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Technique alternatives for breast radiation oncology: Conventional radiation therapy to tomotherapy.

Fournier-Bidoz N, Kirova Y, Campana F, El Barouky J, Zefkili S, Dendale R, Bollet MA, Mazal A, Fourquet A - J Med Phys (2009)

Bottom Line: This conventional approach can be improved by a field-in-field technique using the linac multi-leaf collimator (MLC).However, careful quality assurance of the treatment planning system must be performed.Tomotherapy is a valuable recourse for complex irradiations like bilateral breast or mammary plus axillary irradiation while a field-in-field associated with a unique isocenter technique can be used for majority of the patients.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, Institut Curie, 26 rue d'Ulm, Paris 75005, France.

ABSTRACT
Breast conserving radiotherapy uses tangential fields and compensating wedges. This conventional approach can be improved by a field-in-field technique using the linac multi-leaf collimator (MLC). A simplified field-in-field technique that planners can easily achieve and which improves dose uniformity in the breast volume is presented here. Field junction problems are more easily solved by the use of a virtual simulation. A unique isocenter can be set at the junction between the supra-clavicular field and the breast tangential fields. However, careful quality assurance of the treatment planning system must be performed. Tomotherapy has promising clinical advantages: the ability of a tomographic image to correct for random set-up errors, a continuous cranio-caudal delivery which suppresses junction problems, the conformality of the dose distribution throughout the complex volumes formed by the lymph nodes and the breasts. Tomotherapy is a valuable recourse for complex irradiations like bilateral breast or mammary plus axillary irradiation while a field-in-field associated with a unique isocenter technique can be used for majority of the patients.

No MeSH data available.


Calculated (plain) and measured (dashed) profiles along the two orthogonal lines. Mean difference is two to three per cent (Std deviation four per cent)
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Figure 0007: Calculated (plain) and measured (dashed) profiles along the two orthogonal lines. Mean difference is two to three per cent (Std deviation four per cent)

Mentions: The calculated iso-dose 90% fits well with the measured 90% [Figure 6b]. However, discrepancies are found at the corners of the asymmetric field furthest from the isocenter -85% iso-dose on film does not thus agree with the calculated 85% [Figure 6b]. Two profiles [dashed lines on Figure 6a] are then analized [Figure 6c]. The measured profile dose is higher than the calculated dose. The shoulders of the calculated profiles are more rounded than the measured ones. Even though the mean dose difference remains within three per cent, it is relevant to come back to the TPS beam data base and look at the accuracy of large fields and MLC edges and transmissions modelization.


Technique alternatives for breast radiation oncology: Conventional radiation therapy to tomotherapy.

Fournier-Bidoz N, Kirova Y, Campana F, El Barouky J, Zefkili S, Dendale R, Bollet MA, Mazal A, Fourquet A - J Med Phys (2009)

Calculated (plain) and measured (dashed) profiles along the two orthogonal lines. Mean difference is two to three per cent (Std deviation four per cent)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2807680&req=5

Figure 0007: Calculated (plain) and measured (dashed) profiles along the two orthogonal lines. Mean difference is two to three per cent (Std deviation four per cent)
Mentions: The calculated iso-dose 90% fits well with the measured 90% [Figure 6b]. However, discrepancies are found at the corners of the asymmetric field furthest from the isocenter -85% iso-dose on film does not thus agree with the calculated 85% [Figure 6b]. Two profiles [dashed lines on Figure 6a] are then analized [Figure 6c]. The measured profile dose is higher than the calculated dose. The shoulders of the calculated profiles are more rounded than the measured ones. Even though the mean dose difference remains within three per cent, it is relevant to come back to the TPS beam data base and look at the accuracy of large fields and MLC edges and transmissions modelization.

Bottom Line: This conventional approach can be improved by a field-in-field technique using the linac multi-leaf collimator (MLC).However, careful quality assurance of the treatment planning system must be performed.Tomotherapy is a valuable recourse for complex irradiations like bilateral breast or mammary plus axillary irradiation while a field-in-field associated with a unique isocenter technique can be used for majority of the patients.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, Institut Curie, 26 rue d'Ulm, Paris 75005, France.

ABSTRACT
Breast conserving radiotherapy uses tangential fields and compensating wedges. This conventional approach can be improved by a field-in-field technique using the linac multi-leaf collimator (MLC). A simplified field-in-field technique that planners can easily achieve and which improves dose uniformity in the breast volume is presented here. Field junction problems are more easily solved by the use of a virtual simulation. A unique isocenter can be set at the junction between the supra-clavicular field and the breast tangential fields. However, careful quality assurance of the treatment planning system must be performed. Tomotherapy has promising clinical advantages: the ability of a tomographic image to correct for random set-up errors, a continuous cranio-caudal delivery which suppresses junction problems, the conformality of the dose distribution throughout the complex volumes formed by the lymph nodes and the breasts. Tomotherapy is a valuable recourse for complex irradiations like bilateral breast or mammary plus axillary irradiation while a field-in-field associated with a unique isocenter technique can be used for majority of the patients.

No MeSH data available.