Pelvic Ewing sarcomas. Three-dimensional conformal vs. intensity-modulated radiotherapy

Area of Science:

• Radiation Oncology
• Medical Physics
• Pediatric Oncology

Background:

• Pelvic Ewing sarcoma requires precise radiotherapy planning.
• Comparing advanced radiotherapy techniques is crucial for optimizing treatment outcomes.

Purpose of the Study:

• To evaluate the advantages of intensity-modulated radiotherapy (IMRT) over three-dimensional conformal radiotherapy (3D-CRT) for pelvic Ewing sarcoma.
• To assess dose coverage, conformity, homogeneity, and organ-at-risk sparing.

Main Methods:

• Retrospective analysis of 8 patients with pelvic Ewing sarcoma.
• Calculation and comparison of 3D-CRT and IMRT treatment plans.
• Evaluation of planning target volume (PTV) coverage, conformity, and homogeneity indices, alongside organ-at-risk dose parameters.

Main Results:

• Both IMRT and 3D-CRT achieved excellent PTV coverage (V95 > 98%).
• IMRT demonstrated superior dose conformity (CI: 0.79 vs. 0.54, p=0.012) but lower homogeneity (HI: 0.11 vs. 0.07, p=0.035) compared to 3D-CRT.
• IMRT significantly reduced radiation dose to the bowel and rectum at higher dose levels, while increasing low-dose bath to normal tissues.

Conclusions:

• IMRT provides significantly better dose conformity and bowel sparing than 3D-CRT in pelvic Ewing sarcoma.
• The improved dose distribution with IMRT facilitates dose escalation, potentially enhancing treatment efficacy.
• IMRT represents a valuable advancement for radiotherapy planning in this patient population.