Reirradiation Brain

Reirradiation Brain

Suruchi Singh 18 May 2011 04:13

Young 35 yr old well preserved male, previously (september 2005) operated n irradiated (Co-60, partial brain, parallel opposed portals, ?54 Gy/27 fr) for rt frontal lobe astro Gr I, has now presented with GBM within the post op cavity. The tumor was small approx 4X4 cms, n has been completely resected. the queries would be,
1. Wat wd be total target dose to the tumor.
2. wat wd be max allowable dose to previously treated n untreated brain (hairline being the only evidence for portals)
3. Critical structures viz. optic apparatus, eyes etc are quite distant from the tumor but must have been fired during first course of treatment, 0 dose to these structures might not be possible, do we have any evidence of recovery of these structures from radiation induced injury with time?
Suruchi

Re: Reirradiation Brain

Palex80 19 May 2011 14:33

You can probably try giving 45 Gy with 1,8 Gy / day.
We have lots of studies with reirradiation of Glioblastoma after 60/2, where the patients received doses of 30-36 Gy with FSRT and 3-5 Gy / day. Risk of major damage to sensitive structures like optic apparatus is surely there, but it really depends on how much dose they received during the first course of therapy. Can you retrospectively plan the first series and see how much dose was delivered to these structures?