A single-gradient junction technique to replace multiple-junction shifts for craniospinal irradiation treatment

Area of Science:

• Radiation Oncology
• Medical Physics

Background:

• Craniospinal irradiation (CSI) necessitates abutting radiation fields at the cervical spine.
• Conventional CSI uses weekly junction shifts to mitigate setup error-induced dose discrepancies.
• This approach can lead to geographic misses or overlapping doses at the junction.

Purpose of the Study:

• To compare the dosimetric outcomes of a single-gradient junction technique versus conventional multiple-junction shifts in CSI.
• To evaluate the impact of setup errors on dose distributions for both techniques.
• To assess the effectiveness of these techniques over a single fraction and the entire treatment course.

Main Methods:

• Retrospective replanning of 4 CSI patients using a single-gradient junction technique with intensity-modulated radiation therapy (IMRT) and dose painting.
• Fields were extended for a minimum 3-cm overlap.
• Setup errors (±3mm and ±5mm) were simulated to assess dose distribution impacts.

Main Results:

• The single-gradient technique achieved superior dose uniformity and conformity to target volumes.
• It resulted in lower mean and maximum doses to organs at risk (OARs) and diminished hot spots.
• Both single-fraction and treatment course dose profiles showed improvements with the gradient technique, especially concerning positioning errors.

Conclusions:

• The single-gradient junction technique offers improved conformity, dose uniformity, and reduced OAR doses in CSI.
• It effectively diminishes hot spots caused by systematic positioning errors over the treatment course.
• This technique simplifies planning to a single plan for the entire treatment, reducing potential human error.