engleski

Conformal radiotherapy of relapsing meningeoma

Introduction: Meningeomas are tumors of arachnoid origin, which account for about 15-20% of primary intracranial tumors. Surgery is a primary method of treatment. Indications for radiotherapy are: residual tumor, malignant meningeoma and relapse. Adjuvant dose is 54 Gy, dose on gross disease is 60 Gy. When using conformal radiotherapy margin on GTV is 1 cm ; margin to get PTV is another 5 mm (1). Patient and method: In 2002, patient J. Z., born in 1963, was diagnosed with large meningeoma on the basis of anterior right portion of the scull. The first resection was performed in April 2002 (PHD: Meningeoma transitional). Until January 2009, 9 resections were performed. MR (January 2009) showed multiple tumors in the right endocranium: next to sinus cavernosus (32 mm), several tumors temporally (up to 20 mm), frontobasally next to craniotomy (35 mm), frontally (27 mm), in the right orbit (19 mm) and in soft tissue below the right orbit (24 mm). In February 2009, another tumor reduction was preformed (PHD: Meningeoma malignum). In March 2009, the patient was referred to radiotherapy. GTV was contoured and 5 mm margin for PTV was added ; 1 cm margin for CTV was omitted due to the huge volume of the tumor. Planned dose was 60 Gy in 30 fractions. The aim was to achieve homogenous dose to PTV, up to 95% and to preserve function of the left eye. Five portals were used: 2 anterior, photon energy 6 MeV, 2 posterior, photon energy 18 MeV and one lateral, photon energy 6 MeV. Medium dose to PTV was 5955 cGy (maximal dose 6410 cGy). According to literature review, TD 50/5 for lens is 12 Gy and for peripheral nerves 65- 77 Gy (2). In our patient medium dose to the left lens was 302 cGy (maximal dose 491 cGy), to the left eye 709 cGy (maximal dose 3619 cGy) and to the optic nerve 850 cGy (maximal dose 3745 cGy) Conclusion: Using 3DCRT we have managed to achieve adequate homogenous dose to PTV while preserving organs of risk.

meningeoma; conformal radiotherapy

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