ESTRO 2024 - Abstract Book

S3847

Physics - Image acquisition and processing

ESTRO 2024

Plan 1

Stage\ Irradiation

Nominal

2 mm shift

5 mm shift

1st energy layer (109.3 MeV)

76.5±2.5

74.6± 1.8

72.4±3.2

Treatment

68.3± 0.7

66.5±0.6

63.7± 0.6

Decay

64.9±0.6

63.0±0.4

60.5±0.5

Table 1. Ranges (in mm) were measured from the distal beam direction profiles of PET images for all irradiations at different time stages

Figure 2 . Left: PET images of the HN phantom for the nominal brain irradiation: a) beam-off period after 1st energy layer (~700 ms), b) treatment stage, and c) decay stage. Right: d) Beam-direction profile for the 1st energy layer stage (nominal irradiation in blue, 2 mm-shift in red, and 5 mm-shift in pink), treatment stage (black) and decay stage (green).

Conclusion:

The in-beam PET imaging approach has shown to be promising for precise real-time range measurements for the clinically realistic head and neck irradiations addressed in this study. However, a range calibration is required because there is a distal broadening of the activity profile due to the large positron range of the short half-life positron