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vs. HIFU: Adjustable Power Levels
Ablatherm vs Sonablate (Page 6 of 8)
Adjustable Power Levels and Hands-on Physician Control
 Effectively
treating the prostate with HIFU is a science not an art. Precise
power levels have been determined and validated and modifying
them during the procedure may result in under-treatment of the
cancer. The three power levels of the Ablatherm are scientifically
based – the foundation of which is the thermal properties
of the prostate which is different for the three situations (primary,
repeat HIFU, and salvage (post-radiation treatment)). There is
no long term data to back up a variable power level, and long
term data is critical in analyzing the effectiveness of
prostate cancer treatments.
The "adjustable power levels" which are promoted
as a Sonablate 500 advantage because they allow for customization
are actually a disadvantage. The risk of reducing the power in
order to protect the rectum from injury is that it may result
in tissue sparing. The same risks apply when decreasing power
when encroaching on the neurovascular bundles as this involves
treating the lateral posterior parts of the prostate, a region
known to often contain cancer.
When a computer guided system is used to deliver the treatment,
the optimal treatment power can be used throughout the entire
prostate without endangering sensitive nearby structures. HIFU
is a technology based procedure and ‘Hands on Physician
Control’ has been replaced with automated computer guided
control in the Ablatherm to provide the most precise treatment
possible. The precise power levels employed with the Ablatherm® can
be used without fear of damage to the rectum since the Ablatherm
has an automatic safety system which stops the machine from treating
if treatment comes too close to the rectum. Because of this safety
system the appropriate level of energy needed to effectively
treat can be uniformly given to all areas of the prostate by
computer guidance.
The importance of the points made above is illuminated in the
2007 Journal of Urology article on the Sonablate Phase I/II trial
results. The author described the cause of a fistula that occurred
in one of the patients. He said that it “developed after
a second treatment in a patient after we increased the energy
delivered. We believe in retrospect that it was due to positioning
the focal zone too close to the rectal wall.” 1 Automation
prevents precisely these sorts of events and is the primary reason
why no rectourethral fistulas have occurred during an Ablatherm
treatment since parameters were updated in 2002.
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