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1.
Article in Chinese | WPRIM | ID: wpr-888645

ABSTRACT

Dose verification is carried out on the individualized three-dimensional phantom based on 3D printing technology, which simulates the anatomical structure of human body, contour shape, tumor anatomical structure and other dangerous organs to the greatest extent, and produces a reasonable and effective dose validation phantom. According to the need to obtain effective patient data, import Mimics software to reconstruct the parts of the body and its surrounding tissues and organs that need to be measured, and make them into three-dimensional shell components. The 3D printing is used to assemble and fill the equivalent tissue, and then the body phantom is made. The phantom was scanned by CT and the data was transmitted to TPS system. The previously completed treatment plan was transplanted to the phantom. The phantom was placed according to the patient's location information, irradiated and measured data. The three-dimensional shell assembly is completely reconstructed according to the patient's data, and the contour difference is not significant. The shell is filled with tissue radiation equivalent material whose CT value is the same as the average CT value of the shell volume. The CT image data show that the radiation equivalence of the phantom is similar to the actual tissue of the patient, and the equivalent dose distribution conforms to the conventional treatment range. It can provide a reliable means of dose verification for the accurate design of intensity modulated radiation therapy.


Subject(s)
Humans , Phantoms, Imaging , Printing, Three-Dimensional , Radiotherapy Dosage , Radiotherapy Planning, Computer-Assisted , Radiotherapy, Intensity-Modulated
2.
Article in English | WPRIM | ID: wpr-880684

ABSTRACT

OBJECTIVES@#To study the feasibility of ArcCHECK-3DVH system in dosimetric verification for stereotactic body radiaotherapy (SBRT) with flattening filter free (FFF) model.@*METHODS@#SBRT treatment plans for 57 patients were introduced into ArcCHECK phantom and recalculated. The calculated dose distribution of treatment planning system and the measured dose distribution of ArcCHECK phantom were compared by γ analysis. Then the 3 dimensional dose distribution of target and organs at risk was reconstructed by 3DVH software. The reconstructed dose and calculated dose with treatment planning system (TPS) were compared, and the dose volume γ pass rate and deviation of dose volume parameters to the target and organs at risk were quantitatively valuated.@*RESULTS@#Based on the threshold criteria (3%, 3 mm, 10%), namely the deviation of measuring points between the planned value and the measured value was less than 3%, and the proportion of points with similar values in the plane or sphere with the center of the point and the radius of 3 mm was 10%, the relative and absolute dose pass rates of SBRT treatment plans in ArcCHECK system via γ analysis were greater than 95%. Based on the stricter threshold criteria (2%, 2 mm, 10%), the relative and absolute dose pass rates of SBRT treatment plan in ArcCHECK system via γ analysis were about 93%. In 3DVH dose verification, the γ pass rate of target and organs at risk was exceed 97%, and the deviations in 3DVH of the target and organs at risk were less than ±5%.@*CONCLUSIONS@#The ArcCHECK-3DVH system in dose verification can provide more comprehensive dose distribution information to reasonably evaluate the SBRT plan, with more significance for guiding clinical treatment.


Subject(s)
Humans , Phantoms, Imaging , Quality Assurance, Health Care , Radiometry , Radiosurgery , Radiotherapy Dosage , Radiotherapy Planning, Computer-Assisted , Radiotherapy, Intensity-Modulated
3.
Article in Chinese | WPRIM | ID: wpr-880444

ABSTRACT

In order to adapt to different target shapes and protect the surrounding normal tissues, the design of two-dimensional electron beam radiotherapy planning requires additional lead blocks. But the Pinnacle treatment planning system can not directly shape the lead block conformity to the size of the beam field given by the doctor. Every time, physicists need to manually drag the lead block to form the required beam field. When meeting a two-dimensional electron beam treatment planning with the same field parameters as before, physicists need to rearrange the field for dose calculation, which greatly reduces the design efficiency of the two-dimensional electron beam treatment planning. In this study, we independently developed a two-dimensional electron beam radiotherapy planning system based on Qt Creator. The system can quickly design a two-dimensional electron beam radiotherapy plan, which reduces the repeated work of physicists.


Subject(s)
Electrons , Radiotherapy Dosage , Radiotherapy Planning, Computer-Assisted
4.
Article in Chinese | WPRIM | ID: wpr-880435

ABSTRACT

The transportation of electron is inseparable from vacuum environment. The maintenance of the vacuum system of Elekta linear accelerator depends on two sputtering ionic pumps at the gun end and the target end. The traveling wave acceleration were used in Elekta linear accelerators. And the design of the electron gun filament is detachable. Because of these two reasons, the vacuum stability is relatively weak. Only two vacuum values are used to reflect the operation state of the whole vacuum system, which causes a few failures but will not trigger a the machine interlock. Considering the complexity of whole vacuum system, the problem of vacuum caused by the failure of various components in vacuum system is analyzed in this paper. It is hoped that some useful repairing experience and suggestions for the maintenance engineers of linear accelerator to solve the vacuum fault and rebuild the vacuum can be provided quickly.


Subject(s)
Electrons , Particle Accelerators , Radiotherapy Dosage , Vacuum
5.
Article in Chinese | WPRIM | ID: wpr-880434

ABSTRACT

Clinically, beam matching can greatly improve the flexibility and efficiency of treating patients between different medical electron linacs. However, in addition to the regular quality assurance (QA) test of the machine performance of linacs, there is still a lack of comprehensive evaluation of the clinical radiotherapy performance of beam-matched linacs. In this paper, the performance of volumetric modulated arc therapy (VMAT) between three closely matched linacs was evaluated by statistical process control (SPC) technology. It was found that the average and median γ passing rates of the VMAT QA processes of the three linacs had little difference, but the process capability levels were at three different levels. The results show that SPC technology can effectively evaluate the performance of beam matching for medical electron linacs, improve the patient-specific VMAT QA processes, and guide clinical decision-making.


Subject(s)
Electrons , Particle Accelerators , Quality Assurance, Health Care , Radiotherapy Dosage , Radiotherapy Planning, Computer-Assisted , Radiotherapy, Intensity-Modulated
6.
Article in Chinese | WPRIM | ID: wpr-879903

ABSTRACT

OBJECTIVE@#To study the efficacy and safety of intensity-modulated radiotherapy (IMRT) in children with high-risk neuroblastoma (NB).@*METHODS@#A retrospective analysis was performed on the medical data of 24 children with high-risk NB who were diagnosed and treated with IMRT in the Department of Hematology and Oncology, Hunan Provincial People's Hospital, from April 2018 to December 2020. The medical data included age, radiotherapy dose, times of radiotherapy, laboratory examination results, adverse reactions, and survival.@*RESULTS@#All 24 children (14 boys and 10 girls) received IMRT, with a mean age of (65±23) months and a median age of 59 months. The primary tumor was located in the abdomen in 23 children and 1 child had primary tumor in the mediastinum. The median age was 41.5 months at the time of radiotherapy. The radiation dose of radiotherapy ranged from 14.4 to 36.0 Gy, with a mean dose of (22±3) Gy and a daily dose of 1.8-2.0 Gy. The radiotherapy was performed for a total number of 8-20 times, with a mean number of 11.9 times. Among these children, 6 received radiotherapy for the residual or metastatic lesion. Of all the 23 children, 3 experienced cough, 2 experienced diarrhea, and 1 experienced vomiting during radiotherapy. At 2 weeks after radiotherapy, serum creatinine ranged from 2.3 to 70.1 μmol/L and alanine aminotransferase ranged from 9.1 to 65.3 μ/L. Ten children experienced grade Ⅲ bone marrow suppression and 2 experienced grade Ⅳ bone marrow suppression 1 to 2 weeks after radiotherapy. Four children experienced grade Ⅲ bone marrow suppression and 1 experienced grade Ⅳ bone marrow suppression 3 to 4 weeks after radiotherapy. During a median follow-up time of 13.5 months, 23 children (96%) achieved stable disease and 1 died. Up to the follow-up date, second malignant tumor or abnormal organ function was not observed.@*CONCLUSIONS@#IMRT can improve the local control rate of NB. IMRT appears to be safe in the treatment of children with NB.


Subject(s)
Child , Child, Preschool , Female , Humans , Male , Neuroblastoma/radiotherapy , Radiotherapy Dosage , Radiotherapy, Intensity-Modulated/adverse effects , Retrospective Studies
7.
Clinics ; 76: e2769, 2021. tab, graf
Article in English | LILACS | ID: biblio-1278923

ABSTRACT

OBJECTIVES: To explore the effect of tumor and normal lung volumes on lung volume-dose parameters in patients with non-small-cell lung cancer (NSCLC) who had undergone intensity-modulated radiation therapy (IMRT). METHODS: The clinical data of 208 patients with NSCLC who underwent radical IMRT between June 2014 and June 2018 were retrospectively analyzed. A regression model curve was used to evaluate the effect of tumor and normal lung volumes on normal lung relative volumes receiving greater than 5 and 20 Gy (V5, V20), on mean lung dose (MLD), and on absolute volumes spared from greater than 5 and 20 Gy (AVS5, AVS20). RESULTS: The V5, V20, and MLD of the bilateral lung were fitted to a quadratic equation curve with the change in tumor volume, which increased initially and then decreased when the tumor volume increased. The V5, V20, and MLD of the lung reached their apex when the tumor volumes were 288.07, 341.69, and 326.83 cm3, respectively. AVS5 and AVS20 decreased in a logarithmic curve with an increase in tumor volume. The V5, V20, and MLD of the small normal lung volume group were all significantly higher than those of the large normal lung volume group (p<0.001, p=0.004, p=0.002). However, the AVS5 and AVS20 of the small normal lung volume group were all significantly lower than those of the large normal lung volume group (p<0.001). CONCLUSION: The effects of tumor volume and normal lung volume on dose-volume parameters should be considered. AVS5 is an important supplementary dose limitation parameter for patients whose tumor volume exceeds a certain boundary value (approximately 300 cm3).


Subject(s)
Humans , Carcinoma, Non-Small-Cell Lung/radiotherapy , Carcinoma, Non-Small-Cell Lung/diagnostic imaging , Radiotherapy, Intensity-Modulated , Lung Neoplasms/radiotherapy , Lung Neoplasms/diagnostic imaging , Radiotherapy Dosage , Retrospective Studies , Lung/diagnostic imaging , Lung Volume Measurements
8.
Rev. Assoc. Med. Bras. (1992) ; 66(6): 728-731, June 2020.
Article in English | SES-SP, LILACS, SES-SP | ID: biblio-1136289

ABSTRACT

SUMMARY Voluminous tumors represent a challenge in radiation oncology, particularly when surgical resection is not possible. Lattice radiotherapy (LTR) is a technique that may provide equivalent or superior clinical response in the management of large tumors while limiting toxicity to adjacent normal tissues. LRT can precisely deliver inhomogeneous high doses of radiation to different areas within the gross tumor volumes (GTV). The dosimetric characteristic of LTR is defined by the ratio of the valley dose (lower doses - cold spots) and the peak doses, also called vertex (higher doses - hot spots), or the valley-to-peak dose ratio. The valley-to-peak ratio thereby quantifies the degree of spatial fractionation. LRT delivers high doses of radiation without exceeding the tolerance of adjacent critical structures. Radiobiological experiments support the role of radiation-induced bystander effects, vascular alterations, and immunologic interactions in areas subject to low dose radiation. The technological advancements continue to expand in Radiation Oncology, bringing new safety opportunities of treatment for bulky lesions.


RESUMO Tumores volumosos representam um desafio para a radio-oncologia, em especial quando a ressecção cirúrgica não é possível. A radioterapia com técnica Latisse (LTR) pode gerar resposta clínica equivalente ou superior ao tratamento convencional de grandes tumores, limitando a toxicidade nos tecidos normais adjacentes. A LRT pode fornecer com precisão altas doses não homogêneas de radiação em diferentes áreas do volume tumoral (GTV). A característica dosimétrica da LTR é definida pela razão entre a dose na região do vale (doses mais baixas - pontos frios) e as doses de pico, também chamadas de vértice (doses mais altas - pontos quentes) ou a razão da dose vale/pico. Dessa forma, a razão vale/pico quantifica o grau de fracionamento espacial da entrega de dose. A LRT entrega, dessa forma, altas doses de radiação sem exceder a tolerância de estruturas críticas adjacentes. Experimentos radiobiológicos suportam o chamado "efeito espectador" induzido por radiação, o qual promove alterações vasculares e interações imunológicas, levando à resposta tumoral mesmo em áreas expostas a baixas doses de radiação. Os avanços tecnológicos continuam a se expandir na radio-oncologia, trazendo, por meio da LTR, uma nova oportunidade segura de tratamento para lesões volumosas.


Subject(s)
Humans , Radiotherapy , Immunotherapy , Neoplasms/therapy , Radiation Injuries , Radiotherapy Dosage , Radiotherapy Planning, Computer-Assisted , Dose Fractionation, Radiation , Immunomodulation
9.
Article in Chinese | WPRIM | ID: wpr-879211

ABSTRACT

Patient-specific volumetric modulated arc therapy (VMAT) quality assurance (QA) process is an important component of the implementation process of clinical radiotherapy. The tolerance limit and action limit of discrepancies between the calculated dose and the delivered radiation dose are the key parts of the VMAT QA processes as recognized by the AAPM TG-218 report, however, there is no unified standard for these two values among radiotherapy centers. In this study, based on the operational recommendations given in the AAPM TG-218 report, treatment site-specific tolerance limits and action limits of gamma pass rate in VMAT QA processes when using ArcCHECK for dose verification were established by statistical process control (SPC) methodology. The tolerance limit and action limit were calculated based on the first 25 in-control VMAT QA for each site. The individual control charts were drawn to continuously monitor the VMAT QA process with 287 VMAT plans and analyze the causes of VMAT QA out of control. The tolerance limits for brain, head and neck, abdomen and pelvic VMAT QA processes were 94.56%, 94.68%, 94.34%, and 92.97%, respectively, and the action limits were 93.82%, 92.54%, 93.23%, and 90.29%, respectively. Except for pelvic, the tolerance limits for the brain, head and neck, and abdomen were close to the universal tolerance limit of TG-218 (95%), and the action limits for all sites were higher than the universal action limit of TG-218 (90%). The out-of-control VMAT QAs were detected by the individual control chart, including one case of head and neck, two of the abdomen and two of the pelvic site. Four of them were affected by the setup error, and one was affected by the calibration of ArcCHECK. The results show that the SPC methodology can effectively monitor the IMRT/VMAT QA processes. Setting treatment site-specific tolerance limits is helpful to investigate the cause of out-of-control VMAT QA.


Subject(s)
Calibration , Humans , Quality Assurance, Health Care , Radiotherapy Dosage , Radiotherapy Planning, Computer-Assisted , Radiotherapy, Intensity-Modulated
10.
Article in Chinese | WPRIM | ID: wpr-880401

ABSTRACT

Flash radiotherapy is a kind of radiotherapy method using ultra-high dose rate radiation. Compared with the traditional dose rate radiotherapy, it has unique radiobiological advantages. In this paper, the principle of flash radiotherapy, the process and results of biological experiments are summarized. At the same time, the advantages and challenges of flash radiotherapy are analyzed, and the future clinical application is prospected.


Subject(s)
Radiotherapy/methods , Radiotherapy Dosage , Technology
11.
Rev. méd. Urug ; 35(4): 258-266, dic. 2019. tab, fig
Article in Spanish | LILACS | ID: biblio-1026104

ABSTRACT

Introducción: el cáncer de canal anal representa aproximadamente un 2% a 3% de todas las neoplasias digestivas. Nigro describió el tratamiento conservador del cáncer de canal anal utilizando radioterapia y quimioterapia con 5-fluorouracilo (5-FU) y mitomicina C (MMC), desde entonces este tratamiento es estándar. Objetivo: describir la técnica utilizada en nuestro servicio y los resultados en el control locorregional del cáncer de canal anal. Método: descriptivo, longitudinal, retrospectivo. Se analizaron historias de 72 pacientes consecutivos sin exclusiones, portadores de cáncer de canal anal, entre 1988 y 2016. El 67% recibió radioquimioterapia y el 33% de los pacientes radioterapia exclusiva por presentar contraindicaciones médicas específicas y fueron analizados en su conjunto. No se planificaron interrupciones en los tratamientos. Las interrupciones obligatorias fueron de 1 a 17 días con una media de 3 días. Las reacciones agudas fueron moderadas y no se comprobaron complicaciones tardías. Todos recibieron radioterapia locorregional. Resultados: el control local en N0 fue de 86% en T1 y T2 versus 42% en T3 y T4 a seis años, p=0,01 significativo. Conclusiones: la radioterapia con la técnica utilizada en nuestro servicio es efectiva en el tratamiento del cáncer de canal anal. La recidiva local ha sido la causa principal de persistencia lesional o recidiva. La curabilidad de la enfermedad está en relación directa con la extensión clínica/imagenológica de la lesión local.


Introduction: cancer of the anal canal accounts for approximately 2 to 3% of all digestive neoplasms. Nigro described the conservative treatment of cancer of the anal canal using radiation and chemotherapy of 5-fluorouracil (5-FU) and mitomycin-C (MMC). Since then, this is the standard therapy. Objective: to describe the technique used in our service and its results in the locoregional follow up of cancer of the anal canal. Method: descriptive, longitudinal, retrospective. The medical history of 72 consecutive patients with no exclusions, who were carriers of cancer of the anal canal were analysed between 1988 and 2016. 67% underwent radiation and chemotherapy and 33% only radiation therapy due to specific medical contraindications. All cases were comprehensively studied and no interruption of treatments were planned. Mandatory interruptions were from 1 to 17 days long and average length was 3 days. Severe reactions were moderate and no late complications were seen. All patients underwent locoregional radiation therapy. Results: local control in N0 was 86% in T1 and T2 versus 42% in T3 and T4 after 6 years p=0,01 meaningful. Conclusions: radiation therapy with the technique used in our service is effective to treat cancer of the anal canal. Local relapse has been the main cause of lesions or relapse. Curability of the disease is directly linked to the clinical/imaging extent of the local lesion.


Introdução: o câncer de canal anal representa aproximadamente 2 a 3% das neoplasias digestivas. Nigro descreveu o tratamento conservador do câncer de canal anal utilizando radioterapia e quimioterapia com 5-Fluorouracilo (5-FU) e Mitomicina C (MMC) que tem sido o tratamento padrão. Objetivo: descrever a técnica utilizada no nosso serviço e os resultados do controle locorregional do câncer de canal anal. Método: descritivo, longitudinal, retrospectivo. Foram analisados os prontuários de 72 pacientes consecutivos sem exclusões, portadores de câncer de canal anal, do período 1988-2016. 67% receberam radio quimioterapia e 33% radioterapia exclusivamente devido a contraindicações médicas específicas; os resultados foram analisados conjuntamente. Não se planejou interrupções nos tratamentos. As interrupções obrigatórias foram de 1 a 17 dias com uma média de 3 dias. As reações agudas foram moderadas e não se comprovaram complicações tardias. Todos receberam radioterapia locorregional. Resultados: o controle local em N0 foi de 86% em T1 e T2 versus 42% em T3 e T4 a 6 anos p=0,01 significativo. Conclusões: a radioterapia com a técnica utilizada no nosso Serviço é efetiva no tratamento do câncer de canal anal. A recidiva local foi a causa principal de persistência lesional ou recidiva. A curabilidade da enfermidade está diretamente relacionada com a extensão clínica e das imagens da lesão local.


Subject(s)
Humans , Anal Canal , Anus Neoplasms/therapy , Radiotherapy Dosage , Digestive System Neoplasms
12.
Int. braz. j. urol ; 45(6): 1105-1112, Nov.-Dec. 2019. tab, graf
Article in English | LILACS | ID: biblio-1056339

ABSTRACT

ABSTRACT Purpose: To compare the treatment outcomes of a cohort of prostate cancer patients treated with conventional schedule using IMRT or 3DRT technique. Materials and Methods: Between 2010-2017, 485 men with localized prostate cancer were treated with conventional radiotherapy schedule with a total dose ≥74Gy using IMRT (231) or 3DCRT (254). Late gastrointestinal (GI) and genitourinary (GU) toxicity were retrospectively evaluated according to modified RTOG criteria. The biochemical control was defined by the Phoenix criteria (nadir + 2ng/mL). The comparison between the groups included biochemical recurrence free survival (bRFS), overall survival (OS) and late toxicity. Results: With a median follow-up of 51 months (IMRT=49 and 3DRT=51 months), the maximal late GU for >=grade- 2 during the entire period of follow-up was 13.1% in the IMRT and 15.4% in the 3DRT (p=0.85). The maximal late GI ≥ grade- 2 in the IMRT was 10% and in the 3DRT 24% (p=0.0001). The 5-year bRFS for all risk groups with IMRT and 3D-CRT was 87.5% vs. 87.2% (p=0.415). Considering the risk-groups no significant difference for low-, intermediate- and high-risk groups between IMRT (low-95.3%, intermediate-86.2% and high-73%) and 3D-CRT (low-96.4%, intermediate-88.2% and high-76.6%, p=0.448) was observed. No significant differences for OS and DMFS were observed comparing treatment groups. Conclusion: IMRT reduces significantly the risk of late GI severe complication compared with 3D-CRT using conventional fractionation with a total dose ≥74Gy without any differences for bRFS and OS.


Subject(s)
Humans , Male , Aged , Prostatic Neoplasms/radiotherapy , Radiotherapy, Conformal/methods , Radiotherapy, Intensity-Modulated/methods , Prostatic Neoplasms/mortality , Prostatic Neoplasms/pathology , Radiation Injuries , Radiotherapy Dosage , Time Factors , Urogenital System/radiation effects , Retrospective Studies , Risk Factors , Risk Assessment , Disease-Free Survival , Radiotherapy, Conformal/adverse effects , Gastrointestinal Tract/radiation effects , Dose-Response Relationship, Radiation , Radiotherapy, Intensity-Modulated/adverse effects , Kaplan-Meier Estimate , Neoplasm Grading , Middle Aged
13.
Int. braz. j. urol ; 45(2): 237-245, Mar.-Apr. 2019. tab, graf
Article in English | LILACS | ID: biblio-1002192

ABSTRACT

ABSTRACT Objective: To build a model to evaluate the impact of salvage radiotherapy (SRT) in men with PSA rise or persistent PSA after undergoing radical prostatectomy (RP). Materials and Methods: The study included 107 node-negative patients treated with SRT after RP at a single institution. Patients received SRT for either prostate-specific antigen (PSA) rising, or PSA persistence after RP. All patients received local radiation to the prostate / seminal vesicle bed. The primary measured outcome was the biochemical recurrence (BCR) free survival. Multivariable Cox regression analysis was used to develop a risk-stratification group to identify predictive factors associated with the probability of BCR at 5yr. Results: At a median follow-up of 52 months, the BCR free survival rate and overall survival in 5 years was 73% and 94%, respectively. At multivariable analysis, pre-SRT PSA level > 0.35ng / mL (p = 0.023), negative margins (p = 0.038), and seminal vesicles invasion (p = 0.001) were significantly associated with BCR free survival. Three risk groups using regression analysis for SRT administration was built. Low-, intermediate- and the high-risk groups had a BCR free survival in 5-years of 96%, 84%, and 44% (p = 0.0001), respectively. Conclusions: We developed a risk group stratification to show the impact of SRT based on prostate cancer characteristics. SRT showed to be extremely beneficial for patients with low- and intermediate-risk tumors. Moreover, the risk-group built could identify patients classified as high-risk who might benefit from more aggressive treatment for SRT.


Subject(s)
Humans , Male , Aged , Prostatectomy , Prostatic Neoplasms/surgery , Salvage Therapy/adverse effects , Neoplasm Recurrence, Local/radiotherapy , Prostatic Neoplasms/pathology , Prostatic Neoplasms/radiotherapy , Radiotherapy Dosage , Survival Rate , Retrospective Studies , Risk Factors , Follow-Up Studies , Prostate-Specific Antigen/blood , Disease-Free Survival , Early Medical Intervention , Middle Aged , Neoplasm Recurrence, Local/pathology , Neoplasm Staging
14.
J. health med. sci. (Print) ; 5(1): 7-14, Ene-Mar. 2019. ilus, tab
Article in Spanish | LILACS | ID: biblio-1151804

ABSTRACT

En esta investigación se planteó como objetivo la verificación del comportamiento dosimétrico del Sistema de Planificación de Tratamiento (TPS) de Radioterapia mediante las curvas de calibración de Densidades Electrónicas Relativas (DER). Este estudio se realizó en el Hospital de la Sociedad de Lucha Contra el Cáncer (SOLCA) Núcleo Loja, usando un fantoma antropomorfo CIRS 062M y un tomógrafo Toshiba Activion 16. Para determinar la nueva curva de calibración DER se tomaron los valores de densidades electrónicas especificadas en el manual del fantoma y las Unidades Hounsfield de la imagen tomográfica. Se realizó controles de calidad dosimétricos y verificación dosimétrica en tres casos clínicos: tórax, pelvis y cráneo; para realizar las pruebas dosimétricas se utilizó un acelerador CLINAC CX, cámara de ionización PTW tipo Farmer con volumen sensible de 0,6 cm3 y un electrómetro PTW UNIDOS E. Los resultados mostraron que las medidas para cada inserto del fantoma en ningún caso excedieron los límites establecidos de ± 20 UH, para el tomógrafo y el TPS; las pruebas de control de calidad no superaron el límite máximo de desviaciones en el cálculo de dosis absorbida por el TPS y la obtenida por medición de ± 4 % establecida por la IAEA y las verificaciones dosimétricas en tórax, pelvis y cráneo, determinaron que las desviaciones en el cálculo de la dosis absorbida por el TPS y la obtenida por medición no superaban la tolerancia del ± 5 % establecida por la ICRU.


In this research, the aim was to verify the dosimetric behavior of the Radiotherapy Treatment Planning System (TPS) using the Relative Electron Density (DER) calibration curves. This study was carried out at the SOLCA (Society of Fight Against Cancer) hospital in Loja, using an CIRS model 062M anthropomorphic phantom and a Toshiba Activion 16 tomograph. To determine the new DER calibration curve, the values of the electron densities specified in the manual of the phantom and the Hounsfield Units of the tomographic image were taken. Dosimetric quality controls were made in the location of three clinical cases: thorax pelvis and skull; used a CLINAC CX accelerator was used to perform the dosimetric tests, PTW ionization chamber type Farmer with sensitive volume of 0.6 cm3 and a PTW UNIDOS E electrometer. The results showed that the measurements for each insert of the phantom in no case exceeded the established limits of ± 20 UH, for the tomograph and the TPS; the quality control tests did not exceed the maximum limit of deviations in the calculation of dose absorbed by the TPS and the one obtained by measurement of ± 4% established by the IAEA and the clinical planning in the thorax, pelvis and skull, determine that the deviations in the calculation of the dose absorbed by the TPS and that obtained by measurement, they do not exceed the tolerance of ± 5% established by the ICR.


Subject(s)
Radiotherapy, Computer-Assisted/instrumentation , Radiotherapy Planning, Computer-Assisted/methods , Electrons , Radiation Dosage , Radiometry , Radiotherapy Dosage , Bone Density/physiology , Phantoms, Imaging , Ecuador , Cone-Beam Computed Tomography/methods
15.
Radiation Oncology Journal ; : 185-192, 2019.
Article in English | WPRIM | ID: wpr-761011

ABSTRACT

PURPOSE: The effectiveness of thoracic radiation therapy (TRT) in extensive-stage small cell lung cancer (ES-SCLC) patients is increasingly reported, but there is no definite consensus on its application. The aim of this study was to identify factors associated with better outcomes of TRT among patients with ES-SCLC, focusing on whether a higher TRT dose could improve treatment outcome. MATERIALS AND METHODS: The medical records of 85 patients with ES-SCLC who received TRT between January 2008 and June 2017 were retrospectively reviewed. Eligibility criteria were a biological effective dose with α/β = 10 (BED) higher than 30 Gy₁₀ and completion of planned radiotherapy. RESULTS: During a median follow-up of 5.3 months, 68 patients (80.0%) experienced disease progression. In univariate analysis, a BED >50 Gy₁₀ was a significant prognostic factor for overall survival (OS; 40.8% vs. 12.5%, p = 0.006), progression-free survival (PFS; 15.9% vs. 9.6%, p = 0.004), and intrathoracic PFS (IT-PFS; 39.3% vs. 20.5%, p = 0.004) at 1 year. In multivariate analysis, a BED >50 Gy₁₀ remained a significant prognostic factor for OS (hazard ratio [HR] = 0.502; 95% confidence interval [CI], 0.287–0.876; p = 0.015), PFS (HR = 0.453; 95% CI, 0.265–0.773; p = 0.004), and IT-PFS (HR = 0.331; 95% CI, 0.171–0.641; p = 0.001). Response to the last chemotherapy was also associated with better OS in both univariate and multivariate analysis. CONCLUSION: A TRT dose of BED >50 Gy₁₀ may be beneficial for patients with ES-SCLC. Further studies are needed to select patients who will most benefit from high-dose TRT.


Subject(s)
Consensus , Disease Progression , Disease-Free Survival , Drug Therapy , Follow-Up Studies , Humans , Medical Records , Multivariate Analysis , Radiotherapy , Radiotherapy Dosage , Retrospective Studies , Small Cell Lung Carcinoma , Treatment Outcome
16.
Int. braz. j. urol ; 44(1): 114-120, Jan.-Feb. 2018. tab, graf
Article in English | LILACS | ID: biblio-892954

ABSTRACT

ABSTRACT Objectives Report the long-term outcomes of the AMS 800 artificial sphincer (AS) for the treatment post-prostatectomy incontinence (PPI) in a single center in Brazil. Materials and Methods Clinical data from patients who underwent the procedure were retrieved from the medical records of individuals with more than 1 year of follow-up from May 2001 to January 2016. Continence status (number of pads that was used), complications (erosion or extrusion, urethral atrophy, and infection), malfunctions, and need for secondary implantation were evaluated. The relationship between complications and prior or subsequent radiation therapy (RT) was also examined. Results From May 2001 to January 2016, 121 consecutive patients underwent AS implantation for PPI at an oncological referral center in Brazil. At the last visit, the AS remained implanted in 106 patients (87.6%), who reported adequate continence status (maximum of 1 pad/day). Eight-two subjects (67.8%) claimed not to be using pads on a regular basis at the final visit (completely dry). Revision occurred in 24 patients (19.8%). Radiation therapy (RT) for prostate cancer following radical prostatectomy was used in 47 patients before or after AS placement. Twelve patients with a history of RT had urethral erosion compared with 3 men without RT (p=0.004). Conclusion Considering our outcomes, we conclude that AS implantation yields satisfactory results for the treatment of PPI and should remain the standard procedure for these patients. Radiation therapy is a risk factor for complication.


Subject(s)
Humans , Male , Postoperative Complications/therapy , Prostatectomy/adverse effects , Urinary Incontinence/therapy , Urinary Sphincter, Artificial , Prosthesis Implantation/methods , Postoperative Complications/etiology , Radiotherapy Dosage , Urethra/surgery , Urinary Incontinence/etiology , Urodynamics , Brazil , Retrospective Studies , Risk Factors
17.
Article in Chinese | WPRIM | ID: wpr-771470

ABSTRACT

OBJECTIVE@#To compare the accuracy of different methods for image registration in image-guided adaptive brachytherapy (IGABT) for cervical cancer.@*METHODS@#The last treatment planning CT images (CT1) and the first treatment planning CT images (CT2) were acquired from 15 patients with cervical cancer and registered with different match image qualities (retained/removed catheter source in images) and different match regions [target only (S Group)/ interested organ structure (M Group)/body (L Group)] in Velocity3.2 software. The dice similarity coefficient (DSC) between the clinical target volumes (CTV) of the CT1 and CT2 images (CTVCT1 and CTVCT2, respectively) and between the organs-at-risk (OAR) of the two imaging datasets (OARCT1 and OARCT2, respectively) were used to evaluate the image registration accuracy.@*RESULTS@#The auto-segmentation volume of the catheter source using Velocity software based on the CT threshold was the closest to the actual volume within the CT value range of 1700-1800 HU. In the retained group, the DSC for the OARs of was better than or equal to that of the removed group, and the DSC value of the rectum was significantly improved ( < 0.05). For comparison of different match regions, the high-risk target volume (HRCTV) and the low-risk target volume (IRCTV) had the best precision for registration of the target area, which was significantly greater than that of M group and L group ( < 0.05). The M group had better registration accuracy of the target area and the best accuracy for the OARs. The DSC values of the bladder and rectum were significantly better than those of the other two groups ( < 0.05).@*CONCLUSIONS@#The CT value range of 1700-1800 HU is optimal for automatic image segmentation using Velocity software. Automatic segmentation and shielding the volume of the catheter source can improve the image quality. We recommend the use of interested organ structures regions for image registration in image-guided adaptive brachytherapy for cervical cancer.


Subject(s)
Brachytherapy , Methods , Reference Standards , Female , Humans , Organs at Risk , Diagnostic Imaging , Radiotherapy Dosage , Radiotherapy Planning, Computer-Assisted , Methods , Reference Standards , Radiotherapy, Image-Guided , Methods , Reference Standards , Software , Tomography, X-Ray Computed , Methods , Reference Standards , Uterine Cervical Neoplasms , Diagnostic Imaging , Radiotherapy
18.
Article in Chinese | WPRIM | ID: wpr-813183

ABSTRACT

To study the feasibility of ArcCheck verification system in dosimetric verification for stereotactic radiotherapy (SRT) the stereotactic radiotherapy (SRT) with flattening filter free (FFF) model.
 Methods: A total of 76 cases under SRT treatment plans were introduced into ArcCheck phantom and recalculated. Threshold criteria was set as (3%, 3 mm, 10%) or (2%, 2 mm, 10%). The calculated dose distribution and the measured dose distribution of ArcCheck phantom were compared by means of distance to agree (DTA) and Gamma analysis method respectively.
 Results: Based on the threshold criteria (3%, 3 mm, 10%), the relative and absolute mean pass rates of SRT treatment plans by DTA and Gamma analysis were greater than 95%. Based on the threshold criteria (2%, 2 mm, 10%), the relative and absolute mean pass rates of SRT treatment plan by DTA and Gamma analysis were about 90%. The dose pass rate of Gamma analysis method was slightly higher than that of DTA analysis method (P<0.001).
 Conclusion: The ArcCheck verification system is a rapid and accurate method for SRT dose verification, and discrepancies are found in different analysis methods.


Subject(s)
Feasibility Studies , Humans , Phantoms, Imaging , Radiosurgery , Methods , Radiotherapy Dosage , Radiotherapy Planning, Computer-Assisted , Radiotherapy, Intensity-Modulated
19.
Article in English | WPRIM | ID: wpr-741930

ABSTRACT

PURPOSE: To evaluate clinical outcomes according to radiation dose in patients with limited-stage small-cell lung cancer (LS-SCLC) treated with concurrent chemoradiotherapy (CCRT). MATERIALS AND METHODS: From January 2006 to December 2015, 38 patients with LS-SCLC were treated with CCRT with etoposide and cisplatin. Total radiation doses ranged from 45 Gy to 66 Gy (1.8–2 Gy/fraction) and were classified into three groups: 45–54 Gy, 60–63 Gy, and 66 Gy. The impact of radiation dose on survival outcomes were evaluated. Toxicities were evaluated according to the Common Terminology Criteria for Adverse Events version 4.03. RESULTS: The median follow-up period was 21 months. The 2-year overall survival (OS) and local failure-free survival (LFFS) rates were 45.8% and 67.5%, respectively. The 2-year LFFS rates were 33.3% for 45–54 Gy group, 68.6% for 60–63 Gy group, and 87.1% for 66 Gy group (p = 0.014). In multivariate analysis, radiation dose was a significant factor for LFFS (p = 0.015). Although radiation dose was not a significant factor for OS and disease-free survival (DFS) in multivariate analysis, both OS and DFS of 66 Gy group tended to be better than that of 45–63 Gy group in univariate analysis. However, there were no differences in severe toxicities among three groups. CONCLUSION: Higher radiation dose achieved better local control in patients with LS-SCLC treated with CCRT. In addition, a total dose of 66 Gy tended to improve OS and DFS.


Subject(s)
Chemoradiotherapy , Cisplatin , Disease-Free Survival , Etoposide , Follow-Up Studies , Humans , Lung Neoplasms , Lung , Multivariate Analysis , Radiotherapy Dosage , Small Cell Lung Carcinoma
20.
Article in Chinese | WPRIM | ID: wpr-775548

ABSTRACT

This paper introduces the failure phenomenon, failure analysis, maintenance process and method of SIEMENS PRIMUS linear accelerator.


Subject(s)
Particle Accelerators , Radiotherapy Dosage
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