Evaluation of the respiratory prostate motion with four-dimensional computed tomography scan acquisitions using three implanted markers

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• 作者：Corina Udrescu^a ; ^b ; Patrice Jalade^b ; Berardino de Bari^a ; Gé ; raldine Michel-Amadry^b ; Olivier Chapet^a ; ^{olivier.chapet@chu-lyon.fr}
• 关键词：Respiratory-induced ; Prostate motion ; 4D ; Gold markers
• 刊名：Radiotherapy and Oncology
• 出版年：2012
• 期刊代码：231_01678140
• 类别：med
• 出版时间：May, 2012
• 卷：103
• 期：2
• 页码：266-269
• 文件大小：155 K

摘要

Background and purpose

During the irradiation of the prostate cancer, it is crucial to take into account the possible displacements in defining the planning target volume. The objective of this study was to specifically analyze the respiratory-induced prostate motion using a four-dimensional CT scan (4DCT).

Materials and methods

Ten patients have been treated for prostate cancer in the supine position and with three implanted gold markers; they underwent a 4DCT using a GE LightSpeed16庐 CT scan (slice thickness 2.5 mm). This acquisition was divided into 10 phases over the respiratory cycle using the Advantage4D software. For each phase, digitally-reconstructed radiographs (DRRs) were created at 0掳 and 90掳 with the view of the markers. The coordinates of each marker center were generated from the scan isocenter. The motion amplitude was: visually analyzed on the dynamic 4DCT sequences and then more precisely calculated by comparing the marker coordinates on the 10 scans.

Results

There was not any difficulty in defining the coordinates of the markers on each series. No prostate motion was observed on a simple visual analysis of the dynamic 4DCT sequences. After a more specific analysis, using the coordinates of the fiducials on the 10 phases, the prostate motion remained below 1 mm in all directions, except for the cranio-caudal, where it was undetectable (thereby below the slice thickness of 2.5 mm).

Conclusions

To our knowledge, this is the first study that evaluates the respiratory-induced prostate motion, using a 4DCT scan. Even if important prostate displacement can occur during the prostate treatment, because of the bladder or rectum filling, in the present study no respiratory-induced prostate motion was observed.