RESUMEN
OBJECTIVE: To design a new afterloading brachytherapy simulation system based on CT images. METHODS: This paper mainly focuses on the anthropomorphic pelvic phantom spiled by three pipelines and the nasopharyngeal carcinoma spiled by two pipelines. Microsoft Visual C++ was used to parse CT images for some information, then to reconstruct pipelines in the body of phantom or the patient and to give the three-dimensional coordinate of dwelling points. The dose distribution displayed on CT images was processed by the dose distribution calculation methods near single afterloading source and the dose optimization methods. VTK technology was used in the 3D display in the system. RESULTS: According to the reference points applied by doctors, the system can calculate reversely the dwelling time of dwelling points in pipelines and get satisfying dose distribution on CT images. Besides, it can reflect the 3D relationship between the dose volume and the normal tissues. CONCLUSIONS: This system overcomes some deficiencies of 2D afterloading brachytherapy simulation system based on X-ray films which are used widely in China. It supplies 3D display of dose distribution for clinical doctors. At present, the system is being tested in clinics.
Asunto(s)
Braquiterapia/métodos , Simulación por Computador , Imagenología Tridimensional , Tomografía Computarizada por Rayos X , Programas InformáticosRESUMEN
In nasopharyngeal cancer (NPC) intracavitary brachytherapy, an anatomical dose reference point (in line with that for gynecology work), e.g., at the sphenoid floor, is more precise than the empirical point of 1 cm from the source. However, such increases of the single-source-plan treatment distances may deliver excessive doses inferiorly, to the soft palate. As shielding may help, its efficacy was studied by Monte Carlo simulations in water for 20 and 30 mm diameter spherical NP applicators (representing extremes of sizes for the small NP cavity), with/without lead shielding inferiorly, using a single linear Ir-192, 2 mm steps, equal dwell times for 5 (5DP) and 9 dwell positions (9DP). Dose reductions of the selected points of interest ranged from 1.2% to 40.5% for the 20 mm shielded applicator and a range of 2.9% to 17.9%, for the 30 mm shielded applicator. Dose volume histograms of the "region of interest" (ROI)-a cuboid of 4 x 4 x 0.5 cm3 at the most inferior aspect of the applicator, also differed significantly. The highest doses of the 50% (D50) and 20% (D20) volumes of ROI (for 5DP and 9DP plans) were reduced by 11.9% to 17.9% for the 20 mm applicator and a range of 9.0% to 11.5% for the 30 mm shielded applicator. Doses in unshielded directions were insignificantly changed, for example, with a 20 mm applicator simulated in a 5DP plan, the dose distribution close to the source in the unshielded direction has less than 4% difference at the 50% isodose relative to the dose prescription point. For the 30 mm shielded applicator, despite smaller dose reduction percentages, a more pronounced effective dose reduction was obtained than nominal values when considering radiobiological equivalent doses. Our system was demonstrated to be ready for clinical assessment.
Asunto(s)
Braquiterapia/métodos , Método de Montecarlo , Neoplasias Nasofaríngeas/radioterapia , Protección Radiológica/métodos , Radiometría/métodos , Braquiterapia/instrumentación , Radioisótopos de Iridio/uso terapéutico , Fantasmas de Imagen , Protección Radiológica/instrumentación , Radiometría/instrumentación , Dosificación Radioterapéutica , Planificación de la Radioterapia Asistida por Computador , Medición de Riesgo , Agua/químicaRESUMEN
Toxicity, response, and long-term results of a definitive chemotherapy/radiation therapy (RT) protocol in patients with unresectable stage III non-small-cell lung cancer (NSCLC) were evaluated. Two cycles of cisplatin-based chemotherapy were delivered before RT, and another 2 cycles were added for patients who responded to the first 2 cycles of chemotherapy. The first course of radiation covered the primary lesion and elective nodal regions, given in 2 Gy per fraction, 5 days a week for a dose of 40 Gy. Late-course hyperfractionated accelerated RT was delivered to the gross tumor twice a day for an additional 27 Gy within 2 weeks, using 1.5 Gy per fraction. Fifty-three patients with unresectable stage IIIA (N2) and IIIB NSCLC were eligible for analysis. Twelve patients developed grade 3 neutropenia, and 3 patients developed grade 4 neutropenia. Grade 2 or 3 esophagitis was observed in 14 and 2 patients, respectively, and grade 2 or 3 pneumonitis was observed in 9 and 1 patient, respectively. Six patients developed grade 2 and 1 patient developed grade 3 late lung toxicity. The median survival time was 15.5 months. Twenty-six of 53 patients (49%) have died of locoregional progression inside the thorax. The distant metastasis rate was 59.5% (22 of 37 patients) for those who did not respond to chemotherapy and 18.8% (3 of 16 patients) for those who responded to chemotherapy (P = 0.006). Late-course hyperfractionated accelerated RT combined with induction chemotherapy was well tolerated and yielded long-term results that compare favorably with those of studies using 2 cycles of induction chemotherapy and conventional fractionated RT. However, local control was still discouraging.
Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Carcinoma de Pulmón de Células no Pequeñas/tratamiento farmacológico , Carcinoma de Pulmón de Células no Pequeñas/radioterapia , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/radioterapia , Adulto , Anciano , Carcinoma de Pulmón de Células no Pequeñas/mortalidad , Carcinoma de Pulmón de Células no Pequeñas/patología , Fraccionamiento de la Dosis de Radiación , Femenino , Humanos , Neoplasias Pulmonares/mortalidad , Neoplasias Pulmonares/patología , Masculino , Persona de Mediana Edad , Terapia Neoadyuvante , Estadificación de Neoplasias , Análisis de Supervivencia , Resultado del TratamientoRESUMEN
BACKGROUND & OBJECTIVE: It has been reported that ataxia- telangiectasia mutant(ATM) protein is closely correlated with cellular radiosensitivity in several malignant tumors. This study was designed to determine the expression of ATM protein in two nasopharyngeal carcinoma (NPC) cell lines with different radiosensitivity. METHODS: Two NPC cell lines, CNE1 and CNE2, with different radiosensitivity were established. The localization and quantity of ATM protein were analyzed by fluorescence immunohistochemical method and laser scanning confocal microscope(LSCM). RESULTS: ATM protein was located in both karyon and cytoplasm, especially strongly expressed in karyon. The intense fluorescence of ATM protein was stronger in karyon of CNE1 than that in CNE2. CONCLUSION: The expression levels of ATM protein differ in CNE1 and CNE2. The variance may be a potential factor, which links with their different radiosensitivity.