Types
of Radiation Therapy Treatments
- External Beam EBRT (teletherapy)
:
Short
– 15cm from where radiation is produced to
the patients skin (SSD)
Superficial
Unit : operates at a SSD of 15cm
Roentgens(dose
rate) are very high / need filters
Medium –
50cm
Orthovoltage : treat a distance of 50cm
Long –
100cm
LINAC : treats to a distance of 100cm
2.
Brachytherapy (short distance therapy)
:
- Molds and Applicators
(obsolete)
•
Used for skin lesions
•
Make a lead mold filled with sources and put it on the patient
for a set amount of time
2. Intracavitary (within-cavity)
•
Only performed where thers is a pre-existing space
•
GYN tumors
Afterloading : (tandem and
ovoid)
•
LDR – low dose rate
•
Empty applicator is placed into patient
•
Sources then pushed through tubes when the treatment begins
Remote
afterloading :
•
HDR – high dose rate
•
Template is placed (ex. In Vagina)
•
Leads(catheters) placed into the template
•
The source(cesium 132) comes out of the machine and oscillates
back and forth
•
Patient is done in 2-3 sessions
*patients
anatomy determines whether LDR or HDR will be used
3. INTERSTITIAL
2
types : permanent and temporary
Permanent
interstitial :
•
Sources are put in and left in (stapled into tissue)
•
Permanent sources are used in inaccessible sites – prostate,
brain, lung, etc…..
•
Iodine 125 is used (short half life)
•
Disadvantage is dose cannot be controlled
Temporary interstitial :
•
Sources are taken out
•
Advantage of this is better control of dose, sources can be
reused
•
Disadvantage is can only be used in easily accessible sites
– breast boosts, anus, tongue and floor of mouth
*advantage
of brachytherapy :
- is sparring of normal tissue
- can be useful as a boost for later
therapies (ex. Boost for EBRT)
*disadvantage
of brachytherapy :
- invasive procedure
- can only be used with small tumors
- does not address nodal involvment
(metastasis)
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