Surface-guided radiation therapy for breast cancer: more precise positioning

Introduction Hypofractionated radiation therapy for breast cancer requires highly precise delivery through the use of image-guided radiotherapy (IGRT). Surface-guided radiation therapy (SGRT) is being increasingly used for patient positioning in breast radiotherapy. We aimed to assess the role of SGRT for verification of breast radiotherapy and the tumour bed. Materials and method Prospective study of 252 patients with early stage breast cancer. A total of 1170 determinations of daily positioning were performed. Breast surface positioning was determined with SGRT (AlignRT) and correlated with the surgical clips in the tumour bed, verified by IGRT (ExacTrac). Results SGRT improved surface matching by a mean of 5.3 points compared to conventional skin markers (98.0 vs. 92.7), a statistically significant difference (p < 0.01, Wilcoxon Test). For surface matching values > 95%, ≥ 3 clips coincided in 99.7% of the determinations and all markers coincided in 92.5%. For surface matching rates > 90%, the location of ≥ 3 clips coincided in 99.55% of determinations. Conclusions SGRT improves patient positioning accuracy compared to skin markers. Optimal breast SGRT can accurately verify the localisation of the tumour bed, ensuring matching with ≥ 3 surgical clips. SGRT can eliminate unwanted radiation from IGRT verification systems (AU)

Surface-guided radiation therapy for breast cancer: more precise positioning.

INTRODUCTION: Hypofractionated radiation therapy for breast cancer requires highly precise delivery through the use of image-guided radiotherapy (IGRT). Surface-guided radiation therapy (SGRT) is being increasingly used for patient positioning in breast radiotherapy. We aimed to assess the role of SGRT for verification of breast radiotherapy and the tumour bed. MATERIALS AND METHODS: Prospective study of 252 patients with early stage breast cancer. A total of 1170 determinations of daily positioning were performed. Breast surface positioning was determined with SGRT (AlignRT) and correlated with the surgical clips in the tumour bed, verified by IGRT (ExacTrac). RESULTS: SGRT improved surface matching by a mean of 5.3 points compared to conventional skin markers (98.0 vs. 92.7), a statistically significant difference (p < 0.01, Wilcoxon Test). For surface matching values > 95%, ≥ 3 clips coincided in 99.7% of the determinations and all markers coincided in 92.5%. For surface matching rates > 90%, the location of ≥ 3 clips coincided in 99.55% of determinations. CONCLUSIONS: SGRT improves patient positioning accuracy compared to skin markers. Optimal breast SGRT can accurately verify the localisation of the tumour bed, ensuring matching with ≥ 3 surgical clips. SGRT can eliminate unwanted radiation from IGRT verification systems.

Failure modes and effects analysis of total skin electron irradiation technique

Purpose. Total skin electron irradiation (TSEI) is a radiotherapy technique which consists of an homogeneous body surface irradiation by electrons. This treatment requires very strict technical and dosimetric conditions, requiring the implementation of multiple controls. Recently, the Task Group 100 report of the AAPM has recommended adapting the quality assurance program of the facility to the risks of their processes. Materials and methods. A multidisciplinary team evaluated the potential failure modes (FMs) of every process step, regardless of the management tools applied in the installation. For every FM, occurrence (O), severity (S) and detectability (D) by consensus was evaluated, which resulted in the risk priority number (RPN), which permitted the ranking of the FMs. Subsequently, all the management tools used, related to the TSEI process, were examined and the FMs were reevaluated, to analyze the effectiveness of these tools and to propose new management tools to cover the greater risk FMs. Results. 361 FMs were identified, 103 of which had RPN ≥80, initially, and 41 had S ≥ 8. Taking this into account the quality management tools FMs were reevaluated and only 30 FMs had RPN ≥80. The study of these 30 FMs emphasized that the FMs that involved greater risk were related to the diffuser screen placement and the patient’s position during treatment. Conclusions. The quality assurance program of the facility has been adapted to the risk of this treatment process, following the guidelines proposed by the TG-100. However, clinical experience continually reveals new FMs, so the need for periodic risk analysis is required (AU)

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Failure modes and effects analysis of total skin electron irradiation technique.

PURPOSE: Total skin electron irradiation (TSEI) is a radiotherapy technique which consists of an homogeneous body surface irradiation by electrons. This treatment requires very strict technical and dosimetric conditions, requiring the implementation of multiple controls. Recently, the Task Group 100 report of the AAPM has recommended adapting the quality assurance program of the facility to the risks of their processes. MATERIALS AND METHODS: A multidisciplinary team evaluated the potential failure modes (FMs) of every process step, regardless of the management tools applied in the installation. For every FM, occurrence (O), severity (S) and detectability (D) by consensus was evaluated, which resulted in the risk priority number (RPN), which permitted the ranking of the FMs. Subsequently, all the management tools used, related to the TSEI process, were examined and the FMs were reevaluated, to analyze the effectiveness of these tools and to propose new management tools to cover the greater risk FMs. RESULTS: 361 FMs were identified, 103 of which had RPN ≥80, initially, and 41 had S ≥ 8. Taking this into account the quality management tools FMs were reevaluated and only 30 FMs had RPN ≥80. The study of these 30 FMs emphasized that the FMs that involved greater risk were related to the diffuser screen placement and the patient's position during treatment. CONCLUSIONS: The quality assurance program of the facility has been adapted to the risk of this treatment process, following the guidelines proposed by the TG-100. However, clinical experience continually reveals new FMs, so the need for periodic risk analysis is required.

Looking for complementary alternatives to CTCAE for skin toxicity in radiotherapy: quantitative determinations

INTRODUCTION: Radiotherapy (RT) is an essential part of the patient's treatment diagnosed with cancer. Determination of the most common RT secondary effect, the cutaneous toxicity, is usually based on visual rating scales, like Common Terminology Criteria for Adverse Events with an inherent subjectivity. The aim of this work is to perform an objective method to evaluate the radiodermatitis using a non-invasive imaging technique based on laser Doppler flowmetry (LDF). MATERIALS AND METHODS: A prospective study was performed analysing 1,824 measurements. A LDF was used to measure the cutaneous microcirculation in real time. A basal measurement was taken prior to radiotherapy treatment. To be able to observe the microcirculation changes related to the delivered dose, several sets of measurements were taken in the irradiated area along the RT treatment and in the contralateral non-irradiated area. RESULTS: A relative increase in blood flow at all measured points was found in the irradiated area. This relative increase in blood flow increases with the dose administered. In the non-irradiated contralateral area, the relative increase in blood flow is not significant and is independent of the dose administered. After treatment, a decrease in blood flow was detected with a trend towards returning to the baseline measurements. CONCLUSIONS: LDF is an objective technique that assesses early radiodermatitis. This method is useful to develop strategies to prevent onset of radiation dermatitis in patients irradiated, such as the modification and individualization of fractionation parameters of the RT. This allows the reduction of radiation morbidities and maintains patient quality of life (AU)

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Looking for complementary alternatives to CTCAE for skin toxicity in radiotherapy: quantitative determinations.

INTRODUCTION: Radiotherapy (RT) is an essential part of the patient's treatment diagnosed with cancer. Determination of the most common RT secondary effect, the cutaneous toxicity, is usually based on visual rating scales, like Common Terminology Criteria for Adverse Events with an inherent subjectivity. The aim of this work is to perform an objective method to evaluate the radiodermatitis using a non-invasive imaging technique based on laser Doppler flowmetry (LDF). MATERIALS AND METHODS: A prospective study was performed analysing 1,824 measurements. A LDF was used to measure the cutaneous microcirculation in real time. A basal measurement was taken prior to radiotherapy treatment. To be able to observe the microcirculation changes related to the delivered dose, several sets of measurements were taken in the irradiated area along the RT treatment and in the contralateral non-irradiated area. RESULTS: A relative increase in blood flow at all measured points was found in the irradiated area. This relative increase in blood flow increases with the dose administered. In the non-irradiated contralateral area, the relative increase in blood flow is not significant and is independent of the dose administered. After treatment, a decrease in blood flow was detected with a trend towards returning to the baseline measurements. CONCLUSIONS: LDF is an objective technique that assesses early radiodermatitis. This method is useful to develop strategies to prevent onset of radiation dermatitis in patients irradiated, such as the modification and individualization of fractionation parameters of the RT. This allows the reduction of radiation morbidities and maintains patient quality of life.

Tumor bed segmentation: first step for partial breast irradiation

INTRODUCTION: In breast IMRT simultaneous integrated boost (SIB) treatment and accelerated partial breast irradiation (APBI), proper delineation of the tumor bed is necessary. Conservative oncoplastic surgery causes changes in peritumoral breast tissue that complicates locating the site of the tumor. Nevertheless, there are still centers that do not use surgical clips to delineate the site. This study aims to show how the lack of clips affects the techniques of SIB and APBI in terms of dose distribution and safety margins in the tumor bed. MATERIALS AND METHODS: On 30 patients, the defining of the tumor bed obtained from the pre-surgery CT scan to that outlined on the basis of clips on the post-surgery CT was compared. Tumor bed deviation from the original tumor site was quantified. In addition, the margins to the original tumor site necessary to guarantee the coverage of the tumor bed were calculated. RESULTS: Variations were detected in the distances between geometric centers of the PTV (minimum 0.5-maximum 3 cm). The maximum margin necessary to include the entire tumor bed was 4.5 cm. Lesions located in the upper outer quadrant required the widest margins. If margins are not added, the tumor bed volume defined with clips will be underdosed. CONCLUSIONS: The definition of the tumor bed based on studies before surgery does not have the necessary accuracy. Clips need to be placed in the surgical bed to identify the changes occurring after the restorative mammoplasty. Without clips, SIB and APBI are not safe (AU)

[Incidence of pulmonary scintigraphic changes in women irradiated for breast cancer]. / Incidencia de alteraciones gammagráficas pulmonares en mujeres irradiadas por cáncer de mama.

OBJECTIVE: To determine the incidence of respiratory function changes on quantified ventilation-perfusion scintigraphy produced by breast cancer radiation therapy and its correlation with irradiated lung volume. MATERIAL AND METHODS: Prospective study on 43 patients with breast cancer who received adjuvant radiotherapy. Quantified ventilation-perfusion scintigraphy was carried out before and after radiotherapy (3 and 9 months). The differences of ventilation and perfusion were calculated subtracting the irradiated lung values from the contralateral lung values, and their correlations with the irradiated lung volume were analyzed. RESULTS: The scintigraphic parameter means of the irradiated lung were significantly lower than those of the contralateral lung, after radiotherapy. The incidence of patients with a total perfusion and ventilation decrease over 10 % was 21 %, except for the three-month ventilation, which was 23 %. The total ventilation difference was significantly correlated with the lung volume, presenting decreases over 10 % for volumes of 100 cm3 or more. All patients remained asymptomatic. CONCLUSIONS: The pulmonary scintigraphy changes derived from the breast cancer radiotherapy produced no clinical symptomatology. Regarding scintigraphy, ventilation decreases when the irradiated lung volume increases, so a follow-up of these patients' pulmonary function should be performed when the lung volume irradiation cannot be lower than 100 cm3.

Incidencia de alteraciones gammagráficas pulmonares en mujeresirradiadas por cáncer de mama / Incidence of pulmonary scintigraphic changes in women irradiated for breast cancer

Objetivo: Determinar, mediante gammagrafía de ventilación y perfusión cuantificada, la incidencia de alteraciones en la función respiratoria producidas por la irradiación en el cáncer de mama, y su correlación con el volumen de pulmón irradiado.Material y métodos: Estudio prospectivo de 43 pacientes con cáncer de mama sometidas a radioterapia complementaria. Se practicó gammagrafía pulmonar de ventilación y perfusión cuantificada antes y después de la radioterapia (a los 3 y 9 meses). Las diferencias de perfusión y ventilación se calcularon restando a los valores obtenidos para el pulmón irradiado los valores del pulmón contralateral y se estudió su relación con el volumen pulmonar irradiado.Resultados: Las medias de los parámetros gammagráficos del pulmón irradiado fueron inferiores a las del pulmón contralateral, de forma significativa, después de la radioterapia. La incidencia de pacientes con descenso de perfusión y ventilación global superiores al 10 por ciento fue 21 por ciento, excepto para la ventilación a los 3 meses, que fue 23 por ciento. La diferencia de ventilación global se correlacionó de forma significativa con el volumen pulmonar, apreciándose descensos superiores al 10 por ciento a partir de 100 cm3.Todas las pacientes permanecieron asintomáticas.Conclusiones: Los cambios gammagráficos de ventilación y perfusión derivados de la irradiación pulmonar no produjeron sintomatología clínica alguna. Gammagráficamente, la ventilación desciende con el incremento del volumen pulmonar irradiado, siendo recomendable llevar a cabo un seguimiento de la función pulmonar de estas pacientes cuando no sea factible la irradiación de un volumen de pulmón inferior a 100 cm3. (AU)