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PubMed1989

Breast cancer after multiple chest fluoroscopies: second follow-up of Massachusetts women with tuberculosis.

A second follow-up was conducted of 1742 women with tuberculosis who were treated in one of two sanatoria in Massachusetts between 1930 and 1956. One hospital treated only children under the age of 17. Patient follow-up was extended from 1975 through 1980, and an additional 18 breast cancers were identified from hospital records, death certificates, and responses to a mailed questionnaire. Vital status was established for 97% of the subjects. Among 1044 women who were examined an average of 101 times with X-ray fluoroscopies during lung collapse therapy, 55 breast cancers were observed in contrast to 35.8 expected, based on incidence rates from the general population. No excess was found for 698 women treated by other means (19 observed versus 22.8 expected). Excess breast cancer risk did not appear until 15 years after initial exposure and was present at the end of 50 years of observation. Risk appeared to decrease with increasing age at exposure. Estimates of radiation dose to the breast for individuals (mean = 96 rad) were based on the most current information for the numbers of fluoroscopies, reconstruction of exposure conditions, and absorbed dose calculations. The relation between dose and breast cancer risk was consistent with linearity up to 400 rads (4 Gy). For 10-year survivors, the absolute excess risk was 5.5/1 million woman-year-rad, the excess relative risk per rad was 0.73%, and the relative risk at 100 rad was 1.7. These data indicate that a woman's lifetime risk of breast cancer is influenced by events occurring in early reproductive life, that low-dose fractionated exposures are as effective as single exposures of the same total dose in inducing breast cancer, and that risk of radiogenic breast cancer persists for many years, and perhaps for life.

Adolescent↗
PubMed1994

Breast reconstruction with myocutaneous flaps in previously irradiated patients.

Breast reconstructions performed with latissimus dorsi and transverse rectus abdominis myocutaneous (TRAM) flaps in 82 patients with a history of previous chest-wall irradiation were compared with similar reconstructions in 202 nonirradiated patients to determine whether prior irradiation was associated with more frequent complications and to determine the success rate of breast reconstruction using distant flaps in irradiated patients. The mean dose of radiation administered was 5637 cGy. Complications in the reconstructed breast were more frequent in the irradiated patients (39 percent) than in the nonirradiated patients (25 percent; p = 0.03). In the irradiated group, breast complications were more common in reconstructions performed with the latissimus dorsi flap (63 percent) than in those performed with the TRAM flap (33 percent; p = 0.063). Aesthetic outcomes also were slightly poorer in the irradiated patients. Although complications were more common and aesthetic outcomes not as good in previously irradiated patients, we do not consider such irradiation to be a contraindication to breast reconstruction.

Abdominal Muscles↗
PubMed1992

Internal dose following a major nuclear war.

The PATHWAY model results were used, in conjunction with a hypothetical major nuclear attack on the U.S., to arrive at the ratio of internal to external dose for humans from early (48 h) fallout. Considered were the four nuclides (137Cs, 89Sr, 90Sr, 131I) that account for most of the reconstructed whole-body committed equivalent dose from internal radiation in people who lived downwind of the Nevada Test Site during atmospheric tests. Effects of climate perturbations (the "nuclear winter" effect) on food crops were considered. These could increase internal dose estimates, depending on the severity of the climate perturbations. Internal and external doses to humans for 10 locations within the U.S. have been calculated, with varying local conditions and varying assumption about their shelters. The estimated 50-y internal dose commitment ranged from 0.0-0.17 Sv, the 48-h external dose from 0.15-4.6 Sv. The resultant ratios of internal to external committed dose received in the first months (until food transport was restored) varied from less than 0.01 to about 0.2. In all cases examined, the total dose from early fallout was found to be dominated by the external dose.

Humans↗
PubMed1982

High resolution computerized tomography with coronal and sagittal reconstruction in the diagnosis of brain tumors in children.

We present 4 children with brain tumors that were missed or incompletely characterized conventional computerized tomography (CT) scanning. Using high resolution CT with high dose contrast and three-dimensional reconstruction, we were able to define the anatomy of each tumor and its associated aberrant vasculature. High resolution CT scanning with reconstruction is very helpful in diagnostic problems in which conventional CT scanning fails to provide a clear diagnosis.

Brain Neoplasms↗
PubMed2005

[On the way to isotopic spatial resolution: technical principles and applications of 16-slice CT].

The broad introduction of multi-slice CT by all major vendors in 1998 was a milestone with regard to extended volume coverage, improved axial resolution and better utilization of the tube output. New clinical applications such as CT-examinations of the heart and the coronary arteries became possible. Despite all promising advances, some limitations remain for 4-slice CT systems. They come close to isotropic resolution, but do not fully reach it in routine clinical applications. Cardiac CT-examinations require careful patient selection. The new generation of multi-slice CT-systems offer simultaneous acquisition of up to 16 sub-millimeter slices and improved temporal resolution for cardiac examinations by means of reduced gantry rotation time (0.4 s). In this overview article we present the basic technical principles and potential applications of 16-slice technology for the example of a 16-slice CT-system (SOMATOM Sensation 16, Siemens AG, Forchheim). We discuss detector design and dose efficiency as well as spiral scan- and reconstruction techniques. At comparable slice thickness, 16-slice CT-systems have a better dose efficiency than 4-slice CT-systems. The cone-beam geometry of the measurement rays requires new reconstruction approaches, an example is the adaptive multiple plane reconstruction, AMPR. First clinical experience indicates that sub-millimeter slice width in combination with reduced gantry rotation-time improves the clinical stability of cardiac examinations and expands the spectrum of patients accessible to cardiac CT. 16-slice CT-systems have the potential to cover even large scan ranges with sub-millimeter slices at considerably reduced examination times, thus approaching the goal of routine isotropic imaging.

Cardiovascular Diseases↗
PubMed1998

Dosimetric verification of the 95% isodose surface for a conformal irradiation technique.

In the treatment planning of conformal radiotherapy, field shapes are often designed in such a way that a high-value isodose surface fully encompasses the target volume. Therefore, knowledge about the accuracy with which the treatment planning system calculates the position of that isodose surface is essential to prevent field shapes which are either too large or too small. To determine this accuracy for a conformal multi-field technique, the dose in the high-dose region must be measured with a high spatial resolution. A method is presented to reconstruct and evaluate the experimental high-dose region from a set of water phantom scans. This method, which assesses combined dose profiles for multi-field irradiation techniques, can be used for the commissioning and/or quality assurance of a 3-D treatment planning system. For a specific conformal technique, the measured and calculated 95% isodose positions along lines in several directions have been compared. It is shown that different dose values of single beam profiles determine the resulting 95% isodose position, which is important to recognize for quality assurance of treatment planning calculations. It is further found that the uncertainty in the calculated 95% isodose surface can be described by a standard deviation in dose value, which relates to a positional uncertainty through the local dose gradient. Thus the confidence region of the calculated 95% isodose can be indicated in the treatment plan by plotting isodoses at the 95% level plus and minus its standard deviation. Such a procedure is recommended instead of plotting the 95% isodose with a constant width. In addition, restrictions for the cumulative dose-volume histogram of acceptable treatment plans can be formulated, based on the sensitivity of the actual target coverage on the uncertainty with which the prescribed isodose surface is calculated.

Brachytherapy↗
PubMed2002

Cardiac and pulmonary doses and complication probabilities in standard and conformal tangential irradiation in conservative management of breast cancer.

BACKGROUND AND PURPOSE: The clinical benefit of irradiating the intact breast after lumpectomy must be weighted against the risk of severe toxicity. We present a study on cardiac and pulmonary dose-volume data and the related complication probabilities of tangential breast irradiation having the following objectives: (1) to quantify the sparing of the organs at risk (ORs), the heart and the lung, achieved by three-dimensional (3-D) conformal tangential irradiation (CTI) as compared to standard tangential irradiation (STI); (2) to elucidate the uncertainty in radiation tolerance data; and (3) to analyse the relation between the amount of OR irradiated and the resulting morbidity risk. MATERIAL AND METHODS: Computed tomography (CT)-based 3-D treatment plans of 26 patients prescribed to CTI of the intact breast were applied. Contour-based STI has been our routine treatment, and was reconstructed for all patients. Dose-volume data and normal tissue complication probability (NTCP) predictions from the probit and relative seriality models with several cardiac and pulmonary tolerance parameterizations were analysed and compared. RESULTS AND CONCLUSIONS: A significant amount of normal tissues can be spared from radiation by using CT-based CTI, resulting in a 50% reduction of the average excess cardiac mortality risk in the left-sided cases. The risks for pericarditis and pneumonitis were too low to reveal any clinically significant difference between the treatments. For the STI set-up, a regression analysis showed that the excess cardiac mortality risk increased when larger parts of the heart were inside the fields. However, the different excess cardiac mortality and pneumonitis tolerance parameters resulted in statistically significant different NTCPs, which precluded the ability to accurately predict absolute NTCPs after tangential breast irradiation. Despite this uncertainty the different series of cardiac and pulmonary risk predictions were in relatively good agreement when small volumes of the ORs were irradiated. From the present data and without consideration of patient or organ motion, it therefore appears that tangential breast irradiation with less than 1 cm of the heart and 2-2.5 cm of the lung included inside the treatment fields will cause at most 1 per thousand risk for cardiac mortality and pulmonary morbidity. CT-based CTI should be considered, in particular for the left-sided cases, if these requirements cannot be met.

Adult↗
PubMed1994

Three-dimensional reconstruction of monoclonal antibody uptake in tumor and calculation of beta dose-rate nonuniformity.

BACKGROUND: The measurement of the heterogeneity of radiolabeled monoclonal antibody uptake in tumor has an essential role in the calculation and interpretation of the absorbed dose of radiation. Large data arrays and long calculation times have been limiting factors in the calculation of three-dimensional dose-rate distributions used to study the relationship between uptake heterogeneity and dose. METHODS: Serial autoradiographs of tumor sections were digitized with approximately 100 microns resolution using a laser densitometer. The section images were aligned to form a registered tumor-image data set. The image data were corrected for film response versus activity density to create a three dimensional activity density distribution using features of a three-dimensional radiotherapy treatment planning system. Dose-rate distributions were formed by convolution with a beta dose kernel using fast Fourier transforms. RESULTS: Differential dose-rate-volume histograms (derived from the dose-rate distribution) were created to summarize the dose-rate nonuniformity throughout the tumor volume. Effects of section sampling interval, interpolation methods between section planes, and calculation resolution on the dose-rate-volume histograms were illustrated. CONCLUSIONS: The several orders of magnitude improvement in calculational speed provided by the fast Fourier transform technique allowed an investigation of the effects of the calculational parameters. This investigation enabled tuning of both data acquisition and dose computation. These studies can lead to further enhancements in the calculational efficiency of three-dimensional dose-rate distributions. These improvements will allow the study of summing techniques to yield average total dose distributions.

Animals↗
PubMed2005

Dose classification scheme for computed tomography of the paranasal sinuses.

PURPOSE: The purpose of this study was to define objective and reproducible standards for the quality of CT images as a function of radiation doses and therapeutic validity. MATERIALS AND METHODS: CT images of the paranasal sinuses of 145 patients (77 female, 68 male; 5-83 years old; mean age, 39.9 years) were classified both subjectively (with a view toward their validity for the planning of functional endoscopic sinus surgery, FESS) and objectively by defining the pixel noise (the standard deviation, STD, of the CT number) in a homogeneous region of interest (ROI), centered on the M. masseter and on the frontal lobe. These measurements were then compared to measurements obtained from scan images of a water-filled Perspex phantom. RESULTS: The pixel noise measured in the phantom images was nearly identical to the respective values on the M. masseter on the patient images. The use of an edge-enhancing reconstruction algorithm and low-dose protocols, with a pixel noise amounting to 70-90 Hounsfield Units (HU), are indicated for children, chronic sinusitis, and septum deviation, while standard protocols, with a pixel noise of 50-70 HU, are recommended for the preoperative planning and postoperative control of FESS. The pixel noise for high-dose protocols is less than 50 HU; nonetheless, such protocols should generally be avoided. CONCLUSION: The pixel noise measured in a water-filled Perspex phantom is indicative of the clinical potential and image quality of paranasal sinus CT scans. Alternatively, the M. masseter can be chosen as an ROI to measure the pixel noise in order to obtain a rough estimate of the image quality or radiation dose class.

Adolescent↗
PubMed1982

Value of multi-planar CT images in interactive dosimetry planning of intracavitary therapy.

A method of intracavitary treatment planning and dosimetry analysis which uses multi-planar reconstructed computerized tomography (CT) images is presented. The aim of the method is to improve ability to precisely locate clinical reference points, to fully define pertinent anatomic structures and to provide dose distributions and their relationship to these structures in multiple planes. Our approach is based on interactive treatment planning and point dose display on sagittal and coronal reconstructed CT images as well as the usual transaxial image. The advantages of clinical evaluation of isodoses directly on multi-planar CT images are assessed. These include precise anatomic and dose relationships between the cervix and paracervical structures, the bladder, rectum and pelvic node-bearing sites. Problems of image magnification, blurred images and inadequate resolution attendant to orthogonal radiographs, which are the basis of current techniques, are minimal. Analysis and results of the method and a comparison with the technique of orthogonal radiographs are presented for a demonstration case.

Adenocarcinoma↗
PubMed2002

Influence of initial electron beam characteristics on monte carlo calculated absorbed dose distributions for linear accelerator electron beams.

The least known parameters in a Monte Carlo simulation of a linear accelerator treatment head are often the properties of the initial electron beam directed onto the exit vacuum window. Several initial beams with different spatial fluence distributions, angular divergences and energy spectra have been transported through the geometry of a scattering foil accelerator. The electron beam characteristics (energy spectrum and angular distribution) at the phantom surface and the subsequent relative absorbed dose distribution in a water phantom were calculated. The dose distribution was found to be insensitive to the geometrical properties of the initial beam. Furthermore, the lateral dose profiles are unaffected by the energy spectrum of the initial beam. The effect on the depth-dose curve is negligible if the initial energy spectrum is symmetric (e.g., Gaussian shaped) and its full width at half maximum (FWHM) is less than approximately 10% of the most probable energy. A larger FWHM will decrease the normalized dose gradient, but will not affect the dose in the build-up region. An asymmetric wedge shaped spectrum with a low-energy extension simultaneously increases the dose in the build-up region and decreases the dose gradient. The relationship between the energy spectral width and the normalized dose gradient is, however, smaller than published analytical expressions indicate. Some well-established energy-range relationships were shown to be accurate for most of the initial beams studied. The energy spectrum at the phantom surface was also derived from a measured depth-dose curve through different methods. The extracted spectrum depends on the beam model and the spectral reconstruction algorithm. Even though the depth-dose curve is fairly independent of initial beam characteristics, a correct description of the low-energy tail of the energy spectrum is important to obtain good agreement between measured and Monte Carlo calculated doses in the build-up region.

Electrons↗
PubMed1994

Cancer following radiotherapy for peptic ulcer.

BACKGROUND: Radiotherapy for peptic ulcer was used between 1937 and 1965 to control excessive gastric acid secretions (mean dose, 14.8 Gy). Patients with this benign condition live many years after treatment and are at risk for late effects. PURPOSE: Our purpose was to investigate the risk of death from cancer following radiotherapy for peptic ulcer. METHODS: A mortality study was conducted of 3609 patients with peptic ulcer; 1831 were treated with radiation and 1778 were treated by other means. Extensive methods were used to trace patients. Radiation doses to specific organs were reconstructed from the original radiotherapy records. RESULTS: Nearly 70% of patients were found to have died. The average period of observation was 21.5 years (maximum 51 years). Compared with the general population, patients treated with or without radiation were at significantly increased risk of dying of cancer and non-malignant diseases of the digestive system. Risk of death due to heart disease was slightly higher following radiotherapy. Cancers of the stomach, pancreas, lung, and prostate were increased in both irradiated and nonirradiated patients. Radiotherapy was linked to significantly high relative risks (RRs) for all cancers combined (RR = 1.53; 95% confidence interval [CI] = 1.3-1.8), for cancers of the stomach (RR = 2.77; 95% CI = 1.6-4.8), pancreas (RR = 1.87; 95% CI = 1.0-3.4), and lung (RR = 1.70; 95% CI = 1.2-2.4), and for leukemia (RR = 3.28; 95% CI = 1.0-10.6). Radiation combined with surgery, or given to treat gastric ulcer, appeared to increase the risk of stomach cancer 10-fold, which was greater than the sum of individual effects. Patients with gastric ulcers were at higher risk for stomach cancer than patients with duodenal ulcers. CONCLUSIONS: Patients with peptic ulcer are at increased risk of dying of cancer, related in part to lifestyle factors and treatment. Radiotherapy and surgery together appear to induce carcinogenic processes that greatly enhance the development of stomach cancer. The risk of radiation-induced stomach cancer was 0.25 extra deaths per 10,000 persons per year per Gy, somewhat lower than reported in other studies. High-dose radiation may have increased the risk of pancreatic cancer, a condition rarely found elevated in irradiated populations, but misclassified death notices may have contributed to the excess. Cancer mortality remained high for up to 50 years, indicating that radiation damage may persist to the end of life.

Aged↗
PubMed1996

CT-guided interstitial implantation of gynecologic malignancies.

PURPOSE: To establish the efficacy of computed tomography (CT)-based planning and analysis of transperineal implants. METHODS AND MATERIALS: For patients with bulky disease or geometrically unfavorable anatomy, transperineal interstitial implantation of gynecologic tumors offers an alternative to standard intracavitary techniques. Control of dose rate and total dose distributions to produce a homogenous, low dose rate implant presents a challenge to the radiation oncologist in these complex implants, as does the relationship of these distributions to the patients's anatomy. We have used CT imaging following needle implantation, prior to source loading, in 25 patients (28 implants), as an aid in both the planning of the implant and the analysis of the dosimetry. RESULTS: The spatial relationship between the needles and the normal anatomy can be clearly defined, despite the presence of some artifacts. Tumor volume is less clearly visualized but the adequacy of needle placement can be assessed and adjusted if necessary. Modifications of the planned source placement, based upon the location of specific needles and critical structures, can be made prior to loading the patient. Dose rate and total dose distributions are displayed with the appropriate anatomy on axial images and on reconstructed sagittal and coronal planes. Multiple points of dose specification for the rectum and the bladder are easily defined. Dose rate adjustment can be made by selectively changing the activity associated with a particular needle or needles. Multiple implants as well as external beam irradiation can also be integrated. CONCLUSIONS: CT-based dosimetry has permitted intelligent planning decisions to be made prior to and during these implants. It has further allowed more accurate anatomically based dosimetric analysis, with visualization and control of dose rate and total dose distributions displayed together with the patient's anatomy. This more elaborate analysis should ultimately lead to a better understanding of the reasons for local control and complications and their relationships to dose rate, total dose, and volume.

Brachytherapy↗
PubMed1996

Gamma Knife radiosurgery for intracranial metastases: from local tumor control to increased survival.

We have analyzed a series of 225 patients with intracranial metastases (343 lesions), treated in our department by Gamma Knife radiosurgery over a 30-month period. We have used a modified Pittsburgh protocol and performed 242 procedures on 164 single/78 multiple lesions. Primary tumors were mostly carcinomas of the lung (52%) and breast (11.6%). Neuroradiological localization of the target was usually performed by stereotactic computed tomography. Magnetic resonance imaging was only used in special circumstances. Routine dose planning was assisted by three-dimensional reconstruction programs. Mean tumor volume was larger than expected (5.7 ml). Mean prescription dose and average dose were 21.1 and 29.9 Gy, respectively. Middle- and long-term results were evaluated in a subset of 152 patients (236 lesions) with adequate (> 4 months) follow-up. Mean follow-up was 53.1 weeks with 61/152 patients still living. There was a predominance of retrospectively classified 'not fully eligible cases' among the survivors, mainly because of uncontrolled primary tumor. The 1-year local tumor control rate was 88.2%. Treatment-related radiological (3.9%) and clinical (1.6%) sequelae were minimal. Overall mean survival in these patients (40 weeks) turned out to be higher than that commonly reported after conventional surgical-radiation treatments. It was encouraging that the mean survival of 'fully' eligible patients was 51 weeks. Karnofsky performance status and neurological (Order Grading) performance scores were consistently high for most of the follow-up period. Functional Independence and the Palliative Index were not far from the value of mean survival. The main cause of death remains uncontrolled systemic disease (64.8%). On the other hand, the relative incidence of intracranial tumor progression was considerably decreased. This indicated that these patients should perhaps be treated more aggressively and underlines the need for randomized trials to determine the optimal treatment.

Adult↗
PubMed1987

Secondary arterio-enteric fistulae: a surgical challenge.

Ten cases of secondary arterio-enteric fistulae are described. There were nine graft enteric fistulae and one fistula involving the aortic suture line following elective resection of an infected graft. Only four of the patients initially received prophylactic antibiotics (single dose) at the original aortic reconstruction, and the vascular suture line had only been protected in two. Eight patients presented with bleeding and two with groin abscesses. One patient died before operation. Graft resection was undertaken in all patients and organisms were grown from six of eight grafts cultured. No patient died during operation but one died after 3 days. Axillofemoral bypass grafts were constructed in seven patients (four immediately after resection of prosthetic grafts and three within 4 days of operation). Only three of the eight patients who survived operation are still alive; two died of a ruptured aorta and one from a recurrent fistula. Two patients died of other causes. Four of five axillofemoral grafts in surviving patients subsequently occluded.

Aged↗
PubMed2005

A fast, high spatial resolution optical tomographic scanner for measurement of absorption in gel dosimetry.

A fast tomographic optical density measurement system has been constructed and evaluated for application in Fricke 3D gel dosimetry. Although the potential for full three-dimensional radiation dosimetry with Fricke gel dosimeters has been extensively reported, its application has been limited due to a lack of fast optical density measurement systems. In this work, the emphasis of the design has been to achieve a short scan time through the use of precision optics and minimal moving parts. The system has been demonstrated in the laboratory to be able to achieve better than 1mm resolution and a scanning time per tomographic slice of 2.4 seconds. Full volumetric sampling of a 10 cm diameter by 7cm long cylinder can be achieved in 3 minutes. When applied with a Fricke based gel dosimeter a linear response between reconstructed CT number and absolute dose was better than 3%.

Absorption↗
PubMed1987

The innermost chorionic layer of Drosophila. I. The role of chorin octamers in the formation of a family of interdigitating crystalline plates.

The innermost chorionic layer (ICL) within egg shells of Drosophila melanogaster is composed of thin, abutting three-dimensional crystalline plates which form a closed, membrane-like sheath. Collectively, the crystals within the sheath appear to form a family of related three-dimensional crystals in space group C222; however, specimens prepared for electron microscopy are actually two-dimensional crystals in c222. The projected structures of the negatively stained crystals have been studied by minimal dose electron microscopy employing image reconstruction methods. Thin sections indicate that unit cells within the ICL are composed of paired layers; top and bottom layers are related by centrally located 2-fold axes, aligned parallel to the surface of the ICL. The most probable structural unit of the crystals is a tetramer of chorin dimers with a point group symmetry of 222, which is denoted a chorin octamer. Projection maps were computed from average transforms of two-dimensional crystals for delta (the primitive unit cell angle) equal to 84 degrees, 90 degrees and 97 degrees (+/- 1.5 degrees). The maps indicate that the molecular transitions responsible for the observed family of crystals involve concerted intramolecular rearrangements about molecular 2-fold axes. The significance in vivo of the family of crystals within the ICL is not known; however, structural considerations suggest that the observed polymorphism may reflect one facet of an intrinsic bonding flexibility of the ICL octamer that may play a role in the formation of interplate junctions and the assembly of a continuous closed sheath. The ICL may therefore serve as a structural bridge between the vitelline membrane-wax layer and the endochondrial floor, allowing the larva to shed the inner egg shell layers during hatching.

Animals↗
PubMed1994

SICH-9.1--a unique whole-body counting system for measuring SR-90 via bremsstrahlung. The main results from a long-term investigation of the Techa River population.

A unique body counting system (SICH-9.1) has been constructed which allows an in vivo determination of body burdens of Sr-90 with high accuracy. To date about half of the population residing in the Techa River basin has been examined using this counting system. The information on the dependence of Sr-90 content in the human body on time, age and sex presents a unique basis for studies of metabolism of this element. The data base containing the findings of the above-described measurements has established a foundation for the reconstruction of individual and collective doses in the Techa River population.

Adult↗