SU‐GG‐J‐81: Efficacy of Patient Setup Correction Procedure in Prostate Radiotherapy

S. Zhou, S. Das, F. Yin, S. Yoo, W. Lee, H. Yan, Q. Wu, Z. Wang, L. Marks

Research output: Contribution to journalArticle

Abstract

Purpose: Using an on‐board cone‐beam CT (CBCT) based statistical margin model to determine whether a prostate center‐of‐mass (COM) based translation correction procedure can significantly reduce the CTV‐to‐PTV margin required for prostate patients who were first setup based on skin/alpha‐cradle markers (SAM). Method and Materials: A total 110 CBCT scans were performed, daily in the first week of radiotherapy and once weekly afterward, for 10 prostate patients immediately after their clinical setup based on SAM. Soft tissue matching was used to estimate the required translation corrections by matching the COM of the observed prostate volumes on treatment planning CT and CBCTs. Based on the CBCT prostate volumes, a statistical model (Bayesian margin expectation model) provided patient specific optimal margins before and after a prostate COM based translation correction was added to the patient SAM based setup. We compared these margins to determine the efficacy of prostate COM based translation correction when it is added to the SAM based setup. Results: After the 5 daily CBCTs from the first week, all 10 patient prostate uniform margins for 95% tumor geometric coverage were reduced after applying the prostate COM based translation correction to their SAM based setup. However, the percentage reduction varied from patient to patient, ranging from 1% to 60% with a median value of 22%. In 4 of 10 patients, margin reduction greater than 4mm was obtained. In general, patients with more deformable prostates benefited less from COM translation. Beyond the first 5 CBCTs, very little further margin change was obtained. Conclusions: The addition of prostate COM based translation correction to SAM based setup did reduce the uniform margin required to achieve 95% tumor geometric coverage, but the extent of reduction was patient specific. In general, incorporating COM translation in prostate margin determination can help reduce bladder/rectal doses.

Original languageEnglish (US)
Number of pages1
JournalMedical physics
Volume35
Issue number6
DOIs
StatePublished - Jun 2008

Fingerprint

Prostate
Radiotherapy
Skin
Statistical Models
Cone-Beam Computed Tomography
Neoplasms
Urinary Bladder

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging

Cite this

SU‐GG‐J‐81 : Efficacy of Patient Setup Correction Procedure in Prostate Radiotherapy. / Zhou, S.; Das, S.; Yin, F.; Yoo, S.; Lee, W.; Yan, H.; Wu, Q.; Wang, Z.; Marks, L.

In: Medical physics, Vol. 35, No. 6, 06.2008.

Research output: Contribution to journalArticle

Zhou, S, Das, S, Yin, F, Yoo, S, Lee, W, Yan, H, Wu, Q, Wang, Z & Marks, L 2008, 'SU‐GG‐J‐81: Efficacy of Patient Setup Correction Procedure in Prostate Radiotherapy', Medical physics, vol. 35, no. 6. https://doi.org/10.1118/1.2961631
Zhou, S. ; Das, S. ; Yin, F. ; Yoo, S. ; Lee, W. ; Yan, H. ; Wu, Q. ; Wang, Z. ; Marks, L. / SU‐GG‐J‐81 : Efficacy of Patient Setup Correction Procedure in Prostate Radiotherapy. In: Medical physics. 2008 ; Vol. 35, No. 6.
@article{16aa8a199c3545dd8f74b7a5c8b65dd1,
title = "SU‐GG‐J‐81: Efficacy of Patient Setup Correction Procedure in Prostate Radiotherapy",
abstract = "Purpose: Using an on‐board cone‐beam CT (CBCT) based statistical margin model to determine whether a prostate center‐of‐mass (COM) based translation correction procedure can significantly reduce the CTV‐to‐PTV margin required for prostate patients who were first setup based on skin/alpha‐cradle markers (SAM). Method and Materials: A total 110 CBCT scans were performed, daily in the first week of radiotherapy and once weekly afterward, for 10 prostate patients immediately after their clinical setup based on SAM. Soft tissue matching was used to estimate the required translation corrections by matching the COM of the observed prostate volumes on treatment planning CT and CBCTs. Based on the CBCT prostate volumes, a statistical model (Bayesian margin expectation model) provided patient specific optimal margins before and after a prostate COM based translation correction was added to the patient SAM based setup. We compared these margins to determine the efficacy of prostate COM based translation correction when it is added to the SAM based setup. Results: After the 5 daily CBCTs from the first week, all 10 patient prostate uniform margins for 95{\%} tumor geometric coverage were reduced after applying the prostate COM based translation correction to their SAM based setup. However, the percentage reduction varied from patient to patient, ranging from 1{\%} to 60{\%} with a median value of 22{\%}. In 4 of 10 patients, margin reduction greater than 4mm was obtained. In general, patients with more deformable prostates benefited less from COM translation. Beyond the first 5 CBCTs, very little further margin change was obtained. Conclusions: The addition of prostate COM based translation correction to SAM based setup did reduce the uniform margin required to achieve 95{\%} tumor geometric coverage, but the extent of reduction was patient specific. In general, incorporating COM translation in prostate margin determination can help reduce bladder/rectal doses.",
author = "S. Zhou and S. Das and F. Yin and S. Yoo and W. Lee and H. Yan and Q. Wu and Z. Wang and L. Marks",
year = "2008",
month = "6",
doi = "10.1118/1.2961631",
language = "English (US)",
volume = "35",
journal = "Medical Physics",
issn = "0094-2405",
publisher = "AAPM - American Association of Physicists in Medicine",
number = "6",

}

TY - JOUR

T1 - SU‐GG‐J‐81

T2 - Efficacy of Patient Setup Correction Procedure in Prostate Radiotherapy

AU - Zhou, S.

AU - Das, S.

AU - Yin, F.

AU - Yoo, S.

AU - Lee, W.

AU - Yan, H.

AU - Wu, Q.

AU - Wang, Z.

AU - Marks, L.

PY - 2008/6

Y1 - 2008/6

N2 - Purpose: Using an on‐board cone‐beam CT (CBCT) based statistical margin model to determine whether a prostate center‐of‐mass (COM) based translation correction procedure can significantly reduce the CTV‐to‐PTV margin required for prostate patients who were first setup based on skin/alpha‐cradle markers (SAM). Method and Materials: A total 110 CBCT scans were performed, daily in the first week of radiotherapy and once weekly afterward, for 10 prostate patients immediately after their clinical setup based on SAM. Soft tissue matching was used to estimate the required translation corrections by matching the COM of the observed prostate volumes on treatment planning CT and CBCTs. Based on the CBCT prostate volumes, a statistical model (Bayesian margin expectation model) provided patient specific optimal margins before and after a prostate COM based translation correction was added to the patient SAM based setup. We compared these margins to determine the efficacy of prostate COM based translation correction when it is added to the SAM based setup. Results: After the 5 daily CBCTs from the first week, all 10 patient prostate uniform margins for 95% tumor geometric coverage were reduced after applying the prostate COM based translation correction to their SAM based setup. However, the percentage reduction varied from patient to patient, ranging from 1% to 60% with a median value of 22%. In 4 of 10 patients, margin reduction greater than 4mm was obtained. In general, patients with more deformable prostates benefited less from COM translation. Beyond the first 5 CBCTs, very little further margin change was obtained. Conclusions: The addition of prostate COM based translation correction to SAM based setup did reduce the uniform margin required to achieve 95% tumor geometric coverage, but the extent of reduction was patient specific. In general, incorporating COM translation in prostate margin determination can help reduce bladder/rectal doses.

AB - Purpose: Using an on‐board cone‐beam CT (CBCT) based statistical margin model to determine whether a prostate center‐of‐mass (COM) based translation correction procedure can significantly reduce the CTV‐to‐PTV margin required for prostate patients who were first setup based on skin/alpha‐cradle markers (SAM). Method and Materials: A total 110 CBCT scans were performed, daily in the first week of radiotherapy and once weekly afterward, for 10 prostate patients immediately after their clinical setup based on SAM. Soft tissue matching was used to estimate the required translation corrections by matching the COM of the observed prostate volumes on treatment planning CT and CBCTs. Based on the CBCT prostate volumes, a statistical model (Bayesian margin expectation model) provided patient specific optimal margins before and after a prostate COM based translation correction was added to the patient SAM based setup. We compared these margins to determine the efficacy of prostate COM based translation correction when it is added to the SAM based setup. Results: After the 5 daily CBCTs from the first week, all 10 patient prostate uniform margins for 95% tumor geometric coverage were reduced after applying the prostate COM based translation correction to their SAM based setup. However, the percentage reduction varied from patient to patient, ranging from 1% to 60% with a median value of 22%. In 4 of 10 patients, margin reduction greater than 4mm was obtained. In general, patients with more deformable prostates benefited less from COM translation. Beyond the first 5 CBCTs, very little further margin change was obtained. Conclusions: The addition of prostate COM based translation correction to SAM based setup did reduce the uniform margin required to achieve 95% tumor geometric coverage, but the extent of reduction was patient specific. In general, incorporating COM translation in prostate margin determination can help reduce bladder/rectal doses.

UR - http://www.scopus.com/inward/record.url?scp=85024802464&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85024802464&partnerID=8YFLogxK

U2 - 10.1118/1.2961631

DO - 10.1118/1.2961631

M3 - Article

AN - SCOPUS:85024802464

VL - 35

JO - Medical Physics

JF - Medical Physics

SN - 0094-2405

IS - 6

ER -