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PubMed1991

Code of practice for clinical proton dosimetry.

The objective of this document is to make recommendations for the determination of absorbed dose to tissue for clinical proton beams and to achieve uniformity in proton dosimetry. A Code of Practice has been chosen, providing specific guidelines for the choice of the detector and the method of determination of absorbed dose for proton beams only. This Code of Practice is confined specifically to the determination of absorbed dose and is not concerned with the biological effects of proton beams. It is recommended that dosimeters be calibrated by comparison with a calorimeter. If this is not available, a Faraday cup, or alternatively, an ionization chamber, with a 60Co calibration factor should be used. Physical parameters for determining the dose from tissue-equivalent ionization chamber measurements are given together with a worksheet. It is recommended that calibrations be carried out in water at the centre of the spread-out-Bragg-peak and that dose distributions be measured in a water phantom. It is estimated that the error in the calibrations will be less than +/- 5% (1 S.D.) in all cases. Adoption and implementation of this Code of Practice will facilitate the exchange of clinical information.

Cobalt Radioisotopes↗
PubMed1991

PET studies of fluorodeoxyglucose metabolism in patients with recurrent colorectal tumors receiving radiotherapy.

Forty-four patients with recurrent colorectal carcinoma were examined prior to a combination of conventional photon radiotherapy (40 Gy) and neutron therapy (10 Gy). Twenty-one of these underwent a PET examination after photon therapy and 12 also were studied after the end of combined therapy. CEA plasma levels were measured from blood samples taken immediately before the PET study. A significant decrease in FDG uptake despite good palliative results were observed in only 50% of the patients. This may be explained by inflammatory reactions caused by radiation injury. Inflammation and metabolically active residual tumor tissue cannot be distinguished. It is concluded that an observation interval longer than 6 mo may more effectively detect residual tumor activity. In 14 of 41 examinations, an increased FDG uptake was associated with a normal CEA value, and in only two cases were normal FDG uptake values and increased CEA levels found, suggesting that PET is more sensitive than the measurements of CEA plasma levels for tumor recurrence.

Adult↗
PubMed1992

Prognostic significance of DNA quantitation in stage D1 prostate carcinoma with the use of image analysis.

BACKGROUND: A characteristic feature of prostatic adenocarcinoma is its great variation in biologic behavior. This variation and the observation that most carcinomas are of intermediate grade make standard histologic grading of limited value in determining the prognosis of a patient. METHODS: DNA quantitation with the use of computer-assisted image analysis on Feulgen-stained nuclei was performed on the metastatic lymph nodes from patients with Stage D1 prostate carcinoma to determine whether ploidy was a useful predictor of survival or progression. The Gleason histologic score of the primary tumor, the number and extent of lymph node metastases, and the progression and survival intervals were documented. Treatment modalities included pelvic lymph node dissection, radical prostatectomy, external beam radiation therapy, and iodine 125 implantation. RESULTS: DNA ploidy quantitation showed that 65% (33 of 51) of cases were aneuploid, 2% (1 of 51) were tetraploid, and 33% (17 of 51) were in the diploid range. Progression to Stage D2 disease occurred in 76% of the patients with aneuploid cases and 53% of those with cases in the diploid range. CONCLUSION: There was a significant difference in progression between the two ploidy groups (Cox regression analysis, P less than 0.05).

Combined Modality Therapy↗
PubMed1992

Computer-assisted 3D-reconstruction and statistics of the limbic system. 1. Computer-assisted 3D-reconstruction of the hippocampal formation, the fornix, and the mamillary bodies.

The hippocampal formation of eight perfusion-fixed human brains was examined using new methods according to stereotactic and morphometric principles (macrovibratome and computer-aided 3D reconstruction). The reconstructions form part of a neuroanatomical reference system (NeuRef). This reference system allows for 3D visualisation of the brain and its components on a computer graphic workstation, as well as for the presentation of the union set based on a neuroanatomical structure taken from this sample of brains. This retrievable knowledge of neurofunctional systems is important for the preoperative planning of neurosurgeons and the adjustment of radiotherapy.

Adult↗
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↗
PubMed1992

[Stereotaxic biopsy of cerebral lesions. Results based on a series of 250 cases].

With the help of modern computer-assisted imaging techniques, direct evidence of intracerebral lesions can be provided earlier and in more detail, often before the patient begins to exhibit symptoms. In asymptomatic cases, however, it is often difficult to establish an indication for a certain therapy. The choice of treatment chiefly depends on the histological nature of the lesion. Even in the age of computer-assisted imaging techniques, the specific diagnosis can only be made under the microscope. CT-guided stereotactic biopsy is a valuable and safe diagnostic tool for classifying intracranial lesions. It provides the basis for selecting the appropriate therapy, whether it be surgery, radiotherapy, or conservative treatment. We present a series of 250 stereotactic biopsies. The indications, technique, complications and limits of the method are discussed, as well as the diagnostic yield which achieved 97.6% in our series.

Biopsy, Needle↗
PubMed1991

[Three-dimensional reconstructions in neuroanatomy].

Computer-aided 3D reconstructions of neurofunctional systems and structures are generated as a reference for neuroimaging (CT, MRI, PET). The clinical application of these 3D reconstructions requires a coordinate system and conditions resembling the intravital neuroanatomy as far as possible. In this paper the neuroanatomical Reference System (NeuRef) of the Department of Neuroanatomy of Hannover Medical School is presented. This consists of methods to record brain structures from serial sections with minimal error (less than 1 mm) and to display 3D brain models derived from such a data base. In addition, NeuRef is able to generate sections through, for instance, the visual and pyramidal system and to transfer these data onto a corresponding CT image. Therefore, this method can serve as a diagnostic aid in neuroradiology, in operation planning, and radiotherapy. It can also be used in PACS.

Brain↗
PubMedDate not supplied

A multiple projection method for digital tomosynthesis.

A new method of optimized efficiency for the retrospective reconstruction of tomograms is presented. The method has been developed for use with isocentric fluoroscopic units and is capable of performing digital tomosynthesis of anatomical planes of user selected orientation and distance from the isocenter. Optimization of efficiency has been achieved by segmenting the reconstruction process into discrete transformations that are specific to groups of pixels, rather than performing pixel by pixel operations. These involve a number of projections of the acquired image matrices as well as parallel translations and summing. Application of this method has resulted in a significant reduction of computing time. The proposed algorithm has been experimentally tested on a radiotherapy simulator unit with the use of a phantom and the obtained results are reported and discussed.

Algorithms↗
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↗
PubMed1990

Outcome of patients with small-cell lung cancer: effect of changes in staging procedures and imaging technology on prognostic factors over 14 years.

In a study of 411 patients with small-cell lung cancer (SCLC) entered on therapeutic clinical trials between 1973 and 1987, we analyzed whether changes in the prognostic importance of pretreatment factors had occurred during the 14-year time period. After adjusting for other prognostic factors, brain involvement was associated with shorter survival in patients treated before December 1979 (P = .024) but not in patients treated thereafter (P = .54). The patients diagnosed before 1979 had brain metastases documented by radionuclide scan while computed cranial tomography (CCT) was more commonly used after 1979. Patients who had brain metastases diagnosed by radionuclide scan lived a shorter period of time than patients who had the diagnosis made by the more sensitive CCT scan (P = .031). In contrast, Cox proportional hazards modeling showed that liver metastases in patients were associated with shorter survival in patients treated after 1979 (P = .0007) but not in patients treated before then (P = .30). A larger proportion of patients had a routine liver biopsy before 1979 than after 1979 when more patients had the liver staged with less sensitive imaging studies and biochemical parameters. Patients with SCLC whose cancer was confined to the thorax but had medical or anatomic contraindications to intensive chest radiotherapy had similar survival compared with patients with limited-stage SCLC who were treated with combination chemotherapy alone (P = .68). From these data we conclude: (1) the sensitivity of the staging procedures used can affect the impact on survival of cancer involvement of a given site; and (2) patients with cancer confined to their chest with medical or anatomic contraindications to chest radiotherapy do not have a shorter survival than patients with limited-stage disease treated with chemotherapy alone.

Adult↗
PubMed1992

The effect of head and neck radiation therapy on voice quality.

Twenty-five patients with squamous cell carcinoma of the head and neck who received radiation therapy as their only form of treatment underwent a computer-assisted voice analysis before, and 6 months following treatment. Those with early laryngeal tumors had a significant improvement in intelligibility (P = .07), percent of sound voiced (P = .04), and sound perturbation. Those with nonlaryngeal tumors had no change in any measured parameters. Head and neck radiation therapy can significantly improve the voice quality of patients with laryngeal tumors, while having a minimal effect on the voice quality of those with nonlaryngeal tumors.

Carcinoma, Squamous Cell↗
PubMed1992

The use of parallel EEL spectral imaging and elemental mapping in the rapid assessment of anti-cancer drug localization.

Both electron spectroscopic imaging (ESI) and electron energy-loss spectroscopy (EELS) have great potential for use in several areas of cancer research. In biologically targeted radiotherapy, cytotoxic drug therapy and boron neutron capture therapy the effectiveness of many drugs is often critically dependent upon the intracellular localization of the agent employed. We describe the use of parallel EEL spectral imaging to assess the penetration and location of the iodine-containing drug meta-iodobenzyl guanidine, of potential value in targeted radiotherapy, and for the rapid detection of boron within borate-adsorbed polystyrene beads, of potential value in boron neutron capture therapy. We also describe elemental mapping of boron following low-temperature embedding. These results show how the techniques could be applied to many forms of cancer research by discussing the validity and limitations of the techniques experimentally. We also provide an outline of other areas in this field which could benefit from the future application of ESI and EELS.

3-Iodobenzylguanidine↗
PubMed1992

Reduction of the dose to the lens in prophylactic cranial irradiation: a comparison of three different treatment techniques and two different beam qualities.

Three treatment techniques using two beam qualities have been compared on the basis of dose to the lens in prophylactic cranial irradiation. The dose to the lens and the globe was measured with thermoluminescent crystals in an anthropomorphic phantom and calculated by a computer-assisted planning system. A comparison was made of large field and small field techniques using 60Co and 8 MV photons. Modifications to the basic techniques studied included angulation of the gantry, angulation of the couch, and placement of an additional eye block close to the surface. The dose to the lens could be reduced to four percent of the midplane dose by applying the small-field technique combined with the use of 8 MV energy photons, by placing an additional block close to the surface, and by five degree occipitally angling the gantry, as well as rotating the treatment couch to account for the divergence of the beam. The use of 60Co produced an underdosage of the posterior segment of the globe in angled treatment techniques.

Cataract↗
PubMed1990

Intraductal breast carcinoma: initial results of a morphometric study using computerized digital image analysis.

Extensive ductal carcinoma in situ (DCIS) and necrosis in breast carcinoma have been correlated with a higher incidence of local recurrence in patients treated with breast-conserving surgery and radiotherapy. In an attempt quantitatively to assess duct size distribution and necrosis in DCIS, the authors devised a method utilizing computerized digital image analysis. The method and results of a pilot study comparing 21 patients with DCIS, and 21 normal breast specimens are presented. Normal breast tissue from autopsy material revealed a mean duct diameter of 90 microns, whereas the mean diameter of ducts in patients with DCIS was 359 microns (P less than 0.001). The presence of necrosis in DCIS correlated strongly with average duct size. Of the ducts larger than 360 microns in diameter 94% exhibited intraductal necrosis, whereas ducts less than 360 microns showed necrosis in only 30% of the measurements. Ducts with necrosis revealed a mean diameter of 498 microns versus 198 microns in ducts without necrosis (P less than 0.001). The authors suggest that necrosis develops in response to tumour cell hypoxia associated with cross-sectional duct expansion in DCIS. This growth pattern predisposing to tumour cell hypoxia could be a factor contributing to radioresistance and increased local recurrence.

Adult↗
PubMed1990

Nuclear morphometry as a prognostic indicator for genitourinary rhabdomyosarcoma: a preliminary investigation.

Rhabdomyosarcoma of the urogenital tract is a malignant mesenchymal tumor seen primarily in childhood. Multimodal therapy, encompassing surgery, radiotherapy and chemotherapy, has dramatically improved the survival of patients with this disease. However, the quest for markers of tumor aggression is important to decrease the morbidity of treatment given to patients with good prognosis tumors, while at the same time intensifying treatment of tumors with poor prognosis. Using archival tumor specimens from 13 patients with genitourinary rhabdomyosarcoma, a multivariate analysis of multiple nuclear shape descriptors was done with the Hopkins Morphometry System. Three nuclear shape descriptors clearly separated patients with no evidence of disease recurrence or progression from those with recurrent disease, progressive disease or death of disease. These nuclear shape descriptors were standard error of the chain code standard deviation analysis (p = 0.010), range of the feret ellipticity distribution (p = 0.016) and standard error of the chain code range analysis (p = 0.037). With multivariate analysis these shape descriptors taken together separated patients with good and poor prognoses to a level of significance of p = 0.007. Thus, nuclear morphometric analysis may prove to be useful as an individual prognostic indicator in childhood genitourinary rhabdomyosarcoma and warrants further analysis in a much larger, blinded, controlled study.

Cell Nucleus↗
PubMedDate not supplied

A computerized brain atlas: construction, anatomical content, and some applications.

An adjustable computerized atlas of the human brain has been developed, which can be adapted to fit individual anatomy. It is primarily intended for positron emission tomography (PET) but may also be used for single photon emission CT, transmission CT, magnetic resonance imaging, and neuroimaging-based procedures, such as stereotactic surgery and radiotherapy. The atlas is based on anatomical information obtained from brains fixed in situ soon after death. All structures have been drawn in on digitized photos of slices from one cryosectioned brain. The definition and classification of the anatomical structures and divisions are in agreement with the standard textbooks of anatomy, and the nomenclature is that of the Nomina Anatomica of 1965. The boundaries of the cortical cytoarchitectonic areas (Brodmann areas) have been determined using information from several sources, since three-dimensional literature data on their distribution are incomplete, scarce, and partly contradictory. However, no analysis of the cytoarchitectonics of the atlas brain itself has been undertaken. At present the data base contains three-dimensional representations of the brain surface, the ventricular system, the cortical gyri and sulci, as well as the Brodmann cytoarchitectonic areas. The major basal ganglia, the brain stem nuclei, the lobuli of the vermis, and the cerebellar hemispheres are also included. The computerized atlas can be used to improve the quantification and evaluation of PET data in several ways. For instance, it can serve as a guide in selecting regions of interest. It may also facilitate comparisons of data from different individuals or groups of individuals, by applying the inverse atlas transformation to PET data volume, thus relating the PET information to the anatomy of the reference atlas rather than to the patient's anatomy. Reformatted PET data from individuals can thus be averaged, and averages from different categories or different functional states of patients can be compared.

Anatomy, Artistic↗
PubMed1991

The use of T2 distribution to study tumor extent and heterogeneity in head and neck cancer.

Demarcation of the extent of malignant tissue is essential for planning a course of radiotherapy. MR images may provide additional information for delineating the target volume because of the large difference in the proton magnetic resonance relaxation times between normal and malignant tissues. In 13 patients with head and neck tumors the distribution of the proton spin-spin relaxation times, T2, at 1.5 Tesla were evaluated throughout the physician designated target volume and normal surrounding tissue. The T2 values within the tumor were always elevated compared with normal tissue, the highest values being in the nominal center of the tumor and decreasing toward the periphery. The regional distribution of T2 values within the tumor is a measure of the tissue heterogeneity within the tumor volume. In addition, the large differences in T2 relaxation times between normal and disease tissues were used in a computer algorithm to automatically demarcate the boundary of abnormal tissue in each axial MRI section. This potentially could significantly expedite the time required to identify the target volume on multiple sections and thus remove one of the major time constraints for 3D treatment planning.

Head and Neck Neoplasms↗