18F-FET-PET-based dose painting by numbers with protons

Area of Science:

• Radiation Oncology
• Nuclear Medicine
• Medical Physics

Background:

• (18)F-fluoroethyltyrosine-positron emission tomography ((18)F-FET-PET) offers high specificity to brain tumor cells, making it suitable for dose painting.
• Biological image-based dose painting can lead to inhomogeneous dose prescriptions, requiring advanced treatment planning.

Purpose of the Study:

• To investigate the feasibility of (18)F-FET-PET-based dose painting by numbers using proton therapy.
• To compare the dose calculation and distribution of protons versus photons for this technique.

Main Methods:

• Utilized an intensity-modulated radiotherapy (IMRT) algorithm with a Monte Carlo dose-calculation algorithm for spot-scanning protons.
• Employed a linear tracer uptake to dose model to derive dose prescriptions from (18)F-FET-PET images.
• Evaluated the modulation transfer function (MTF) of protons against photons and conducted a planning study on three glioblastoma multiforme patients.

Main Results:

• Proton therapy demonstrated a higher MTF compared to photons.
• Proton therapy resulted in smaller standard deviations in dose differences between prescribed and optimized doses.
• Dose escalation within biologically defined subvolumes was achieved while maintaining constant doses to organs at risk.

Conclusions:

• The study confirms the feasibility of (18)F-FET-PET-based dose painting with protons.
• Proton therapy offers advantages for precise dose painting in brain tumor treatment planning.