASELLAR EXTENSION
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HARDY’S CLASSIFICATION
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RIGHT CAVERNOUS SINUS
INVOLVEMENT
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KNOSP CLASSIFICATION
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CAVERNOUSSINUS
INVOLVEMENT
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SLOW MY FLOW
• INTRODUCTION
• IMMOBILIZATION
• IMAGING
• FUSION
• PLANNING
• EVALUATION
• EXECUTION
• MONITORING
• FOLLOW UP
• OUTCOME
3/30/2019 74

IMAGE FUSION
1. Soft tissue extension
2. Delineating optic
apparatus
3. Differentiating packing
material
4. Differentiating
cavernous sinus from
tumor
3/30/2019 75

DIFFERENTIATING PACKING MATERIAL
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DIFFERENTIATING FROM CAVERNOUS
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DIFFERENTIATING FROM CAVERNOUS
PITUITARY ADENOMA-MRI SEQUENCE
1. WITH CONTRAST MRI
PITUITARY AS WELL
CAVERNOUS SINUS
BOTH ENHANCE.
2. T2 FLAIR SEQUENCE IS
REQUIRED TO
DIFFERENTIATE
PITUITARY FROM
CAVERNOUS SINUS.
3. IN T2 CAVERNOUS
SINUS LOOKS
HYPOINTENSE
3/30/2019 81

SLOW MY FLOW
• INTRODUCTION
• IMMOBILIZATION
• IMAGING
• FUSION
• PLANNING
• EVALUATION
• EXECUTION
• MONITORING
• FOLLOW UP
• OUTCOME
3/30/2019 82

TARGET VOLUMES-GCP PARAMETER
GTV The tumor bed as defined as the enhancing
mass on the post-contrast T1-MRI
CTV CTV = GTV
TMH - 0.5 cm
PTV GTV /CTV + 3.0–5.0 mm, depending on setup
error and the reproducibility of patient
positioning
3/30/2019 83

PITUITARY SPARING
3/30/2019 84

LONDON CANCER GUIDELINES
3/30/2019 85

IDENTIFYING PITUITARY
• It is oval-shaped (craniocaudally up to 12 mm) and lies in the
sella turcica.
• Laterally, the pituitary gland is bordered by the cavernous
sinuses, which are well visible with intravenous contrast
agent, it is just inferior to the brain, and is connected to the
hypothalamus by its pituitary stalk.
• The borders of the pituitary gland can be defined best in the
sagittal view .
• Alternatively, the inner part of the sella turcica can be used
as a surrogate anatomical bony structure
• Best identified using bone 1500/950 or soft tissue 350/50
WL/WW on CT
3/30/2019 87

IDENTIFYING OPTIC CHIASM
• The optic chiasm (14 mm transverse, 8 mm antero-posterior
and 2–5 mm thick) is located 1 cm superior to the pituitary
gland, which has high signal on T1 MRI, and just
• Anterior to the pituitary stalk (located above the sella turcica).
• The lateral border is the internal carotid artery.
• The chiasm is superiorly located in the antero-inferior part of
the third ventricle, below the supra-optic recess and above
the infundibular recess of the third ventricle, with the optic
nerves in front and the divergence of the optic tracts behind.
• The anterior cerebral arteries and the anterior communicating
artery are located ventral to the chiasm
3/30/2019 88

SLOW MY FLOW
• INTRODUCTION
• IMMOBILIZATION
• IMAGING
• FUSION
• PLANNING
• EVALUATION
• EXECUTION
• MONITORING
• FOLLOW UP
• TOXICITY
• OUTCOME
3/30/2019 89

WHAT SHOULD BE THE DOSE?
3/30/2019 90
UNIVERSITY OF FLORIDA EXPERIENCE

TARGET DOSE
3/30/2019 92
1. Radiation dose was not significantly predictive of control in our
experience with a narrow dose range.
2. No benefit to doses greater than 45 Gy confirms our earlier
experience.
3. In light of previous studies confirming the need for at least 40 Gy
and other reports suggesting superiority for 50 Gy,
4. we will continue to recommend 45 Gy because it remains the
lowest dose with proven efficacy.
5. Our experience shows no dose response above 45 Gy. This may
be particularly important for analysis of sequelae in the future.

SLOW MY FLOW
1. INTRODUCTION
2. CASE SELECTION AND INDICATION
3. PRE RADIOTHERAPY EVALUATION
4. IMMOBILIZATION
5. IMAGING
6. FUSION
7. TARGET DELINEATION [GTV, CTV, PTV]
8. DOSE PRESCRIPTION[TARGET, OAR]
9. PLANNING
10. EVALUATION
11. EXECUTION
12. MONITORING
13. FOLLOW UP
14. TOXICITY
15. OUTCOME
3/30/2019 94

PLANNING
1.General planning strategies include 3D-CRT,
IMRT
2.VMAT depending on the orientation, location,
and size of the tumor.
3.The typical energy used is 6 MV photons or
higher
3/30/2019 95

CLASSICAL 2D PLAN
3/30/2019 96

CONSIDERATION OF STEREOTAXY
1. Commonly not practiced
1. Conventional results are best
2. Close proximity to chiasm
2. Functional tumors need higher dose16–25 Gy in a
single fraction prescribed to at least the 50 % isodose
line. Higher doses are preferred
3. Nonfunctional tumors: 14–16 Gy in a singlefraction
prescribed to at least the 50 % isodose line,
4. Fractionated radiation therapy is recommended for
tumors in close proximity to the optic chiasm (3 mm)
or with marked extension into the cavernous sinus
3/30/2019 99

FSRT FOR PITUITARY
• Stereotactic radiotherapy originally referred to radiotherapy
treatment delivered to an intracranial target lesion that was located
by stereotactic means in a patient immobilised in a neurosurgical
stereotactic head frame. The improved patient immobilisation,
more accurate
• Tumour target localisation using cross-sectional image for treatment
planning, and high precision radiation treatment delivery to the
tumour target, enabled a reduction in the margins around the
radiotherapy target volume (the GTV to PTV margin), therefore
achieving greater sparing of surrounding normal tissues than can be
obtained with standard CRT techniques
3/30/2019 102

SCRT VS SRT
• While SCRT is suitable for the treatment of all
pituitary tumours, irrespective of size, shape
or proximity to critical normal tissue
structures,
• SRS is only suitable for treatment of small
tumours away from the optic chiasm
3/30/2019 103

SLOW MY FLOW
• INTRODUCTION
• IMMOBILIZATION
• IMAGING
• FUSION
• PLANNING
• EVALUATION
• EXECUTION
• MONITORING
• FOLLOW UP
• TOXICITY
• OUTCOME
3/30/2019 104

SLOW MY FLOW
• INTRODUCTION
• IMMOBILIZATION
• IMAGING
• FUSION
• PLANNING
• EVALUATION
• EXECUTION
• MONITORING
• FOLLOW UP
• TOXICITY
• OUTCOME
3/30/2019 105

IGRT
IGRT examples commonly integrated into
treatment units and utilized when treating
CNS tumors include orthogonal KV X-rays and
volume-based cone-beam CTs.
3/30/2019 106

SLOW MY FLOW
• INTRODUCTION
• IMMOBILIZATION
• IMAGING
• FUSION
• PLANNING
• EVALUATION
• EXECUTION
• MONITORING
• FOLLOW UP
• TOXICITY
• OUTCOME
3/30/2019 107

DISCONTINUOUS OF HORMONAL THERAPY
Discontinuation of pituitary suppressive medications at least 1 month before
radiosurgery significantly improved endocrine outcomes for patients with acromegaly
B. E. Pollock et al
J. Neurosurg. / Volume 106
/ May, 2007
3/30/2019 108

SLOW MY FLOW
• INTRODUCTION
• IMMOBILIZATION
• IMAGING
• FUSION
• PLANNING
• EVALUATION
• EXECUTION
• MONITORING
• FOLLOW UP
• TOXICITY
• OUTCOME
3/30/2019 109

FOLLOW UP
• 3 MONTHLY FIRST 2 YEARS THEN 6 MONTHLY
• HORMONAL CHECK UP FOR NORMALIZATION
• HORMONAL CHECK UP FOR INSUFFICIENCY
• OPHTHALMIC EVALUATION FOR RECOVERY
• OPHTHALMIC EVALUATION FOR NEURITIS
3/30/2019 110

FOLLOW UP IMAGING
• BASELINE EVALUATION AT 3 MONTH OF POST
RADIATION
• MRI PREFERRED
• FURTHER IMAGING AT SYMPTOMATIC
PROGRESSION
3/30/2019 111

SLOW MY FLOW
• INTRODUCTION
• IMMOBILIZATION
• IMAGING
• FUSION
• PLANNING
• EVALUATION
• EXECUTION
• MONITORING
• FOLLOW UP
• TOXICITY
• OUTCOME
3/30/2019 112

VISUAL COMPLICATION
3/30/2019 113

OPTIC NEUROPATHY
• Usual radiotherapy doses are 45 to 50Gy range.
• This dose is below the tolerance of optic pathway
including optic chiasm.
• It allows for the treatment of pituitary adenomas
of all sizes, including large tumors with
suprasellar extension frequently encasing or in
close proximity to the optic apparatus.
• The toxicity of fractionated external beam RT is
low, with a 1.5% risk of radiation-induced optic
neuropathy
• 0.2% risk of necrosis of normal brain structures
3/30/2019 114

PITUITARY INSUFFICIENCY
 The most frequent late morbidity of radiation
is hypopituitarism likely to be primarily the
result of hypothalamic injury, although
direct effect on the pituitary gland cannot be
excluded.
 In patients who have normal pituitary
function around the time of RT, hormone
replacement therapy is required in 20% to
40% at 10 years
3/30/2019 115

SLOW MY FLOW
• INTRODUCTION
• IMMOBILIZATION
• IMAGING
• FUSION
• PLANNING
• EVALUATION
• EXECUTION
• MONITORING
• FOLLOW UP
• TOXICITY
• OUTCOME
3/30/2019 116

A. The 10-year PFS reported in seven large series
of conventional external beam RT for pituitary
adenoma is 80% to 94% .
B. In the largest series of 411 patients, the 10-
year PFS was 94% at 10 years and 89% at 20
years
3/30/2019 117

HORMONAL CONTROL
3/30/2019 118

CONTROL AFTER STEREOTAXY
Patients with GH–producing pituitary adenomas should not
undergo further radiation therapy or surgery for at least 5
years after radiosurgery because GH and IGF-I levels
continue to normalize over that interval
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RADIOSURGERY OUTCOMES
3/30/2019 122

SRS SERIES FOR GROWTH HORMONE
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SRS SERIES FOR ACTH
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SRS SERIES FOR PROLACTINOMA
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PROLACTINOMA IS MORE
RADIO-RESISTANCE
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LITERATURE REVIEW
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PATIENT COUNSELING
3/30/2019 130

Radiotherapy Planning for Pituitary Adenoma

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