In-vivo dosimetry with Gafchromic films for multi-isocentric VMAT irradiation of total marrow lymph-nodes: A feasibility study

Pietro Mancosu, Pierina Navarria, Giacomo Reggiori, Luca Cozzi, Antonella Fogliata, Anna Gaudino, Francesca Lobefalo, Lucia Paganini, Valentina Palumbo, Barbara Sarina, Antonella Stravato, Luca Castagna, Stefano Tomatis, Marta Scorsetti

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Abstract

Background: Total marrow (lymph-nodes) irradiation (TMI-TMLI) by volumetric modulated arc therapy (VMAT) was shown to be feasible by dosimetric feasibility studies. It was demonstrated that several partially overlapping arcs with different isocenters are required to achieve the desired coverage of the hematopoietic or lymphoid tissues targets and to spare the neighbouring healthy tissues. The effect of isocenter shifts was investigated with the treatment planning system but an in- vivo verification of the procedure was not carried out. The objective of this study was the in-vivo verification of the consistency between the delivered and planned doses using bi-dimensional GafChromic EBT3 films. Methods: In a first phase a phantom study was carried out to quantify the uncertainties under controlled conditions. In a second phase three patients treated with TMLI were enrolled for in-vivo dosimetry. The dose prescription was 2Gy in single fraction. Ten arcs paired on 4-6 isocenters were used to cover the target. Cone Beam Computed Tomography (CBCT) was used to verify the patient positioning at each isocenter. GafChromic EBT3 films were placed below the patient on the top of a dedicated immobilization system specifically designed. The dose maps measured with the EBT3 films were compared with the corresponding calculations along the patient support couch. Gamma Agreement Index (GAI) with dose difference of 5% and distance to agreement of 5 mm was computed. Results: In the phantom study, optimal target coverage and healthy tissue sparing was observed. GAI(5%,5 mm) was 99.4%. For the patient-specific measurements, GAI(5%,5 mm) was greater than 95% and GAI (5%,3 mm) > 90% for all patients. Conclusions: In vivo measurements demonstrated the delivered dose to be in good agreement with the planned one for the TMI-TMLI protocol where partially overlapping arcs with different isocenters are required.

Original languageEnglish
Article number86
JournalRadiation Oncology
Volume10
Issue number1
DOIs
Publication statusPublished - Apr 12 2015

Fingerprint

Intensity-Modulated Radiotherapy
Feasibility Studies
Lymph Nodes
Bone Marrow
Patient Positioning
Cone-Beam Computed Tomography
Lymphoid Tissue
Immobilization
Uncertainty
Prescriptions
In Vivo Dosimetry

Keywords

  • Bone transplantation
  • GafChromics
  • In vivo dosimetry
  • Plan optimization
  • Radiotherapy
  • Total marrow irradiation

ASJC Scopus subject areas

  • Oncology
  • Radiology Nuclear Medicine and imaging

Cite this

@article{7ef920381a254a269bd2caa0dc62b97f,
title = "In-vivo dosimetry with Gafchromic films for multi-isocentric VMAT irradiation of total marrow lymph-nodes: A feasibility study",
abstract = "Background: Total marrow (lymph-nodes) irradiation (TMI-TMLI) by volumetric modulated arc therapy (VMAT) was shown to be feasible by dosimetric feasibility studies. It was demonstrated that several partially overlapping arcs with different isocenters are required to achieve the desired coverage of the hematopoietic or lymphoid tissues targets and to spare the neighbouring healthy tissues. The effect of isocenter shifts was investigated with the treatment planning system but an in- vivo verification of the procedure was not carried out. The objective of this study was the in-vivo verification of the consistency between the delivered and planned doses using bi-dimensional GafChromic EBT3 films. Methods: In a first phase a phantom study was carried out to quantify the uncertainties under controlled conditions. In a second phase three patients treated with TMLI were enrolled for in-vivo dosimetry. The dose prescription was 2Gy in single fraction. Ten arcs paired on 4-6 isocenters were used to cover the target. Cone Beam Computed Tomography (CBCT) was used to verify the patient positioning at each isocenter. GafChromic EBT3 films were placed below the patient on the top of a dedicated immobilization system specifically designed. The dose maps measured with the EBT3 films were compared with the corresponding calculations along the patient support couch. Gamma Agreement Index (GAI) with dose difference of 5{\%} and distance to agreement of 5 mm was computed. Results: In the phantom study, optimal target coverage and healthy tissue sparing was observed. GAI(5{\%},5 mm) was 99.4{\%}. For the patient-specific measurements, GAI(5{\%},5 mm) was greater than 95{\%} and GAI (5{\%},3 mm) > 90{\%} for all patients. Conclusions: In vivo measurements demonstrated the delivered dose to be in good agreement with the planned one for the TMI-TMLI protocol where partially overlapping arcs with different isocenters are required.",
keywords = "Bone transplantation, GafChromics, In vivo dosimetry, Plan optimization, Radiotherapy, Total marrow irradiation",
author = "Pietro Mancosu and Pierina Navarria and Giacomo Reggiori and Luca Cozzi and Antonella Fogliata and Anna Gaudino and Francesca Lobefalo and Lucia Paganini and Valentina Palumbo and Barbara Sarina and Antonella Stravato and Luca Castagna and Stefano Tomatis and Marta Scorsetti",
year = "2015",
month = "4",
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doi = "10.1186/s13014-015-0391-y",
language = "English",
volume = "10",
journal = "Radiation Oncology",
issn = "1748-717X",
publisher = "BioMed Central",
number = "1",

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TY - JOUR

T1 - In-vivo dosimetry with Gafchromic films for multi-isocentric VMAT irradiation of total marrow lymph-nodes

T2 - A feasibility study

AU - Mancosu, Pietro

AU - Navarria, Pierina

AU - Reggiori, Giacomo

AU - Cozzi, Luca

AU - Fogliata, Antonella

AU - Gaudino, Anna

AU - Lobefalo, Francesca

AU - Paganini, Lucia

AU - Palumbo, Valentina

AU - Sarina, Barbara

AU - Stravato, Antonella

AU - Castagna, Luca

AU - Tomatis, Stefano

AU - Scorsetti, Marta

PY - 2015/4/12

Y1 - 2015/4/12

N2 - Background: Total marrow (lymph-nodes) irradiation (TMI-TMLI) by volumetric modulated arc therapy (VMAT) was shown to be feasible by dosimetric feasibility studies. It was demonstrated that several partially overlapping arcs with different isocenters are required to achieve the desired coverage of the hematopoietic or lymphoid tissues targets and to spare the neighbouring healthy tissues. The effect of isocenter shifts was investigated with the treatment planning system but an in- vivo verification of the procedure was not carried out. The objective of this study was the in-vivo verification of the consistency between the delivered and planned doses using bi-dimensional GafChromic EBT3 films. Methods: In a first phase a phantom study was carried out to quantify the uncertainties under controlled conditions. In a second phase three patients treated with TMLI were enrolled for in-vivo dosimetry. The dose prescription was 2Gy in single fraction. Ten arcs paired on 4-6 isocenters were used to cover the target. Cone Beam Computed Tomography (CBCT) was used to verify the patient positioning at each isocenter. GafChromic EBT3 films were placed below the patient on the top of a dedicated immobilization system specifically designed. The dose maps measured with the EBT3 films were compared with the corresponding calculations along the patient support couch. Gamma Agreement Index (GAI) with dose difference of 5% and distance to agreement of 5 mm was computed. Results: In the phantom study, optimal target coverage and healthy tissue sparing was observed. GAI(5%,5 mm) was 99.4%. For the patient-specific measurements, GAI(5%,5 mm) was greater than 95% and GAI (5%,3 mm) > 90% for all patients. Conclusions: In vivo measurements demonstrated the delivered dose to be in good agreement with the planned one for the TMI-TMLI protocol where partially overlapping arcs with different isocenters are required.

AB - Background: Total marrow (lymph-nodes) irradiation (TMI-TMLI) by volumetric modulated arc therapy (VMAT) was shown to be feasible by dosimetric feasibility studies. It was demonstrated that several partially overlapping arcs with different isocenters are required to achieve the desired coverage of the hematopoietic or lymphoid tissues targets and to spare the neighbouring healthy tissues. The effect of isocenter shifts was investigated with the treatment planning system but an in- vivo verification of the procedure was not carried out. The objective of this study was the in-vivo verification of the consistency between the delivered and planned doses using bi-dimensional GafChromic EBT3 films. Methods: In a first phase a phantom study was carried out to quantify the uncertainties under controlled conditions. In a second phase three patients treated with TMLI were enrolled for in-vivo dosimetry. The dose prescription was 2Gy in single fraction. Ten arcs paired on 4-6 isocenters were used to cover the target. Cone Beam Computed Tomography (CBCT) was used to verify the patient positioning at each isocenter. GafChromic EBT3 films were placed below the patient on the top of a dedicated immobilization system specifically designed. The dose maps measured with the EBT3 films were compared with the corresponding calculations along the patient support couch. Gamma Agreement Index (GAI) with dose difference of 5% and distance to agreement of 5 mm was computed. Results: In the phantom study, optimal target coverage and healthy tissue sparing was observed. GAI(5%,5 mm) was 99.4%. For the patient-specific measurements, GAI(5%,5 mm) was greater than 95% and GAI (5%,3 mm) > 90% for all patients. Conclusions: In vivo measurements demonstrated the delivered dose to be in good agreement with the planned one for the TMI-TMLI protocol where partially overlapping arcs with different isocenters are required.

KW - Bone transplantation

KW - GafChromics

KW - In vivo dosimetry

KW - Plan optimization

KW - Radiotherapy

KW - Total marrow irradiation

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