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Neuro-oncology
Brain metastases
Glioma Grade 4 > Grade 3 > Grade 2
Pituitary tumours
Ependymomas
Lymphoma
P.N.E.T. (Primitive neuro ectodermal tumour)
Pineal Tumours inc germ cell tumours
Atypical Meningiomas
Primary spinal tumours
Pituitary Irradiation
Questions
What are the indications for radiotherapy ?
What does conventional radiotherapy involve?
Radiosurgery ?
What is stereotactic linear accelerator based radiotherapy ?
Indications for Pituitary Irradiation
Suprasellar extension
Cavernous sinus involvement
Recurrent Disease
Uncontrolled endocrinopathy
Medically unfit
Suprasellar Extension
Pre op Post op
Cavernous sinus involvement
Recurrent Disease
Uncontrolled Endocrine Effects
Results
Results
90% control of Pituitary tumour at 10 years following surgery and radiotherapy
Visible tumour Gross Tumour Volume (GTV)
GTV plus Normal tissue containing microscopic disease Clinical Target Volume (CTV)
CTV plus Further tissue to allow for organ movement, set up Planning Target Volume (PTV)
Radiotherapy Planning
Suprasellar Extension
Pre op Post op
Conventional Radiotherapy
Standard immobilisation shell
CT planning scan
Fractionated treatment (25 usually)
Conventional Radiotherapy
Intention is to reduce the set up margin by more rigid immobilisation and conforming beams.
Field size restricted to smaller fields
Main indication when the subclinical invasion is minmalBenign, AVM, or only treating GTV
Stereotactic Radiotherapy
Stereotactic Radiotherapy
Precise positioning in three-dimensional space.
In stereotactic surgery, a system of three-dimensional coordinates is used to locate the site to be operated on.
In stereotactic radiotherapy, a system of three-dimensional coordinates is used to locate the site to be irradiated bya number of precisely aimed beams of ionizing radiation from diverse directions meeting at a specific point.
Stereotactic Radiotherapy
Leksell Unit
Stereotactic Radiosurgery
Leksell Unit
Stereotactic Radiosurgery
Single fraction
Ablative dose
Use for lesions where there is no significant subclinical spread.
Small fields 4cm or less
Immobilisation imperative
Examples AVMAcoustic neuromasMeningiomasMetastases
Stereotactic Radiosurgery
Linac based system
Stereotactic Radiosurgery Stereotactic Radiotherapy
Multiple conventional fractions exploits reduced patient movement to reduce morbidity
Use for lesions where there is minimal subclinical spread or as a boost to GTV only
Immobilisation device must allow for repositioning daily
Examples Pituitary tumoursMeningiomasGliomas (needs further studies)
Stereotactic Linear accelerator based Radiotherapy
Conventional Radiotherapy Plan unavoidable dose to normal structures outside target volume
Intensity Modulated Radiotherapy (I.M.R.T.)
Multiple beams, non uniform dose across the beam
Intensity Modulated Radiotherapy (I.M.R.T.)
Radiotherapy Side Effects
During Tired, Hair loss, tumour swell
2 months Somnolence, Recurrent symptoms: recurrence, necrosis or tumour swell
6 months Late radiation necrosis
2 years Intellectual deterioration
Radiotherapy side effectsLate Damage up to 10 years +
• Thickening of endothelial lining
• Hypoxia
• Necrosis.
Loss of functionLoss of functionEg. Brain necrosis, Eg. Brain necrosis, Brachial plexopathy following breast cancer treatmentBrachial plexopathy following breast cancer treatment
Late EffectsTumourigenesis
Some studies find patients who have had standard pituitary radiation therapy are at a 9.4- to 16-fold increased risk for malignant brain tumours (such as astrocytomas or gliomas) in comparison with the risk in the general population.
Pituitary Irradiation
Summary
Indications
Conventional vs more technical radiotherapy
Side effects usually rare and manageable