RESUMO
Since radiotherapy is widely used in cancer treatment, it is essential to develop strategies which lower the irradiation burden while increasing efficacy and become efficient even in radio resistant tumors. Our new strategy is relying on the development of solid hybrid nanoparticles based on rare-earth such as gadolinium. In this paper, we then evidenced that gadolinium-based particles can be designed to enter efficiently into the human glioblastoma cell line U87 in quantities that can be tuned by modifying the incubation conditions. These sub-5 nm particles consist in a core of gadolinium oxide, a shell of polysiloxane and are functionalized by diethylenetriaminepentaacetic acid (DTPA). Although photoelectric effect is maximal in the [10-100 keV] range, such particles were found to possess efficient in-vitro radiosensitizing properties at an energy of 660 keV by using the "single-cell gel electrophoresis comet assay," an assay that measures the number of DNA damage that occurs during irradiation. Even more interesting, the particles have been evidenced by MTT assays to be also efficient radiosensitizers at an energy of 6 MeV for doses comprised between 2 and 8 Gy. The properties of the gadolinium-based particles give promising opening to a particle-assisted radio-therapy by using irradiation systems already installed in the majority of hospitals.
Assuntos
Neoplasias Encefálicas/patologia , Gadolínio , Glioblastoma/patologia , Nanopartículas , Radiossensibilizantes , Neoplasias Encefálicas/genética , Linhagem Celular Tumoral , Ensaio Cometa , Dano ao DNA , Glioblastoma/genética , Humanos , Técnicas In VitroRESUMO
Indications, doses and techniques of conformal radiotherapy for anal canal cancers are presented. The recommendations for delineation of the target volumes and organs at risk are detailed.
Assuntos
Neoplasias do Ânus/radioterapia , Braquiterapia/métodos , Radioterapia Conformacional/métodos , Neoplasias do Ânus/tratamento farmacológico , Neoplasias do Ânus/cirurgia , Braquiterapia/efeitos adversos , Braquiterapia/normas , Quimiorradioterapia , Terapia Combinada , Fracionamento da Dose de Radiação , Humanos , Irradiação Linfática , Metástase Linfática , Órgãos em Risco , Lesões por Radiação/prevenção & controle , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Radioterapia Adjuvante/métodos , Radioterapia Conformacional/efeitos adversos , Radioterapia Conformacional/normas , Radioterapia Guiada por Imagem/métodosRESUMO
Indications, doses and techniques of conformal radiotherapy for rectal carcinoma are presented. The recommendations for delineation of the target volumes and organs at risk are detailed.
Assuntos
Carcinoma/radioterapia , Radioterapia Conformacional/métodos , Neoplasias Retais/radioterapia , Carcinoma/cirurgia , Terapia Combinada , Fracionamento da Dose de Radiação , Humanos , Irradiação Linfática , Metástase Linfática , Órgãos em Risco , Lesões por Radiação/prevenção & controle , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Radioterapia Adjuvante/métodos , Radioterapia Conformacional/efeitos adversos , Radioterapia Conformacional/normas , Radioterapia Guiada por Imagem/métodos , Neoplasias Retais/cirurgiaRESUMO
PURPOSE: The purpose of this work was to implement a simple dosimetric alert tool in a retrospective study for six patients suffering from head and neck cancer to detect when a patient might require an adaptive radiotherapy. MATERIALS AND METHODS: The dosimetric tool generates a 3D cartography of two dosimetric complementary information: a dose variation tolerance map and a dose differential map. The tolerance map is calculated on the initial scanner (CTinit) using the planned dose distribution. It shows for each voxel of each delineated volume the availability for local dose variations during the course of radiotherapy without exceeding the dose threshold. The differential dose map is generated on the tomographic image CBCT (CBCTtreatment). It shows dose variations between the planned and the actual delivered dose distribution for each voxel. By comparing both maps, when a voxel presents a value superior to the corresponding dose variation tolerance, an alert is generated and the anatomical areas concerned are visually indicated to the physician. RESULTS: The application of the dosimetric tool on six patients with head and neck cancers reveals the ability of the tool to detect cases requiring a new treatment plan. Two patients whose the tumour shrinkage produced an increase of the delivered dose to the spinal cord beyond 45 Gy have been detected. CONCLUSION: The development of the dosimetric tool allows the automatic detection, with no delineation needs, of patients suffering from head and neck cancers requiring an adaptive strategy.
Assuntos
Neoplasias de Cabeça e Pescoço/radioterapia , Planejamento da Radioterapia Assistida por Computador , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias Otorrinolaringológicas/radioterapia , Seleção de Pacientes , Estudos RetrospectivosRESUMO
PURPOSE: Intensity-modulated radiotherapy (IMRT) has proven its dosimetric superiority over conformational radiotherapy for cervix cancers in terms of digestive toxicity. Volumetric modulated arctherapy (VMAT) has shown its dosimetric interest when compared to IMRT with static beams. The purpose of our study was to compare conformational radiotherapy, VMAT and tomotherapy for cervical cancers with para-aortic lymph nodes irradiation. PATIENTS AND METHODS: The dosimetric data from ten patients were compared between the three techniques, with collection of the dose received by the planning target volume, kidneys, bowel, rectum, bladder, bone marrow and spinal cord, as well as the complete dose. RESULTS: There was a significant difference in favour of VMAT and tomotherapy when compared with conformational radiotherapy for the organs at risk: intestines (V(20 Gy), V(30 Gy) and V(45 Gy)), rectum (V(30 Gy) and V(45 Gy)), bladder (V(30 Gy) and V(45 Gy)) and kidneys (V(12 Gy), Daverage, V(20 Gy)). Volumes receiving 20, 30 and 45 Gy were significantly higher in conformational radiotherapy than in VMAT and tomotherapy. There was a significant difference in favour of tomotherapy when compared with VMAT for V(12 Gy) in kidneys and V(45 Gy) in the bladder. CONCLUSION: This study confirms the interest of VMAT and tomotherapy for pelvic and para-aortic lymph nodes irradiation of cervix cancer when compared with conformational radiotherapy. There was little difference between VMAT and tomotherapy, except for kidney sparing, which was better with tomotherapy and thus may be interesting for patients receiving nephrotoxic chemotherapy.
Assuntos
Doses de Radiação , Radioterapia de Intensidade Modulada/métodos , Neoplasias do Colo do Útero/radioterapia , Aorta Abdominal , Feminino , HumanosRESUMO
BACKGROUND AND PURPOSE: To compare the accuracy of the Block Matching deformable registration (DIR) against rigid image registration (RIR) for head-and-neck multi-modal images CT to cone-beam CT (CBCT) registration. MATERIAL AND METHODS: Planning-CT and weekly CBCT of 10 patients were used for this study. Several volumes, including medullary canal (MC), thyroid cartilage (TC), hyoid bone (HB) and submandibular gland (SMG) were transposed from CT to CBCT images using either DIR or RIR. Transposed volumes were compared with the manual delineation of these volumes on every CBCT. The parameters of similarity used for analysis were: Dice Similarity Index (DSI), 95%-Hausdorff Distance (95%-HD) and difference of volumes (cc). RESULTS: With DIR, the major mean difference of volumes was -1.4 cc for MC, revealing limited under-segmentation. DIR limited variability of DSI and 95%-HD. It significantly improved DSI for TC and HB and 95%-HD for all structures but SMG. With DIR, mean 95%-HD (mm) was 3.01 ± 0.80, 5.33 ± 2.51, 4.99 ± 1.69, 3.07 ± 1.31 for MC, TC, HB and SMG, respectively. With RIR, it was 3.92 ± 1.86, 6.94 ± 3.98, 6.44 ± 3.37 and 3.41 ± 2.25, respectively. CONCLUSION: Block Matching is a valid algorithm for deformable multi-modal CT to CBCT registration. Values of 95%-HD are useful for ongoing development of its application to the cumulative dose calculation.
Assuntos
Algoritmos , Tomografia Computadorizada de Feixe Cônico/métodos , Neoplasias de Cabeça e Pescoço/diagnóstico por imagem , Neoplasias de Cabeça e Pescoço/radioterapia , Processamento de Imagem Assistida por Computador/métodos , Humanos , Variações Dependentes do Observador , Planejamento da Radioterapia Assistida por ComputadorRESUMO
PURPOSE: To compare the dosimetric results of different techniques of dynamic intensity modulated radiation therapy (IMRT) in patients treated for a pelvic cancer with nodal irradiation. PATIENTS AND METHODS: Data of 51 patients included prospectively in the Artpelvis study were analyzed. Thirty-six patients were treated for a high-risk prostate cancer (13 with helical tomotherapy, and 23 with Rapid'Arc(®)) and 15 patients were treated for a localized anal cancer (nine with helical tomotherapy and six with Rapid'Arc(®)). Plan quality was assessed according to several different dosimetric indexes of coverage of planning target volume and sparing of organs at risk. RESULTS: Although some dosimetric differences were statistically significant, helical tomotherapy and Rapid'Arc provided very similar and highly conformal plans. Regarding organs at risk, Rapid'Arc(®) provided better pelvic bone sparing with a lower non-tumoral integral dose. CONCLUSION: In pelvis cancer with nodal irradiation, Rapid'Arc and helical tomotherapy provided very similar plans. The clinical evaluation of Artpelvis study will verify this equivalence hypothesis.
Assuntos
Neoplasias do Ânus/radioterapia , Neoplasias da Próstata/radioterapia , Radioterapia de Intensidade Modulada , Humanos , Linfonodos/efeitos da radiação , Masculino , Modelos Estatísticos , Tratamentos com Preservação do Órgão , Órgãos em Risco , Estudos Prospectivos , Dosagem RadioterapêuticaRESUMO
Onboard volumetric imaging systems can provide accurate data of the patient's anatomy during a course of head and neck radiotherapy making it possible to assess the actual delivered dose and to evaluate the dosimetric impact of complex daily positioning variations and gradual anatomic changes such as geometric variations of tumors and normal tissues or shrinkage of external contours. Adaptive radiotherapy is defined as the correction of a patient's treatment planning to adapt for individual variations observed during treatment. Strategies are developed to selectively identify patients that require replanning because of an intolerable dosimetric drift. Automated tools are designed to limit time consumption. Deformable image registration algorithms are the cornerstones of these strategies, but a better understanding of their limits of validity is required before adaptive radiotherapy can be safely introduced to daily practice. Moreover, strict evaluation of the clinical benefits is yet to be proven.
Assuntos
Neoplasias de Cabeça e Pescoço/radioterapia , Radioterapia de Intensidade Modulada/métodos , Algoritmos , Tomografia Computadorizada de Feixe Cônico , Relação Dose-Resposta a Droga , Humanos , Posicionamento do Paciente , Radiometria , Radioterapia Guiada por ImagemRESUMO
PURPOSE: Concurrent radiochemotherapy is the standard treatment for locally advanced cervical cancer. This treatment is responsible for bowel and hematologic toxicities. The use of intensity-modulated radiotherapy (IMRT), in static beams, allows a decrease of this toxicity. The technique of RapidArc(®) IMRT could lower the dose delivered to the organs at risk and improve the homogeneity of the planning target volume coverage, while decreasing the processing time. PATIENTS AND MATERIALS: For 20 patients, treatment plans performed with IMRT and RapidArc(®) were compared. The target volumes were: the clinical target volume (gross tumour volume, uterus, upper third of the vagina, the hypogastric, iliac and presacral nodal regions), and the planning target volume (clinical target volume+1cm). The delineated organs at risk were: rectum, bladder, bowel and bone marrow. The dose was 45 Gy in 25 fractions. IMRT were delivered with five beams and RapidArc(®) with two arcs. The comparisons were made by the non-parametric test of Wilcoxon. RESULTS: Medium coverage of the planning target volume was better with RapidArc(®) (P=0.01). It was also better regarding the sparing of bowel (P=0.01) and IMRT was better regarding the sparing of bladder (P=0.01) and rectum (P=0.05). The total volume receiving 20 Gy was less important with RapidArc(®) (P<0.001). RapidArc(®) allowed to decrease the treatment time (3 versus 12 minutes with IMRT) and the number of monitor units (MU) (376.5 versus 962.2, on average, P=0.0001). CONCLUSION: The technique of RapidArc(®) seems to obtain better dosimetric results compared to RCMI, with fewer MU, and a significant decrease in treatment time.
Assuntos
Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Intensidade Modulada/métodos , Neoplasias do Colo do Útero/radioterapia , Medula Óssea/diagnóstico por imagem , Feminino , Humanos , Intestinos/diagnóstico por imagem , Órgãos em Risco/diagnóstico por imagem , Posicionamento do Paciente , Radiografia , Dosagem Radioterapêutica , Reto/diagnóstico por imagem , Fatores de Tempo , Carga Tumoral , Bexiga Urinária/diagnóstico por imagem , Neoplasias do Colo do Útero/tratamento farmacológico , Neoplasias do Colo do Útero/patologia , Útero/patologiaRESUMO
Anal canal carcinoma are highly curable by irradiation, combined with chemotherapy in locally advanced disease, with preservation of sphincter function. The clinical target volume for the nodes is extended, often including the inguinal nodes, which is not usual for other pelvic tumours. Acute and late effects are correlated with the volume and dose delivered to organs at risk, i. e. small bowel, bladder and increased by concomitant chemotherapy. Intensity modulated irradiation (IMRT) makes it possible to optimize the dose distribution in this "complex U shaped" volume, while maintaining the dose distribution for the target volumes. The conversion from conformal irradiation to IMRT necessitates good knowledge of the definition and skills to delineate target volumes and organs at risk, including new volumes needed to optimize the dose distribution. Dosimetric and clinical benefits of IMRT are described, based on early descriptions and evidence-based publication. The growing development of IMRT in anal canal radiotherapy must be encouraged, and long-term benefits should be soon published. Radiation oncologists should precisely learn IMRT recommendations before starting the technique, and evaluate its early and late results for adverse effects, but also for long-term tumour control.
Assuntos
Neoplasias do Ânus/radioterapia , Carcinoma/radioterapia , Radioterapia de Intensidade Modulada , Antineoplásicos/uso terapêutico , Neoplasias do Ânus/tratamento farmacológico , Carcinoma/tratamento farmacológico , Ensaios Clínicos como Assunto , Terapia Combinada , Humanos , Estudos Multicêntricos como Assunto , Órgãos em Risco , Guias de Prática Clínica como Assunto , Estudos Prospectivos , Radioterapia Conformacional , Radioterapia de Intensidade Modulada/métodos , Estudos RetrospectivosRESUMO
PURPOSE: The first purpose of this study was to illustrate the contribution of statistical process control for a better security in intensity modulated radiotherapy (IMRT) treatments. This improvement is possible by controlling the dose delivery process, characterized by pretreatment quality control results. So, it is necessary to put under control portal dosimetry measurements (currently, the ionisation chamber measurements were already monitored by statistical process control thanks to statistical process control tools). The second objective was to state whether it is possible to substitute ionisation chamber with portal dosimetry in order to optimize time devoted to pretreatment quality control. PATIENTS AND METHODS: At Alexis-Vautrin center, pretreatment quality controls in IMRT for prostate and head and neck treatments were performed for each beam of each patient. These controls were made with an ionisation chamber, which is the reference detector for the absolute dose measurement, and with portal dosimetry for the verification of dose distribution. Statistical process control is a statistical analysis method, coming from industry, used to control and improve the studied process quality. It uses graphic tools as control maps to follow-up process, warning the operator in case of failure, and quantitative tools to evaluate the process toward its ability to respect guidelines: this is the capability study. The study was performed on 450 head and neck beams and on 100 prostate beams. RESULTS: Control charts, showing drifts, both slow and weak, and also both strong and fast, of mean and standard deviation have been established and have shown special cause introduced (manual shift of the leaf gap of the multileaf collimator). Correlation between dose measured at one point, given with the EPID and the ionisation chamber has been evaluated at more than 97% and disagreement cases between the two measurements were identified. CONCLUSION: The study allowed to demonstrate the feasibility to reduce the time devoted to pretreatment controls, by substituting the ionisation chamber's measurements with those performed with EPID, and also that a statistical process control monitoring of data brought security guarantee.