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IAEA Pediatric Radiation Oncology TrainingDr Laskar Version 1 June 2009

PEDIATRIC ORBITAL TUMORS

RADIOTHERAPY PLANNING


ANATOMY


ANATOMY CONT


ANATOMY CONT…….


ANATOMY CONT…….


EYE OF A CHILD


Normal tissue tolerance doses (in conventional #)

TD 5/5 Gy

TD 50/5 Gy

Endpoint

Optic nerve 50 65 Blindness

Chiasma 50 65 Blindness

Lens 10 18 Cataract

Retina 45 65 Blindness


COMMON PEDIATRIC ORBITAL TUMORS

Intraocular Tumors Intraorbital Tumors

_ Retinoblastoma - Rhabdomyosarcoma_ Uveal Melanoma - Lymphoma

_ Metastasis - Optic Nerve Glioma

- Optic nerve sheath

meningioma

- Metastasis


Rhabdo- myosarcoma

Most common orbital malignant tumor


When To Treat ?Age

- > 1 yr- < 1 yr

Extent of disease at presentation.- Localised to Orbit - Orbit with

intracranial extension


PLANNING ……..


IMMOBILIZATIONThermoplastic mould Vacuum bagSedation General anesthesia

Planning CT scan ~ 3mm cuts


RADIOTHERAPY PLANNING……….Depending upon

SITE to be treated

DEPTH to be treated

How to plan ?


What to treat ?GTV

gross tumor volume ( what is seen)


CTV Pre chemotherapy disease

+ 0.5 cm margin to GTV.


PTV 0.5 - 1 cm margin to CTV.


BEAM ARRANGEMENT


Two fields : anterior and lateral

CORNEAL /

LENS SHIELD



Lateral beam : angled 5-10 degree posteriorly



SUPERIOR AND INFERIOR OBLIQUE



Medial obliques


Electron beam

Single anterior electron beam.

Combined electron –photon beam.


3 D CRT



DVH


IMRT

IMRT shows potential for protecting normal tissues in patients requiring external beam radiation therapy for retinoblastoma.

Intensity-modulated radiation therapy for children with intraocular retinoblastoma: potential sparing of the bony orbit

KRASIN et al Clin Oncol 2004






Conclusion :

,IMRT planning significantly reduced lens doses. This was not accomplished to the same degree with 3D-CRT.

Our study underlines the importance of appropriate selection of planning objectives to maximize the specific capabilities and advantages of IMRT in terms of sufficient target coverage and simultaneous sparing of critical structures.



stereotactic radiation therapy

fractionated stereotactic radiation therapy of uveal melanoma results in excellent local control with only mild side effects

.

Karin Muller M.D.IJROBP63(1)2005 116-122

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T7X-4G54CS1-2&_user=2090688&_coverDate=09%2F01%2F2005&_alid=468481495&_rdoc=1&_fmt=full&_orig=search&_qd=1&_cdi=5070&_sort=d&_docanchor=&view=c&_acct=C000052195&_version=1&_urlVersion=0&_userid=2090688&md5=a5e46b3f86a0aa87a8978ca0d0c34f18&artImgPref=F#cor1

mailto:[email protected]


Stereotactic radiosurgery as a salvage treatment for recurrent skul base adenoied cystic carcinoma

Yoshimasa MORI , STEREOTACTIC AND FUNCTIONAL NEUROSURGERY 2006


PROTON BEAM THERAPY


Proton radiation therapy for retinoblastoma: Comparison of various intraocular tumor locations and beam arrangements

KRENGLI Marco

. Doses of 46 cobalt grey equivalent (CGE) to gross tumor volume (GTV) and 40 CGE to clinical target volume (CTV).

. The anterolateral oblique approach with an intrarotated eye resulted in additional reduction of bony volume and exposure of only one growth center.No appreciable dose was delivered to the contralateral eye, brain tissue, or pituitary gland. Conclusions: Proton therapy achieved homogeneous target coverage with true lens sparing. Doses to orbit structures, including bony growth centers, were minimized with different beam arrangements and eye positions.Proton therapy could reduce the risks of second malignancy and cosmetic and functional sequelae.

IGROBP 2005


Lymph node irradiation

Pre-auricular / upper deep cervical ~ 20%


Radiation DoseRetinoblastoma

Radical : ~ 45 Gy / 25 #Post operative : ~ 40 Gy / 25 #Palliative 30Gy / 10 #

Rhabdomyosarcoma Radical : >/= 55 Gy ( conventional # )41.5 Gy + 10 Gy

Lymphoma : 20-25 Gy/30 -35 Gy (conventional #) Optic nerve gloima : 50–54 Gy (conventional # )Metastatic disease : ~ 30Gy / 2 wks, 8 – 10 Gy / 1 wk, 10x3 / 5x4Leukemic retinopahy : 10 – 15 Gy / 4- days


Re-irradiationConservation treatment of the eye: Conformal proton reirradiation for recurrent uveal melanoma.

31 patienttotal doses between 118 and 140 CGE 20 NED , 9 enucleationMarucci L IJROBP. 2006 Mar 15;64(4):1018-22

.

Radiotherapy for localised relapse in patient with NHL

Katsumasa, Radiation Medicine ,2000


Complication post radiotherapy

Radiation induced Second malignant neoplasmwithin RT field ………..

_ Osteosarcoma / fibrosarcoma / other spindle cell sarcoma / malignant melanoma / thyroid carcinoma

Incidence : Abramson et al 198520% - 10 yr

50% - 20 yr 90 % - 30 yr

Facial / orbital deformitiesShort strature / precocious puberty


Ophthalmic :

Dry eye> 30Gy/ 3wks

Corneal damage>50 Gy/ 5wks

Cataractopacities >200rad,cataract >800 rads

Retinal damage>50 Gy / 5 wks

Radiation recall phenomenon

RADIOTHERAPY PLANNING - International Atomic …videoserver1.iaea.org/media/HHW/Radiotherapy/pediatric course/060... · RADIOTHERAPY PLANNING. IAEA Pediatric Radiation Oncology Training

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