Brain Mets

Question 1

SRS dose based on size

Answer 1

<2cm: 24Gy
2-3cm: 18Gy
3-4 cm: 15Gy

Question 2

RTOG 90-05

Remember as May 1990

Answer 2

Q: To determine the maximum tolerated dose of single fraction radiosurgery in patients with recurrent previously irradiated primary brain tumors and brain metastases.

A:The maximum tolerated doses of single fraction radiosurgery were defined for this population of patients as 24 Gy, 18 Gy, and 15 Gy for tumors </= 20 mm, 21-30 mm, and 31-40 mm in maximum diameter.
.
.
Unacceptable CNS toxicity was more likely in patients with larger tumors,
.
.
Eligibility criteria:
1) non brainstem tumors
2) Size <4cm
3) recurrents disease were eligible

Question 3

SRS vs WBRT

Answer 3

SRS had better cognitive outcomes and no difference in local control

Question 4

SRS vs observation

Answer 4

SRS better local control no difference in OS

Question 5

GK Parameters

Answer 5

CI: Conformity index= ideal value is 1
Prescription isodose volume/ tumor volume
reflects how conformal prescription is
.
.

HI: Heterogeneity index = ideal value<2
Max tumor dose/prescription dose
reflects how heterogeneous the dose distribution is
.
.

GI: Gradient Index = ideal value is 3
Volume receiving 50% of prescription dose/volume receiving 100% of the prescription dose
reflects* how rapid and steep the dose fall off is*