Prostate cancer radiation therapy shape variation analysis

Area of Science:

• Oncology
• Medical Imaging
• Biostatistics

Background:

• Prostate cancer is a prevalent global disease in men.
• External beam radiation therapy (EBRT) is a common treatment modality.
• Accurate identification of prostate tissue boundaries is critical for effective radiation therapy planning and minimizing side effects.

Purpose of the Study:

• To investigate prostate shape variations during radiotherapy using Principal Component Analysis (PCA).
• To analyze the evolution of prostate shape and target tumor volume over an eight-week treatment period.
• To identify specific regions of significant shape change and determine the timing of these variations.

Main Methods:

• Utilized 261 mesh prostate surfaces from 33 patients, manually contoured by radiation oncologists.
• Applied PCA for trajectory analysis to track prostate shape evolution during treatment.
• Employed PCA for variation pattern analysis to examine changes in target tumor volume.

Main Results:

• Trajectory analysis identified significant prostate shape variations in the left superior and inferior to posterior-right regions.
• Variation pattern analysis showed an overall increase in target tumor volume, with the highest variation in the anterior superior region.
• The majority of prostate shape variations were observed within the first week of treatment.

Conclusions:

• Prostate shape undergoes significant changes during EBRT, particularly early in the treatment course.
• Implementing updated contours after the initial week of treatment could enhance the accuracy of target volume definition.
• These findings support adaptive radiotherapy strategies for improved treatment precision in prostate cancer.