Brachytherapy Flashcards
use of radioactive sources in close proximity to target area for radiotherapy
brachytherapy
other names for brachytherapy
internal radiation therapy
sealed therapy
radium therapy
curie therapy
plesiotherapy
endocurie therapy
Advantage of brachytherapy
improved localized dose to target
Disadvantage of brachytherapy
only good for well-localized tumors, small lesions, labor intensive
Contraindications of brachy
- if tumor not clearly delineated
- active infection
- if evidence of bone involvement
earliest form of radiotherapy 19th century
radium
ideal brachytherapy source
pure gamma emitter
medium gamma energy
high specific activity
stable daughter product
long half live (temporary implants)
medium half life (permanent implants)
- 226 Ra
Half life:
Proton E.:
HVL:
226 - Radium
1600 years
0.047-2.45 MeV
8.0 mm Hg
- 222 Rn
Half life:
Proton E.:
HVL:
222 - Radon
3.83 yrs
0.047-2.45 MeV
8.0 mm Hg
- 60 Co
Half life:
Proton E.:
HVL:
60- Cobalt
5,26 yrs
1.17, 1.33 MeV
11.0 mmHg
- 137- Ce
Half life:
Proton E.:
HVL:
137- Cesium
30.0 yrs
0.662 MeV
5.5 mmHg
- 192 -Ir
Half life:
Proton E.:
HVL:
192 - Iridium
74.2 yrs
0.36-1.06 MeV
2.5 mmHg
- 198 - Au
Half life:
Proton E.:
HVL:
198- Gold
2.7 yrs
0.412 MeV
2.5 mmHg
- 125 - I
Half life:
Proton E.:
HVL:
125 - Iodine
60.2 years
0.028 MeV
0.025 mmHg
- 103-Pd
Half life:
Proton E.:
HVL:
103 -Paladium
17.0 yrs
0.21 MeV
0.008 mmHg
first radioisotope used clinically in 1903
Radium
Reasons why radon and radium is not used anymore
a. wide energy spectrum - high dose close to source (difficult shielding)
b. Radon - daughter product is a noble gas (contamination risk)
c. long half life means disposal is difficult
main substitute for radium
used in gynecological applications
137 Ce
measure estimate radioactive decay
decay correction
decay correction for 137 Cs [..]
must be replaced every [..]
every 6 mos
10-15 yrs
most important source for HDR (high dose rate) applications
192 Ir