Impact of the Delineation Accuracy of Lumpectomy Cavity on Planning Target Volume in Partial-Breast Irradiation Using Brachytherapy and External-Beam Radiotherapy
Publish place: Archives of Breast Cancer، Vol: 9، Issue: 4
Publish Year: 1401
نوع سند: مقاله ژورنالی
زبان: English
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JR_ARCHB-9-4_003
تاریخ نمایه سازی: 14 آذر 1402
Abstract:
Background: In partial-breast irradiation (PBI), an accurate target volume
delineation based on the lumpectomy cavity (LC) has been reported to remain
difficult due to uncertain LC identification. However, the impact of accurate LC
delineation on the planning target volume (PTV) has not been investigated.
Material and methods: Between September ۲۰۱۸ and April ۲۰۲۰, ۱۵۹ patients
receiving perioperative PBI with multicather-interstitial brachytherapy were
evaluated. While LC delineation using implanted catheters as fiducial markers was
used as a reference, conventional LC was virtually delineated on computed
tomography with clips. PTV۱-cm margin and PTV۲-cm margin, which means ۱cm and ۲cm
expansion from LC, were developed and assumed for brachytherapy and externalbeam
PBI, respectively. The target accuracy and the impact of the delineation
accuracy of LC on PTVs were evaluated. The geographic miss index (GMI) and
normal tissue index (NTI) were used as accuracy indices and were defined as the
percentage of under- and overestimating volume, respectively.
Results: The PTV۱-cm margin and PTV۲-cm margin were significantly larger than the
reference volume, ۵۷.۹cm۳ vs. ۳۷.۹cm۳ (P<۰.۰۰۱) and ۱۱۳.۲cm۳ vs. ۹۳.۸cm۳
(P<۰.۰۰۱), respectively. The GMI and NTI of LC were ۲۷.۳% and ۴۱.۲%,
respectively. Although the GMI in the PTV۱-cm margin and PTV۲-cm margin was
significantly reduced to ۹.۸% (P<۰.۰۰۰۱) and ۹.۹% (P<۰.۰۰۰۱), respectively, the NTI
was not significantly improved in the PTV۱-cm margin, which was ۴۱.۸% (P=۰.۶۰) but
was improved in PTV۲-cm margin, which was ۲۳.۱% (P<۰.۰۰۰۱).
Conclusion: The GMI in PTV۱-cm margin was reduced to be as low as PTV۲-cm margin.
Although PTV۲-cm margin was associated with lower NTI, the absolute volume was
almost double with PTV۱-cm margin. Although further research is required,
brachytherapy-based PBI may be a reasonable option to achieve tumor control and
cosmesis using the conventional delineation method.
Keywords:
Authors
Kazuhiko Sato
Department of Breast Oncology, Tokyo-West Tokushukai Hospital, Tokyo, Japan
Takahiro Shimo
Department of Radiation Oncology, Tokyo-West Tokushukai Hospital, Tokyo, Japan
Nana Natsume
Department of Radiation Oncology, Tokyo-West Tokushukai Hospital, Tokyo, Japan
Naoko Takeda
Department of Breast Oncology, Tokyo-West Tokushukai Hospital, Tokyo, Japan