Brachytherapy
Volume 10, Issue 2 , Pages 98-106, March 2011

Dynamic intraoperative dosimetry for prostate brachytherapy using a nonisocentric C-arm

This paper was presented at American Society for Radiation Oncology 51st Annual Meeting, 2009.

  • Danny Y. Song

      Affiliations

    • Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University, School of Medicine, Baltimore, MD
    • Corresponding Author InformationCorresponding author. Department of Radiation Oncology and Molecular Radiation Sciences, 401 N Broadway, Suite 1440, Baltimore, MD 21231. Tel.: +1-410-502-5875; fax: +1-410-502-1419.
    • ,
  • Ameet K. Jain

      Affiliations

    • Philips Research North America, Briarcliff Manor, NY
    • ,
  • Zhe Zhang

      Affiliations

    • Oncology Biostatistics, Johns Hopkins University, Baltimore, MD
    • ,
  • Anton Deguet

      Affiliations

    • Whiting School of Engineering, Johns Hopkins University, Baltimore, MD
    • ,
  • Yi Le

      Affiliations

    • Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University, School of Medicine, Baltimore, MD
    • ,
  • Elwood Armour

      Affiliations

    • Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University, School of Medicine, Baltimore, MD
    • ,
  • E. Clif Burdette

      Affiliations

    • Acoustic Medsystems, Champagne, IL
    • ,
  • Gabor Fichtinger

      Affiliations

    • School of Computing, Queen’s University, Kingston, Ontario, Canada

Received 11 December 2009; received in revised form 27 June 2010; accepted 29 June 2010. published online 09 August 2010.

Abstract 

Purpose

To evaluate a prototypical system of dynamic intraoperative dosimetry for prostate brachytherapy using registered ultrasound and fluoroscopy (RUF) with a nonisocentric C-arm (GE OEC, Salt Lake City, UT) and to compare intraoperative dosimetry of RUF as well as ultrasound-based seed localization (USD) with Day 0 CT dosimetry.

Methods

Seed positions were independently determined using RUF and USD. RUF uses a radio-opaque fiducial for registration to ultrasound and 3-dimensional reconstruction of seeds relative to prostate using nonisocentric C-arm fluoroscopy. Postimplant CT was performed on Day 0. Squared differences between dosimetric measures for RUF vs. CT and USD vs. CT were calculated and mean squared differences evaluated. Paired t test was used to evaluate which method was more closely aligned with CT. Accuracies of USD and RUF compared with CT were estimated using a nonparametric approach.

Results

Six patients were treated and compared with USD. RUF identified areas of underdosage intraoperatively in all patients and median 5 additional seeds were placed. In 40 of 42 measures, RUF was equally or more closely correlated with CT than USD. USD showed statistically significant variation from CT for 6 of 7 parameters compared with 1 of 7 parameters for RUF. Mean squared differences from CT were significantly smaller for RUF in 4 of 7 parameters compared with USD.

Conclusions

Dynamic intraoperative dosimetry is possible with a conventional nonisocentric C-arm. Compared with an USD method, RUF-based intraoperative dosimetry was more closely aligned with immediate postimplant CT. RUF identified areas of underdosage, which were not detected using USD.

Keywords: Prostate brachytherapy, Dynamic dosimetry, C-arm, Real-time dosimetry, Intraoperative

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 This study was supported by Department of Defense W81XWH-05-1-0407 and W81XWH-06-1-0003, National Institutes of Health NIH 2 R44 CA099374-02/04, and National Science Foundation NSF EEC-9731478.

 Conflicts of interest notification: Dr. E. Clif Burdette is employed by Acoustic Medsystems, which holds patents related to the registered ultrasound and fluoroscopy technology and Dr. Gabor Fichtinger holds patents related to the registered ultrasound and fluoroscopy technology. No other conflicts of interest exist.

PII: S1538-4721(10)00249-7

doi:10.1016/j.brachy.2010.06.005

Brachytherapy
Volume 10, Issue 2 , Pages 98-106, March 2011

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