740-741 / 3581
•
547 daily CBCT from 15 pts
03/01/13
Ost P, IJROBP 2011
Gill S, Radiother Oncol 2013
Post operative margins
Discussion
Ghilezan et al. reviewed IGART techniques and clinical out-
comes in prostate cancer recently and found that adaptive radio-
therapy in prostate cancer enabled better target coverage and
reduced rectal dose with clinical follow-up demonstrating encour-
aging clinical outcomes
[19]
. In the intact prostate setting, Liu et al.
compared a multiple replan rolling-average adaptive strategy to a
single replan adaptive strategy and IGRT alone and found that mul-
tiple replanning was superior but significantly more complex
[20]
.
The framework and techniques used in on-line IGART in the intact
prostate setting have been fairly broad and range from direct beam
aperture modification
[21]
to online adaptive inverse re-planning
[22]
. The post-prostatectomy target however undergoes noticeably
more deformation than the intact prostate and adaptive techniques
in the post-prostatectomy setting are sparse in the literature. The
results of this study confirm that a ‘‘plan of the day’’ online strategy
for IGART is feasible in the post-prostatectomy setting, because the
difference in isocentre location and volume selection was small,
and can be accounted for in a clinically acceptable CTV to PTV mar-
gin. At the moment, we have insufficient evidence to suggest that
margins can yet be reduced with IGART with the current protocol.
The conventional margin for post-prostatectomy radiotherapy rec-
that not all cli
bed deformatio
and largest ad
week of radiot
the prostate be
RTTs and ROs
possible, the Pl
These data sup
statectomy sett
There are s
localization var
was taken as a
seen on the sa
touring guideli
5 mm below t
the CTV from t
instructed to e
the penile bulb
same distance
suggests that t
touring guideli
be taken as re
where vesico-u
usually the cas
mend that if s
should be used
the vesico-uret
the penile bulb
get, we recom
penile bulb ide
This study also
credentialing f
tocols are empl
able cutoff ma
>50% of the an
has previously
ingful action th
tact prostate ra
This study c
comparison of
answer. A dosi
dose fall-off ou
dependent and
Our data do po
Fig. 4.
Distance between RTT volume and reference answer volume (in mm) in the
SI, AP and LR directions that would required to cover the entire reference answer
selected adaptive CTV volume for all 165 test answers.
S. Gill et al. / Radiotherapy and Oncology 107 (2013) 1