A spreadsheet technique for dosimetry of transperineal prostate implants

Area of Science:

• Medical Physics
• Radiation Oncology
• Urology

Background:

• Permanent 125I seed prostate brachytherapy requires accurate dosimetry.
• Clinical implementation of dosimetry can be challenging, particularly with existing Radiation Treatment Planning (RTP) systems.
• Institutions may face limitations in modifying commercial RTP systems for dosimetry tasks.

Purpose of the Study:

• To develop practical spreadsheet-based techniques for dosimetry in permanent 125I seed prostate implants.
• To facilitate both pre-implant treatment planning and post-implant dosimetric evaluation.
• To provide a viable dosimetry solution for institutions unable or unwilling to alter their commercial RTP systems.

Main Methods:

• Utilized spreadsheet techniques for dosimetry calculations.
• Developed a first spreadsheet to convert seed distribution from grid coordinates to RTP system input format, determining needle positions and loading.
• Created a second spreadsheet macroprogram, modifying an existing technique, for interactive determination of physical seed locations from post-implant CT images.

Main Results:

• The developed spreadsheet techniques effectively aid in dosimetry for 125I seed prostate implants.
• The first spreadsheet facilitates conversion of seed data and needle planning for RTP systems.
• The second spreadsheet allows for interactive localization of seeds from CT data, proving acceptable for clinical use.

Conclusions:

• Spreadsheet-based dosimetry methods offer a practical solution for permanent 125I seed prostate implants.
• These techniques are adaptable for institutions with constraints on modifying commercial RTP systems.
• The developed approach provides acceptable clinical practice for dosimetry in prostate brachytherapy.