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Updated: Aug 6, 2026
Proton Therapy Delivery and Its Clinical Application in Select Solid Tumor Malignancies
Published on: February 6, 2019
Comparison of model-based and delineation-based target volume definition for ocular proton therapy
Lisa Klaassen1, Coen R N Rasch2, Jan-Willem M Beenakker1
1Dept. of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands; Dept. of Radiology, Leiden University Medical Center, Leiden, the Netherlands; Dept. of Radiation Oncology, Leiden University Medical Center, Leiden, the Netherlands; HollandPTC, Delft, the Netherlands.
Ocular proton therapy uses model-based target volumes, but these models can overestimate tumour size. This study compared model-based and delineation-based methods for ocular tumours, finding models acceptable but often larger than actual tumours.
Area of Science:
- Ophthalmology
- Radiation Oncology
- Medical Imaging
Background:
- High-resolution MRI enables 3D delineation of ocular tumours.
- Current ocular proton therapy often uses model-based target volumes.
- A gap exists between advanced imaging and current treatment planning for ocular tumours.
Purpose of the Study:
- To compare model-based and delineation-based target volume definitions for ocular tumours.
- To evaluate the accuracy of model-based tumour definition in ocular proton therapy.
Main Methods:
- Seventy uveal melanoma patients' tumours were delineated.
- Polynomial models of varying degrees were generated from tumour bases.
- Models were assessed for 98% coverage or <0.4 mm underestimation; the smallest acceptable model was chosen.
Main Results:
- Acceptable tumour models were generated for 69/70 patients.
- Models often overestimated tumour volume by 20.5% at 98% coverage.
- Irregular tumours showed greater overestimation (36.6%) than dome-shaped tumours (16.4%).
Conclusions:
- Tumour models in ocular proton therapy can achieve acceptable coverage.
- However, these models tend to overestimate the actual delineated tumour volume.
- This overestimation may impact treatment planning precision.
