RESUMO
PURPOSE: To evaluate the impact of different machines on plan quality using both intensity modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) techniques. MATERIALS AND METHODS: Eight patients with squamous cell carcinoma of the oropharynx were selected at random. Plans were computed for IMRT and VMAT Smart Arc, using Pinnacle TPS for an Elekta (IMRT-E, VMAT-E) and Varian linac (IMRT-V, VMAT-V). A three-dose level prescription was used to deliver 70, 63 and 58.1 Gy to regions of macroscopic, microscopic high- and low-risk disease, respectively. All doses were given in 35 fractions. Comparisons were performed on dose-volume histogram data, monitor units (MU), and delivery time. RESULTS: VMAT-E plans resulted slightly MU efficient (-24 % p < 0.05) compared to VMAT-V while IMRT-V shortened delivery time (-19 % p < 0.05) compared to IMRT-E. All the delivery techniques resulted in equivalent target coverage in terms of D(98) % and D(2) %. For VMAT technique, a significant improvement of 7 % in homogeneity index (HI) for PTV58.1 was observed for Varian machine. A slight improvement in OARs sparing was observed with Elekta machine both for IMRT and VMAT techniques. CONCLUSION: Similar plan quality was observed for Elekta and Varian linacs, significant differences were observed in delivery efficiency, as MU number and delivery times, in favor of Elekta and Varian, respectively.
Assuntos
Aceleradores de Partículas/normas , Planejamento da Radioterapia Assistida por Computador/instrumentação , Planejamento da Radioterapia Assistida por Computador/normas , Radioterapia de Intensidade Modulada/instrumentação , Radioterapia de Intensidade Modulada/normas , Carcinoma de Células Escamosas/radioterapia , Desenho de Equipamento , Humanos , Tratamentos com Preservação do Órgão , Órgãos em Risco , Neoplasias Orofaríngeas/radioterapia , Controle de Qualidade , Dosagem Radioterapêutica , Radioterapia Guiada por Imagem/instrumentação , Radioterapia Guiada por Imagem/normasRESUMO
INTRODUCTION: To evaluate the delivery accuracy of dynamic (DMLC) and static (SMLC) intensity modulated radiation therapy (IMRT) techniques using portal dosimetry (PD) in Varian Eclipse Treatment Planning System. MATERIALS AND METHODS: Seven DMLC IMRT Head and Neck plans were retrospectively generated for the study using SMLC mode at 20, 10 and 5 levels of intensity (SMLC20, SMLC10, SMLC5). Dosimetric verifications performed by PD on a total of 107 fields were evaluated using the gamma index (maximum (γmax), average (γavg), percentage of points with (γ%) ≤ 1). The images were acquired at a source-detector distance of 100 cm at gantry zero degree and also at clinically planned gantry angles. RESULTS: For both modes, measurements are within acceptable criteria. (γ%) ≤ 1 improves by increasing SMLC levels (+3.4 % from SMLC5 to SMLC20, p < 0.001) and using DMLC (+3.9 % and +0.6 % compared to SMLC5 and SMLC20, respectively, p < 0.001). Also (γmax) parameter improves significantly by increasing SMLC levels (+22 % from SMLC5 to SMLC20) and using DMLC (+34 % and +16 % compared to SMLC5 and SMLC20, respectively). The effect of the gantry rotation influences the delivery accuracy by up to -7 % (p < 0.05). The effect of leaves travelling direction was almost negligible (1 %). CONCLUSIONS: A good agreement between calculated and measured fluences was obtained for DMLC and SMLC techniques at higher intensity levels; however, DMLC delivery ensures the best reproduction of computed fluence maps. The gantry rotation influences the delivery accuracy in particular for SMLC modes at lower intensity levels.
Assuntos
Radiometria/métodos , Planejamento da Radioterapia Assistida por Computador , Radioterapia Guiada por Imagem , Radioterapia de Intensidade Modulada , Humanos , Órgãos em Risco , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/instrumentação , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia Guiada por Imagem/instrumentação , Radioterapia Guiada por Imagem/métodos , Radioterapia Guiada por Imagem/normas , Radioterapia de Intensidade Modulada/instrumentação , Radioterapia de Intensidade Modulada/métodos , Estudos Retrospectivos , Sensibilidade e EspecificidadeRESUMO
PURPOSE: The major uncertainties in treating lung cancer are the repositioning errors and respiratory lung tumor motion. Typically, margins are added to the clinical target volume (CTV) to obtain a planning target volume (PTV) allowing the accommodation of such uncertainties. We want to test a new technique to assess the adequacy of the chosen PTV using an aSi electronic portal imaging device (EPID). METHODS: Four patients affected by lung cancer and treated by radical 3D conformal radiotherapy (3DRT) were studied. During treatment the EPID was used in cine mode acquisition: acquired images were used to the aim. RESULTS AND CONCLUSIONS: Treatment monitoring with an EPID in cine mode is shown to be a clinically feasible and useful tool.
Assuntos
Neoplasias Pulmonares/radioterapia , Radioterapia Conformacional , Fracionamento da Dose de Radiação , Feminino , Humanos , Neoplasias Pulmonares/patologia , Masculino , Pessoa de Meia-Idade , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por ComputadorRESUMO
PURPOSE: To correlate comorbidity and acute radiation toxicity in elderly patients treated with adjuvant external beam radiotherapy (EBRT) plus brachytherapy-high dose rate (HDR-BRT) for endometrial cancer (EC). METHODS: Endometrial cancer patients over 65 were treated and evaluated for comorbidity assessment with ACE-27 and Charlson comorbidity index (CCI). EBRT total dose was 45-50.4 Gy (1.8 Gy/day). The vault vagina boost of dose was performed by HDR-BRT with 2/3 fractions with a total dose of 10-15 Gy. RESULTS: From 2008 to 2011, 35 patients were analyzed. Eighteen patients (51.43 %) had not ACE-27 comorbidity; while 27 patients (77.14 %) had CCI lower than three. During treatment, acute toxicity was mild and not influenced by the comorbidity score. Two-year Progression Free and Overall Survival were 69 and 80 %. ACE-27 and CCI did not affect progression-free survival (p = 0.51, p = 0.3) and OS (p = 0.26, p = 0.5). CONCLUSION: External beam radiotherapy plus BRT-HDR are well tolerated in EC elderly with good performance status and low comorbidity profile.
Assuntos
Braquiterapia/efeitos adversos , Neoplasias do Endométrio/radioterapia , Radioterapia Adjuvante/efeitos adversos , Idoso , Idoso de 80 Anos ou mais , Comorbidade , Neoplasias do Endométrio/epidemiologia , Feminino , Humanos , Estudos RetrospectivosRESUMO
PURPOSE: To evaluate the dosimetric changes of parotid glands (PG) during a course of intensity-modulated radiotherapy (IMRT) in head and neck (H&N) cancer patients. METHODS: Ten patients with H&N cancer treated by IMRT were analyzed. The original treatment plan (CT(plan)) was transferred to cone-beam computed tomography (CBCT) acquired at the 15th and 20th treatment day (CBCT(plan) I and II, respectively). The PG mean dose (D(mean)), the dose to 50 % of the volume, and the percent of volume receiving 30 and 50 Gy were measured by the dose volume histogram. RESULTS: 30 IMRT plans were evaluated (3 plans/patient). All dosimetric end points increased significantly for both PG only when CT(plan) was compared to CBCT(plan) I. The D(mean) increased significantly only for ipsilateral PG (p = 0.02) at week 3. CONCLUSION: During a course of IMRT, CBCT is a feasible method to check the PG dosimetric variations. Perhaps, the 3rd week of radiotherapy could be considered as the time-check-point.