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Image guidance using 3D-ultrasound (3D-US) for daily positioning of lumpectomy cavity for boost irradiation.

Chadha M, Young A, Geraghty C, Masino R, Harrison L - Radiat Oncol (2011)

Bottom Line: For electron boosts, shifts were 1.0 ± 0.5 cm and 52% fell outside the dosimetric penumbra.Interfraction analysis relative to the first fraction noted the shifts to be 0.8 ± 0.4 cm and 36% fell outside the penumbra.Further studies to better define the protocol for clinical application of IGRT in breast cancer is needed.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Radiation Oncology, Beth Israel Medical Center, New York, NY, USA. mchadha@chpnet.org

ABSTRACT

Purpose: The goal of this study was to evaluate the use of 3D ultrasound (3DUS) breast IGRT for electron and photon lumpectomy site boost treatments.

Materials and methods: 20 patients with a prescribed photon or electron boost were enrolled in this study. 3DUS images were acquired both at time of simulation, to form a coregistered CT/3DUS dataset, and at the time of daily treatment delivery. Intrafractional motion between treatment and simulation 3DUS datasets were calculated to determine IGRT shifts. Photon shifts were evaluated isocentrically, while electron shifts were evaluated in the beam's-eye-view. Volume differences between simulation and first boost fraction were calculated. Further, to control for the effect of change in seroma/cavity volume due to time lapse between the 2 sets of images, interfraction IGRT shifts using the first boost fraction as reference for all subsequent treatment fractions were also calculated.

Results: For photon boosts, IGRT shifts were 1.1 ± 0.5 cm and 50% of fractions required a shift >1.0 cm. Volume change between simulation and boost was 49 ± 31%. Shifts when using the first boost fraction as reference were 0.8 ± 0.4 cm and 24% required a shift >1.0 cm. For electron boosts, shifts were 1.0 ± 0.5 cm and 52% fell outside the dosimetric penumbra. Interfraction analysis relative to the first fraction noted the shifts to be 0.8 ± 0.4 cm and 36% fell outside the penumbra.

Conclusion: The lumpectomy cavity can shift significantly during fractionated radiation therapy. 3DUS can be used to image the cavity and correct for interfractional motion. Further studies to better define the protocol for clinical application of IGRT in breast cancer is needed.

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US and CT image co-registration in axial, sagittal and coronal views. The CT cavity (GTV) is in blue, US seroma (RV) in green, and the blue represents PTV. The RV is not always in the geometric center of the GTV.
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Figure 7: US and CT image co-registration in axial, sagittal and coronal views. The CT cavity (GTV) is in blue, US seroma (RV) in green, and the blue represents PTV. The RV is not always in the geometric center of the GTV.

Mentions: The GTV-CT target volume in most cases was defined by surgical clips and seroma cavity identified on the CT image, Figure 6. The relationship between the GTV-CT and RV on US images showed that RV was smaller than the GTV-CT on average by 38% (SD 23%). Further, it was also noted that the RV-US was not always in the geometric center of the GTV-CT, Figure 7.


Image guidance using 3D-ultrasound (3D-US) for daily positioning of lumpectomy cavity for boost irradiation.

Chadha M, Young A, Geraghty C, Masino R, Harrison L - Radiat Oncol (2011)

US and CT image co-registration in axial, sagittal and coronal views. The CT cavity (GTV) is in blue, US seroma (RV) in green, and the blue represents PTV. The RV is not always in the geometric center of the GTV.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3113959&req=5

Figure 7: US and CT image co-registration in axial, sagittal and coronal views. The CT cavity (GTV) is in blue, US seroma (RV) in green, and the blue represents PTV. The RV is not always in the geometric center of the GTV.
Mentions: The GTV-CT target volume in most cases was defined by surgical clips and seroma cavity identified on the CT image, Figure 6. The relationship between the GTV-CT and RV on US images showed that RV was smaller than the GTV-CT on average by 38% (SD 23%). Further, it was also noted that the RV-US was not always in the geometric center of the GTV-CT, Figure 7.

Bottom Line: For electron boosts, shifts were 1.0 ± 0.5 cm and 52% fell outside the dosimetric penumbra.Interfraction analysis relative to the first fraction noted the shifts to be 0.8 ± 0.4 cm and 36% fell outside the penumbra.Further studies to better define the protocol for clinical application of IGRT in breast cancer is needed.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Radiation Oncology, Beth Israel Medical Center, New York, NY, USA. mchadha@chpnet.org

ABSTRACT

Purpose: The goal of this study was to evaluate the use of 3D ultrasound (3DUS) breast IGRT for electron and photon lumpectomy site boost treatments.

Materials and methods: 20 patients with a prescribed photon or electron boost were enrolled in this study. 3DUS images were acquired both at time of simulation, to form a coregistered CT/3DUS dataset, and at the time of daily treatment delivery. Intrafractional motion between treatment and simulation 3DUS datasets were calculated to determine IGRT shifts. Photon shifts were evaluated isocentrically, while electron shifts were evaluated in the beam's-eye-view. Volume differences between simulation and first boost fraction were calculated. Further, to control for the effect of change in seroma/cavity volume due to time lapse between the 2 sets of images, interfraction IGRT shifts using the first boost fraction as reference for all subsequent treatment fractions were also calculated.

Results: For photon boosts, IGRT shifts were 1.1 ± 0.5 cm and 50% of fractions required a shift >1.0 cm. Volume change between simulation and boost was 49 ± 31%. Shifts when using the first boost fraction as reference were 0.8 ± 0.4 cm and 24% required a shift >1.0 cm. For electron boosts, shifts were 1.0 ± 0.5 cm and 52% fell outside the dosimetric penumbra. Interfraction analysis relative to the first fraction noted the shifts to be 0.8 ± 0.4 cm and 36% fell outside the penumbra.

Conclusion: The lumpectomy cavity can shift significantly during fractionated radiation therapy. 3DUS can be used to image the cavity and correct for interfractional motion. Further studies to better define the protocol for clinical application of IGRT in breast cancer is needed.

Show MeSH
Related in: MedlinePlus