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Results for “Radiotherapy, Computer-Assisted”

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PubMed1976

Diagnosis of radiosensitive hypothalamic tumors without craniotomy: endocrine and neuroradiologic studies of intracranial atypical teratomas.

Three patients with intracranial atypical teratomas presented with symptoms of endocrine dysfunction (diabetes insipidus, hyperprolactinemia, and anterior hypopituitarism) suggestive of a hypothalamic disorder. Computer-assisted tomography done in two of the three cases enabled us to document the presence of a mass and institute radiotherapy, without prior neurosurgical exploration. Computer-assisted tomography also provided a safe and effective method of assessing the effects of radiotherapy.

Adolescent↗

PubMed1992

CCRT (computer controlled radiation therapy) for non-small cell lung cancer: sensitivity of clinical gains to organ tolerance restrictions.

A method is described for allowing the entrance angles of beams to vary along the longitudinal axis of the target volume using a computer controlled radiation therapy (CCRT) treatment technique. The increase in tumor dose potentially available with this technique is evaluated for the case of a non-small cell carcinoma of the lung for which treatment is constrained by a clinically relevant tolerance condition. Tolerance is expressed in terms of that volume of unaffected contralateral lung allowed to receive greater than 20 Gy. The evaluation is repeated with small changes made to the constraining condition in order to explore the sensitivity of the dose gain to the definition of tolerance. For the chosen example, at least an additional 10 Gy could be prescribed to the tumor with the CCRT technique when the 20 Gy contralateral lung volume was held to less than 30%. A gain of 7 Gy was found when the 20 Gy volume was held to 27% and 1 Gy when the 20 Gy volume was reduced to 25%. CCRT treatment can result in a significant dose gain under a clinically relevant condition for tolerance. Its measured advantage strongly depends on the dose constraints specified. Sensitivity analysis is necessary to meaningfully evaluate the merits of alternative treatment techniques.

Carcinoma, Non-Small-Cell Lung↗

PubMed1977

A computerized tomographic evaluation of malignancies of the bladder and prostate.

Twenty cases of malignancies of the bladder and prostate were evaluated by computed tomography. This study was performed in a community hospital adjacent to a large retirement community in Southern California. Although the series was small, the results indicate that, for example, staging of carcinoma of the bladder malignancy beyond Jewitt-Marshall A can be accomplished with some ease using this modality. The extensive malignancies are easily demonstrated and their extents, in relationship to surrounding pelvic structures, are seen with considerable clarity. The use in radiation treatment planning is obvious.

Aged↗

PubMed1992

Three-dimensional imaging for brachytherapy planning.

A computerized 3-D brachytherapy treatment planning program has been developed which simulates catheter trajectories, radioisotope seed positioning and percentage dosimetry zones about a catheter/seed array in relationship to CT or MRI images. The high activity 125I seed is used in this program. A visual and a non-linear mathematical optimization program will also be described.

Brachytherapy↗

PubMed1992

Template-guided stereotactic implantation of malignant brain tumors for interstitial thermoradiotherapy.

A phase I trial of 25 patients with anaplastic astrocytoma or glioblastoma multiforme is described. Hyperthermia and radiation were delivered stereotactically by means of template-guided interstitial catheters loaded with ferromagnetic wires and then 192Ir seeds. Implant volumes ranged from 15 to 113 ml (mean 54 ml) involving 9-38 catheters (mean 18); parallel catheters used hexagonal spacing of 1.0-1.5 cm. Patient tolerance of these procedures was excellent. Postoperative morbidity due to additional mass effect or edema was low, but there has been one death and one complication of hydrocephalus, bleeding and symptomatic pneumocephalus, each.

Adult↗

PubMed1992

[Development of a moving target aiming system using an ultrasound imaging unit].

We developed an ultrasound imaging unit for gating the irradiation of proton beams or acquiring CT scan data for treatment planning according to the motion of tumors in the abdomen. In proton therapy, it is essential that the maximum region of dose rate distribution in a body always coincide with the volume of the tumor in motion during irradiation. Gated proton bean irradiation based on tumor motion could solve this problem and minimize undesirable dose distribution to normal tissues in the vicinity of the tumor. This device can generate the TTL level signal of time width corresponding to the period that the tumor would be sited in a region determined in advance, to control the various kinds of machines. Results of our preliminary experiment using X-ray irradiation showed that this aiming device was able to make the width of the gated irradiation area coincide with that of the planned area within a difference of about 0.5 mm.

Humans↗

PubMedDate not supplied

[The CT-stereotaxic neutron brachytherapy of brain tumors with californium sources on the ANET-B apparatus].

A method for stereotaxic intratissue radiotherapy of brain tumors based on the findings of computed tomography is described. Radiosurgical implantation of sources with increased 252Cf content emitting mixed neutron + gamma-radiation was accomplished by means of an ANET-B apparatus by the afterloading method. Neutron irradiation is particularly effective in patients with malignant tumors possessing a large fraction of cells in a state of deep anoxia. Dosimetric planning was conducted by means of an original computer system. Devices and radiation-technical equipment for adaptation of the ANET-B apparatus for irradiation of neurosurgical patients are described. The indications for the use of this method and its place among the complex of measures for the treatment of patients with new growths of the brain are discussed. The first experience in using CT-stereotaxic neutron brachytherapy with californium sources on the ANET-B apparatus for the treatment of 6 patients with malignant glial tumors of the brain is dwelt on.

Adult↗

PubMedDate not supplied

Bayesian statistics: a guided tour.

An overview of Bayesian statistical decision theory is presented in the tutorial spirit. A section on fundamental principles is followed by selected applications of the Bayesian approach to parameter estimation, pattern recognition, image processing, computer-aided medical diagnosis, optimal diagnostic test selection, and radiotherapy treatment planning.

Decision Making↗

PubMed1977

Computer-aided medical decision making in radiotherapy.

Radiotherapy departments are becoming sophisticated in working with computers for isodose computations, treatment machine verifications and administrative and medical records. The next step lies in computer-assisted medical decision making. The logic for a patient's diagnostic work-up and treatment protocol can be stored in a computer. It can then be used as an aid in making the diagnosis, in prescribing the treatment and for quality control. For patients who fit established protocols the computer can select and list treatment using the logic of that protocol. Such a system has been implemented for the postoperative radiotherapy of breast cancer on a trial basis. Its potential usefulness is illustrated by results in 25 consecutive patients. Physician acceptance and costs of the program are under investigation.

Breast Neoplasms↗

PubMed1978

[Ultrasound in tumor diagnostics and treatment planning (author's transl)].

The fundamental requirements of irradiation planning are discussed delimitating the minimum and maximum demands of planning. Different possibilities to represent the topographic relations within the irradiation plane of the patient's cross-section are described. The computer-assisted system for irradiation planning, installed at our hospital by means of MAT construction, is discussed. A pathway is shown which leads to individual treatment planning and considers dosimetrically the actual conditions of the patient who will undergo radiation therapy. The possibilities and limits of ultrasonic cross-sectional imaging are demonstrated.

Diagnosis, Computer-Assisted↗

PubMed1992

Our experience in the diagnosis of intraocular tumours by a B-scan computerized system and angiodynography (Doppler). Preliminary results.

The authors compare the ultrasound diagnostic results of intraocular tumours by A/B-scans (Sonomed B 3000, Sonocare, Sonovision STT-100) with images obtained using computerized B-scan (Sonocare, Sonovision STT-100, Acoustic Tissue Typing ATT) and angiodynopgraphy systems (Quantum Philips). The Sonovision uses a computerized ultrasound spectrum analysis to assess the probability that a given lesion is a certain tumour, rather than another. The ATT system provides diagnostic probability for type B and type E melanoma, for haemangioma and metastatic carcinoma. The Quantum ultrasound equipment was developed for studying the heart and the major blood vessels. It is a colour Doppler that simplifies the Doppler technique, allowing it to study small anatomical parts such as tumour-like lesions of the eye. The Doppler technique ascertains the presence and the velocity of blood flow in the tumours. In presenting the preliminary results with the new techniques the authors are aware that the ATT system is not designed for some of the lesions under study (melanomas after conservative radiotherapy).

Blood Flow Velocity↗

PubMed1976

A preloaded radium needle implant device for maintenance of needle spacing.

A small stainless steel bar was machined to accept radium needles. The stainless steel bar will hold a rack of two, three, four, or five radium needles in a single plane. The crossing needle may be affixed to the bar so that textbook-like geometry is possible. The stainless steel bar remains in place during the entire implant. Spacing between needles is close to perfect. The time required to insers the implant is reduced compared to free-hand insertions, and less variation in dose is seen on computer-assisted calculations. Two years' experience in the use and development of the radium needle holder will be reviewed.

Head and Neck Neoplasms↗

PubMed1976

New methods of imaging in diagnostic radiology Sylvanus Thompson Memorial Lecture.

A brief history of the recent developments in computer-assisted tomography (CAT) is presented. The development of whole-body scanners from the basic brain scanner, the trend towards higher-speed scanners using multiple detectors in a fan-type geometry, and some of the unsolved problems related to CAT scanners are discussed, as well as the potential use of whole-body scanning in radiotherapy treatment planning and in radiobiology. A review of recent developments in electrostatic imaging is presented and a new method of imaging called ionography is described in detail. It is shown how a single exposure can be used to produce a number of copies, each with a different amount of edge contrast, under the control of the radiologist. Further, it is shown how this can be done using a closed system so that the ionography chamber never needs to be opened. Some of the recent commercial developments in this field are described. It is suggested that in the future radiology departments may be replaced by departments of imaging, which will include all ways of obtaining diagnostic information and where such a department would be problem oriented rather than technique oriented. The need for basic scientific support by a medical physics and engineering group in such a department is emphasized.

Electrons↗

PubMed1978

A computer-assisted three-dimensional treatment planning system.

The three-dimensional treatment planning system developed at the Rhode Island Hospital visualizes the spatial interrelationships of the radiation beam, the tumor, and the adjacent organs within the patient. It is possible to rotate and vary the scale of the display to better comprehend the extent of these structures. By viewing the display as if from along the radiation beam, one can design shaped treatment fields which best suit the three-dimensional nature of the disease. With this system, it is possible to reduce the volume of normal tissue which would typically be irradiated if two-dimensional treatment planning techniques and assumptions were employed.

Computers↗

PubMed1975

Backgrounds of computer-assisted treatment planning in radiation therapy.

Interaction of ionising radiation and living materials causes biological damage of tempory or permanent nature. In radiation therapy this phenomenon is used in a controlled fashion in order to stop the proliferation of malignant cells, while at the same time limiting the permanent damage to healthy tissues and organs to at least tolerable levels. Because of the often relatively small differences in response of malignant growths and normal tissues, the margins between tolerable and intolerable are so small that the greatest precision in treatment planning and execution is required. The nature of this treatment agent implies that the radiation therapist has to rely very much on instrumentally obtained and processed information, in all phases of this medical activities around the patient. In this paper a description is given of the backgrounds of computer-assisted methods which have enabled modern individualised and optimised planning for therapy with high enery X - and gamma beams.

Cobalt Radioisotopes↗

PubMed1975

[The effectiveness of treatment for breast cancer patients].

The study of late results of treatment in 1166 patients with breast cancer permitted to find the percentage of a 5-year survival to be equal to 55.58, 37.93% of patients survived for 10 years, 28.25% -- for 15 years. In the first stage a 5-year survival was 87.20%, while in the second and third -- 57.7% and 31.56% of patients survived for 5 years, accordingly. The modern methods of radiotherapy (radiosurgical method, interstitial gamma therapy with Au-198 granules, distance grammatherapy on the machine LUCH) enhanced the efficacy of therapeutic measures in patients with widespread breast cancer. A complex diagnosis -- cytology, non-contrast mammography and mathematical analysis by means of a computer contributes to recognition of early forms of breast cancer.

Adenocarcinoma↗

PubMed1977

[Optimization in planning and application of 60 Co gamma irradiations - analysis of the problem (author's transl)].

As an aspect of the complex problem of optimization in therapeutical transmission of radiation energy to Man, the dose distribution within a cross-sectional area of the body is considered. For the judgement on optimal dose distributions, involving judgement on irradiation technique, boundary conditions are needed which encompass important parameters of a dose distribution (= criterion for optima). For computer-assisted optimization the boundary conditions are to be scheduled by an appropriate algorithm. The parameters describing a dose distribution are indicated. Practical utilization of computer-assisted optimization of dose is represented by means of two optimization schedules.

Cobalt Radioisotopes↗

PubMed1978

[Possibilities, limitations and errors with ultrasound tomography in computer-assisted treatment planning (author's transl)].

Ultrasound tomography provides two-dimensional images, true in scale, of sonographic interfaces within nearly every sectional plane desired; it has become especially important, therefore, in irradiation planning. Complementary to results from a therapy simulator, an improvement in localization of tumor and target volume or of critical organs and of tissue inhomogeneities is possible. The hard-copy of gray-scale sonotomograms furnishes all essential geometric and anatomical input data needed for electronic systems used in irradiation planning. Technical, physical and diagnostic limitations of the method are stated. The possible systematic or technical-instrumental errors in sonographic treatment planning are discussed and the necessary calibration controls specified.

Abdomen↗