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Purpose The aim of this study was to assess the distribution of CT dose index (CTDI) values reported by sites undergoing ACR CT accreditation between 2002 and 2004. Methods Weighted CTDI (CTDI w ) values were measured and reported by sites applying for ACR CT accreditation, and the percentage of scanners with values above the 2002 ACR diagnostic reference levels (DRLs) was determined. Acquisition parameters for a site's adult head, adult abdominal, and pediatric abdominal examinations were used to calculate volume CTDI (CTDI vol ), and the average and standard deviation were calculated by year. Histogram analysis was performed to determine 75th and 90th percentiles of CTDI vol . Results Between September 2002 and December 2004, 829 scanners underwent the accreditation process. Volume CTDI values (average ± SD) for 2002, 2003, 2004, and 2002 to 2004, respectively, were 66.7 ± 23.5, 58.5 ± 17.5, 55.8 ± 15.7, and 59.1 ± 18.6 mGy for adult head examinations; 18.7 ± 8.0, 19.2 ± 8.6, 17.0 ± 7.6, and 18.4 ± 8.3 for adult abdominal examinations; and 17.2 ± 9.7, 15.9 ± 8.6, 14.0 ± 7.0, and 15.5 ± 8.4 for pediatric abdominal examinations. For 2004 data, 23.8%, 2.3%, and 6.9% of sites reported doses above the 2002 CTDI w reference levels, compared with 49.6%, 4.7%, and 15% for 2002 data for adult head, adult abdominal, and pediatric abdominal examinations, respectively. Seventy-fifth percentiles of CTDI vol were 76.8 mGy (adult head, 2002 only), 22.2 mGy (adult abdominal), and 20.0 mGy (pediatric abdominal). Conclusions From 2002 to 2004, average CTDI vol values decreased by 10.9, 1.7, and 3.2 mGy for adult head, adult abdominal, and pediatric abdominal examinations. Effective January 1, 2008, the ACR program implemented United States-specific diagnostic reference levels of 75, 25, and 20 mGy, respectively, for the CTDI vol of routine adult head, adult abdominal, and pediatric abdominal CT scans.

i a f e t uestion: Over last New Year’s oliday, the U.S. Department of nergy dispatched casually dressed uclear scientists with sophisticated adiation detection equipment to ook for radiation “dirty” bombs 1] in at least 10 major cities and irports [2]. With increased radiaion surveillance, will patients who ave received permanent brachyherapy implants (I or Pd rostate seeds) or nuclear medicine adiopharmaceuticals be stopped or questioning? If so, what should or an be done to help these patients? Answer: Yes. Patients who have edical procedures that make hem radioactive should be given D cards that describe the nature of he radioactive procedures. At our ospital, we use laminated wallet ards as well as information sheets o document radioactive proceures. Figure 1 displays an example f a wallet card that is given to prosate implant patients. These cards an be printed using a color printer nd laminated using clear packing ape or a lamination machine.

Recent developments have permitted accurate seed placement and dosimetry for interstitial brachytherapy of selected patients with localized prostate cancer. We present our experience with 76 patients divided into 2 groups. Group 1 included 45 patients with smaller, more well differentiated tumors, usually less than 2 cm. in diameter on digital rectal examination or transrectal ultrasound and a Gleason score of less than 7 who were treated with 125 iodine alone. Group 2 consisted of 31 patients with localized tumors greater than 2 cm. in diameter and/or a Gleason sum equal to or greater than 7 who were treated with low dose external beam radiation followed by 125 iodine boost 4 weeks later. Complete clinical progression-free survival, including prostate specific antigen, digital rectal examination and biopsy, was 51% for group 1 and 63.3% for group 2, with a mean followup of 26.3 months. Prostate specific antigen progression-free survival was 97.7% for group 1 and 94.7% for group 2.These results ap...

Image quality is proportional to radiation dose. Improvements in image quality come at a cost of increased radiation dose. CT scanners are more robust today than even 5 years ago. X-ray tubes are capable of producing high levels of almost continuous radiation for rapid CT volume acquisitions and angiographic studies. All parameters of modern CT scanners provide rapid subsecond, large-volume CT acquisitions. How high we go needs to be tempered by how high we should go regarding radiation dose from CT examinations. Radiologists, referring physicians, medical physicists, CT technologists, CT equipment manufacturers, and regulators need to evaluate the appropriateness of radiation dose for different CT studies.

The ACR CT accreditation program, begun in 2002, requires the submission of approximately 20 images, several completed data sheets and printouts of three Excel worksheets. The procedure manual is very detailed, yet participants unfamiliar with the program or having minimal CT experience have needed to redo aspects of their submission, or in some cases do not receive accreditation, due to mistakes made by the physicist. This review of the phantom portion of the ACR CT accreditation program supplements the ACR provided instructions with additional photos of phantom setup, region-of-interest (ROI), and image placement on the film sheets, and examples of completed portions of actual (but anonymous) submissions. Common mistakes, as well as uncommon but interesting images, are shown and explanations are given as to what could have been done to avoid the problem. Additionally, a review of CT dose measurement techniques and calculations will enable the physicist to better assist sites where typical exam doses are above the ACR reference values.

Performance evaluation of equipment for computed tomography (CT) involves the integration of: (a) establishing performance criteria; (b) designing and implementing test procedures; and (c) reconciling test results in terms of desired performance. Precision (noise), contrast scale, linearity, accuracy, spatial independence, spatial resolution, artifacts, reproducible performance, and patient exposure are several parameters discussed, as are problems of measurement with regard to non-water bath scanners. Performance and quality control tests for the ACTA, Delta, and EMI scanners are outlined. Guidance for the prospective purchaser of CT equipment is presented as a summary of the ideas discussed.

Accurate dose prediction for megavoltage photon therapy of carcinoma of the esophagus requires information on tumor depth, lung thickness, and lung density. The authors found that CT localization of internal and external contours is accurate within +/- 1 mm. Lung density can be measured with an error of less than 0.02 g/cm3 in the range 0.25-1.00 g/cm3. Variance between predicted and measured dosage was less than 3% in all patients and in most RANDO phantom measurements. Accurate radiation therapy planning is possible with CT information from a commercial scanner.

An argument is presented for organization of a Computed Tomography Scanner Performance Repository. Performance data on CT scanners would be distributed in statistical form to the radiological community. A Protocol is presented for the uniform collection of data. Results of exposure, resolution and visibility measurements made by the authors are presented for the EMI 5005/U, Pfizer 0200 FS and General Electric CT/T scanners.

Computerized tomographic scanners have gained quick and widespread acceptance in diagnostic radiological practice. The cost of such units is currently about a half million dollars. Technologically, they are one of the most complicated pieces of equipment to be found in a radiology department. Because of the cost and complexity, it seems logical to set up performance specifications, acceptance tests, and a quality assurance program for a CT scanner. Pertinent performance specifications are herein described and discussed. In order to assure that the CT unit does meet specifications, appropriate acceptance tests are likewise discussed. Finally, a basic quality assurance program is outlined with an indication of the tests to be performed and their time frequency.

In Anger camera imaging, probably the most important parameter of camera performance is field uniformity. For the majority of camera users, field uniformity is evaluated in a subjective manner by simply viewing polaroid field floods. Due to film lim-itations, viewing conditions and statistical limitations, it is questionable if count density differences less than 15-20% can really be identified. To shift from a qualitative to quantitative method of field uniformity determination, a photographic method using high count density 70mm images has been developed. For the majority of Nuclear Medical imaging procedures, the current instrument of choice is the Anger camera. Of the An camera performance parameters, probably the most important is field uniformity. For those few institutions with dedicated computers interfaced to an Anger camera, field uniformity can be assessed and even corrected by the computer. However, for the majority of camera users, no quantitative method of uniformity evaluation exists. To shift from a qualitative to quantitative method of field uniformity determination without an interfaced dedicated computer, a phogographic method using high count density 70mm images has been developed; similar to film isodore methods in radiation therapy.© (1975) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Little technical information has been made available on CT image format or viewers. For large matrix displays (320 x 320 or 512 x 512), a high quality TV monitor with a bandwidth of 10 MHz or greater is required. If only a single field of a two to one positive interlaced TV monitor is displayed, an 875 line rate TV would be required in order to display the entire matrix. For image recording, a transparency system such as a multi-format unit or a 105 mm roll film camera will generally provide the best results. Finally, in order to improve the final CT image, various picture processing routines may be used. These include pre- and post-reconstruction smoothing, edge enhancement and image subtraction.© (1976) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The immediate goal of clinically based x-ray-transmission computed tomography (CT) is to provide a measurement of the x-ray linear attenuation coefficient in cross section with the ultimate goal of impacting on patient management and care. To do this with the accuracy needed for clinical goals requires the careful integration of x-ray physics, detector technology, and mathematical reconstruction theory. Performance evaluation and quality assurance are necessary adjuncts to a CT scanning program. A number of investigative studies are underway.

THE RELATIONSHIP of phlebitis of the lower limbs to pulmonary embolus was established by Virchow in 1846-1856.1Since that time much has been learned about the incidence of phlebitis and the statistical relationship of the various types of phlebitis to pulmonary embolism. However, the serious problem of preventing emboli from reaching the lungs has not been satisfactorily solved to date. As a corollary of this, the prevention of further emboli after the initial one has reached the lungs is also a serious problem. It is with these two problems that this paper is concerned. The treatment of thrombophlebitis complicated by pulmonary emboli has gone through three general eras which have been marked by waves of enthusiasm, unpopularity, and final acceptance for a definite set of clinical circumstances. The concept of venous interruption was proposed in 1934.2This has since been applied to all levels in the lower extremities

IN THIS paper we propose to review some of our experiences with peripheral arteriosclerosis and to comment on endarterectomy in particular. Burt, Learmonth, and Richards 1 quote an earlier description of aortic occlusion given in 1914 by Robert Graham, of Glasgow. The condition was recognized and described by others also, notably Severinus (1632) and Fantanus (1679). In 1894 Severenau broke up a thrombus through the orifice of a main obliterated artery and then was able to amputate at the site of election rather than through the thigh. Lejars * performed disobliteration through arteriotomies in 1902. Delbet * stated in 1911 that the easiest operation that can be done to cure arterial obstruction is incision of the artery, extraction of the thrombus, and closure of the vessel—in thrombosis due to endarteritis one can hope for but little from visualization of the artery. On the impaired walls the clot reforms with a distressing rapidity.

Submucous lipoma is the second commonest benign neoplasm of the gastrointestinal tract. However, its appearance not infrequently causes surprise, and its true nature may not be suspected until after an extensive surgical procedure has been carried out to remove it. The lesion is thus very important because it occurs in patients of the cancer age. In dealing with these persons, the surgeon is conditioned to removing lesions with adjacent normal tissue. The recognition of the true nature of the lesion is most important, if it be a submucous lipoma. Fortunately, this lesion can be easily identified at surgery, in most instances, if it is suspected. With this in mind, an illustrative case of lipoma of the colon is reported which showed all the characteristics of such a lesion. This report and attendant discussion may serve as a reminder of the existence of such a surgically pleasant lesion. REPORT OF CASE

Since the pioneer work of Fritsch and Hitzig 1 in 1870 and of Ferrier 2 in 1873, many investigators have stimulated the cerebral cortex of animals and of man. Most such experiments have been carried out with the brain exposed and the subject anesthetized, at least lightly, or controlled with local anesthesia. Talbert, 3 in 1899, using a method and (according to a recent personal communication) the very electrodes devised by Ewald, 4 reported the results of stimulation of the cortex of unanesthetized and unrestrained animals in whose skulls were implanted permanent electrodes. It is surprising that Talbert's work was for so long a time unappreciated, since work in this laboratory for several years 5 has indicated the value of implanted electrodes in cortical stimulation. Convulsions elicited in unanesthetized and unrestrained animals by electrical stimulation of fixed cortical points 6 were similar to jacksonian epileptic attacks in man. The animals