- It uses a highly focused and precisely targeted radiation to the target tissue while minimizing the exposure to adjacent structure.
- The main aim is to long term arrest of tumour growth.
- Radiosurgery differs fundamentally from radiotherapy in that it delivers a single high dose of radiation rather than as a fractionated course or dose.
- Source: 201 cobalt (Gamma knife)
- Efficacy: 20 Gy in single fraction= 50-110 Gy in doses( in fractions)
- It can be done in LA.
- It is painless like having another scan.
- It causes less damage to surrounding tissue.
- It has low morbidty e.g. less incidence of FN palsy but more chances of hearing preservation.
- Slow growing tumour: VS, meningioma, glomus, angiofibroma.
- Thrombo-obliterative effect of radiosurgery for vascular tumour eg hemangiopericytoma and endolymphatic sac adenocarcinoma.
- Limited control of chrdoma and chondrosarcoma.
- As a booster dose or adjuvant to surgery or radiotherapy for NPC, SCC of skull base.
- It is unsuitable for larger tumour >3 cm
- Disease extending to neck as machine are designed for cranial disease
- Risk of radiation: high dose may cause malignant transformation
- Peritumoural scarring causing subsequent surgery difficult
- Tumour continues to grow in 20 % so life long monitoring is necessary.
- Gamma technique
- Proton beam
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