ESTRO 2024 - Abstract Book

S4705

Physics - Optimisation, algorithms and applications for ion beam treatment planning

ESTR0 2024

Figure 1. Scissor-beam method. (a): conventional proton RT method (CONV); (b) scissor-beam (SB) method for UTD proton GRID; (c) and (e): planar dose distribution along the beam direction for CONV and SB respectively; (d) and (f): planar dose distribution perpendicular to the beam direction for CONV and SB respectively; (d) and (f): 1D dose profiles of OAR and CTV for CONV and SB respectively. Both CONV and SB plans have single-field, single-energy-layer, and equal-weight spots, with the only difference that half of PB in CONV is tilted to become CB in SB.

Results:

The new methods SB and SB-TVL1 were validated in comparison with CONV. Compared to CONV of relatively homogeneous dose distribution, SB had modulated spatial dose pattern in normal tissues with UTD and comparable plan quality. Compared to SB, SB-TVL1 further maximized PVDR, with comparable dose objectives.

Table 1. Plan parameters. The dosimetric quantities include conformity index (CI), max CTV dose D CTV , mean body dose D body , mean OAR dose D OAR , and PVDR per field. OAR refers to esophagus for the lung case.

CONV

SB

SB-TVL1

CI

0.86

0.79

0.88

D CTV

2.34

2.68

2.28

D body

2.38

2.44

2.30

D OAR

4.20

4.80

3.74

PVDR 0°

-

1.28

1.56