Comportamiento dosimétrico de un sistema de planificación mediante curvas de calibración de densidades electrónicas relativas / Dosimetric behaviour of a planning system through calibration curves of relative electron density

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.

A novel serial port auto trigger system for MOSFET dose acquisition / 中国医疗器械杂志

To synchronize the radiation of microSelectron-HDR (Nucletron afterloading machine) and measurement of MOSFET dose system, a trigger system based on interface circuit was designed and corresponding monitor and trigger program were developed on Qt platform. This interface and control system was tested and showed stable operate and reliable work. This adopted serial port detect technique may expand to trigger application of other medical devices.

An electronic medical record information system of DICOM-RT module-based in radiation therapy / 生物医学工程学杂志

Electronic medical records (EMR) is the clinical diagnosis, guiding intervention and digital medical service record of outpatient, hospital patients (or care object) in medical institution. And it is the complete, detailed clinical information resource which has produced and recorded in all previous medical treatments. Radiotherapy electronic medical records contain texts, images and graphics, therefore the information is more complicated. This paper proposes an EMR information system based on DICOM-RT standard, through the use of seven objects of DICOM-RT to achieve the information exchange and sharing between different systems, equipments, convenient radiotherapy treatment data management, improve the efficiency of radiation treatment.

Increased pretreatment levels of serum LDH and ALP as poor prognostic factors for nasopharyngeal carcinoma / 癌症

Serum enzymes that play potential roles in tumor growth have recently been reported to have prognostic relevance in a diverse array of tumors. However, prognosis-related serum enzymes are rarely reported for nasopharyngeal carcinoma(NPC). To clarify whether the level of serum enzymes is linked to the prognosis of NPC, we reviewed the pretreatment data of lactate dehydrogenase(LDH), alkaline phosphatase (ALP), and glutamyl transferase (GGT) in 533 newly diagnosed NPC patients who underwent radical radiotherapy between May 2002 and October 2003 at Sun Yat-sen University Cancer Center. Patients were grouped according to the upper limit of normal values of LDH, ALP, and GGT. The Kaplan-Meier method and log-rank test were used for selecting prognostic factors from clinical characteristics and serum enzymes, and the chi-square test was applied to analyze the relationships of clinical characteristics and serum enzymes. Finally, a Cox proportional hazards model was used to identify the independent prognostic factors. We found that increased levels of LDH had poor effects on both overall survival and distant metastasis-free survival (P = 0.009 and 0.035, respectively), and increased pretreatment level of serum ALP had poor effects on both overall survival and local recurrence-free survival (P = 0.037 and 0.039, respectively). In multivariate analysis, increased LDH level was identified as an independent prognostic factor for overall survival. Therefore, we conclude that increased pretreatment serum LDH and ALP levels are poor prognostic factors for NPC.

Radioterapia de intensidad modulada (imrt) / Intensity modulation radiation therapy (imrt)

La radioterapia es un tratamiento efectivo en el manejo del cáncer. Es responsable de mejorar significativamente el control locorregional, la supervivencia global y la calidad de vida en múltiples tumores. Históricamente, sin embargo, sus complicaciones agudas y crónicas han reducido estos beneficios. La incorporación de la computación a la radioterapia ha permitido el desarrollo de diversas técnicas de tratamiento, incluyendo la radioterapia conformada 3D (3D-CRT) y la intensidad modulada (IMRT). Éstas permiten aumentar la dosis tumoral protegiendo los tejidos sanos, con un potencial aumento en el control del tumor y reducción de las complicaciones agudas y crónicas asociadas. Múltiples estudios prospectivos y retrospectivos han evaluado los beneficios de la IMRT en distintos tumores primarios. Hasta ahora sus principales indicaciones son cáncer de próstata y de cabeza y cuello. En otras localizaciones se han obtenido mejorías dosimétricas significativas. Se requiere mayor seguimiento para conocer los resultados clínicos tardíos de esta tecnología.

Radiation therapy is an effective treatment in cancer management. It is responsible for significant improvements in local/regional control, overall and cause-specific survival and better quality of life in many tumors. Nevertheless, in the past, acute and chronic radiation toxicity has reduced this benefits. The introduction of computer technologies to radiotherapy has allowed the development of various planning and treatment techniques, including 3D conformal radiotherapy (3D-CRT) and intensity modulation (IMRT), permiting to escalate tumor doses while protecting healthy tissues. This can improve tumor control and reduce acute and late complication rates associated with radiotherapy. Multiple prospective and retrospective studies have evaluated the benefits of IMRT in different primary tumors. Their main indications are head and neck and prostate cancer. In other locations, a significant dosimetric improvements of IMRT have been found, but longer follow-up is required to identify long term effects.

The application and development of computer vision technology in radiotherapy / 中国医疗器械杂志

In this paper, the principle of computer vision was introduced and several typical radiotherapy devices based on computer vision were described, including their principle and applications.

Prediction of respiratory motion based on nonparametric regression for real-time tumor-tracking radiotherapy / 南方医科大学学报

<p><b>OBJECTIVE</b>It is necessary to compensate the system latencies in real-time tumor-tracking radiotherapy by prediction. However, due to the irregularities of respiratory motions, the results obtained with traditional methods were not acceptable. The purpose of this study is to evaluate the value of nonparametric regression model in respiratory motion prediction.</p><p><b>METHODS</b>The data of respiratory trajectory of 11 volunteers were obtained and predicted based on nonparametric regression method. The results were compared with those of autoregressive model and back propagation neural network. An improved method was proposed to deal with the abnormal state in respiration. We combined the prediction method with the tracking system to test its performance in practical application.</p><p><b>RESULTS</b>The results indicated that the proposed method could predict the motion accurately in real-time for different latencies. This method decreased the error of the abnormal state substantially and also allowed effective prediction of respiration motion when combined with the tracking system.</p><p><b>CONCLUSION</b>The nonparametric regression model can predict the respiratory motion accurately in real-time and therefore meets the requirement of real-time tumor-tracking radiotherapy.</p>

Análise da distribuição espacial de dose absorvida em próton terapia ocular / Spatial distribution analysis of absorbed dose in ocular proton radiation therapy

OBJETIVO: Propõe-se avaliar os perfis de dose em profundidade e as distribuições espaciais de dose para protocolos de radioterapia ocular por prótons, a partir de simulações computacionais em código nuclear e modelo de olho discretizado em voxels. MATERIAIS E MÉTODOS: As ferramentas computacionais empregadas foram o código Geant4 (GEometry ANd Tracking) Toolkit e o SISCODES (Sistema Computacional para Dosimetria em Radioterapia). O Geant4 é um pacote de software livre, utilizado para simular a passagem de partículas nucleares com carga elétrica através da matéria, pelo método de Monte Carlo. Foram executadas simulações computacionais reprodutivas de radioterapia por próton baseada em instalações pré-existentes. RESULTADOS: Os dados das simulações foram integrados ao modelo de olho através do código SISCODES, para geração das distribuições espaciais de doses. Perfis de dose em profundidade reproduzindo o pico de Bragg puro e modulado são apresentados. Importantes aspectos do planejamento radioterápico com prótons são abordados, como material absorvedor, modulação, dimensões do colimador, energia incidente do próton e produção de isodoses. CONCLUSÃO: Conclui-se que a terapia por prótons, quando adequadamente modulada e direcionada, pode reproduzir condições ideais de deposição de dose em neoplasias oculares.

OBJECTIVE: The present study proposes the evaluation of the depth-dose profiles and the spatial distribution of radiation dose for ocular proton beam radiotherapy protocols, based on computer simulations in nuclear codes and an eye model discretized into voxels. MATERIALS AND METHODS: The employed computational tools were Geant4 (GEometry ANd Tracking) Toolkit and SISCODES (Sistema Computacional para Dosimetria em Radioterapia - Computer System for Dosimetry in Radiotherapy). Geant4 is a toolkit for simulating the passage of particles through the matter, based on Monte Carlo method. Computer simulations of proton therapy were performed based on preexisting facilities. RESULTS: Simulation data were integrated into SISCODES on the eye's model generating spatial dose distributions. Dose depth profiles reproducing the pure and modulated Bragg peaks are presented. Relevant aspects of proton beam radiotherapy planning are considered such as material absorber, modulation, collimator dimensions, incident proton energy and isodose generation. CONCLUSION: The conclusion is that proton therapy when properly modulated and directed can reproduce the ideal conditions for the dose deposition in the treatment of ocular tumors.

PET and CT cross-modality medical image fusion based on out-location frame / 南方医科大学学报

<p><b>OBJECTIVE</b>To develop a new method of PET and CT cross-modality medical image fusion based on out-location frame.</p><p><b>METHODS</b>PET/CT cross-modality medical images were obtained based on the out-location frame and the external fiducial marker on the frame was used for rigid medical image registration. A variation model based on the wavelet transform was used for image fusion.</p><p><b>RESULTS</b>The CT images were displayed by grey scale and overlaid with the PET images displayed by chromatic scale to obtain the image after registration and fusion.</p><p><b>CONCLUSION</b>The method of external markers registration can be effective and accurate in achieving PET and CT image fusion.</p>

Present and future of radiotherapy in Pakistan

Incidence of cancer is rising worldwide with highest burden in the developing countries including Pakistan. Ensuring that these patients receive standard radiotherapy is a major challenge. To see existing radiotherapy services in Pakistan and suggest future strategies for radiotherapy services. Various technical personnel from 22 radiotherapy centers were contacted through phone calls and emails and asked about the number of therapy machines, simulators, number of technical staff and radiotherapy technologists that they had in their centre in the year 2009. Inconsistencies in the data collection were resolved through frequent phone calls. Main outcome measure was the current radiotherapy services per million populations. Each radiotherapy center covers a mean population of 1.96 million [3.54-19.63] with more access of cancer patients to the public sector due to low costs of radiotherapy treatment. At present, there are only 56 radiation oncologists, 55 medical physicists and 145 radiotherapy technologists. Further only 20 Cobalt-60, 17 linear accelerators, 12 fluoroscopic simulators and 4 CT simulators are present. Majority of modern equipment and treatment delivery is available in private sector. It was estimated that 55-60% of all new cases of cancer are currently being referred for radiotherapy each year and existing services are inadequate. The increase need of radiotherapy services demands unified, better and effective measures to deliver state of art radiotherapy to each patient to improve the outcomes of treatment. More radiotherapy services should be provided to public to reduce accessibility issues

Sistema on-line para o cálculo de doses fetais de pacientes e trabalhadoras ocupacionalmente expostas em radiologia diagnóstica / On-line software for the estimation of fetal radiation dose to patients and staff members in diagnostic radiology

Neste trabalho descrevemos um sistema on-line, chamado “Dose Fetal Web”, que calcula a dose fetal e os riscos radiológicos devido a exposições clínicas ou ocupacionais de gestantes. O sistema utiliza a metodologia matemática onde são usados coeficientes de conversão de dose uterina para dose fetal, gerados por meio de simulações pelo método de Monte Carlo. Para exposição médica de uma paciente gestante, uma base de dados de informações de operação de equipamentos acompanhados por um programa de garantia de qualidade e parâmetros fetais e maternos coletados durante exames de ultrassonografia obstétrica são incorporados na estimativa da dose fetal. No caso de dose fetal de uma trabalhadora gestante sujeita à exposição ocupacional (IOE),informações de uma base de dados de monitoração pessoal como dose ocupacional e carga de trabalho são usadas nos cálculos. No primeiro caso, considerando-se uma paciente gestante de 26 semanas submetida a um procedimento abdominal AP (tensão aplicada ao tubo de 70 kVp e filtração total de 3 mmAl), a dose fetal calculada pelo sistema foi 4,61 mGy e os riscos radiológicos obtidos foram 5,0·10-4 e 0,14 para a probabilidade de indução de retardamento mental e declínio de pontos de QI, respectivamente. No segundo caso, considerando-se uma IOE gestante, e assumindo-se que ela utilize um avental de proteção de 0,5 mm de equivalência em chumbo durante cada procedimento de radiologia intervencionista, e que a leitura pessoal de um dosímetro TLD portado fora do avental foi de 2 mGy/mês, a dose fetal calculada pelo sistema foi 0,02 mSv/mês.

In this paper we describe an online software, named “Dose Fetal Web”, which calculates the dose of the fetus and the radiological risks from both medical and occupational exposures of pregnant women. The software uses a mathematical methodology where coefficients for converting uterus to fetal dose, NUD, have been calculated by using Monte Carlo simulation. In the fetal dose from diagnostic medical examination of the pregnant patient, database information regarding output and other equipment related parameters from the QA database, maternal and fetal parameters collected by ultrasound procedures were used for the fetal dose estimation. In the case of fetal dose of the pregnant staff member the database information regarding routine individual monitoring dosimetry, such as occupational dose and workload, were used for the estimation. In the first case, suppose a 26 weeks pregnant patient had to undergo a single AP Abdomen procedure (70 kVp peak tube voltage and total filtration 3 mmAl), the fetal dose calculated by the software was 4.61 mGy and the radiological risks would be 5.0·10-4 and 0.14 to the probability of mental retardation induction and decline in the IQ score, respectively. In the second case,considering that the staff member can be pregnant, and assuming that she wore a 0.5 mm lead equivalent apron during every interventional radiology procedure and a personal dosimetry reading of 2 mGyTLD/month measured with the TLDs outside the apron, the fetal dose calculated by the software was 0.02 mSv/month.

Brain metastasis treated with Cyberknife / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Cyberknife can greatly raise the fractional dose of stereotactic radiosurgery, thus improving its clinical efficacy. We retrospectively analyzed clinical outcomes of brain metastasis treated with Cyberknife.</p><p><b>METHODS</b>We analyzed 40 cases of brain metastases treated with Cyberknife in the Tianjin Cancer Hospital from August 1, 2006 to August 1, 2007, for a total of 68 lesions with maximal diameter of 0.4 - 7.5 cm (average 1.88 cm). Total hypofractional radiated dosage was 18 - 36 Gy (5 - 25 Gy/F, 1 - 5 F) by Cyberknife. We evaluated the remission rate of clinical symptoms, correlation factors to new foci, 3-month local control rates, and 3-month and 1-year survival rates. All patients were followed up for more than 14 months.</p><p><b>RESULTS</b>After 1 week, clinical remission was 90.0% (36/40). After 3 months, the local control rate and therapeutic effective rate were 77.9% (53/68) and 94.1% (64/68), respectively, as observed by cranium augmentation CT or MRI. The three-month, six-month and 1-year survival rates were 97.5% (39/40), 82.5% (33/40) and 67.5% (27/40), respectively. Fourteen patients had neopathy outside the original lesion after 3 months. Neopathy was not correlated with age, whole-brain radiotherapy, number of original lesions, maximum diameter of the original lesion, therapeutic dose per fraction, therapeutic frequency or total therapeutic dose.</p><p><b>CONCLUSIONS</b>Cyberknife got perfect clinical outcomes by higher dosage per fraction. It is an appropriate and valid treatment shortcut for brain metastasis.</p>

A fast 3-D medical image registration algorithm using principal component analysis / 南方医科大学学报

This paper presents a new 3-D image registration method based on the principal component analysis (PCA). Compared with intensity-based registration methods using the whole volume intensity information, our approach utilizes PCA to estimate the centroid and principal axis, and completes the registration by aligning the centroid and principal axis. We evaluated the effectiveness of this approach by applying it to simulated and actual brain image data (MR, CT, PET, and SPECT). The experimental results indicate that the algorithm is effective, especially for registration of 3-D medical images.

[Ethical issues of new communication and information technologies applied in medicine]

The fast development of New Communication and Information Technologies [NTIC] and their use in increasingly numerous fields in medicine; raised new ethical issues. The aim of this paper is to highlight ethical and deontological guidelines for health professionals and physicians which must guide their use of the NTIC. A research in the Anglophone and French medical literature and on the Internet, using various key words related to ethics and medical computing. Ethical issues are mainly related to the property, the access and the use of the broad data bases of medical records, the legal obligations and ethics which must govern the course of a teleconsultation or a therapeutic remote intervention and the rules which must define the relationship between the teleconsultants and their patients. The use, increasingly frequent, of various expert systems of decision-making and/or of expertise in various clinical settings, also, poses ethical problems relating to the reliability of such systems, the qualifications necessary for their application and the responsibility for their development, maintenance and use. Medical information available on the Internet, of a very unequal and not controlled quality, raises many questions about the responsibility for the medical professionals in the education for the patients and their warning against sometimes erroneous information published on the Web. The ethical rules of research on the Internet must also be clearly formulated and diffused among the researchers. The general principles infront of an ethical problem related to the use of the NTIC remain based on the interest of the patient, the absence of a harmful effect, the respect of the professional secrecy and the safeguarding of the quality of the care and its conformity to the most recent scientific data

Análisis dosimétrico en braquiterapia ginecológica de alta tasa de dosis / Dosimetric analysis in high dose rate gynecological brachytherapy

OBJETIVO: Analizar la dosimetría en braquiterapia ginecólogica para el dispositivo Fletcher-Suit-Delclos con alta tasa de dosis, mediante placas radiográficas ortogonales (anteroposterior y lateral) versus tomografía axial computada (TAC). MATERIAL Y MÉTODOS: Se compararon dosimetrías de 4 implantes, realizadas con placas ortogonales y TAC pélvico en la Unidad de Braquiterapia del Instituto Nacional del Cáncer durante el mes de febrero del año 2006. Se prescribieron dosis de 8 Gy/fracción a punto H y se evaluó dosis a vejiga, recto y vagina según norma internacional. RESULTADOS: Las dosimetrías por TAC mostraron puntos calientes superiores a las placas ortogonales, para recto un 133% y para vejiga un 260% más aproximadamente. El porcentaje de volumen blanco incluido es subestimado con la dosimetría efectuada por placas ortogonales. CONCLUSIONES: La dosimetría por placas ortogonales muestra menor exactitud que el TAC. Los volúmenes blanco no son satisfactoriamente cubiertos por la curva de isodosis prescrita. La dosis acumulada, probablemente, sea más relevante que la dosis fracción.

OBJECTIVE: We analyze the gynecologycal high dose rate brachytherapy dosimetry using the Fletcher-Suit-Delclos device, comparing orthogonal films (anteroposterior and lateral) versus axial computarized tomography. METHODS: 4 implants were analized with orthogonal films and axial computarized tomography in the Brachyhterapy Unit of the National Cancer Institute on February 2006. The dose/fraction was 8 Gy to the H point. The bladder, rectal and vaginal dose point were evaluated according to international specifications. RESULTS: Axial computarized tomography reveals hot points higher than orthogonal films dosimetries (133% and 260% for bladder and rectum respectively). The target volumen included was underestimated with the classical orthogonal film dosimetry. CONCLUSIONS: The orthogonal film dosimetry shows smaller accuracy than axial computarized tomography. The target volumens were not satisfactorily covered by the prescribed isodosis curve. The dose accumulated could, probably, be more prominent than the dose/fraction.

Radioterapia por modulación de intensidad (IMRT): una nueva modalidad en el tratamiento del cáncer de cabeza y cuello / Radiotherapy through intensity modulation (IMRT): a new modality in the treatment of head and neck cancer

Objetivo: Describir el tratamiento y evaluar las ventajas de IMRT en el tratamiento del cáncer de cabeza y cuello. Material y métodos: Hace cuatro años se implementó en el Centro de Cáncer de la Pontificia Universidad Católica la técnica de IMRT para el tratamiento de los tumores de cabeza y cuello. La técnica de IMRT se basa en modificar la intensidad del haz de radiación mediante un colimador multihojas para producir una distribución más exacta de la dosis de radiación. Los resultados se evalúan mediante histogramas dosis/volumen. Se comparan las distribuciones de dosis y toxicidad para radioterapia conformada tridimensional (CRT-3D) e IMRT. Resultados: La distribución de la dosis en los histogramas dosis/volumen demostró una mejor cobertura del volumen blanco (PTV), con IMRT. La dosis recibida por los órganos a riesgo: glándulas salivales, ojos, oídos y cerebro disminuyen con IMRT. La médula espinal se protege con IMRT sin dividir el campo de tratamiento, evitando puntos con menor dosis que podrían disminuir el control del tumor. Conclusiones: La IMRT logra una mejor conformación de la dosis logrando una mejor cobertura del tumor y mayor protección de los órganos a riesgo.

Applications of the digital network in radiotherapy / 中国医疗器械杂志

Construction of the digital radiotherapy network is the need of contemporary radiotherapy, and is also an important part of the construction of a modernized hospital. This article analyzes the basic technical requirements and functions of the digital radiotherapy network, and gives opinions on the application of the digital radiotherapy network.

Developing a PC- based portal image contrast enhancement program

Delivering the radiation dose to the target volume and minimizing the dose to normal tissues are the main objectives in radiotherapy. The aim of our study is to enhance the contrast of the portal image to increase the accuracy of delineation of the organs in the irradiation field. The software was written based on local enhancement of the pixel values in image matrix. The portal images were digitized by charged coupled device [CCD] in compatible format to be read with this program. This program was applied as an m-file in MATLAB imaging tool box to the matrices of the portal images. The imaging parameters before and after application of the program were compared. The quantitative information of images was obtained. Analysis of the mean and standard deviations of the results has shown that the difference of the criteria between two groups of the images is significant [p< 0.01]. In qualitative analysis, final images scores were based on "special weight ". The result of this test confirms the superior quality of the post-processed images from the professional view point. Superiority of final images within the three studied parameters by the experts [superiority of lung image, superiority of thorax and its soft tissue images] can be used to increase the accuracy of the treatment set up and decrease the probability of normal tissue complications

The implementation of sharing treatment planning system based on DICOM / 生物医学工程学杂志

Based on DICOM, three DICOM objects of RT S. S, RT Plan, RT Image are designed to implement the information sharing of different TPS, and to implement the information exchanging and sharing of the radiotherapy planning systems (TPS) of different manufacturers. The information exchange of different TPS based on DICOM is feasible.

Novas tecnologias e inovaçäo organizacional: estudos de caso para analisar a relevância da variável confiança nos processos de implementaçäo de tecnologia em um hospital privado / New technologies to analyse the relevance of variable reliable in technology implementation process in a private hospital

Analisa quatro casos de implementaçäo de novas tecnologias em uma instituiçäo hospitalar privada de grande porte na cidade de Säo Paulo. Estuda as tecnologias de produçäo e distrIbuiçäo de medicamentos e materiais, tratamento de radioterapia, diagnósticos por imagem e "palm-tops". Serve-se de uma metodologia qualitativa e indutiva. Levanta dados através de entrevistas semi-estruturadas com profissionais envolvidos ou afetados pelas novas tecnologias, além da observaçäo passiva e análise de documentos. Tem por objetivo verificar se o aumento da complexidade organizacional, oriunda do emprego crescente de novas tecnologias, foi acompanhado por uma redefiniçäo das relaçöes de confiança na instituiçäo hospitalar. Pretende investigar o papel da confiança como variável social de adaptaçäo das organizaçöes às exigências do meio ambiente.