ESTRO 2024 - Abstract Book

S3497

Physics - Dose prediction, optimisation and applications of photon and electron planning

ESTRO 2024

demonstrate much better distal normal tissue sparing which is as expected. In the table below are the coverages for each test case and a brief description of the site and technique being used.

Case #

Site description

Electron technique

VMAT technique

Electron D95%

VMAT D95%

1

Zygoma

9MeV + 1cm bolus

6FFF + 0.5cm bolus 6FFF + 0.5cm bolus 6FFF + 0.5cm bolus 6FFF + 0.5cm bolus 6FFF + 1cm bolus 6FFF + 0.5cm bolus 6FFF + 0.5cm bolus

59.8%

98.9%

2

Dupuytrens (palms)

6MeV + 0.5cm bolus

92.5%

96.1%

3

SCC right neck by ear

9MeV + 0.5cm bolus

72.0%

99.7%

4

SCC left cheek

9MeV + 0.5cm bolus

57.4%

97.0%

5

SCC

nostril/inner

9MeV + 1cm bolus

79.6%

99.8%

canthus

6 (sim)

SCC left temple near eye

6MeV + 0.5cm bolus

89.6%

97.4%

7 (sim)

SCC apex of scalp

6MeV + 0.5cm bolus

94.4%

96.3%

Conclusion:

Using VMAT with bolus is an effective way to treat difficult and superficial lesions that would have otherwise been traditionally sent for electron beam therapy. The dose distribution patterns of electron beams are not normally shown to clinicians and the ability to include them in a modern TPS has aided clinician understanding considerably. Taken together it can be shown that the small amount of sites that could be treated by electrons can instead be treated more effectively by a modern VMAT technique. To bring this technique into the clinic requires discussion with consultants as they would be required to contour appropriate target volumes whereas previously this has not been needed. For dose objectives related to the target and adjacent organs at risk, VMAT plans achieve better results than electron treatments. However, the clinician would have to weigh any concerns regarding the increased dose to distal structures against the improved dose distribution.

Keywords: VMAT, Electrons, LINAC replacement

786

Mini-Oral

Utilizing Pareto optimization to refine ML training data in prostate radiotherapy planning

Hunor Benedek 1,2 , Michael Lempart 3,2 , Niklas Svanberg 2 , Adalsteinn Gunnlaugsson 2 , Per Nilsson 1,2 , Sven Bäck 1,2 , Tommy Knöös 1,2 , Crister Ceberg 1