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@ARTICLE{Saito:136796,
author = {N. Saito$^*$ and D. Schmitt$^*$ and M. Bangert$^*$},
title = {{C}orrelation between intrafractional motion and dosimetric
changes for prostate {IMRT}: {C}omparison of different
adaptive strategies.},
journal = {Journal of applied clinical medical physics},
volume = {19},
number = {4},
issn = {1526-9914},
address = {Reston, Va.},
publisher = {ACMP},
reportid = {DKFZ-2018-01234},
pages = {87 - 97},
year = {2018},
abstract = {To retrospectively analyze and estimate the dosimetric
benefit of online and offline motion mitigation strategies
for prostate IMRT.Intrafractional motion data of 21 prostate
patients receiving intensity-modulated radiotherapy was
acquired with an electromagnetic tracking system. Target
trajectories of 734 fractions were analyzed per delivered
multileaf-collimator segment in five motion metrics:
three-dimensional displacement, distance from beam axis
(DistToBeam), and three orthogonal components. Time-resolved
dose calculations have been performed by shifting the target
according to the sampled motion for the following scenarios:
without adaptation, online-repositioning with a minimum
threshold of 3 mm, and an offline approach using a modified
field order applying horizontal before vertical beams.
Change of D95 (targets) or V65 (organs at risk) relative to
the static case, that is, ΔD95 or ΔV65, was extracted per
fraction in percent. Correlation coefficients (CC) between
the motion metrics and the dose metrics were extracted. Mean
of patient-wise CC was used to evaluate the correlation of
motion metric and dosimetric changes. Mean and standard
deviation of the patient-wise correlation slopes (in
$\%/mm)$ were extracted.For ΔD95 of the prostate, mean
DistToBeam per fraction showed the highest correlation for
all scenarios with a relative change of $-0.6 ± 0.7\%/mm$
without adaptation and $-0.4 ± 0.5\%/mm$ for the
repositioning and field order strategies. For ΔV65 of the
bladder and the rectum, superior-inferior and
posterior-anterior motion components per fraction showed the
highest correlation, respectively. The slope of bladder
(rectum) was 14.6 ± 5.8 $(15.1 ± 6.9) \%/mm$ without
adaptation, 14.0 ± 4.9 $(14.5 ± 7.4) \%/mm$ for
repositioning with 3 mm, and 10.6 ± 2.5
$(8.1 ± 4.6) \%/mm$ for the field order approach.The
correlation slope is a valuable concept to estimate
dosimetric deviations from static plan quality directly
based on the observed motion. For the prostate, both
mitigation strategies showed comparable benefit. For organs
at risk, the field order approach showed less sensitive
response regarding motion and reduced interpatient
variation.},
cin = {E040},
ddc = {530},
cid = {I:(DE-He78)E040-20160331},
pnm = {315 - Imaging and radiooncology (POF3-315)},
pid = {G:(DE-HGF)POF3-315},
typ = {PUB:(DE-HGF)16},
pubmed = {pmid:29862644},
pmc = {pmc:PMC6036361},
doi = {10.1002/acm2.12359},
url = {https://inrepo02.dkfz.de/record/136796},
}