Light flashes during proton and photon radiotherapy: A multicenter prospective observational study

Area of Science:

• Radiological Physics
• Ophthalmology
• Radiation Oncology

Background:

• Patients undergoing radiation therapy occasionally report visual phenomena, specifically light flashes.
• The characteristics and prevalence of these light flashes during radiotherapy have not been well-documented.

Purpose of the Study:

• To systematically evaluate the occurrence and characteristics of light flashes experienced by patients during photon and proton radiotherapy.
• To identify factors associated with the perception of light flashes during radiation treatment.

Main Methods:

• A prospective observational study involving adult patients (≥20 years) receiving photon or proton therapy.
• Data collected via weekly checklists assessing presence, intensity, color, movement, and duration of light flashes.
• Exclusion criteria included patients unable to communicate or with pre-existing visual abnormalities.

Main Results:

• 16.1% of patients (88/621) reported sensing light flashes during radiotherapy.
• Higher retinal radiation dose and younger patient age were significantly associated with light flash perception (p < 0.001).
• Light perception increased with higher retinal isodose lines (6.7% with no irradiation vs. 64.1% with 60-100% isodose).

Conclusions:

• Light flashes are a commonly perceived phenomenon during radiotherapy.
• Retinal radiation dose and patient age are key factors influencing the frequency and likelihood of experiencing light flashes.