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1.
Lung Cancer (Auckl) ; 15: 149-159, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-39494146

RESUMEN

Purpose: Small-cell lung cancer (SCLC) accounts for approximately 10-15% of all lung cancers and is characterized by a high recurrence rate, early metastasis, and poor prognosis. Before the FDA approved lurbinectedin for SCLC that progressed on or after platinum-based chemotherapy in 2020, topotecan was the sole second-line option associated with hematological toxicities and modest efficacy. Lurbinectedin received conditional approval in Korea in September 2022 for metastatic SCLC progression, with the same indications. Real-world data on its efficacy remains scarce owing to its recent implementation. Patients and Methods: Patients with metastatic SCLC who progressed on or after first-line therapy (n = 51) at Yonsei Cancer Center, Seoul, received lurbinectedin at 3.2 mg/m². Efficacy data, including tumor response, progression, survival, and demographics, were recorded. Results: A total of fifty-one patients received lurbinectedin between April 2023 and March 2024, with thirty-four patients being eligible for the assessment. At diagnosis, approximately one-third of the patients were female, 3% had a poor performance status with an Eastern Cooperative Oncology Group Performance Score (ECOG PS ≥ 2), and the median age was 68. Most patients (80%) had extensive disease. Overall objective response rate (ORR) and disease control rate (DCR) were 20% and 47%, respectively. The median progression-free survival (PFS) was 2.8 months, and the median overall survival (OS) was 3.3 months. Never smokers showed prolonged OS compared with current/former smokers (Smokers; 3.0 vs 7.3 months). Common adverse effects were nausea (53%), loss of appetite (24%), general weakness (18%), anemia (29%), neutropenia (12%), dizziness (6%), alopecia (6%), thrombocytopenia (3%), and pneumonia (3%). Overall, 24% of the patients experienced grade ≥3 adverse events (AEs), with the most common being anemia (9%) and neutropenia (9%). Conclusion: Real-world data suggest that lurbinectedin is a viable option for patients with SCLC who have progressed on or after platinum-based chemotherapy.

2.
ACS Sens ; 8(7): 2533-2542, 2023 07 28.
Artículo en Inglés | MEDLINE | ID: mdl-37335579

RESUMEN

This manuscript proposes a new dual-mode cell imaging system for studying the relationships between calcium dynamics and the contractility process of cardiomyocytes derived from human-induced pluripotent stem cells. Practically, this dual-mode cell imaging system provides simultaneously both live cell calcium imaging and quantitative phase imaging based on digital holographic microscopy. Specifically, thanks to the development of a robust automated image analysis, simultaneous measurements of both intracellular calcium, a key player of excitation-contraction coupling, and the quantitative phase image-derived dry mass redistribution, reflecting the effective contractility, namely, the contraction and relaxation processes, were achieved. Practically, the relationships between calcium dynamics and the contraction-relaxation kinetics were investigated in particular through the application of two drugs─namely, isoprenaline and E-4031─known to act precisely on calcium dynamics. Specifically, this new dual-mode cell imaging system enabled us to establish that calcium regulation can be divided into two phases, an early phase influencing the occurrence of the relaxation process followed by a late phase, which although not having a significant influence on the relaxation process affects significantly the beat frequency. In combination with cutting-edge technologies allowing the generation of human stem cell-derived cardiomyocytes, this dual-mode cell monitoring approach therefore represents a very promising technique, particularly in the fields of drug discovery and personalized medicine, to identify compounds likely to act more selectively on specific steps that compose the cardiomyocyte contractility.


Asunto(s)
Calcio , Células Madre Pluripotentes Inducidas , Humanos , Miocitos Cardíacos , Cinética , Isoproterenol/farmacología
3.
Biomed Opt Express ; 12(11): 7064-7081, 2021 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-34858700

RESUMEN

Digital holography can provide quantitative phase images related to the morphology and content of biological samples. After the numerical image reconstruction, the phase values are limited between -π and π; thus, discontinuity may occur due to the modulo 2π operation. We propose a new deep learning model that can automatically reconstruct unwrapped focused-phase images by combining digital holography and a Pix2Pix generative adversarial network (GAN) for image-to-image translation. Compared with numerical phase unwrapping methods, the proposed GAN model overcomes the difficulty of accurate phase unwrapping due to abrupt phase changes and can perform phase unwrapping at a twice faster rate. We show that the proposed model can generalize well to different types of cell images and has high performance compared to recent U-net models. The proposed method can be useful in observing the morphology and movement of biological cells in real-time applications.

4.
Opt Express ; 28(18): 26284-26301, 2020 Aug 31.
Artículo en Inglés | MEDLINE | ID: mdl-32906903

RESUMEN

This paper shows that deep learning can eliminate the superimposed twin-image noise in phase images of Gabor holographic setup. This is achieved by the conditional generative adversarial model (C-GAN), trained by input-output pairs of noisy phase images obtained from synthetic Gabor holography and the corresponding quantitative noise-free contrast-phase image obtained by the off-axis digital holography. To train the model, Gabor holograms are generated from digital off-axis holograms with spatial shifting of the real image and twin image in the frequency domain and then adding them with the DC term in the spatial domain. Finally, the digital propagation of the Gabor hologram with Fresnel approximation generates a super-imposed phase image for the C-GAN model input. Two models were trained: a human red blood cell model and an elliptical cancer cell model. Following the training, several quantitative analyses were conducted on the bio-chemical properties and similarity between actual noise-free phase images and the model output. Surprisingly, it is discovered that our model can recover other elliptical cell lines that were not observed during the training. Additionally, some misalignments can also be compensated with the trained model. Particularly, if the reconstruction distance is somewhat incorrect, this model can still retrieve in-focus images.

5.
Opt Express ; 27(16): 22147-22160, 2019 Aug 05.
Artículo en Inglés | MEDLINE | ID: mdl-31510508

RESUMEN

Recent developments in 3D computational optical imaging such as digital holographic microscopy has ushered in a new era for biological research. Therefore, efficient and secure storage and retrieval of digital holograms is a challenging task for future cloud computing services. In this study, we propose a novel scheme to securely store and retrieve multiple encrypted digital holograms by using phase encoding multiplexing. In the proposed schemes, an encrypted hologram can only be accessed using a binary phase mask, which is the key to retrieve the image. In addition, it is possible to independently store, retrieve, and manage the encrypted digital holograms without affecting other groups of the encrypted holograms multiplexed using different sets of binary phase masks, due to the orthogonality properties of the Hadamard matrices with high autocorrelation and low cross-correlation. The desired encrypted holograms may also be searched for, removed, and added independently of other groups of the encrypted holograms. More and more 3D images or digital holograms can be securely and efficiently stored, retrieved, and managed.

6.
Clin Exp Nephrol ; 23(2): 223-230, 2019 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-30168048

RESUMEN

OBJECTIVES: We investigated whether low serum C3 level can cross-sectionally estimate severe antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) in immunosuppressive drug-naïve patients at diagnosis. METHODS: We retrospectively reviewed the medical records of 139 patients with AAV, who were first classified as AAV at Severance Hospital. We obtained clinical and laboratory data including serum complement 3 (C3) level and calculated Birmingham vasculitis activity score (BVAS) at diagnosis. We stratified AAV patients into three groups according to the tertile of BVAS and defined the lower limit of the highest tertile as the cutoff for severe AAV (BVAS at diagnosis ≥ 16) at diagnosis. Low serum C3 level was defined as C3 < 90 mg/dL. The odds ratio (OR) was assessed using the multivariable logistic regression. RESULTS: The mean age at diagnosis was 56.3 years and 41 patients were men (29.5%). The mean initial BVAS was 12.8. The mean serum C3 and C4 levels were 110.6 and 26.8 mg/dL. Thirty-one patients (22.3%) exhibited low serum C3 level at diagnosis. In the multivariable analysis, serum C3 level at diagnosis < 90 mg/dL (OR 2.963) exhibited the significant association with severe AAV at diagnosis. Patients with low serum C3 level exhibited a significantly high relative risk (RR) for severe AAV at diagnosis compared to those without (RR 3.600). Patients with low serum C3 level at diagnosis exhibited poor renal prognosis than those without. CONCLUSION: Low serum C3 level can estimate severe AAV and predict poor renal outcome in immunosuppressive drug-naïve patients at diagnosis.


Asunto(s)
Vasculitis Asociada a Anticuerpos Citoplasmáticos Antineutrófilos/sangre , Complemento C3/análisis , Adulto , Anciano , Vasculitis Asociada a Anticuerpos Citoplasmáticos Antineutrófilos/diagnóstico , Vasculitis Asociada a Anticuerpos Citoplasmáticos Antineutrófilos/inmunología , Biomarcadores/sangre , Estudios Transversales , Regulación hacia Abajo , Femenino , Humanos , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Pronóstico , Estudios Retrospectivos , Seúl , Índice de Severidad de la Enfermedad
7.
Nephrology (Carlton) ; 24(7): 711-717, 2019 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-30203901

RESUMEN

OBJECTIVES: We investigated whether systemic immune-inflammation index (SII) at diagnosis can estimate the cross-sectional high activity and predict the poor outcomes in immunosuppressive drug-naïve patients with antineutrophil cytoplasmic antibody-associated vasculitis (AAV). METHODS: We retrospectively reviewed the medical records of 163 patients with AAV and obtained clinical and laboratory data. We calculated Birmingham vasculitis activity score (BVAS) as well as five-factor score (FFS) (2009) at diagnosis. SII at diagnosis was calculated by the equation of (SII at diagnosis = platelet count × neutrophil count/lymphocyte count at diagnosis). Severe AAV was defined as BVAS at diagnosis ≥16. The odds ratio was assessed using the multivariable logistic regression analysis and cumulative survival rates were compared by the Kaplan-Meier survival analysis. RESULTS: The median age at diagnosis was 58.0 years old and 51 patients were men. The median BVAS was 12.0. Fifty-seven patients had severe AAV. The median SII at diagnosis was 1349.6. In the multivariable analysis, only SII exhibited a significant odds ratio for the cross-sectional severe AAV (P = 0.043). We obtained the cut-off of SII at diagnosis for severe AAV as 1573.56. Patients with SII at diagnosis ≥1573.56 exhibited a significantly high relative risk of the cross-sectional severe AAV compared to those without (relative risk 4.625). Furthermore, patients with SII at diagnosis ≥1573.56 exhibited significantly the lower cumulative relapse free and renal survivals than those without. CONCLUSION: Systemic immune-inflammation index at diagnosis could estimate the cross-section severe AAV and predict the poor outcomes in AAV patients.


Asunto(s)
Vasculitis Asociada a Anticuerpos Citoplasmáticos Antineutrófilos/tratamiento farmacológico , Inmunosupresores/uso terapéutico , Inflamación/inmunología , Adulto , Anciano , Anciano de 80 o más Años , Vasculitis Asociada a Anticuerpos Citoplasmáticos Antineutrófilos/inmunología , Vasculitis Asociada a Anticuerpos Citoplasmáticos Antineutrófilos/mortalidad , Estudios Transversales , Femenino , Humanos , Fallo Renal Crónico/etiología , Modelos Logísticos , Masculino , Persona de Mediana Edad , Pronóstico , Estudios Retrospectivos
8.
Nanoscale Res Lett ; 9(1): 191, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-24940170

RESUMEN

In this study, the properties of blue organic light-emitting diodes (OLEDs), employing quantum well-like structure (QWS) that includes four different blue emissive materials of 4,4'-bis(2,2'-diphenylyinyl)-1,1'-biphenyl (DPVBi), 9,10-di(naphth-2-yl)anthracene (ADN), 2-(N,N-diphenyl-amino)-6-[4-(N,N-diphenyl amine)styryl]naphthalene (DPASN), and bis(2-methyl-8-quinolinolate)-4-(phenyl phenolato) aluminum (BAlq), were investigated. Conventional QWS blue OLEDs composed of multiple emissive layers and charge blocking layer with lower highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy level, and devices with triple emissive layers for more significant hole-electron recombination and a wider region for exciton generation were designed. The properties of triple emissive layered blue OLEDs with the structure of indium tin oxide (ITO) /N,N'-diphenyl-N,N'-bis(1-naphthyl-phenyl)-(1,1'-biphenyl)-4,4'-diamine (NPB) (700 Ǻ)/X (100 Ǻ)/BAlq (100 Ǻ)/X (100 Ǻ)/4,7-diphenyl-1,10-phenanthroline (Bphen) (300 Ǻ)/lithium quinolate (Liq) (20 Ǻ)/aluminum (Al) (1,200 Ǻ) (X = DPVBi, ADN, DPASN) were examined. HOMO-LUMO energy levels of DPVBi, ADN, DPASN, and BAlq are 2.8 to 5.9, 2.6 to 5.6, 2.3 to 5.2, and 2.9 to 5.9 eV, respectively. The OLEDs with DPASN/BAlq/DPASN QWS with maximum luminous efficiency of 5.32 cd/A was achieved at 3.5 V.

9.
J Nanosci Nanotechnol ; 13(1): 294-9, 2013 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-23646729

RESUMEN

High efficiency blue organic light emitting diodes (OLEDs), based on 2-me-thyl-9,10-di(2-naphthyl) anthracene (MADN) doped with 4,4'-bis(9-ethyl-3-carbazovinylene)-1,1'-biphenyl (BCzVBi), were fabricated using two different electron transport layers (ETLs) of tris(8-hydroxyquinolino)-aluminum (Alq3) and 4,7-di-phenyl-1,10-phenanthroline (Bphen). Bphen ETL layers favored the efficient hole-electron recombination in the emissive layer of the BCzVBi-doped blue OLEDs, leading to high luminous efficiency and quantum efficiency of 8.34 cd/A at 100 mA/cm2 and 5.73% at 100 cd/m2, respectively. Maximum luminance of blue OLED with Bphen ETL and Alq3 ETL were 10670 cd/m2, and CIExy coordinates of blue OLEDs were (0.180, 0279) and (0.155, 0.212) at 100 cd/m2.


Asunto(s)
Iluminación/instrumentación , Semiconductores , Color , Transporte de Electrón , Diseño de Equipo , Análisis de Falla de Equipo , Fluorescencia
10.
Radiat Prot Dosimetry ; 153(1): 92-9, 2013 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-22772453

RESUMEN

With the introduction of digital radiography, patients undergoing radiographic procedures are subject to being overexposed to radiation. Therefore, it is necessary to estimate the absorbed organ dose and the effective dose, which are significant for patient health, along with body type. During chest radiographic examinations conducted in 899 patients for screening, the absorbed dose of the 13 major organs, the average whole-body dose, and two effective doses weighted by factors published in ICRP 60 and ICRP 103 were calculated on the basis of patient information such as height, weight and examination condition, including kilovolt potential, focus-skin distance and entrance surface dose (ESD), using a PC-based Monte Carlo program simulation. It was found that dose per unit ESD had a tendency to decrease with body mass index (BMI). In particular, the absorbed dose for most organs was larger at high voltages (140 kVp) than at low voltages (120 kVp, 100 kVp). In addition, the effective dose which was based on ICRP 60 and ICRP 103 also represented the same tendency in respect of BMI and tube voltage.


Asunto(s)
Carga Corporal (Radioterapia) , Índice de Masa Corporal , Método de Montecarlo , Fantasmas de Imagen , Dosis de Radiación , Intensificación de Imagen Radiográfica , Humanos , Radiometría
11.
Opt Lett ; 37(24): 5235-7, 2012 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-23258063

RESUMEN

High contrast blue organic light-emitting diodes were fabricated using an inorganic multilayer of NPB (700 Å)/MADN (200 Å)/Alq3 (300 Å)/LiF (10 Å)/Al (70 Å)/ZnSe (300 Å)/Al (1000 Å). The optical and electrical characteristics were measured and compared to conventional organic light-emitting devices (OLEDs) and OLEDs with polarizers. OLEDs with the metal multilayer cathodes had an improved contrast ratio of 135∶1 compared to 104∶1 for OLEDs with polarizers. In addition, the multilayer OLEDs had a low turn-on voltage of 3.5 V due to energy band fitting of ZnSe with Al and the electron transport layer.

12.
J Radiat Res ; 53(6): 978-88, 2012 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-22915778

RESUMEN

A bio-anatomical quality assurance (QA) method employing tumor control probability (TCP) and normal tissue complication probability (NTCP) is described that can integrate radiobiological effects into intensity-modulated radiation therapy (IMRT). We evaluated the variations in the radiobiological effects caused by random errors (r-errors) and systematic errors (s-errors) by evaluating TCP and NTCP in two groups: patients with an intact prostate (G(intact)) and those who have undergone prostatectomy (G(tectomy)). The r-errors were generated using an isocenter shift of ±1 mm to simulate a misaligned patient set-up. The s-errors were generated using individual leaves that were displaced inwardly and outwardly by 1 mm on multileaf collimator field files. Subvolume-based TCP and NTCP were visualized on computed tomography (CT) images to determine the radiobiological effects on the principal structures. The bio-anatomical QA using the TCP and NTCP maps differentiated the critical radiobiological effects on specific volumes, particularly at the anterior rectal walls and planning target volumes. The s-errors showed a TCP variation of -40-25% in G(tectomy) and -30-10% in G(intact), while the r-errors were less than 1.5% in both groups. The r-errors for the rectum and bladder showed higher NTCP variations at ±20% and ±10%, respectively, and the s-errors were greater than ±65% for both. This bio-anatomical method, as a patient-specific IMRT QA, can provide distinct indications of clinically significant radiobiological effects beyond the minimization of probable physical dose errors in phantoms.


Asunto(s)
Modelos Biológicos , Neoplasias de la Próstata/radioterapia , Garantía de la Calidad de Atención de Salud/métodos , Radiometría/normas , Planificación de la Radioterapia Asistida por Computador/normas , Radioterapia Conformacional/normas , Simulación por Computador , Humanos , Masculino , Dosificación Radioterapéutica , Reproducibilidad de los Resultados , República de Corea , Sensibilidad y Especificidad
13.
Radiat Prot Dosimetry ; 150(4): 523-31, 2012 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-22147923

RESUMEN

In this study, diagnostic reference levels (DRLs) were suggested and patient doses were analysed through the dose-area product value in dental radiography. In intraoral radiography, at three sites, i.e. molar, premolar and incisor on the maxilla and acquired third quartile values: 55.5, 46 and 36.5 mGy cm(2), respectively, were measured. In panoramic, cephalometric and cone beam computed tomography, the values were 120.3, 146 and 3203 mGy cm(2) (16 × 18 cm), respectively. It has been shown that, in intraoral radiography, the patient dose changes proportionally to the value of mA s, but the change in extraoral radiography in response to mA s could not be confirmed. The authors could confirm, however, the difference in dose according to the manufacturer in all dental radiography examinations, except for panoramic radiography. Depending on the size of hospital, there were some differences in patient dose in intraoral radiography, but no difference in patient dose in extraoral radiography.


Asunto(s)
Carga Corporal (Radioterapia) , Dosis de Radiación , Monitoreo de Radiación/estadística & datos numéricos , Radiografía Dental/estadística & datos numéricos , Adulto , Humanos , Masculino , Valores de Referencia , República de Corea/epidemiología
14.
Radiat Prot Dosimetry ; 148(4): 431-8, 2012 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-21525041

RESUMEN

The O-arm system has recently been introduced and has the capability of combined two-dimensional (2-D) fluoroscopy imaging and three-dimensional computed tomography imaging. In this study, an orthopaedic surgical procedure using C-arm and O-arm systems in their 2-D fluoroscopy modes was simulated and the radiation doses to susceptible organs to which operators can be exposed were investigated. The experiments were performed in four configurations of the location of the X-ray source and detector. Shielding effects on the thyroid surface and the direct exposure delivered to the surgeon's hands were also compared. The results obtained show that the O-arm delivered higher doses to the sensitive organs of the operator in all configurations. The thyroid shield cut-off 89 % of the dose in the posteroanterior configuration of both imaging systems. Thus, the operators need to pay more attention to managing radiation exposure, especially when using the O-arm system.


Asunto(s)
Fluoroscopía/instrumentación , Fluoroscopía/métodos , Exposición Profesional , Ortopedia/métodos , Protección Radiológica/instrumentación , Radiometría/instrumentación , Antropometría/métodos , Diseño de Equipo , Humanos , Fantasmas de Imagen , Dosis de Radiación , Protección Radiológica/métodos , Radiometría/métodos , Dispersión de Radiación , Programas Informáticos , Glándula Tiroides/metabolismo , Rayos X
15.
Radiat Prot Dosimetry ; 148(1): 58-64, 2012 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-21335329

RESUMEN

Recently, simulations based on the Monte Carlo code have been increasingly applied for physics phenomena, patient dose and quality assurance of radiation systems. The objective of this study was to use Monte Carlo simulation and measurement to verify dose and dose reduction in cephalography. The collimator was constructed with 3-mm thick lead plate, and attached to the tube head to remove regions of disinterest in the radiation field. A digital phantom patient was constructed to evaluate patient dose. In addition, detectors of pixel size 1×1 cm² and 0.1×0.1 cm² were constructed to check collimator location. The effective dose according to International Commission on Radiological Protection 103 was calculated with and without collimation. The effective doses for simulation with and without collimation were 5.09 and 11.32 µSv, respectively. The results of the calculated effective dose show 61.7 % reduction of field area and 55 % of effective dose. The Monte Carlo simulation is a good evaluation tool for patient dose.


Asunto(s)
Carga Corporal (Radioterapia) , Cefalometría , Modelos Biológicos , Radiografía Dental , Radiometría/métodos , Simulación por Computador , Humanos , Modelos Estadísticos , Método de Montecarlo , Dosis de Radiación , Dispersión de Radiación , Rayos X
16.
Med Phys ; 38(12): 6688-96, 2011 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-22149851

RESUMEN

PURPOSE: To develop a cylindrical phantom with rolled-up radiochromic films and dose analysis software in the rolled-out plane for quality assurance (QA) in volumetric modulated arc therapy (VMAT). METHODS: The phantom consists of an acrylic cylindrical body wrapped with radiochromic film inserted into an outer cylindrical shell of 5 cm thickness. The rolled-up films with high spatial resolution enable detection of specific dose errors along the arc trajectory of continuously irradiated and modulated beams in VMAT. The developed dose analysis software facilitates dosimetric evaluation in the rolled-up and rolled-out planes of the film; the calculated doses on the corresponding points where the rolled-up film was placed were reconstructed into a rectangular dose matrix equivalent to that of the rolled-out plane of the film. The VMAT QA system was implemented in 3 clinical cases of prostate, nasopharynx, and pelvic metastasis. Each calculated dose on the rolled-out plane was compared with measurement values by modified gamma evaluation. Detected positions of dose disagreement on the rolled-out plane were also distinguished in cylindrical coordinates. The frequency of error occurrence and error distribution were summarized in a histogram and in an axial view of rolled-up plane to intuitively identify the corresponding positions of detected errors according to the gantry angle. RESULTS: The dose matrix reconstructed from the developed VMAT QA system was used to verify the measured dose distribution along the arc trajectory. Dose discrepancies were detected on the rolled-out plane and visualized on the calculated dose matrix in cylindrical coordinates. The error histogram obtained by gamma evaluation enabled identification of the specific error frequency at each gantry angular position. The total dose error occurring on the cylindrical surface was in the range of 5%-8% for the 3 cases. CONCLUSIONS: The developed system provides a practical and reliable QA method to detect dosimetric errors according to the gantry angle. Film dosimetry based on rolled-up and rolled-out techniques leads to dose verification in the subspaces of the 3D dose volume. The system can be employed as an alternative tool to detect the pitfalls of planar dose verification.


Asunto(s)
Dosimetría por Película/instrumentación , Fantasmas de Imagen , Garantía de la Calidad de Atención de Salud/métodos , Radioterapia Conformacional/instrumentación , Diseño de Equipo , Análisis de Falla de Equipo , Dosificación Radioterapéutica
17.
Radiat Prot Dosimetry ; 140(4): 362-8, 2010 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-20554581

RESUMEN

This study examined the characteristics of the dental X-ray fluoroscopic equipment, 'DreamRay 60F', which was recently developed in Korea. The output linearity, output reproducibility, half-value layer (HVL), leakage radiation and scattered radiation were measured using an ionisation chamber. The surface dose equivalent rate and estimated dose equivalent of the operator were also calculated. The output linearity was 0.0015-0.0175 and the coefficient of variation for the output reproducibility was 0.0013-0.0074. The experimental HVL was 2.1 mm Al, and the leakage dose rate at 100 cm from the X-ray focus ranged from 2.70 to 19.66 microGy h (-1) depending on the direction. The scattered radiation doses differed significantly (1.7-16.8 times) depending on the distance and direction. If an operator is exposed for 10 min per procedure, 5 procedures a day at 5 days a week, he/she sitting at a 90 degrees direction will receive an annual dose equivalent of 13.0 mSv (at 30 cm) and 63.7 mSv (at 50 cm) in the trunk and face surface, respectively.


Asunto(s)
Fluoroscopía/instrumentación , Dosis de Radiación , Radiografía Dental/instrumentación , Radiometría/métodos , Diseño de Equipo , Fluoroscopía/métodos , Humanos , Modelos Estadísticos , Exposición Profesional , Radiografía Dental/métodos , Reproducibilidad de los Resultados , Rayos X
18.
Int J Radiat Oncol Biol Phys ; 78(3): 920-8, 2010 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-20584579

RESUMEN

PURPOSE: To analyze dose uncertainty using a previously published dose-uncertainty model, and to assess potential dosimetric risks existing in prostate intensity-modulated radiotherapy (IMRT). METHODS AND MATERIALS: The dose-uncertainty model provides a three-dimensional (3D) dose-uncertainty distribution in a given confidence level. For 8 retrospectively selected patients, dose-uncertainty maps were constructed using the dose-uncertainty model at the 95% CL. In addition to uncertainties inherent to the radiation treatment planning system, four scenarios of spatial errors were considered: machine only (S1), S1 + intrafraction, S1 + interfraction, and S1 + both intrafraction and interfraction errors. To evaluate the potential risks of the IMRT plans, three dose-uncertainty-based plan evaluation tools were introduced: confidence-weighted dose-volume histogram, confidence-weighted dose distribution, and dose-uncertainty-volume histogram. RESULTS: Dose uncertainty caused by interfraction setup error was more significant than that of intrafraction motion error. The maximum dose uncertainty (95% confidence) of the clinical target volume (CTV) was smaller than 5% of the prescribed dose in all but two cases (13.9% and 10.2%). The dose uncertainty for 95% of the CTV volume ranged from 1.3% to 2.9% of the prescribed dose. CONCLUSIONS: The dose uncertainty in prostate IMRT could be evaluated using the dose-uncertainty model. Prostate IMRT plans satisfying the same plan objectives could generate a significantly different dose uncertainty because a complex interplay of many uncertainty sources. The uncertainty-based plan evaluation contributes to generating reliable and error-resistant treatment plans.


Asunto(s)
Modelos Estadísticos , Neoplasias de la Próstata/radioterapia , Dosificación Radioterapéutica , Radioterapia de Intensidad Modulada/estadística & datos numéricos , Incertidumbre , Intervalos de Confianza , Humanos , Masculino , Movimiento , Planificación de la Radioterapia Asistida por Computador , Radioterapia de Intensidad Modulada/instrumentación , Recto/efectos de la radiación , Vejiga Urinaria/efectos de la radiación
19.
Radiat Prot Dosimetry ; 138(4): 382-8, 2010 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-19959602

RESUMEN

In this research, using direct measurements and Monte Carlo calculations, the potential dose reduction achieved by bismuth shielding in computed tomography was evaluated. The patient dose was measured using an ionisation chamber in a polymethylmethacrylate (PMMA) phantom that had five measurement points at the centre and periphery. Simulations were performed using the MCNPX code. For both the bare and the bismuth-shielded phantom, the differences of dose values between experiment and simulation were within 9%. The dose reductions due to the bismuth shielding were 1.2-55% depending on the measurement points, X-ray tube voltage and the type of shielding. The amount of dose reduction was significant for the positions covered by the bismuth shielding (34 - 46% for head and 41 - 55% for body phantom on average) and negligible for other peripheral positions. The artefact on the reconstructed images were minimal when the distance between the shielding and the organs was >1 cm, and hence the shielding should be selectively located to protect critical organs such as the eye lens, thyroid and breast. The simulation results using the PMMA phantom was compared with those using a realistically voxelised phantom (KTMAN-2). For eye and breast, the simulation results using the PMMA and KTMAN-2 phantoms were similar with each other, while for thyroid the simulation results were different due to the discrepancy of locations and the sizes of the phantoms. The dose reductions achieved by bismuth and lead shielding were compared with each other and the results showed that the difference of the dose reductions achieved by the two materials was less than 2-3%.


Asunto(s)
Bismuto/química , Simulación por Computador , Método de Montecarlo , Fantasmas de Imagen , Traumatismos por Radiación/prevención & control , Protección Radiológica/métodos , Tomografía Computarizada por Rayos X/métodos , Mama/efectos de la radiación , Cabeza/efectos de la radiación , Humanos , Cristalino/efectos de la radiación , Equipos de Seguridad , Dosis de Radiación , Glándula Tiroides/efectos de la radiación , Tomografía Computarizada por Rayos X/instrumentación
20.
Radiat Prot Dosimetry ; 138(2): 137-43, 2010 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-19864327

RESUMEN

The primary goal of this study was to analyse the state of patient doses in the field of computed tomography (CT) examinations in the Republic of Korea. All survey data including the CT applications and patient dose details were obtained from general hospitals registered in the Korean Hospital Association. The systematic analysis of the patient dose survey gives target values of the weighted computed tomography dose index (CTDI(w)) and the dose-length product (DLP). The targeted CTDI(w) values were 69, 69, 31, 19, 44, 25, 24, 20, 2, 19 and 19 mGy for the brain non-contrast enhancement (BNCE), brain contrast enhancement (BCE), neck, chest, spine, liver, pancreas, stomach, kidneys, abdomen routine and abdomen trauma protocols, respectively. The targeted DLP values were 1056, 2112, 762, 1234, 1338, 2794, 2742, 2378, 2836, 1844 and 1939 mGy cm for the BNCE, BCE, neck, chest, spine, liver, pancreas, stomach, kidneys, abdomen routine and abdomen trauma protocols, respectively. Comparing with the EUR recommendation, especially in the DLP, the adjustment of the total scan phase frequency and the shortening of the scan phase in each scan phase are needed to reduce the patients radiation exposure to international standards.


Asunto(s)
Guías de Práctica Clínica como Asunto , Dosis de Radiación , Radiografía Abdominal , Tomografía Computarizada por Rayos X/normas , Adulto , Anciano , Carga Corporal (Radioterapia) , Unión Europea , Encuestas Epidemiológicas , Humanos , Corea (Geográfico) , Persona de Mediana Edad , Valores de Referencia , Adulto Joven
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