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Accelerated partial breast irradiation: a dosimetric comparison of three different techniques
Daniel W Weed1, Gregory K Edmundson, Frank A Vicini
1Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, MI 48072, USA.
Brachytherapy
|May 17, 2005
Summary
3D-CRT offers superior PTV coverage in partial breast irradiation compared to MammoSite and interstitial HDR brachytherapy. However, 3D-CRT increases the dose to normal breast tissue, making the optimal technique dependent on individual patient needs.
Area of Science:
- Radiation Oncology
- Medical Physics
- Breast Cancer Treatment
Background:
- Accelerated partial breast irradiation (APBI) is an alternative to whole breast irradiation for early-stage breast cancer.
- Three common APBI techniques include interstitial HDR brachytherapy, MammoSite balloon brachytherapy, and 3D conformal external beam quadrant irradiation (3D-CRT).
- Dosimetric comparison is crucial for optimizing treatment efficacy and minimizing toxicity.
Purpose of the Study:
- To perform the first single-institutional dosimetric comparison of interstitial HDR brachytherapy, MammoSite balloon brachytherapy, and 3D-CRT.
- To evaluate the dose distribution to the planning target volume (PTV), ipsilateral breast, heart, and ipsilateral lung for each technique.
Main Methods:
- Retrospective dosimetric analysis of 30 patients (10 per technique).
- Dose-volume histogram (DVH) analysis was used to compare dose coverage of the PTV and organs at risk.
- PTV was defined by a 1.0-1.5 cm expansion from the lumpectomy cavity, with constraints to the chest wall and skin.
Main Results:
- 3D-CRT provided superior PTV coverage (100% at 90% of prescribed dose) compared to MammoSite (91%) and interstitial HDR (68%).
- 3D-CRT delivered a higher percentage of the prescribed dose to the overall breast volume compared to brachytherapy techniques.
- Ipsilateral lung V20 was slightly higher for 3D-CRT (5%) than for brachytherapy techniques (0%).
Conclusions:
- 3D-CRT offers the best PTV coverage among the evaluated APBI techniques, though it results in a higher integral dose to the normal breast.
- MammoSite brachytherapy demonstrated superior PTV coverage compared to interstitial HDR brachytherapy.
- The optimal APBI technique should be selected based on individual clinical circumstances and dosimetric goals.