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Development of a Low Cost, Easily-Made, Interchangeable, Prostate Brachytherapy Phantom for Multi-Imaging Guidance Using Ultrasound, CT and MRI

Y Kim

B Julius1, S Lin1, D Rahmani1, W Rockey2, C Tracy3, E Nixon2, J Modrick2, E Sander1, Y Kim2*, (1) Biomedical Engineering Dept, The University of Iowa, Iowa City, Iowa, USA (2) Radiation Oncology Dept, The University of Iowa, Iowa City, Iowa, USA (3) Urology Dept, The University of Iowa, Iowa City, Iowa, USA

SU-E-J-36 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

Purpose: To develop an easily-made, interchangeable prostate brachytherapy phantom for implant training and/or dummy-run treatment planning that is feasible for ultrasound (US), CT and MRI guidance. Commercially available phantoms are expensive and not reusable for repeated implant practice.

Methods: The phantom consists of two parts: a multiple use lower transrectal-ultrasound part and an interchangeable upper part. Material composition was iteratively updated based upon each scan of US, CT, and MRI. Image quality on US, CT and MRI was evaluated in terms of the contrasts seen in prostate, urethra, seminal vesicles, and periprostatic tissues. Two dummy-run needle implants were tested with transrectal-ultrasound guidance.

Results: An interchangeable phantom was developed using soft polyvinyl chloride (PVC) in the lower transrectal-ultrasound part, the seminal vesicles, and the urethra. The upper interchangeable part consisted of the prostate, urethra, and seminal vesicles, all of which were surrounded by gelatin (2 packets/cup of water). The seminal vesicle (soft PVC) and the prostate (gelatin) were embedded into gelatin. The prostate was made by mixing gelatin (4 packets gelatin and 1.5 tablespoons psyllium/cup of water) into a 50 mL egg shaped mold and then adding the urethra. The first prostate used soft PVC and plasticizer and resulted in poor contrast when using US. After testing with dummy-run needle implants, the concentration of the upper phantom background (gelatin) was doubled to make it more resistant to wear. The developed phantom produced image quality comparable to those of commercial phantoms but at a cost of only $80 and an 8 hour build time.

Conclusion: This study indicates the feasibilities of generating an easily⁻made, interchangeable prostate brachytherapy phantom that is cost-effective. The developed phantom could be imaged across multiple imaging modalities, thus demonstrating its potential for use in implant practice, dummy-runs, and planning studies using US, CT, or MRI guidance.

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