Is it necessary to perform week three dosimetric analysis in low-dose-rate brachytherapy for prostate cancer when day 0 dosimetry is done? A quality assurance assessment

T. Shaikh, Nicholas Zaorsky, K. Ruth, D. Y. Chen, R. E. Greenberg, J. Li, K. Crawford, E. M. Horwitz

Research output: Contribution to journalArticle

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Abstract

Purpose: To determine whether computed tomography/magnetic resonance imaging-based day 0 (d0) dosimetry is a meaningful predictor of day 21 (d21) dosimetry in low-dose-rate brachytherapy for localized prostate cancer. Methods and Materials: The study population consisted of 277 men with localized (T1-2 N0 M0), low-/intermediate-risk prostate cancer treated with low-dose-rate brachytherapy. Computed tomography/magnetic resonance imaging fusion was used for postimplant dosimetry at d0 and d21. Logistic regression was used to construct receiver operating characteristic curves for achieving each constraint at d21, based on d0 D90 and V100, and Youden's index was used to evaluate cutpoints. Freedom from biochemical failure (FBCF) was estimated with the Kaplan-Meier method. Results: The median d0 D90 increased from 133 to 150Gy at d21, and median d0 V100 increased from 87% to 91%. For achieving the D90 constraint at d21, the optimal cut-point for d0 D90 was 135Gy, with 84% of these patients maintaining a d21 D90>145Gy. For achieving the D90 constraint at d21, the optimal cut-point for d0 V100 was 87%, with 83% of these patients maintained a d21 V100>90%. There was no improvement in FBCF in patients with a d0 D90>135Gy or D90>145Gy. Similarly, there was no improvement in FBCF in patients with a d0 V100>87% or V100>90%. Conclusions: Meeting dosimetric constraints on d0 does not obviate d21 dosimetric analysis. Constraints used for dose prescriptions on d0 are not the ideal predictors of d21 dosimetry.

Original languageEnglish (US)
Pages (from-to)316-321
Number of pages6
JournalBrachytherapy
Volume14
Issue number3
DOIs
StatePublished - May 1 2015

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Brachytherapy
Prostatic Neoplasms
Tomography
Magnetic Resonance Imaging
ROC Curve
Prescriptions
Logistic Models
Population

All Science Journal Classification (ASJC) codes

  • Oncology
  • Radiology Nuclear Medicine and imaging

Cite this

Shaikh, T. ; Zaorsky, Nicholas ; Ruth, K. ; Chen, D. Y. ; Greenberg, R. E. ; Li, J. ; Crawford, K. ; Horwitz, E. M. / Is it necessary to perform week three dosimetric analysis in low-dose-rate brachytherapy for prostate cancer when day 0 dosimetry is done? A quality assurance assessment. In: Brachytherapy. 2015 ; Vol. 14, No. 3. pp. 316-321.
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title = "Is it necessary to perform week three dosimetric analysis in low-dose-rate brachytherapy for prostate cancer when day 0 dosimetry is done? A quality assurance assessment",
abstract = "Purpose: To determine whether computed tomography/magnetic resonance imaging-based day 0 (d0) dosimetry is a meaningful predictor of day 21 (d21) dosimetry in low-dose-rate brachytherapy for localized prostate cancer. Methods and Materials: The study population consisted of 277 men with localized (T1-2 N0 M0), low-/intermediate-risk prostate cancer treated with low-dose-rate brachytherapy. Computed tomography/magnetic resonance imaging fusion was used for postimplant dosimetry at d0 and d21. Logistic regression was used to construct receiver operating characteristic curves for achieving each constraint at d21, based on d0 D90 and V100, and Youden's index was used to evaluate cutpoints. Freedom from biochemical failure (FBCF) was estimated with the Kaplan-Meier method. Results: The median d0 D90 increased from 133 to 150Gy at d21, and median d0 V100 increased from 87{\%} to 91{\%}. For achieving the D90 constraint at d21, the optimal cut-point for d0 D90 was 135Gy, with 84{\%} of these patients maintaining a d21 D90>145Gy. For achieving the D90 constraint at d21, the optimal cut-point for d0 V100 was 87{\%}, with 83{\%} of these patients maintained a d21 V100>90{\%}. There was no improvement in FBCF in patients with a d0 D90>135Gy or D90>145Gy. Similarly, there was no improvement in FBCF in patients with a d0 V100>87{\%} or V100>90{\%}. Conclusions: Meeting dosimetric constraints on d0 does not obviate d21 dosimetric analysis. Constraints used for dose prescriptions on d0 are not the ideal predictors of d21 dosimetry.",
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Is it necessary to perform week three dosimetric analysis in low-dose-rate brachytherapy for prostate cancer when day 0 dosimetry is done? A quality assurance assessment. / Shaikh, T.; Zaorsky, Nicholas; Ruth, K.; Chen, D. Y.; Greenberg, R. E.; Li, J.; Crawford, K.; Horwitz, E. M.

In: Brachytherapy, Vol. 14, No. 3, 01.05.2015, p. 316-321.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Is it necessary to perform week three dosimetric analysis in low-dose-rate brachytherapy for prostate cancer when day 0 dosimetry is done? A quality assurance assessment

AU - Shaikh, T.

AU - Zaorsky, Nicholas

AU - Ruth, K.

AU - Chen, D. Y.

AU - Greenberg, R. E.

AU - Li, J.

AU - Crawford, K.

AU - Horwitz, E. M.

PY - 2015/5/1

Y1 - 2015/5/1

N2 - Purpose: To determine whether computed tomography/magnetic resonance imaging-based day 0 (d0) dosimetry is a meaningful predictor of day 21 (d21) dosimetry in low-dose-rate brachytherapy for localized prostate cancer. Methods and Materials: The study population consisted of 277 men with localized (T1-2 N0 M0), low-/intermediate-risk prostate cancer treated with low-dose-rate brachytherapy. Computed tomography/magnetic resonance imaging fusion was used for postimplant dosimetry at d0 and d21. Logistic regression was used to construct receiver operating characteristic curves for achieving each constraint at d21, based on d0 D90 and V100, and Youden's index was used to evaluate cutpoints. Freedom from biochemical failure (FBCF) was estimated with the Kaplan-Meier method. Results: The median d0 D90 increased from 133 to 150Gy at d21, and median d0 V100 increased from 87% to 91%. For achieving the D90 constraint at d21, the optimal cut-point for d0 D90 was 135Gy, with 84% of these patients maintaining a d21 D90>145Gy. For achieving the D90 constraint at d21, the optimal cut-point for d0 V100 was 87%, with 83% of these patients maintained a d21 V100>90%. There was no improvement in FBCF in patients with a d0 D90>135Gy or D90>145Gy. Similarly, there was no improvement in FBCF in patients with a d0 V100>87% or V100>90%. Conclusions: Meeting dosimetric constraints on d0 does not obviate d21 dosimetric analysis. Constraints used for dose prescriptions on d0 are not the ideal predictors of d21 dosimetry.

AB - Purpose: To determine whether computed tomography/magnetic resonance imaging-based day 0 (d0) dosimetry is a meaningful predictor of day 21 (d21) dosimetry in low-dose-rate brachytherapy for localized prostate cancer. Methods and Materials: The study population consisted of 277 men with localized (T1-2 N0 M0), low-/intermediate-risk prostate cancer treated with low-dose-rate brachytherapy. Computed tomography/magnetic resonance imaging fusion was used for postimplant dosimetry at d0 and d21. Logistic regression was used to construct receiver operating characteristic curves for achieving each constraint at d21, based on d0 D90 and V100, and Youden's index was used to evaluate cutpoints. Freedom from biochemical failure (FBCF) was estimated with the Kaplan-Meier method. Results: The median d0 D90 increased from 133 to 150Gy at d21, and median d0 V100 increased from 87% to 91%. For achieving the D90 constraint at d21, the optimal cut-point for d0 D90 was 135Gy, with 84% of these patients maintaining a d21 D90>145Gy. For achieving the D90 constraint at d21, the optimal cut-point for d0 V100 was 87%, with 83% of these patients maintained a d21 V100>90%. There was no improvement in FBCF in patients with a d0 D90>135Gy or D90>145Gy. Similarly, there was no improvement in FBCF in patients with a d0 V100>87% or V100>90%. Conclusions: Meeting dosimetric constraints on d0 does not obviate d21 dosimetric analysis. Constraints used for dose prescriptions on d0 are not the ideal predictors of d21 dosimetry.

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