Radiat Oncol J.  2018 Mar;36(1):11-16. 10.3857/roj.2017.00080.

Interobserver variation in target volume for salvage radiotherapy in recurrent prostate cancer patients after radical prostatectomy using CT versus combined CT and MRI: a multicenter study (KROG 13-11)

Affiliations
  • 1Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea. wonro.park@samsung.com
  • 2Department of Radiation Oncology, Yonsei University College of Medicine, Severance Hospital, Seoul, Korea.
  • 3Department of Radiation Oncology, Dongsan Medical Center, Keimyung University School of Medicine, Daegu, Korea.
  • 4Proton Therapy Center, National Cancer Center, Goyang, Korea.
  • 5Department of Radiation Oncology, Dong-A University College of Medicine, Busan, Korea.
  • 6Department of Radiation Oncology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.
  • 7Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Korea.
  • 8Department of Radiation Oncology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
  • 9Department of Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
  • 10Department of Radiation Oncology, Chonnam National University Medical School, Gwangju, Korea.

Abstract

PURPOSE
To investigate interobserver variation in target volume delineations for prostate cancer salvage radiotherapy using planning computed tomography (CT) versus combined planning CT and magnetic resonance imaging (MRI).
MATERIALS AND METHODS
Ten radiation oncologists independently delineated a target volume on the planning CT scans of five cases with different pathological status after radical prostatectomy. Two weeks later, this was repeated with the addition of planning MRI. The volumes obtained with CT only and combined CT and MRI were compared, and the effect of the addition of planning MRI on interobserver variability was assessed.
RESULTS
There were large differences in clinical target volume (CTV) delineated by each observer, regardless of the addition of planning MRI (9.44-139.27 cm³ in CT only and 7.77-122.83 cm³ in CT plus MRI) and no significant differences in the mean and standard deviation of CTV. However, there were decreases in mean volume and standard deviation as a result of using the planning MRI.
CONCLUSION
This study showed substantial interobserver variation in target volume delineation for salvage radiotherapy. The combination of planning MRI with CT tended to decrease the target volume and the variation.

Keyword

Prostate cancer; Salvage radiotherapy; Target volume; Interobserver variation; Magnetic resonance image

MeSH Terms

Humans
Magnetic Resonance Imaging*
Observer Variation*
Prostate*
Prostatectomy*
Prostatic Neoplasms*
Radiotherapy*
Tomography, X-Ray Computed
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