In vivo dosimetry in low-voltage IORT breast treatments with XR-RV3 radiochromic film.

PURPOSE: The objectives of the study were to establish a procedure for in vivo film-based dosimetry for intraoperative radiotherapy (IORT), evaluate the typical doses delivered to organs at risk, and verify the dose prescription. MATERIALS AND METHODS: In vivo dose measurements were studied using XR-RV3 radiochromic films in 30 patients with breast cancer undergoing IORT using the Axxent® device (Xoft Inc.). The stability of the radiochromic films in the energy ranges used was verified by taking measurements at different depths. The stability of the scanner response was tested, and 5 different calibration curves were constructed for different beam qualities. Six pieces of film were placed in each of the 30 patients. All the pieces were correctly sterilized and checked to ensure that the process did not affect the outcome. All calibration and dose measurements were analyzed using the Radiochromic.com software application. RESULTS: The doses were measured for 30 patients. The doses in contact with the applicator (prescription zone) were 19.8 ± 0.9 Gy. In the skin areas, the doses were as follows: 1-2 cm from the applicator, 1.86 ± 0.77 Gy; 2-5 cm, 0.73 ± 0.14 Gy; and greater than 5 cm, 0.28 ± 0.17 Gy. The dose delivered to the pectoral muscle (tungsten shielding disc) was 0.51 ± 0.27 Gy. CONCLUSIONS: The study demonstrated the viability of XR-RV3 films for in vivo dose measurement in the dose and energy ranges applied in a complex procedure, such as breast IORT. The doses in organs at risk were far below the tolerances for cases such as those studied.

Cirugía oncoplástica y radioterapia intraoperatoria en el cáncer de mama / Oncoplastic surgery and intraoperative radiotherapy in breast cancer

Objetivo: Estudio prospectivo de pacientes con cáncer de mama precoz tratadas con cirugía conservadora oncoplástica y radioterapia intraoperatoria con intención de dosis única o monoterapia. Material y método: Veintitrés pacientes intervenidas entre junio de 2016 y agosto de 2018, que han cumplido criterios de administración de radioterapia intraoperatoria establecidos por nuestro comité multidisciplinar de tumores de mama (carcinoma ductal infiltrante<3cm, unifocal, con axila clínica y radiológicamente negativa, receptores hormonales positivos y HER2 negativo) y han sido candidatas a cirugía oncoplástica. Resultados: Tras el estudio anatomopatológico, todas las piezas de resección tenían márgenes libres y 16 pacientes seguían cumpliendo criterios de radioterapia intraoperatoria como monoterapia. En 7 pacientes se precisó administrar radioterapia glandular externa por no cumplir alguno de los criterios. Conclusiones: La cirugía oncoplástica asociada a radioterapia intraoperatoria es una evolución en el tratamiento del cáncer de mama precoz en un importante número de nuestras pacientes. Presenta un alto grado de satisfacción y una menor percepción de la enfermedad por parte de las pacientes

Objective: Prospective study of patients with early breast cancer treated with oncoplastic conservative surgery and intraoperative radiotherapy with single-dose intent or monotherapy. Material and method: We included 23 patients who underwent surgery between June 2016 and August 2018 and who met the criteria for administration of intraoperative radiotherapy established by our multidisciplinary committee of breast tumours (infiltrating ductal carcinoma<3cm, unifocal, with a clinically and radiologically negative axilla, hormone receptor-positive and HER2-negative) and who were candidates for oncoplastic surgery. Results: After pathological study, all the surgical specimens had free margins and 16 patients continued to meet the intraoperative radiotherapy criteria for monotherapy. In 7 patients who did not meet any of the criteria, external glandular radiotherapy was administered. Conclusions: Oncoplastic surgery associated with intraoperative radiotherapy is a development in the treatment of early breast cancer in a significant number of patients. It produces a high degree of satisfaction and a lower disease perception among patients