Robustness analysis of surface-guided DIBH left breast radiotherapy: personalized dosimetric effect of real intrafractional motion within the beam gating thresholds.

PURPOSE: The robustness of surface-guided (SG) deep-inspiration breath-hold (DIBH) radiotherapy (RT) for left breast cancer was evaluated by investigating any potential dosimetric effects due to the residual intrafractional motion allowed by the selected beam gating thresholds. The potential reduction of DIBH benefits in terms of organs at risk (OARs) sparing and target coverage was evaluated for conformational (3DCRT) and intensity-modulated radiation therapy (IMRT) techniques. METHODS: A total of 192 fractions of SGRT DIBH left breast 3DCRT treatment for 12 patients were analyzed. For each fraction, the average of the real-time displacement between the isocenter on the daily reference surface and on the live surface ("SGRT shift") during beam-on was evaluated and applied to the original plan isocenter. The dose distribution for the treatment beams with the new isocenter point was then calculated and the total plan dose distribution was obtained by summing the estimated perturbed dose for each fraction. Then, for each patient, the original plan and the perturbed one were compared by means of Wilcoxon test for target coverage and OAR dose-volume histogram (DVH) metrics. A global plan quality score was calculated to assess the overall plan robustness against intrafractional motion of both 3DCRT and IMRT techniques. RESULTS: Target coverage and OAR DVH metrics did not show significant variations between the original and the perturbed plan for the IMRT techniques. 3DCRT plans showed significant variations for the left descending coronary artery (LAD) and the humerus only. However, none of the dose metrics exceeded the mandatory dose constraints for any of the analyzed plans. The global plan quality analysis indicated that both 3DCRT and IMRT techniques were affected by the isocenter shifts in the same way and, generally, the residual isocenter shifts more likely tend to worsen the plan in all cases. CONCLUSION: The DIBH technique proved to be robust against residual intrafractional isocenter shifts allowed by the selected SGRT beam-hold thresholds. Small-volume OARs located near high dose gradients showed significant marginal deteriorations in the perturbed plans with the 3DCRT technique only. Global plan quality was mainly influenced by patient anatomy and treatment beam geometry rather than the technique adopted.

Surface-guided DIBH radiotherapy for left breast cancer: impact of different thresholds on intrafractional motion monitoring and DIBH stability.

PURPOSE: To compare two left breast cancer patient cohorts (tangential vs. locoregional deep-inspiration breath-hold - DIBH treatment) with different predefined beam gating thresholds and to evaluate their impact on motion management and DIBH stability. METHODS: An SGRT-based clinical workflow was adopted for the DIBH treatment. Intrafractional monitoring was performed by tracking both the respiratory signal and the real-time displacement between the isocenter on the daily reference surface and on the live surface ("SGRT shift"). Beam gating tolerances were 5 mm/4 mm for the SGRT shifts and 5 mm/3 mm for the gating window amplitude for breast tangential and breast + lymph nodes locoregional treatments, respectively. A total of 24 patients, 12 treated with a tangential technique and 12 with a locoregional technique, were evaluated for a total number of 684 fractions. Statistical distributions of SGRT shift and respiratory signal for each treatment fraction, for each patient treatment, and for the two population samples were generated. RESULTS: Lateral cumulative distributions of SGRT shifts for both locoregional and tangential samples were consistent with a null shift, whereas longitudinal and vertical ones were slightly negative (mean values < 1 mm). The distribution of the percentage of beam on time with SGRT shift > 3 mm, > 4 mm, or > 5 mm was extended toward higher values for the tangential sample than for the locoregional sample. The variability in the DIBH respiration signal was significantly greater for the tangential sample. CONCLUSION: Different beam gating thresholds for surface-guided DIBH treatment of left breast cancer can impact motion management and DIBH stability by reducing the frequency of the maximum SGRT shift and increasing respiration signal stability when tighter thresholds are adopted.

A benchmark study on 883 nasopharyngeal cancer patients treated in two Italian centres from 1977 to 2000. Part I: Evolving technical choices and survival.

PURPOSE: The authors sought to define treatment results according to the different accrual periods and clinical-therapeutic features in a large series of nasopharyngeal cancer (NPC) patients treated in two Italian centres over more than two decades. MATERIALS AND METHODS: A total of 883 patients consecutively treated with radiotherapy between 1977 and 2000 at the Florence (FLO) and Brescia (IRA) Radiation Oncology centres were studied. Five-year overall (OS) and disease-specific (DSS) actuarial survival rates in the different pathological, clinical and therapeutic subgroups were calculated, along with the actuarial local-regional control (LRC) probability. RESULTS: At univariate analysis, survival and local control rates were significantly better in the more recent accrual periods and in the more favourable disease presentations; treatment-related parameters mainly affect LRC. At multivariate analysis, patient- and disease-related factors had a more evident prognostic effect than did therapeutic factors, although dose to the nasopharynx and treatment technique had a marginally significant impact on DSS and OS. CONCLUSIONS: Results of this benchmark study may be useful for understanding the development of new radio-therapy techniques for NPC, such as three-dimensional conformal radiotherapy (3D-CRT) and particularly intensity-modulated radiotherapy (IMRT).

Uterine sarcoma: twenty-seven years of experience.

PURPOSE: A correlation of treatment for uterine sarcoma with outcome, prognostic importance of pathology, and clinical parameters. PATIENTS AND METHODS: One hundred forty-one patients (median age: 56 years, range: 19-85 years) with a histologically verified uterine sarcoma were identified from a database compiled at the Royal Marsden Hospital and the University of Florence between 1974 and 2001. Seventy-two patients had leiomyosarcoma, 42 had mixed müllerian tumors, 22 had endometrial stromal sarcoma, 1 hemangiopericytoma, 1 rhabdomyosarcoma, and 3 patients had unspecified sarcoma. According to FIGO classification, Stage I, II, III, and IV tumors were identified in 71, 13, 31, and 26 patients, respectively. RESULTS: At the time of analysis, 73.7% of patients were dead, and 26.3% were alive with a median survival of 2 years from initial diagnosis. Univariate analysis for cause-specific survival demonstrated statistical significance for histology (p = 0.02), grade (p = 0.003), stage (p = 0.007), and age (p = 0.02). Multivariate analysis demonstrated significant prognostic values for stage (p = 0.02) and histology (p = 0.05) only. Postoperative radiotherapy with a total dose higher than 50 Gy seems to be significant (p = 0.001) in reducing local recurrence. CONCLUSIONS: Our data favor treatment for Stages I, II, and III of uterine sarcoma with radical surgery plus radical dose irradiation comprising both external beam radiotherapy and brachytherapy.

Hipertensión arterial en población pediátrica de 5 a 10 años / Arterial hypertension in pediatric population from 5 to 10 years old

Se presentan los resultados de un estudio realizado con el objetivo de determinar la prevalencia de hipertensión arterial (HTA) en niños. Se determinó la presión arterial (PA) de 3.296 niños de 5 a 10 de edad, 1.664 varones y 1.632 niñas. Se uniformaron tanto el equipo como los procedimientos para la obtención de las determinaciones. Las medidas de error intra e inter-observador fueron consideradas no significativas (NS). Los criterios para la identificación de niños hipertensos fueron los que figuran en el esquema de diagnóstico propuesto por la Second Taske Force on Blood Pressure Control in Children 1987. Del total de la población estudiada, 519 niños (15,7 por ciento) presentaron una o más factores de riesgo de HTA, estos fueron excluidos para la confección de las tablas. Con los 2.777 restantes se elaboraron curvas de presión sistólica para las edades de 5 a 10 con el objeto de comparar su comportamiento con las de referencia. Se universalizó la muestra calculando los errores estándar para los perceptiles 90. No hubo diferencias significativas. Intervalo de Confianza (IC): 95 por ciento en los perceptiles 90 de las curvas para ambos sexos a las edades estudiadas