1. A new three-dimensional conformal radiotherapy (3DCRT) technique for large breast and/or high body mass index patients: evaluation of a novel fields assessment aimed to reduce extra-target-tissue irradiation.
- Author
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Gerardina S, Edy I, Sonia S, Cristina DV, Carla Germana R, Diego G, Michele F, Lucio T, Maria DR, and Sara R
- Subjects
- Adult, Aged, Aged, 80 and over, Female, Humans, Middle Aged, Organ Sparing Treatments methods, Organs at Risk, Radiotherapy Dosage, Body Mass Index, Breast abnormalities, Breast Neoplasms surgery, Hypertrophy complications, Mastectomy, Segmental methods, Radiotherapy, Conformal methods
- Abstract
Objective: To develop an alternative three-dimensional treatment plan with standardized fields class solution for whole-breast radiotherapy in patients with large/pendulous breast and/or high body mass index (BMI)., Methods: Two treatment plans [tangential fields and standardized five-fields technique (S5F)] for a total dose of 50 Gy/25 fractions were generated for patients with large breasts [planning target volume (PTV) >1000 cm(3) and/or BMI >25 kg m(-2)], supine positioned. S5F plans consist of two wedged tangential beams, anteroposterior: 20° for the right breast and 340° for the left breast, and posteroanterior: 181° for the right breast and 179° for the left breast. A field in field in medial-lateral beam and additional fields were added to reduce hot spot areas and extra-target-tissue irradiation and to improve dose distribution. The percentage of PTV receiving 95% of the prescribed dose (PTV V95%), percentage of PTV receiving 105% of the prescribed dose (PTV V105%), maximal dose to PTV (PTV Dmax), homogeneity index (HI) and conformity index were recorded. V10%, V20%, V105% and V107% of a "proper" normal tissue structure (body-PTV healthy tissue) were recorded. Statistical analyses were performed using SYSTAT v.12.0 (SPSS, Chicago, IL)., Results: In 38 patients included, S5F improved HI (8.4 vs 10.1; p ≤ 0.001) and significantly reduced PTV Dmax and PTV V105%. The extra-target-tissue irradiation was significantly reduced using S5F for V105% (cm(3)) and V107% (cm(3)) with a very high difference in tissue irradiation (46.6 vs 3.0 cm(3), p ≤ 0.001 for V105% and 12.2 vs 0.0 cm(3), p ≤ 0.001 for V107% for tangential field and S5F plans, respectively). Only a slight increase in low-dose extra-target-tissue irradiation (V10%) was observed (2.2719 vs 1.8261 cm(3), p = 0.002)., Conclusion: The S5F technique in patients with large breast or high BMI increases HI and decreases hot spots in extra-target-tissues and can therefore be easily implemented in breast cancer radiotherapy., Advances in Knowledge: The treatment planning strategy proposed in this study has several advantages: (a) it is extremely reliable as the standard supine positioning is used; (b) the standardized class solution allows for widespread use;, ((c) time and cost of treatment are not increased; and (d) it can be used for both large breasted and obese patients not compliant to different treatment positioning.)
- Published
- 2016
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