Nonuniform Planning Target Volume Margins for Prostate Bed on the Basis of Surgical Clips on Daily Cone Beam Computed Tomography.
Abstract
Purpose:We hypothesized that the interfraction motions of the superior and inferior
prostate beds differ and therefore require different margins. In this study, we used
daily cone beam computed tomography (CBCT) to evaluate the motion of postprostatectomy
surgical clips (separated to superior and inferior portions) within the planning target
volume (PTV) to derive data-driven PTV margins. Methods and Materials:Our study cohort
included consecutive patients with identifiable surgical clips undergoing prostate
bed irradiation with daily CBCT image guidance. We identified and contoured the clips
within the PTV on the planning computed tomography and CBCT scans. All CBCT scans
were registered to the planning computed tomography scan on the basis of pelvic bony
structures. The superior border of the pubic symphysis was used to mark the division
between the superior and inferior portions. Results:Eleven patients with 263 CBCT
scans were included in the cohort. In the left-right direction, the global mean M,
systematic error Σ, and residue error σ were 0.02, 0.03, and 0.16 cm, respectively,
for superior clips, and 0.00, 0.03, and 0.03 cm, respectively, for inferior clips.
In the anterior-posterior direction, the corresponding values were M = 0.01, Σ = 0.25,
and σ= 0.37, respectively, for superior, and M = 0.08, Σ= 0.13, σ= 0.15, respectively,
for inferior. In the superior-inferior direction, the values were M =-0.06, Σ= 0.23,
and σ= 0.27, respectively, for superior, and M =-0.01, Σ= 0.21, σ= 0.20, respectively,
for inferior. The results of the 2-tailed F tests showed that the anterior-posterior
motion is statistically different between the superior and inferior portions in the
anterior-posterior direction. There is no statistical difference in the superior-inferior
and lateral directions. Therefore, we propose a set of nonuniform PTV margins (based
on the formula 2.5 Σ+ 0.7σ) as 0.2 cm for all prostate beds in the left-right direction,
0.7 cm for all in superior-inferior, and 0.9 to 0.4 for superior-inferior in the anterior-posterior
direction. Conclusions:The difference in motion between the superior and inferior
portions of the prostate bed is statistically insignificant in the left-right and
superior-inferior directions, but statistically significant in the anterior-posterior
direction, which warrants a nonuniform PTV margin scheme.
Type
Journal articlePermalink
https://hdl.handle.net/10161/21118Published Version (Please cite this version)
10.1016/j.adro.2018.09.014Publication Info
Song, Haijun; Salama, Joseph K; Lee, William Robert; & Wu, Qiuwen (2019). Nonuniform Planning Target Volume Margins for Prostate Bed on the Basis of Surgical
Clips on Daily Cone Beam Computed Tomography. Advances in radiation oncology, 4(1). pp. 186-190. 10.1016/j.adro.2018.09.014. Retrieved from https://hdl.handle.net/10161/21118.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
W. Robert Lee
Professor of Radiation Oncology
Prostate cancer, Intensity-modulated radiation therapy (IMRT), Image-guided radiation
therapy (IGRT), Stereotactic Body Radiation Therapy (SBRT), Prostate HDR and LDR Brachytherapy,
Quality of Life, Educational Technology
Joseph Kamel Salama
Professor of Radiation Oncology
I have the privilege to be the Chief of the Durham VA Radiation Oncology Service,
where I care for veterans who have served our country. I am a dedicated educator,
serving as the Residency Program Director for the Duke Radiation Oncology Residency
Program. I am also a cancer researcher developing novel treatment techniques for
patients with head and neck cancer, lung cancer, prostate cancer, and those limited
metastatic disease, and integration of these treatments with drug therapies. 
Haijun Song
Assistant Professor of Radiation Oncology
Reference dosimetry, Experimental dosimetry, Radiation therapy using neutron and charged
particles.
Qiuwen Wu
Professor of Radiation Oncology
My research interests include intensity-modulated radiation therapy (IMRT), volumetric
modulated arc therapy (VMAT), Dynamic Electron Arc Radiotherapy (DEAR) and image-guided
radiation therapy (IGRT). For IMRT, my work include the development of the research
platform, fast and accurate dose calculations, optimization based on physical and
biological objectives such as generalized equivalent uniform dose (gEUD), and delivery
with dynamic multi-leaf collimator (DMLC). For VMAT, I am interested in
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