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@ARTICLE{Rippke:282361,
author = {C. Rippke and C. K. Renkamp and C. Attieh and F. Schlüter
and C. Buchele and J. Debus$^*$ and M. Alber and S. Klüter},
title = {{L}eaf-individual calibration for a double stack multileaf
collimator in photon radiotherapy.},
journal = {Physics $\&$ Imaging in Radiation Oncology},
volume = {27},
issn = {2405-6316},
address = {Amsterdam [u. a.]},
publisher = {Elsevier Science},
reportid = {DKFZ-2023-01745},
pages = {100477},
year = {2023},
abstract = {In online adaptive stereotactic body radiotherapy
treatments, linear accelerator delivery accuracy is
essential. Recently introduced double stack multileaf
collimators (MLCs) have new facets in their calibration. We
established a radiation-based leaf-individual calibration
(LIMCA) method for double stack MLCs.MLC leaf positions were
evaluated from four cardinal angles with test patterns at
measurement positions throughout the radiation field on EBT3
radiochromic film for each single stack. The accuracy of the
method and repeatability of the results were assessed. The
effect of MLC positioning errors was characterized for a
measured output factor curve and a clinical patient plan.All
positions in the motor step - position calibration file were
optimized in the established LIMCA method. The resulting
double stack mean accuracy for all angles was 0.2 ± 0.1 mm
for X1 (left bank) and 0.2 ± 0.2 mm for X2 (right bank).
The accuracy of the leaf position evaluation was 0.2 mm
$(95\%$ confidence level). The MLC calibration remained
stable over four months. Small MLC leaf position errors
(e.g. 1.2 mm field size reduction) resulted in important
dose errors (-5.8 $\%)$ for small quadratic fields of 0.83
× 0.83 cm2. Single stack position accuracy was essential
for highly modulated treatment plans.LIMCA is a new double
stack MLC calibration method that increases treatment
accuracy from four angles and for all moving leaves.},
keywords = {Adaptive radiotherapy (Other) / Image guided radiotherapy
(Other) / MR-Linac (Other) / MR-guided radiotherapy (Other)
/ Multileaf collimator (Other) / Photon radiotherapy (Other)
/ Quality assurance (Other) / Quality control (Other) /
Small field dosimetry (Other)},
cin = {E050 / HD01},
ddc = {610},
cid = {I:(DE-He78)E050-20160331 / I:(DE-He78)HD01-20160331},
pnm = {315 - Bildgebung und Radioonkologie (POF4-315)},
pid = {G:(DE-HGF)POF4-315},
typ = {PUB:(DE-HGF)16},
pubmed = {pmid:37635846},
pmc = {pmc:PMC10457557},
doi = {10.1016/j.phro.2023.100477},
url = {https://inrepo02.dkfz.de/record/282361},
}