TY  - JOUR
AU  - Behrends, C.
AU  - Bäumer, C.
AU  - Verbeek, N.
AU  - Wulff, J.
AU  - Timmermann, B.
TI  - Optimization of proton pencil beam positioning in collimated fields.
JO  - Medical physics
VL  - 50
IS  - 4
SN  - 0094-2405
CY  - College Park, Md.
PB  - AAPM
M1  - DKFZ-2023-00043
SP  - 2540-2551
PY  - 2023
N1  - 2023 Apr;50(4):2540-2551
AB  - The addition of static or dynamic collimator systems to the pencil beam scanning delivery technique increases the number of options for lateral field shaping. The collimator shape needs to be optimized together with the intensity modulation of spots.To minimize the proton field's lateral penumbra by investigating the fundamental relations between spot and collimating aperture edge position.Analytical approaches describing the effect of spot position on the resulting spot profile are presented. The theoretical description is then compared with Monte Carlo simulations in TOPAS and in the RayStation treatment planning system, as well as with radiochromic film measurements at a clinical proton therapy facility. In the model, one single spot profile is analyzed for various spot positions in air. Further, irradiation setups in water with different energies, the combination with a range shifter, and two-dimensional proton fields were investigated in silico.The further the single spot is placed beyond the collimating aperture edge ('overscanning'), the sharper the relative lateral dose fall-off and thus the lateral penumbra. Overscanning up to 5 mm reduced the lateral penumbra by about 20
KW  - Monte Carlo (Other)
KW  - lateral penumbra (Other)
KW  - pencil beam scanning with aperture (Other)
KW  - proton therapy (Other)
KW  - radiobiology (Other)
LB  - PUB:(DE-HGF)16
C6  - pmid:36609847
DO  - DOI:10.1002/mp.16209
UR  - https://inrepo02.dkfz.de/record/186674
ER  -