The Italian multicentre dosimetric study for lesion dosimetry in 223Ra therapy of bone metastases: Calibration protocol of gamma cameras and patient eligibility criteria

Massimiliano Pacilio, Bartolomeo Cassano, Carlo Chiesa, Stefano Giancola, Mahila Ferrari, Cinzia Pettinato, Ernesto Amato, Federica Fioroni, Leda Lorenzon, Rosanna Pellegrini, Elisabetta Di Castro, Roberto Pani, Marta Cremonesi

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Purpose: The aims of this work were to explore patient eligibility criteria for dosimetric studies in 223Ra therapy and evaluate the effects of differences in gamma camera calibration procedures into activity quantification. Methods: Calibrations with 223Ra were performed with four gamma cameras (3/8-inch crystal) acquiring planar static images with double-peak (82 and 154keV, 20% wide) and MEGP collimator. The sensitivity was measured in air by varying activity, source-detector distance, and source diameter. Transmission curves were measured for attenuation/scatter correction with the pseudo-extrapolation number method, varying the experimental setup. 223Ra images of twenty-five patients (69 lesions) were acquired to study the lesions visibility. Univariate ROC analysis was performed considering visible/non visible lesions on 223Ra images as true positive/true negative group, and using as score value the lesion/soft tissue contrast ratio (CR) derived from 99mTc-MDP WB scan. Results: Sensitivity was nearly constant varying activity and distance (maximum s.d.=2%). Partial volume effects were negligible for object area ≥960mm2. Transmission curve measurements are affected by experimental setup and source size, leading to activity quantification errors up to 20%. The ROC analysis yielded an AUC of 0.972 and an optimal threshold of CR of 10, corresponding to an accuracy of 92%. Conclusion: The minimum calibration protocol requires sensitivity and transmission curve measurements varying the object size, performing a careful procedure standardisation. Lesions with 99mTc-MDP CR higher than 10, not overlapping the GI tract, are generally visible on 223Ra images acquired at 24h after the administration, and possibly eligible for dosimetric studies.

Original languageEnglish
JournalPhysica Medica
DOIs
Publication statusAccepted/In press - Jun 15 2016

Fingerprint

Gamma Cameras
metastasis
lesions
Calibration
bones
Multicenter Studies
dosimeters
therapy
cameras
Neoplasm Metastasis
Technetium Tc 99m Medronate
Bone and Bones
ROC Curve
sensitivity
curves
Therapeutics
Area Under Curve
Gastrointestinal Tract
standardization
collimators

Keywords

  • Ra-dichloride
  • Bone metastases
  • Dosimetry
  • Radionuclide therapy

ASJC Scopus subject areas

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

Cite this

The Italian multicentre dosimetric study for lesion dosimetry in 223Ra therapy of bone metastases : Calibration protocol of gamma cameras and patient eligibility criteria. / Pacilio, Massimiliano; Cassano, Bartolomeo; Chiesa, Carlo; Giancola, Stefano; Ferrari, Mahila; Pettinato, Cinzia; Amato, Ernesto; Fioroni, Federica; Lorenzon, Leda; Pellegrini, Rosanna; Di Castro, Elisabetta; Pani, Roberto; Cremonesi, Marta.

In: Physica Medica, 15.06.2016.

Research output: Contribution to journalArticle

Pacilio, Massimiliano ; Cassano, Bartolomeo ; Chiesa, Carlo ; Giancola, Stefano ; Ferrari, Mahila ; Pettinato, Cinzia ; Amato, Ernesto ; Fioroni, Federica ; Lorenzon, Leda ; Pellegrini, Rosanna ; Di Castro, Elisabetta ; Pani, Roberto ; Cremonesi, Marta. / The Italian multicentre dosimetric study for lesion dosimetry in 223Ra therapy of bone metastases : Calibration protocol of gamma cameras and patient eligibility criteria. In: Physica Medica. 2016.
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abstract = "Purpose: The aims of this work were to explore patient eligibility criteria for dosimetric studies in 223Ra therapy and evaluate the effects of differences in gamma camera calibration procedures into activity quantification. Methods: Calibrations with 223Ra were performed with four gamma cameras (3/8-inch crystal) acquiring planar static images with double-peak (82 and 154keV, 20{\%} wide) and MEGP collimator. The sensitivity was measured in air by varying activity, source-detector distance, and source diameter. Transmission curves were measured for attenuation/scatter correction with the pseudo-extrapolation number method, varying the experimental setup. 223Ra images of twenty-five patients (69 lesions) were acquired to study the lesions visibility. Univariate ROC analysis was performed considering visible/non visible lesions on 223Ra images as true positive/true negative group, and using as score value the lesion/soft tissue contrast ratio (CR) derived from 99mTc-MDP WB scan. Results: Sensitivity was nearly constant varying activity and distance (maximum s.d.=2{\%}). Partial volume effects were negligible for object area ≥960mm2. Transmission curve measurements are affected by experimental setup and source size, leading to activity quantification errors up to 20{\%}. The ROC analysis yielded an AUC of 0.972 and an optimal threshold of CR of 10, corresponding to an accuracy of 92{\%}. Conclusion: The minimum calibration protocol requires sensitivity and transmission curve measurements varying the object size, performing a careful procedure standardisation. Lesions with 99mTc-MDP CR higher than 10, not overlapping the GI tract, are generally visible on 223Ra images acquired at 24h after the administration, and possibly eligible for dosimetric studies.",
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T2 - Calibration protocol of gamma cameras and patient eligibility criteria

AU - Pacilio, Massimiliano

AU - Cassano, Bartolomeo

AU - Chiesa, Carlo

AU - Giancola, Stefano

AU - Ferrari, Mahila

AU - Pettinato, Cinzia

AU - Amato, Ernesto

AU - Fioroni, Federica

AU - Lorenzon, Leda

AU - Pellegrini, Rosanna

AU - Di Castro, Elisabetta

AU - Pani, Roberto

AU - Cremonesi, Marta

PY - 2016/6/15

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N2 - Purpose: The aims of this work were to explore patient eligibility criteria for dosimetric studies in 223Ra therapy and evaluate the effects of differences in gamma camera calibration procedures into activity quantification. Methods: Calibrations with 223Ra were performed with four gamma cameras (3/8-inch crystal) acquiring planar static images with double-peak (82 and 154keV, 20% wide) and MEGP collimator. The sensitivity was measured in air by varying activity, source-detector distance, and source diameter. Transmission curves were measured for attenuation/scatter correction with the pseudo-extrapolation number method, varying the experimental setup. 223Ra images of twenty-five patients (69 lesions) were acquired to study the lesions visibility. Univariate ROC analysis was performed considering visible/non visible lesions on 223Ra images as true positive/true negative group, and using as score value the lesion/soft tissue contrast ratio (CR) derived from 99mTc-MDP WB scan. Results: Sensitivity was nearly constant varying activity and distance (maximum s.d.=2%). Partial volume effects were negligible for object area ≥960mm2. Transmission curve measurements are affected by experimental setup and source size, leading to activity quantification errors up to 20%. The ROC analysis yielded an AUC of 0.972 and an optimal threshold of CR of 10, corresponding to an accuracy of 92%. Conclusion: The minimum calibration protocol requires sensitivity and transmission curve measurements varying the object size, performing a careful procedure standardisation. Lesions with 99mTc-MDP CR higher than 10, not overlapping the GI tract, are generally visible on 223Ra images acquired at 24h after the administration, and possibly eligible for dosimetric studies.

AB - Purpose: The aims of this work were to explore patient eligibility criteria for dosimetric studies in 223Ra therapy and evaluate the effects of differences in gamma camera calibration procedures into activity quantification. Methods: Calibrations with 223Ra were performed with four gamma cameras (3/8-inch crystal) acquiring planar static images with double-peak (82 and 154keV, 20% wide) and MEGP collimator. The sensitivity was measured in air by varying activity, source-detector distance, and source diameter. Transmission curves were measured for attenuation/scatter correction with the pseudo-extrapolation number method, varying the experimental setup. 223Ra images of twenty-five patients (69 lesions) were acquired to study the lesions visibility. Univariate ROC analysis was performed considering visible/non visible lesions on 223Ra images as true positive/true negative group, and using as score value the lesion/soft tissue contrast ratio (CR) derived from 99mTc-MDP WB scan. Results: Sensitivity was nearly constant varying activity and distance (maximum s.d.=2%). Partial volume effects were negligible for object area ≥960mm2. Transmission curve measurements are affected by experimental setup and source size, leading to activity quantification errors up to 20%. The ROC analysis yielded an AUC of 0.972 and an optimal threshold of CR of 10, corresponding to an accuracy of 92%. Conclusion: The minimum calibration protocol requires sensitivity and transmission curve measurements varying the object size, performing a careful procedure standardisation. Lesions with 99mTc-MDP CR higher than 10, not overlapping the GI tract, are generally visible on 223Ra images acquired at 24h after the administration, and possibly eligible for dosimetric studies.

KW - Ra-dichloride

KW - Bone metastases

KW - Dosimetry

KW - Radionuclide therapy

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