SU‐E‐J‐152: Prostate IGRT: CT‐MRI Fusion and Target Delineation Accuracy

J. Xue, X. Chen, L. Chen, Qianqian xu, Z. Dong, M. Lin, L. Wang, C‐m ma

Research output: Contribution to journalArticle

Abstract

Purpose: The accuracy of CT‐MR imaging fusion plays an important role in both accurate delineation (using MR data) and dose calculation (using CT data) for image‐guided radiotherapy (IGRT) of prostate cancer. The purpose of this study was to investigate the accuracy of CT‐MRI fusion in target delineation/localization for prostate IGRT. Methods: Sixty‐nine prostate patients were included in this study. Each patient underwent CT/MR simulation prior to the IMRT or RapidArc treatment. Paired CT‐MR images were obtained using a GE 4D‐CT scanner and a GE 1.5T MR scanner. MR and CT scans were performed within 30min to minimize organ or structure changes except for Calypso patients who received MR scans prior to the Beacon implantation. Prostate, rectum and bladder were delineated on CT and MRI, respectively. The difference of prostate centers and the volume variation between CT and MRI were calculated and used as the index for image fusion accuracy. Results: With bony structure matching, all bony structures were fused well between CT and MRI. However, the changes in bladder and rectum fillings between CT and MRI dislocate the prostate and the surrounding structures. The maximal shift of the prostate in the AP direction was up to 8mm and about 15.9% of the patients showed a shift 〉3mm, which was proportional to the difference of the rectum volume. The shift in the SI direction was 0.5–5mm. Of the 11 patients who had 〉3mm shifts, 6 patients (54.5%) were Calypso patients. Conclusions: Significant geometrical shifts of the prostate target were observed correlated with large differences in the bladder/rectal volume between CT and MR images especially for large CT‐MRI intervals. Attention must be paid to the residual fusion error for the soft tissue target and corrections should be made to ensure target delineation accuracy if necessary.

Original languageEnglish (US)
Number of pages1
JournalMedical Physics
Volume39
Issue number6
DOIs
StatePublished - Jan 1 2012

Fingerprint

Prostate
Radiotherapy
Rectum
Urinary Bladder
Cone-Beam Computed Tomography
Prostatic Neoplasms

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging

Cite this

SU‐E‐J‐152 : Prostate IGRT: CT‐MRI Fusion and Target Delineation Accuracy. / Xue, J.; Chen, X.; Chen, L.; xu, Qianqian; Dong, Z.; Lin, M.; Wang, L.; ma, C‐m.

In: Medical Physics, Vol. 39, No. 6, 01.01.2012.

Research output: Contribution to journalArticle

Xue, J. ; Chen, X. ; Chen, L. ; xu, Qianqian ; Dong, Z. ; Lin, M. ; Wang, L. ; ma, C‐m. / SU‐E‐J‐152 : Prostate IGRT: CT‐MRI Fusion and Target Delineation Accuracy. In: Medical Physics. 2012 ; Vol. 39, No. 6.
@article{d5e551e60fa74fa29edbf138e7ab6693,
title = "SU‐E‐J‐152: Prostate IGRT: CT‐MRI Fusion and Target Delineation Accuracy",
abstract = "Purpose: The accuracy of CT‐MR imaging fusion plays an important role in both accurate delineation (using MR data) and dose calculation (using CT data) for image‐guided radiotherapy (IGRT) of prostate cancer. The purpose of this study was to investigate the accuracy of CT‐MRI fusion in target delineation/localization for prostate IGRT. Methods: Sixty‐nine prostate patients were included in this study. Each patient underwent CT/MR simulation prior to the IMRT or RapidArc treatment. Paired CT‐MR images were obtained using a GE 4D‐CT scanner and a GE 1.5T MR scanner. MR and CT scans were performed within 30min to minimize organ or structure changes except for Calypso patients who received MR scans prior to the Beacon implantation. Prostate, rectum and bladder were delineated on CT and MRI, respectively. The difference of prostate centers and the volume variation between CT and MRI were calculated and used as the index for image fusion accuracy. Results: With bony structure matching, all bony structures were fused well between CT and MRI. However, the changes in bladder and rectum fillings between CT and MRI dislocate the prostate and the surrounding structures. The maximal shift of the prostate in the AP direction was up to 8mm and about 15.9{\%} of the patients showed a shift 〉3mm, which was proportional to the difference of the rectum volume. The shift in the SI direction was 0.5–5mm. Of the 11 patients who had 〉3mm shifts, 6 patients (54.5{\%}) were Calypso patients. Conclusions: Significant geometrical shifts of the prostate target were observed correlated with large differences in the bladder/rectal volume between CT and MR images especially for large CT‐MRI intervals. Attention must be paid to the residual fusion error for the soft tissue target and corrections should be made to ensure target delineation accuracy if necessary.",
author = "J. Xue and X. Chen and L. Chen and Qianqian xu and Z. Dong and M. Lin and L. Wang and C‐m ma",
year = "2012",
month = "1",
day = "1",
doi = "10.1118/1.4734989",
language = "English (US)",
volume = "39",
journal = "Medical Physics",
issn = "0094-2405",
publisher = "AAPM - American Association of Physicists in Medicine",
number = "6",

}

TY - JOUR

T1 - SU‐E‐J‐152

T2 - Prostate IGRT: CT‐MRI Fusion and Target Delineation Accuracy

AU - Xue, J.

AU - Chen, X.

AU - Chen, L.

AU - xu, Qianqian

AU - Dong, Z.

AU - Lin, M.

AU - Wang, L.

AU - ma, C‐m

PY - 2012/1/1

Y1 - 2012/1/1

N2 - Purpose: The accuracy of CT‐MR imaging fusion plays an important role in both accurate delineation (using MR data) and dose calculation (using CT data) for image‐guided radiotherapy (IGRT) of prostate cancer. The purpose of this study was to investigate the accuracy of CT‐MRI fusion in target delineation/localization for prostate IGRT. Methods: Sixty‐nine prostate patients were included in this study. Each patient underwent CT/MR simulation prior to the IMRT or RapidArc treatment. Paired CT‐MR images were obtained using a GE 4D‐CT scanner and a GE 1.5T MR scanner. MR and CT scans were performed within 30min to minimize organ or structure changes except for Calypso patients who received MR scans prior to the Beacon implantation. Prostate, rectum and bladder were delineated on CT and MRI, respectively. The difference of prostate centers and the volume variation between CT and MRI were calculated and used as the index for image fusion accuracy. Results: With bony structure matching, all bony structures were fused well between CT and MRI. However, the changes in bladder and rectum fillings between CT and MRI dislocate the prostate and the surrounding structures. The maximal shift of the prostate in the AP direction was up to 8mm and about 15.9% of the patients showed a shift 〉3mm, which was proportional to the difference of the rectum volume. The shift in the SI direction was 0.5–5mm. Of the 11 patients who had 〉3mm shifts, 6 patients (54.5%) were Calypso patients. Conclusions: Significant geometrical shifts of the prostate target were observed correlated with large differences in the bladder/rectal volume between CT and MR images especially for large CT‐MRI intervals. Attention must be paid to the residual fusion error for the soft tissue target and corrections should be made to ensure target delineation accuracy if necessary.

AB - Purpose: The accuracy of CT‐MR imaging fusion plays an important role in both accurate delineation (using MR data) and dose calculation (using CT data) for image‐guided radiotherapy (IGRT) of prostate cancer. The purpose of this study was to investigate the accuracy of CT‐MRI fusion in target delineation/localization for prostate IGRT. Methods: Sixty‐nine prostate patients were included in this study. Each patient underwent CT/MR simulation prior to the IMRT or RapidArc treatment. Paired CT‐MR images were obtained using a GE 4D‐CT scanner and a GE 1.5T MR scanner. MR and CT scans were performed within 30min to minimize organ or structure changes except for Calypso patients who received MR scans prior to the Beacon implantation. Prostate, rectum and bladder were delineated on CT and MRI, respectively. The difference of prostate centers and the volume variation between CT and MRI were calculated and used as the index for image fusion accuracy. Results: With bony structure matching, all bony structures were fused well between CT and MRI. However, the changes in bladder and rectum fillings between CT and MRI dislocate the prostate and the surrounding structures. The maximal shift of the prostate in the AP direction was up to 8mm and about 15.9% of the patients showed a shift 〉3mm, which was proportional to the difference of the rectum volume. The shift in the SI direction was 0.5–5mm. Of the 11 patients who had 〉3mm shifts, 6 patients (54.5%) were Calypso patients. Conclusions: Significant geometrical shifts of the prostate target were observed correlated with large differences in the bladder/rectal volume between CT and MR images especially for large CT‐MRI intervals. Attention must be paid to the residual fusion error for the soft tissue target and corrections should be made to ensure target delineation accuracy if necessary.

UR - http://www.scopus.com/inward/record.url?scp=85024814869&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85024814869&partnerID=8YFLogxK

U2 - 10.1118/1.4734989

DO - 10.1118/1.4734989

M3 - Article

C2 - 28518902

AN - SCOPUS:85024814869

VL - 39

JO - Medical Physics

JF - Medical Physics

SN - 0094-2405

IS - 6

ER -