Magnetic resonance only workflow and validation of dose calculations for radiotherapy of prostate cancer

Publikation: Bidrag til tidsskriftKonferenceartikelForskningpeer review

Resumé

Background: Current state of the art radiotherapy planning of prostate cancer utilises magnetic resonance (MR) for soft tissue delineation and computed tomography (CT) to provide an electron density map for dose calculation. This dual scan workflow is prone to setup and registration error. This study evaluates the feasibility of an MR-only workflow and the validity of dose calculation from an MR derived pseudo CT. Material and methods: Thirty prostate cancer patients were CT and MR scanned. Clinical treatment plans were generated on CT using a single 18 MV arc volumetric modulated arc therapy (VMAT) with a prescription of 78 Gy/39 fractions. Dose was recalculated on pseudo CT and assuming uniform water density. Pseudo CT and uniform density based dose calculations were compared to CT dose calculations by gamma analysis. One patient was treated with a plan based solely on MR and pseudo CT including daily image guided radiotherapy (IGRT) performed by manual match of implanted gold markers. Results: A pseudo CT was generated for 29 of the 30 patients. Median gamma pass rates for 1%/1 mm passing criteria for dose calculated on pseudo CT when compared to CT were 100% for most evaluated structures. Dose calculated on uniform density also yielded high median pass rates, but with a higher occurrence of pass rates below 95%. Cases of pass rate below 95% on pseudo CT proved to originate from the presence of rectal air on CT, not represented by the pseudo CT. Treatment based on MR alone was successfully delivered to one patient, including manually performed daily IGRT. Conclusions: Median gamma pass rates were high for pseudo CT and proved superior to uniform density. Local differences in dose calculations were concluded not to have clinical relevance. Feasibility of the MR-only workflow was demonstrated through successful delivery of a treatment course planned based on MR alone.

OriginalsprogEngelsk
TidsskriftActa Oncologica
Vol/bind56
Udgave nummer6
Sider (fra-til)787-791
ISSN0284-186X
DOI
StatusUdgivet - 2017
Begivenhed4th Symposium of the Nordic Association for Clinical Physics - Radisson Blu Scandinavia Hotel, Oslo, Norge
Varighed: 6. feb. 20178. feb. 2017

Konference

Konference4th Symposium of the Nordic Association for Clinical Physics
LokationRadisson Blu Scandinavia Hotel
LandNorge
ByOslo
Periode06/02/201708/02/2017

Fingeraftryk

Workflow
Prostatic Neoplasms
Intensity-Modulated Radiotherapy
Feasibility Studies
Gold
Prescriptions

Citer dette

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title = "Magnetic resonance only workflow and validation of dose calculations for radiotherapy of prostate cancer",
abstract = "Background: Current state of the art radiotherapy planning of prostate cancer utilises magnetic resonance (MR) for soft tissue delineation and computed tomography (CT) to provide an electron density map for dose calculation. This dual scan workflow is prone to setup and registration error. This study evaluates the feasibility of an MR-only workflow and the validity of dose calculation from an MR derived pseudo CT. Material and methods: Thirty prostate cancer patients were CT and MR scanned. Clinical treatment plans were generated on CT using a single 18 MV arc volumetric modulated arc therapy (VMAT) with a prescription of 78 Gy/39 fractions. Dose was recalculated on pseudo CT and assuming uniform water density. Pseudo CT and uniform density based dose calculations were compared to CT dose calculations by gamma analysis. One patient was treated with a plan based solely on MR and pseudo CT including daily image guided radiotherapy (IGRT) performed by manual match of implanted gold markers. Results: A pseudo CT was generated for 29 of the 30 patients. Median gamma pass rates for 1{\%}/1 mm passing criteria for dose calculated on pseudo CT when compared to CT were 100{\%} for most evaluated structures. Dose calculated on uniform density also yielded high median pass rates, but with a higher occurrence of pass rates below 95{\%}. Cases of pass rate below 95{\%} on pseudo CT proved to originate from the presence of rectal air on CT, not represented by the pseudo CT. Treatment based on MR alone was successfully delivered to one patient, including manually performed daily IGRT. Conclusions: Median gamma pass rates were high for pseudo CT and proved superior to uniform density. Local differences in dose calculations were concluded not to have clinical relevance. Feasibility of the MR-only workflow was demonstrated through successful delivery of a treatment course planned based on MR alone.",
author = "{L{\"u}beck Christiansen}, Rasmus and Jensen, {Henrik R.} and Carsten Brink",
year = "2017",
doi = "10.1080/0284186X.2017.1290275",
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}

Magnetic resonance only workflow and validation of dose calculations for radiotherapy of prostate cancer. / Lübeck Christiansen, Rasmus; Jensen, Henrik R.; Brink, Carsten.

I: Acta Oncologica, Bind 56, Nr. 6, 2017, s. 787-791.

Publikation: Bidrag til tidsskriftKonferenceartikelForskningpeer review

TY - GEN

T1 - Magnetic resonance only workflow and validation of dose calculations for radiotherapy of prostate cancer

AU - Lübeck Christiansen, Rasmus

AU - Jensen, Henrik R.

AU - Brink, Carsten

PY - 2017

Y1 - 2017

N2 - Background: Current state of the art radiotherapy planning of prostate cancer utilises magnetic resonance (MR) for soft tissue delineation and computed tomography (CT) to provide an electron density map for dose calculation. This dual scan workflow is prone to setup and registration error. This study evaluates the feasibility of an MR-only workflow and the validity of dose calculation from an MR derived pseudo CT. Material and methods: Thirty prostate cancer patients were CT and MR scanned. Clinical treatment plans were generated on CT using a single 18 MV arc volumetric modulated arc therapy (VMAT) with a prescription of 78 Gy/39 fractions. Dose was recalculated on pseudo CT and assuming uniform water density. Pseudo CT and uniform density based dose calculations were compared to CT dose calculations by gamma analysis. One patient was treated with a plan based solely on MR and pseudo CT including daily image guided radiotherapy (IGRT) performed by manual match of implanted gold markers. Results: A pseudo CT was generated for 29 of the 30 patients. Median gamma pass rates for 1%/1 mm passing criteria for dose calculated on pseudo CT when compared to CT were 100% for most evaluated structures. Dose calculated on uniform density also yielded high median pass rates, but with a higher occurrence of pass rates below 95%. Cases of pass rate below 95% on pseudo CT proved to originate from the presence of rectal air on CT, not represented by the pseudo CT. Treatment based on MR alone was successfully delivered to one patient, including manually performed daily IGRT. Conclusions: Median gamma pass rates were high for pseudo CT and proved superior to uniform density. Local differences in dose calculations were concluded not to have clinical relevance. Feasibility of the MR-only workflow was demonstrated through successful delivery of a treatment course planned based on MR alone.

AB - Background: Current state of the art radiotherapy planning of prostate cancer utilises magnetic resonance (MR) for soft tissue delineation and computed tomography (CT) to provide an electron density map for dose calculation. This dual scan workflow is prone to setup and registration error. This study evaluates the feasibility of an MR-only workflow and the validity of dose calculation from an MR derived pseudo CT. Material and methods: Thirty prostate cancer patients were CT and MR scanned. Clinical treatment plans were generated on CT using a single 18 MV arc volumetric modulated arc therapy (VMAT) with a prescription of 78 Gy/39 fractions. Dose was recalculated on pseudo CT and assuming uniform water density. Pseudo CT and uniform density based dose calculations were compared to CT dose calculations by gamma analysis. One patient was treated with a plan based solely on MR and pseudo CT including daily image guided radiotherapy (IGRT) performed by manual match of implanted gold markers. Results: A pseudo CT was generated for 29 of the 30 patients. Median gamma pass rates for 1%/1 mm passing criteria for dose calculated on pseudo CT when compared to CT were 100% for most evaluated structures. Dose calculated on uniform density also yielded high median pass rates, but with a higher occurrence of pass rates below 95%. Cases of pass rate below 95% on pseudo CT proved to originate from the presence of rectal air on CT, not represented by the pseudo CT. Treatment based on MR alone was successfully delivered to one patient, including manually performed daily IGRT. Conclusions: Median gamma pass rates were high for pseudo CT and proved superior to uniform density. Local differences in dose calculations were concluded not to have clinical relevance. Feasibility of the MR-only workflow was demonstrated through successful delivery of a treatment course planned based on MR alone.

U2 - 10.1080/0284186X.2017.1290275

DO - 10.1080/0284186X.2017.1290275

M3 - Conference article

C2 - 28464739

AN - SCOPUS:85013170873

VL - 56

SP - 787

EP - 791

JO - Acta Oncologica

JF - Acta Oncologica

SN - 0284-186X

IS - 6

ER -