Optimizing localization accuracy in head and neck, and brain radiotherapy

Area of Science:

• Medical Imaging
• Radiation Oncology
• Radiology

Background:

• Accurate patient localization is crucial for effective radiotherapy.
• Contrast-enhanced CT (CECT) may improve soft tissue visualization for treatment planning.
• The role of radiologist input in contouring for radiotherapy planning requires further investigation.

Purpose of the Study:

• To evaluate the impact of contrast-enhanced CT (CECT) scans and radiologist input on radiotherapy localization.
• To compare contouring differences between oncologists and radiologists using CECT data.
• To assess the effect on planning target volumes (PTVs) and treatment accuracy.

Main Methods:

• Retrospective analysis of 25 head and neck/brain patient CT scans (pre- and post-contrast).
• Radiotherapy plans were initially created on unenhanced CT scans.
• Scans were re-contoured by oncologists and a radiologist; differences in volume, position, and coverage were analyzed.

Main Results:

• Oncologist contouring on CECT showed minimal changes in gross tumor volumes (GTVs) and PTVs for brain cases.
• Head and neck cases showed larger volume changes with oncologist contouring on CECT.
• Radiologist contouring on CECT resulted in statistically significant differences in PTV volume (p < 0.05) and significant differences compared to oncologist-generated GTVs (p < 0.01).
• Geographic shifts were generally within departmental tolerances.

Conclusions:

• Contrast-enhanced CT data has a limited effect on PTVs contoured by oncologists.
• Radiologist input significantly alters PTVs, highlighting the importance of their expertise in radiotherapy planning.
• Significant differences arise when comparing PTVs based on oncologist versus radiologist-generated GTVs.