Physics aspects of prostate tomotherapy: planning optimization and image-guidance issues

Area of Science:

• Radiation Oncology
• Medical Physics
• Urologic Oncology

Background:

• Prostate cancer treatment requires precise radiation delivery to maximize tumor control while minimizing toxicity.
• Helical Tomotherapy (HT) offers advanced capabilities for complex radiotherapy planning and delivery.
• Evaluating long-term clinical experience is crucial for optimizing treatment strategies.

Purpose of the Study:

• To review the planning and image-guidance aspects of Helical Tomotherapy (HT) for prostate cancer treatment.
• To assess the efficacy and safety of HT over more than three years of clinical application.
• To evaluate HT's performance in both post-prostatectomy and radical treatment settings.

Main Methods:

• Analysis of planning data from two Phase I-II clinical studies involving HT for prostate cancer.
• Application of a simultaneous integrated boost (SIB) approach for radical treatment (71.4-74.2 Gy in 28 fractions).
• On-line daily MVCT (Megavoltage Computed Tomography) image guidance using bone match or prostate match, with review of MVCT data from over 250 patients.

Main Results:

• HT demonstrated excellent dose distribution homogeneity within planning target volumes (PTVs) and superior organs at risk (OAR) sparing.
• HT favorably compared to inversely-optimized intensity-modulated radiation therapy (IMRT) for PTV coverage and homogeneity.
• MVCT analysis revealed limited prostate motion (<3 mm deviation in 5% of fractions) with rectal emptying protocols, and direct visualization prostate match proved reliable.

Conclusions:

• Helical Tomotherapy provides excellent planning solutions for prostate cancer, particularly efficient in simultaneous integrated boost (SIB) scenarios.
• Daily MVCT imaging confirmed minimal prostate motion when patients adhere to rectal enema procedures.
• HT offers a reliable and effective treatment option for prostate cancer, supported by extensive clinical experience and advanced image guidance.