RESUMEN
PURPOSE: The use of IMRT for the treatment of breast cancer has been growing considerably in our institution since 2009. Alternatively, helical tomotherapy (HT) using a field width of 2.5 and 5cm (HT_FW_5), volumetric-modulated arc therapy (VMAT), or proton therapy with pencil-beam scanning (PT-PBS) have also been used to reduce treatment duration or optimize organ-at-risk (OAR) sparing. The purpose of this study was to compare the 4 treatment modalities available at our site. PATIENTS AND METHODS: We studied 10 patients treated for breast cancer with lymph node involvement. The prescribed dose was 51.8Gy to the breast with a simultaneous integrated boost up to 63Gy, and 50.4Gy to lymph nodes in 28 fractions. The CTV was delineated according to ESTRO Guidelines. Dosimetric planning in routine clinical practice was performed using HT_FW_2.5. The approved clinical plan was compared to the 3 other plans. Dosimetric goals for PTV coverage were D95%≥95% and D2%≤107% of the prescribed dose. Mean and maximum doses to OAR were recorded. RESULTS: HT_FW_5 and VMAT plans ensure equivalent or even better PTV coverage compared to the initial clinically approved plan but at the cost of poorer OAR sparing. PT_PBS plans showed that an excellent PTV coverage can be maintained with significantly lower doses to OAR. CONCLUSION: HT_FW_5 and VMAT plans allow a significant reduction of treatment duration and can be a good alternative to HT_FW_2.5 for specific populations. HT_FW_2.5 could be chosen for patients at higher risk of side effects. In addition, PT_PBS should be considered in the near future as it has been shown to have a major potential benefit to lower the risk of side effects with the same level of PTV coverage.
Asunto(s)
Radioterapia de Intensidad Modulada/métodos , Neoplasias de Mama Unilaterales/radioterapia , Adulto , Mama/efectos de la radiación , Fraccionamiento de la Dosis de Radiación , Femenino , Corazón/efectos de la radiación , Humanos , Pulmón/efectos de la radiación , Ganglios Linfáticos/patología , Irradiación Linfática , Órganos en Riesgo/efectos de la radiación , Planificación de la Radioterapia Asistida por Computador/métodos , Neoplasias de Mama Unilaterales/diagnóstico por imagen , Neoplasias de Mama Unilaterales/patologíaRESUMEN
PURPOSE: Intensity-modulated radiotherapy needs the strict delineation of target volumes as well as organs at risk and the time used for this procedure is long. The purpose of this study was to evaluate the Workflow Box system (Mirada Medical, UK) for automatic delineation and segmentation for everyday use of organs at risk and lymph nodes delineation in patients treated for early stage breast cancer. MATERIAL AND METHODS: Twenty patients' CT scans in treatment position for their breast cancer radiotherapy were delineated in respect of the ESTRO delineation guidelines to begin the creation of automatic delineation atlas. Then 30 other CT scans were delineated this time by the automatic delineation system and by the radiation oncologist (reference delineation plan). The precision of the delineation was evaluated using the overlap volume index and evaluation of standard deviation (SD). RESULTS: The study of organs at risk has shown that the mean overlap volumes were between 0.49 (SD=0.21) and 0.97 (ET=0.03). Five organs at risk out of nine had overlap volumes at least 0.8. The mean overlap volume for all organs at risk was 0.77 (SD=0.17). The system was less performing for the lymph nodes with a mean overlap volume of 0.43 (SD=0.1) and ranging between 0.23 (SD=0.13) and 0.52 (SD=0.1). The use of this system reduced the delineation time by 40% per patient. CONCLUSIONS: For patients with breast cancer, the system for automatic delineation and segmentation Workflow Box (Mirada Medical, UK) permitted to safely shorten the time for delineation with acceptable organs at risk delineation. Improvement of lymph node volumes is needed. A new evaluation will be realized after using the system in routine practice.