PEDIATRIC ORBITAL TUMORS RADIOTHERAPY PLANNING

Transcription

1 PEDIATRIC ORBITAL TUMORS RADIOTHERAPY PLANNING

2 ANATOMY

3 ANATOMY CONT

4 ANATOMY CONT.

5 ANATOMY CONT.

6 EYE OF A CHILD

7 Normal tissue tolerance doses (in conventional #) TD 5/5 TD 50/5 Endpoint Gy Gy Optic nerve Blindness Chiasma Blindness Lens Cataract Retina Blindness

8 COMMON PEDIATRIC ORBITAL TUMORS Intraocular Tumors Intraorbital Tumors _ Retinoblastoma - Rhabdomyosarcoma _ Uveal Melanoma - Lymphoma _ Metastasis - Optic Nerve Glioma - Optic nerve sheath meningioma - Metastasis

9 Rhabdo- myosarcoma Most common orbital malignant tumor

10 When To Treat? Age - > 1 yr - < 1 yr Extent of disease at presentation. - Localised to Orbit - Orbit with intracranial extension

11 PLANNING..

12 IMMOBILIZATION Thermoplastic mould Vacuum bag Sedation General anesthesia Planning CT scan ~ 3mm cuts

13 How to plan? RADIOTHERAPY PLANNING. Depending upon SITE to be treated DEPTH to be treated

14 What to treat? GTV gross tumor volume ( what is seen)

15 CTV Pre chemotherapy disease cm margin to GTV.

16 PTV cm margin to CTV.

17 BEAM ARRANGEMENT

18 Two fields : anterior and lateral CORNEAL / LENS SHIELD

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20 Lateral beam : angled 5-10 degree posteriorly

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22 SUPERIOR AND INFERIOR OBLIQUE

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24 Medial obliques

25 Electron beam Single anterior electron beam. Combined electron photon beam.

26 3 D CRT

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28 DVH

29 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

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34 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.

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36 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)

37 Stereotactic radiosurgery as a salvage treatment for recurrent skul base adenoied cystic carcinoma Yoshimasa MORI, STEREOTACTIC AND FUNCTIONAL NEUROSURGERY 2006

38 PROTON BEAM THERAPY

39 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

40 Lymph node irradiation Pre-auricular / upper deep cervical ~ 20%

41 Radiation Dose Retinoblastoma Radical : ~ 45 Gy / 25 # Post operative : ~ 40 Gy / 25 # Palliative 30Gy / 10 # Rhabdomyosarcoma Radical : >/= 55 Gy ( conventional # ) 41.5 Gy + 10 Gy Lymphoma : Gy/30-35 Gy (conventional #) Optic nerve gloima : Gy (conventional # ) Metastatic disease : ~ 30Gy / 2 wks, 8 10 Gy / 1 wk, 10x3 / 5x4 Leukemic retinopahy : Gy / 4- days

42 Re-irradiation Conservation treatment of the eye: Conformal proton reirradiation for recurrent uveal melanoma. 31 patient total doses between 118 and 140 CGE 20 NED, 9 enucleation. Marucci L IJROBP Mar 15;64(4): Radiotherapy for localised relapse in patient with NHL Katsumasa, Radiation Medicine,2000

43 Complication post radiotherapy Radiation induced Second malignant neoplasm within RT field.. _ Osteosarcoma / fibrosarcoma / other spindle cell sarcoma / malignant melanoma / thyroid carcinoma Incidence : Abramson et al % - 10 yr 50% - 20 yr 90 % - 30 yr Facial / orbital deformities Short strature / precocious puberty

44 Ophthalmic : Dry eye > 30Gy/ 3wks Corneal damage >50 Gy/ 5wks Cataract opacities >200rad, cataract >800 rads Retinal damage >50 Gy / 5 wks Radiation recall phenomenon