WHO Classification. Louis D ; Acta Neuropathol 2007WHO Classification. Louis D ; Acta Neuropathol 2007

Introduction: Radiosurgery in brain tumourIntroduction: Radiosurgery in brain tumour

Total number of tumours Total number of tumours 132132Total number of malignant glial tumour ~ Total number of malignant glial tumour ~ 2020

Radiation therapy Radiation therapy

Conventional RT: 1.8-2 Gy/#Majority of the tumours are treated with Conv RT

Hypofractionated RT: >2 Gy/#Mainly for palliative treatment

Radiosurgery: Single fraction high dose treatmentUsually curative intent

Fractionated Radiosurgery:Short course high dose treatmentUsually curative

Radiosurgery: Radiosurgery: toolstools

Gamma-Knife

LA based SRS Systems

BrainLAB NovalisTrilogyTomotherapy

CyberKnife

Gamma knifeGamma knife

• Gamma-knife: 201 Cobalt source

• Only for intracranial lesions

• Rigid/ fixed frame required

• Single fraction treatment

Gamma-knifeGamma-knifeIndications

- Small Meningiomas (<3 cm)

- Small acuastic schwannoma (<3 cm)

- Solitary / oligo brain metastasis with controlled primary (RPA Class I)

- Small residual LGG

- AVMs (<3 cm)

- Trigeminal neuralgia (Functional disorder)

More than 40 years experience / results with Gamma-Knife

CyberKnife: CyberKnife: Unique propertiesUnique properties

Highly precise treatment delivery

Motion management method

Tumour tracking

‘Dose painting’

Excellent dose distribution

Fractionation schedule

No rigid fixation

‘CyberKnife is an extension of Gamma-Knife’

- Principles of ‘field arrangement’

- Dose distribution pattern

- Multiple isocentre

-Treatment principles

- Treatment delivery accuracy similar

- Delivered dose in single fractions

- Intra-cranial indications

CK & GK: Similarity

Hence, all the indications of GK are indications of CK also

CyberknifeCyberknifeIndications for single fraction treatment as Gamma-Knife

- Small Meningiomas (<3 cm)

- Small acuastic schwannoma (<3 cm)

- Solitary / oligo brain metastasis with controlled primary

- Small residual LGG

- AVMs (<3 cm)

- Trigeminal neuralgia

- Rec High grade glioma

- Craniopharyngioma

- Pituitary tumour

More than 40 years experience / results with Gamma-Knife

Cyberknife Vs Gamma-Knife: Cyberknife Vs Gamma-Knife: Dissimilarity

GK CK Comments

Immobilization device Rigid frame Orfit CK has favorable orfit

RT source Co60 6MV LA GK need to replace sources every 5/6 yrs

Planning No complex planning Inverse planning Favorable dosimetry in CK

Planning method Simple Complex Even neurosurgeons can plan in GK

Isodose prescription Usually 50% Usually 80-95% GK: more dose heterogeniety

Fractions Single May treat multiple fraction Radiobiology favorable in CK

Tumour size Only smaller lesions can be treated

Larger lesions also can be treated in fractionated schedule

Increased indications with CK

Energy source Radiation Electricity GK can work with less electricity

Verification Not possible Possible Even Intra-fraction movement can be corrected

Indications Only brain lesions Both extra & intra cranial CK more economical

Cyberknife Vs Gamma-Knife: Cyberknife Vs Gamma-Knife: DissimilarityAdvantage of Inverse planning

GK planning

CK planning

Dose to mesial temporal lobe & Choclea is higher with GKMean dose to mesial temporal lobe >6 Gy with SRS: IQ decline

Romanalli, Lancet 2009

% of patient with >10% drop in IQ% of patient with >10% drop in IQ

Left temporal lobe DVH

p=0.39

p=0.06

p=0.03

p=0.06

Vol

um

e (c

c)

Jalali , Dutta et al IJROBP 2009

PTV margin in brain tumourPTV margin in brain tumour

CTV-PTV MarginSystemic Error (Σ)

Random Error (σ)

ICRU 62 Strooms Van Herk’s

NR only Group: Ant-Posterior 0.1 1.36 1.05 mm 1.15 mm 1.20 mm

Med-lateral 0.28 1.04 1.01 mm 1.29 mm 1.43 mm

Sup-Inferior 0.52 1.37 1.48 mm 2.0 mm 2.26 mm

NRF Group:

Ant-Posterior 2.24 1.28 3.14 mm 5.38 mm 6.50 mm

Med-lateral 0.78 1.41 1.77 mm 2.55 mm 2.94 mm

Sup-Inferior 0.94 1.39 1.91 mm 2.85 mm 3.32 mm

PTV margin: 3 mm.

Budrukkar , Dutta et al, JCRT 2008

Prospective study

Two different head rest (NR & NRF)

220images (NR 100, NRF 120)

Error estimation with 2D EPID

Cyberknife Vs Gamma-Knife Vs X-Knife: Cyberknife Vs Gamma-Knife Vs X-Knife: CK: Accuracy similar with Gamma-Knife

Treatment delivery accuracy: GK: ~1 mm CK : ~1 mm LA based SRS: 1-2 mm (iso-centric inacurracy; LUTZ test)

PTV margin: CK: <1 mm GK: <1 mm LA based SRS: 1-2 mm GK/CK LA based SRS

CK has the accuracy of GK and flexibility of LA based SRS

Indications for CyberKnifeIndications for CyberKnife

Intracranial tumours 1.‘oligo’ Brain metastasis

2.Acustic neuromas/ schwannomas

3.Meningiomas

4.Recurrent Low grade gliomas

5.Recurrent High grade gliomas

6. AVMs

7.Trigeminal neuralgias

8.Functional disorders

Extra-cranial tumours1.Early Non small cell lung cancer

2.Localized Prostate cancer

3.Small volume Liver cancer

4.Inoperable Gall bladder, pancreas cancer

5.Recurrent head & neck cancer

6.Recurrent Ca nasopharynx

7.‘Oligo’ Lung metastasis.

8.‘Oligo’ Liver metastasis.

9.‘Oligo’ bone metastasis

10.Eye lesions / tumours

Radiosurgery in brain tumour: Promises Radiosurgery in brain tumour: Promises -

- Radiosurgery is a promising area in brain tumour management

-There is a definite role of radiosurgery with definite indications

-Radiosurgery is a short course, high dose radiation therapy

-Patient compliance is excellent, out-patient procedure

-CyberKnife is the most modern radiosurgery procedure