TY - JOUR
T1 - Observer uncertainties of soft tissue-based patient positioning in IGRT
AU - Hirose, Taka aki
AU - Arimura, Hidetaka
AU - Fukunaga, Jun ichi
AU - Ohga, Saiji
AU - Yoshitake, Tadamasa
AU - Shioyama, Yoshiyuki
N1 - Funding Information:
This work was supported by JSPS KAKENHI Grant Number JP19K16803. The authors are grateful to all members of Arimura Laboratory ( http://web.shs.kyushu-u.ac.jp/~arimura ), whose comments contributed significantly to this study. We would also like to thank Editage ( www.editage.com ) for English language editing.
Publisher Copyright:
© 2020 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.
PY - 2020/2/1
Y1 - 2020/2/1
N2 - Purpose: There remain uncertainties due to inter- and intraobserver variability in soft-tissue-based patient positioning even with the use of image-guided radiation therapy (IGRT). This study aimed to reveal observer uncertainties of soft-tissue-based patient positioning on cone-beam computed tomography (CBCT) images for prostate cancer IGRT. Methods: Twenty-six patients (7–8 fractions/patient, total number of 204 fractions) who underwent IGRT for prostate cancer were selected. Six radiation therapists retrospectively measured prostate cancer location errors (PCLEs) of soft-tissue-based patient positioning between planning CT (pCT) and pretreatment CBCT (pre-CBCT) images after automatic bone-based registration. Observer uncertainties were evaluated based on residual errors, which denoted the differences between soft-tissue and reference positioning errors. Reference positioning errors were obtained as PCLEs of contour-based patient positioning between pCT and pre-CBCT images. Intraobserver variations were obtained from the difference between the first and second soft-tissue-based patient positioning repeated by the same observer for each fraction. Systematic and random errors of inter- and intraobserver variations were calculated in anterior–posterior (AP), superior–inferior (SI), and left–right (LR) directions. Finally, clinical target volume (CTV)-to-planning target volume (PTV) margins were obtained from systematic and random errors of inter- and intraobserver variations in AP, SI, and LR directions. Results: Interobserver variations in AP, SI, and LR directions were 0.9, 0.9, and 0.5 mm, respectively, for the systematic error, and 1.8, 2.2, and 1.1 mm, respectively, for random error. Intraobserver variations were <0.2 mm in all directions. CTV-to-PTV margins in AP, SI, and LR directions were 3.5, 3.8, and 2.1 mm, respectively. Conclusion: Intraobserver variability was sufficiently small and would be negligible. However, uncertainties due to interobserver variability for soft-tissue-based patient positioning using CBCT images should be considered in CTV-to-PTV margins.
AB - Purpose: There remain uncertainties due to inter- and intraobserver variability in soft-tissue-based patient positioning even with the use of image-guided radiation therapy (IGRT). This study aimed to reveal observer uncertainties of soft-tissue-based patient positioning on cone-beam computed tomography (CBCT) images for prostate cancer IGRT. Methods: Twenty-six patients (7–8 fractions/patient, total number of 204 fractions) who underwent IGRT for prostate cancer were selected. Six radiation therapists retrospectively measured prostate cancer location errors (PCLEs) of soft-tissue-based patient positioning between planning CT (pCT) and pretreatment CBCT (pre-CBCT) images after automatic bone-based registration. Observer uncertainties were evaluated based on residual errors, which denoted the differences between soft-tissue and reference positioning errors. Reference positioning errors were obtained as PCLEs of contour-based patient positioning between pCT and pre-CBCT images. Intraobserver variations were obtained from the difference between the first and second soft-tissue-based patient positioning repeated by the same observer for each fraction. Systematic and random errors of inter- and intraobserver variations were calculated in anterior–posterior (AP), superior–inferior (SI), and left–right (LR) directions. Finally, clinical target volume (CTV)-to-planning target volume (PTV) margins were obtained from systematic and random errors of inter- and intraobserver variations in AP, SI, and LR directions. Results: Interobserver variations in AP, SI, and LR directions were 0.9, 0.9, and 0.5 mm, respectively, for the systematic error, and 1.8, 2.2, and 1.1 mm, respectively, for random error. Intraobserver variations were <0.2 mm in all directions. CTV-to-PTV margins in AP, SI, and LR directions were 3.5, 3.8, and 2.1 mm, respectively. Conclusion: Intraobserver variability was sufficiently small and would be negligible. However, uncertainties due to interobserver variability for soft-tissue-based patient positioning using CBCT images should be considered in CTV-to-PTV margins.
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U2 - 10.1002/acm2.12817
DO - 10.1002/acm2.12817
M3 - Article
C2 - 31957964
AN - SCOPUS:85078728894
SN - 1526-9914
VL - 21
SP - 73
EP - 81
JO - Journal of Applied Clinical Medical Physics
JF - Journal of Applied Clinical Medical Physics
IS - 2
ER -
