SRS (stereotactic radiosurgery)

Question 1

srs hallmarks

Answer 1

high degree of dose conformity & beam accuracy

Question 2

srs dose uses what kind of beams

Answer 2

uses circular beams

Question 3

3 types of rad used for srs & srt

Answer 3

• heavy charged particles/p+
• Co-60 gamma rays (30Ci)/MV x-rays (most commonly used)
• neutron

Question 4

srs dosim requires what kind of profiles

Answer 4

cross beam profiles

Question 5

srs dosim complicated by ? relative to field dimension

Answer 5

detector size

Question 6

brw stands for

Answer 6

brown-robert-wells frame

Question 7

srs cross beam measurement done with

Answer 7

diodes & film

Question 8

srs depth dose distrib measurement done with

Answer 8

• parallel plate
• smaller chamber
• films
• diodes

Question 9

srs output measurement for small field done with

Answer 9

• film
• tld
• diodes

Question 10

srs collimation uses what attached below jaws to reduce geometric penumbra

Answer 10

-long cones to extend SDD

Question 11

gamma knife delivers radiation to target by simultaneous irradiation with large # of

Answer 11

isocenter gamma ray beams

Question 12

gamma knife distance

Answer 12

40.3 cm

Question 13

gamma knife tx isoline

Answer 13

50% isoline

Question 14

gamma knife CR tilted angle of

Answer 14

55deg

Question 15

gamma knife apparatus

Answer 15

leksell’s frame

Question 16

gamma knife treats what size lesions

Answer 16

small lesions (4cm)

Question 17

UT- srs dose

Answer 17

15-24 Gy/fx

Question 18

srs uses ? beams delivered through what kind of arcs

Answer 18

narrow multiple beams delivered thru non-coplanar isoctr arcs

Question 19

srs has what size target

Answer 19

larger target

Question 20

srs has a high/low Rx dose

Answer 20

lower

Question 21

srs dose

Answer 21

12-25Gy

Question 22

srt dose

Answer 22

42Gy (7Gy/fx, every other day) or 40Gy (4Gy/fx-10 fx daily)

Question 23

linac srs is used to tx what size tumors-x-ray knife

• large tumors
• use

Answer 23

large tumors

Question 24

linac srs uses what kind of beam orientation

Answer 24

mult non-cop arcs of circular beams converging @ iso placed @ target vol

Question 25

srs dosimetry uses what in formulas

Answer 25

tmr’s or pdd (cax depth distrib), output factors (Sc, Sp), off axis ratios

Question 26

srs dosimetry complicated by possible lack of

Answer 26

charged particle equilibrium

Question 27

in srs dosimetry detector size must be ? compared to field size

Answer 27

as small as possible

Question 28

srs output for large field done with

Answer 28

parallel plate

Question 29

gamma ray vs x-ray knife conformality

Answer 29

gk more conformal than xray knife unless xray knife has dynamic mlc

Question 30

gamma knife max diameter

Answer 30

18mm