High Dose Brachy

Question 1

LDR dose rate ? cGy/min

Answer 1

0.5-2 cGy/min

Question 2

HDR dose rate ? cGy/min

Answer 2

20 cGy/min or higher

Question 3

HDR vs LDR safer?

Answer 3

HDR safer

Question 4

HDR units use a single source of high intensity of ? Ci or ? GBq

Answer 4

~10 Ci or 370 GBq

Question 5

most common source used

Answer 5

Ir-192

Question 6

Ir-192 offers ? specific activity

Answer 6

high specific activity- allows smaller source for same activity

Question 7

Ir-192 t1/2 & replacement

Answer 7

shorter t1/2- source replaced every 3-4 months

Question 8

NRC regulation leakage outside unit do not exceed ? mR/hr @ ? distance

Answer 8

1 mR/hr @ 10 cm distance

Question 9

HDR positioning accuracy

Answer 9

+/- 1 mm

position is in 0.1 sec dwell times

Question 10

dose calc HDR uses

Answer 10

• Sievert integral

- Monte Carlo

Question 11

endobronchial obstruction by lung CA- HDR or LDR?

Answer 11

HDR

Question 12

HDR cold spots > than ? % exist @ ends b/c of gamma ray E

Answer 12

50%

Question 13

HDR source strength ?Ci or ? GBq

Answer 13

10Ci= 370 GBq

Question 14

LDR dose rate ? cGy/hr

Answer 14

40-200 cGy/hr

Question 15

LDR dose rate ? mCi/seed

Answer 15

0.3-100 mCi/seed

Question 16

HDR dose rate ? cGy/hr

Answer 16

1200 cGy/hr

Question 17

HDR dose rate ? Ci/seed

Answer 17

1-10 Ci/seed

Question 18

HDR vs LDR dose distribution

Answer 18

HDR offers greater control over dose distrib

Question 19

HDR vs LDR tumor dose

Answer 19

HDR can concentrate dose to tumor & spare surrounding tissue

Question 20

HDR vs LDR dose homogeneity/conformity

Answer 20

HDR offers better control of dose homogeneity & dose conformity

Question 21

HDR dose calc task group?

Answer 21

TG-43 formalism (khan-advises over sievert is suitable for complex design)