Can the Day 0 CT-scan predict the post-implant scanning? Results from 136 prostate cancer patients

Research output: Contribution to journalArticle

Abstract

Purpose Post-implant CT-scanning is an essential part of permanent prostate brachytherapy. However, the evaluation of post-implant CT dosimetry is not straightforward due to the edema that can modify the dose to the prostate and to the organs at risk. The aim of this study is to evaluate the impact of the timing of the post-implant CT-scan on the dosimetric results and to verify if the Day 0 scan findings can predict Day 50 scanning. Methods 136 consecutive patients who received monotherapy with I-125 implants were selected for this study. Two sets of 8 dosimetric quality parameters corresponding to 2 different CT-scans (Day 0 and Day 50) were calculated and compared. The dosimetric parameters included are the percentage volume of the post-implant prostate receiving 80%, 100% and 150% of the prescribed dose, the doses covering 80% and 90% of the prostate volume and the Dose Homogeneity Index. The values of the dose covering 1 cm3 of the rectum and urethra were assessed. Results All the dosimetric parameters of the Day 50 were higher than those of the Day 0 scan. Linear functions were obtained that calculate D90 and V100 values at Day 50 based on the Day 0 findings. Rectal and urethral parameters tended to be underestimated on Day 0 CT-scan relative to Day 50 based dosimetry. Conclusions Predicting the Day 50 dosimetry from the Day 0 scan could be a possible alternative to a Day 50 scan only in specific situations, but with a degree of uncertainty in the predicted values.

Original languageEnglish
Pages (from-to)66-71
Number of pages6
JournalPhysica Medica
Volume40
DOIs
Publication statusPublished - Aug 1 2017

Fingerprint

Prostate
Prostatic Neoplasms
cancer
dosage
scanning
dosimeters
Organs at Risk
coverings
Brachytherapy
Urethra
edema
rectum
Rectum
Uncertainty
Edema
organs
homogeneity
time measurement
evaluation

Keywords

  • Post-implant dosimetry
  • Prostate brachytherapy
  • Prostate edema

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging
  • Physics and Astronomy(all)

Cite this

@article{78ab2e12dbb146d5b99cde0496c9e932,
title = "Can the Day 0 CT-scan predict the post-implant scanning? Results from 136 prostate cancer patients",
abstract = "Purpose Post-implant CT-scanning is an essential part of permanent prostate brachytherapy. However, the evaluation of post-implant CT dosimetry is not straightforward due to the edema that can modify the dose to the prostate and to the organs at risk. The aim of this study is to evaluate the impact of the timing of the post-implant CT-scan on the dosimetric results and to verify if the Day 0 scan findings can predict Day 50 scanning. Methods 136 consecutive patients who received monotherapy with I-125 implants were selected for this study. Two sets of 8 dosimetric quality parameters corresponding to 2 different CT-scans (Day 0 and Day 50) were calculated and compared. The dosimetric parameters included are the percentage volume of the post-implant prostate receiving 80{\%}, 100{\%} and 150{\%} of the prescribed dose, the doses covering 80{\%} and 90{\%} of the prostate volume and the Dose Homogeneity Index. The values of the dose covering 1 cm3 of the rectum and urethra were assessed. Results All the dosimetric parameters of the Day 50 were higher than those of the Day 0 scan. Linear functions were obtained that calculate D90 and V100 values at Day 50 based on the Day 0 findings. Rectal and urethral parameters tended to be underestimated on Day 0 CT-scan relative to Day 50 based dosimetry. Conclusions Predicting the Day 50 dosimetry from the Day 0 scan could be a possible alternative to a Day 50 scan only in specific situations, but with a degree of uncertainty in the predicted values.",
keywords = "Post-implant dosimetry, Prostate brachytherapy, Prostate edema",
author = "Federica Cattani and Andrea Vavassori and Stefania Comi and Federica Gherardi and Stefania Russo and Roberto Orecchia and Jereczek-Fossa, {Barbara A.}",
year = "2017",
month = "8",
day = "1",
doi = "10.1016/j.ejmp.2017.07.011",
language = "English",
volume = "40",
pages = "66--71",
journal = "Physica Medica",
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publisher = "Associazione Italiana di Fisica Medica",

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T1 - Can the Day 0 CT-scan predict the post-implant scanning? Results from 136 prostate cancer patients

AU - Cattani, Federica

AU - Vavassori, Andrea

AU - Comi, Stefania

AU - Gherardi, Federica

AU - Russo, Stefania

AU - Orecchia, Roberto

AU - Jereczek-Fossa, Barbara A.

PY - 2017/8/1

Y1 - 2017/8/1

N2 - Purpose Post-implant CT-scanning is an essential part of permanent prostate brachytherapy. However, the evaluation of post-implant CT dosimetry is not straightforward due to the edema that can modify the dose to the prostate and to the organs at risk. The aim of this study is to evaluate the impact of the timing of the post-implant CT-scan on the dosimetric results and to verify if the Day 0 scan findings can predict Day 50 scanning. Methods 136 consecutive patients who received monotherapy with I-125 implants were selected for this study. Two sets of 8 dosimetric quality parameters corresponding to 2 different CT-scans (Day 0 and Day 50) were calculated and compared. The dosimetric parameters included are the percentage volume of the post-implant prostate receiving 80%, 100% and 150% of the prescribed dose, the doses covering 80% and 90% of the prostate volume and the Dose Homogeneity Index. The values of the dose covering 1 cm3 of the rectum and urethra were assessed. Results All the dosimetric parameters of the Day 50 were higher than those of the Day 0 scan. Linear functions were obtained that calculate D90 and V100 values at Day 50 based on the Day 0 findings. Rectal and urethral parameters tended to be underestimated on Day 0 CT-scan relative to Day 50 based dosimetry. Conclusions Predicting the Day 50 dosimetry from the Day 0 scan could be a possible alternative to a Day 50 scan only in specific situations, but with a degree of uncertainty in the predicted values.

AB - Purpose Post-implant CT-scanning is an essential part of permanent prostate brachytherapy. However, the evaluation of post-implant CT dosimetry is not straightforward due to the edema that can modify the dose to the prostate and to the organs at risk. The aim of this study is to evaluate the impact of the timing of the post-implant CT-scan on the dosimetric results and to verify if the Day 0 scan findings can predict Day 50 scanning. Methods 136 consecutive patients who received monotherapy with I-125 implants were selected for this study. Two sets of 8 dosimetric quality parameters corresponding to 2 different CT-scans (Day 0 and Day 50) were calculated and compared. The dosimetric parameters included are the percentage volume of the post-implant prostate receiving 80%, 100% and 150% of the prescribed dose, the doses covering 80% and 90% of the prostate volume and the Dose Homogeneity Index. The values of the dose covering 1 cm3 of the rectum and urethra were assessed. Results All the dosimetric parameters of the Day 50 were higher than those of the Day 0 scan. Linear functions were obtained that calculate D90 and V100 values at Day 50 based on the Day 0 findings. Rectal and urethral parameters tended to be underestimated on Day 0 CT-scan relative to Day 50 based dosimetry. Conclusions Predicting the Day 50 dosimetry from the Day 0 scan could be a possible alternative to a Day 50 scan only in specific situations, but with a degree of uncertainty in the predicted values.

KW - Post-implant dosimetry

KW - Prostate brachytherapy

KW - Prostate edema

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