Brachytherapy Flashcards

1
Q

use of radioactive sources in close proximity to target area for radiotherapy

A

brachytherapy

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2
Q

other names for brachytherapy

A

internal radiation therapy
sealed therapy
radium therapy
curie therapy
plesiotherapy
endocurie therapy

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3
Q

Advantage of brachytherapy

A

improved localized dose to target

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4
Q

Disadvantage of brachytherapy

A

only good for well-localized tumors, small lesions, labor intensive

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5
Q

Contraindications of brachy

A
  1. if tumor not clearly delineated
  2. active infection
  3. if evidence of bone involvement
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6
Q

earliest form of radiotherapy 19th century

A

radium

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7
Q

ideal brachytherapy source

A

pure gamma emitter
medium gamma energy
high specific activity
stable daughter product
long half live (temporary implants)
medium half life (permanent implants)

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8
Q
  1. 226 Ra
    Half life:
    Proton E.:
    HVL:
A

226 - Radium
1600 years
0.047-2.45 MeV
8.0 mm Hg

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9
Q
  1. 222 Rn
    Half life:
    Proton E.:
    HVL:
A

222 - Radon
3.83 yrs
0.047-2.45 MeV
8.0 mm Hg

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10
Q
  1. 60 Co
    Half life:
    Proton E.:
    HVL:
A

60- Cobalt
5,26 yrs
1.17, 1.33 MeV
11.0 mmHg

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11
Q
  1. 137- Ce
    Half life:
    Proton E.:
    HVL:
A

137- Cesium
30.0 yrs
0.662 MeV
5.5 mmHg

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12
Q
  1. 192 -Ir
    Half life:
    Proton E.:
    HVL:
A

192 - Iridium
74.2 yrs
0.36-1.06 MeV
2.5 mmHg

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13
Q
  1. 198 - Au
    Half life:
    Proton E.:
    HVL:
A

198- Gold
2.7 yrs
0.412 MeV
2.5 mmHg

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14
Q
  1. 125 - I
    Half life:
    Proton E.:
    HVL:
A

125 - Iodine
60.2 years
0.028 MeV
0.025 mmHg

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15
Q
  1. 103-Pd
    Half life:
    Proton E.:
    HVL:
A

103 -Paladium
17.0 yrs
0.21 MeV
0.008 mmHg

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16
Q

first radioisotope used clinically in 1903

A

Radium

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17
Q

Reasons why radon and radium is not used anymore

A

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

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18
Q

main substitute for radium
used in gynecological applications

A

137 Ce

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19
Q

measure estimate radioactive decay

A

decay correction

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20
Q

decay correction for 137 Cs [..]
must be replaced every [..]

A

every 6 mos
10-15 yrs

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21
Q

most important source for HDR (high dose rate) applications

A

192 Ir

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22
Q

decay correction for 192 Ir [..]
must be replaced every [..]

A

for each treatment
3-4 mos

23
Q

radioisotope with very low energy-shielding is easy and easily absorbed
mostly used in the form of seeds

A

125 I

24
Q

replacement for I 125
permanent implant
dose rate 2.5 larger than 125 I

A

103 Pd

25
Q

energy for 103 Pd

A

22 kV

26
Q

energy for 103 Pd

A

22 keV

27
Q

permanent implant
short enough to let activity decay in patient
energy [..]

A

Gold 198
412 keV

28
Q

wire, low dose rate radioisotope
interstitial implant

A

Iridium 192

29
Q

[source shapes and forms] balls of approx 3mm diameters

A

pellets

30
Q

[source shapes and forms] small cylinders about 1mm diam and 4mm length

A

seeds

31
Q

[source shapes and forms] b/w 15 and 45 mm active length

A

needles

32
Q

[source shapes and forms] about 14 mm length, used for gynecological implants

A

tubes

33
Q

[source shapes and forms] shaped as it is, approx. 60mm active length

A

hairpin

34
Q

[source shapes and forms] any length, customized in the hospital inactive ends may be added

A

wire

35
Q

[source shapes and forms] high activity miniature cylinder sources approx 1mm diam, 10 mm length

A

HDR Sources

36
Q

small containers for activity
usually 125 I, 103 Pd or 198 Au for permanent implant

A

seeds

37
Q

implants in operating theater, directly introduced to ROI
usually 192 Ir for temporary implants

A

needles and hairpins

38
Q

radioisotope used for LDR interstitial implants
cutting manual technique

A

192 Ir wire

39
Q

[applicators] treatm. of superficial lesions with radioactive sources in close contact with skin

A

Surface Moulds

40
Q

introduction of radioactivity using an applicator placed in a body cavity

A

intracavitary implants

41
Q

intracavitary implant usually used in:

A

gynecological
bronchus
esophagus
rectum

42
Q

most common application for cervix cancer
either monotherapy or addition to EBT

A

gynecological implants

43
Q

often used in palliative to open air ways
HDR brachytherapy
most often single catheter

A

bronchus implants

44
Q

implants of needles of flexible catheters directly in the target area
requires surgery - often major

A

interstitial implants

45
Q

interstitial implants are commonly used in:

A

breast
head and neck
sarcomas

46
Q

typically a boost
often utilizes templates to improve source positioning

A

breast implants

47
Q

[implant technique] pt. discharged with implant in place

A

permanent implants

48
Q

[implant technique] implant removed before pt. is discharged from hospital

A

temporary implants

49
Q

treats breast ca from within breast in 5 days with fewr side fx than standard 6 or 7 wks
uses special balloon catheter in lumpectomy cavity and inflated with saline solution

A

Mammosite

50
Q

other name for mammosite

A

balloon catheter radiation

51
Q

Adv. of mammosite

A

completed in 5-7 days
surgical scar but no skin thickening or burns
v. small portion and healthy tissue unaffected

52
Q

Disadv. of mammosite

A

avoid showers for a week
saline filled balloon feels odd
infections can occur

53
Q

used in operating theatre
useful for incomplete removal of ca

A

intraoperative brachytherapy