Brachytherapy
What is prostate brachytherapy?
Permanent Prostate brachytherapy makes use of small (4.5 x 1mm) radioactive
"seeds" which are inserted into the prostate gland through
the skin between the anus and the scrotum.
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I-125 seeds on fluoroscopy (x-ray)
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Rapid Strand Iodine 125 Seeds
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Every man's prostate is a different shape, and hence each treatment
plan is unique. It is the careful attention to detail in the initial
planning stage that minimises the risks of treatment failure or side
effects. With this individualized plan the radiation dose is carefully
matched to the volume and shape of that man's prostate gland and because
of this permanent brachytherapy has been called "superconformal".
The planning is done after mapping out the prostate several weeks before
the implant procedure with trans rectal ultrasound. A specialised computer
program is used to determine the number, strength and placement pattern
of the seeds.
Typically about 110 seeds are used but the number can vary between
80 -150 seeds. The seeds are inserted using thin each needles. Each
needle holds 2 to 6 and the accuracy of the needle placement is monitored
directly by transrectal ultrasound and fluoroscopy (x-ray).
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I-125 seeds on post implant CT scan
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Superconformal dose distribution
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We use Rapid Strand Iodine 125 seeds which deliver a high therapeutic
dose of radiation directly to the prostate and the tumour killing the
cancer cells. However the strength of the radiation dose falls off very
rapidly away from the seeds resulting in a minimum of damage to healthy
tissue surrounding the prostate such as the bladder and lower bowel (rectum).
The Iodine 125 seeds lose 50% of their strength every 2 months and
the effective treatment time is about 6 months. By one year from implant
their radiation is minimal (<1%).
Prostate brachytherapy is also known as transperineal permanent Iodine 125 brachytherapy implant,
seed implant, or low-dose rate (LDR) brachytherapy.
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