Planning the breast boost: comparison of three techniques and evolution of tumor bed during treatment.
OBJECTIVE
To evaluate the accuracy of two clinical techniques for electron boost planning compared with computed tomography (CT)-based planning. Additionally, we evaluated the tumor bed characteristics at whole breast planning and boost planning.


METHODS
A total of 30 women underwent tumor bed boost planning within 2 weeks of completing whole breast radiotherapy using three planning techniques: scar-based planning, palpation/clinical-based planning, and CT-based planning. The plans were analyzed for dosimetric coverage of the CT-delineated tumor bed. The cavity visualization score was used to define the CT-delineated tumor bed as well or poorly defined.


RESULTS
Scar-based planning resulted in inferior tumor bed coverage compared with CT-based planning, with the minimal dose received by 90% of the target volume >90% in 53% and a geographic miss in 53%. The results of palpation/clinical-based planning were significantly better: 87% and 10% for the minimal dose received by 90% of the target volume >90% and geographic miss, respectively. Of the 30 tumor beds, 16 were poorly defined by the cavity visualization score. Of these 16, 8 were well demarcated by the surgical clips. The evaluation of the 22 well-defined tumor beds revealed similar results. A comparison of the tumor bed volume from the initial planning CT scan to the boost planning CT scan revealed a decrease in size in 77% of cases. The mean decrease in volume was 52%.


CONCLUSIONS
The results of our study have shown that CT-based planning allows for optimal tumor bed coverage compared with clinical and scar-based approaches. However, in the setting of a poorly visualized cavity on CT without surgical clips, palpation/clinical-based planning can help delineate the appropriate target volumes and is superior to scar-based planning. CT simulation at boost planning could allow for a reduction in the boost volumes.
Hepel
Jaroslaw T
JT
Department of Radiation Oncology, Tufts University, Tufts Medical Center, Boston, MA, USA. jhepel@tufts-nemc.org
Evans
Suzanne B
SB
Hiatt
Jessica R
JR
Price
Lori Lyn
LL
DiPetrillo
Thomas
T
Wazer
David E
DE
MacAusland
Stephanie G
SG
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001940:Breast / Q000473:pathology; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D016009:Chi-Square Distribution; D002921:Cicatrix / Q000000981:diagnostic imaging / Q000473:pathology; D004583:Electrons; D005260:Female; D006801:Humans; D008327:Mammography; D015412:Mastectomy, Segmental; D008875:Middle Aged; D009929:Organ Size; D010173:Palpation / Q000379:methods*; D011829:Radiation Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D018714:Radiotherapy, Adjuvant / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods*; D047368:Tumor Burden