Journal of X-Ray Science and Technology - Volume 15, issue 1

Authors: Koyuncu, Baki | Pahsa, Alper

Article Type: Research Article

Abstract: In this study, image correlation techniques were applied on opticaldensity information to generate contour lines of a tumor area within abrain slice image. The tumor area was scanned as a digital image and itsintensity amplitudes were converted into optical density amplitudes. Theoriginal image and the reference image which were constructed by theoptical density amplitudes were correlated and the results weregraphically displayed against the spatial coordinate of the brain sliceimage. The peaks of the graphs …showed the healthy and tumor tissuetransitions. Contour profiling of the tumor tissue was generated byjoining these peaks. Show more

Keywords: Optical density detection, image correlation, contour profiling

Citation: Journal of X-Ray Science and Technology, vol. 15, no. 1, pp. 1-7, 2007

Authors: Allert, Keana D. | Vangala, Sravanthi | DiBianca, Frank A.

Article Type: Research Article

Abstract: Acceptance testing and quality control of computed tomography (CT) scanners are of great importance. While most procedures and phantoms for testing other parameters are widely accepted, there is still discussion and uncertainty about low-contrast (LC) performance tests that measure the capability of a CT scanner to discriminate low-contrast objects. This work investigated the development of LC phantoms with available, low-cost polystyrene resin materials and some selected additives. We designed and tested phantoms …with several different contrast steps by generating contrast in two different ways, one based on 'physical density difference' and the other on 'atomic number difference'. Physical density difference was achieved by adding a small amount of glycerin to the polystyrene resin, both having similar low atomic-number elements but differing in the density of their atoms. Atomic number difference was achieved by adding a small amount of iodobenzene to the resin, both having approximately the same physical density (less than 1% variation in density) but different atomic (i.e., elemental) composition. Prototypes were evaluated using a Philips Tomoscan LX system and varying beam properties. The behavior and validity of the results are discussed. Show more

Keywords: Computed tomography, contrast, low-contrast performance, phantoms, atomic number, density

Citation: Journal of X-Ray Science and Technology, vol. 15, no. 1, pp. 9-18, 2007

Authors: Nett, Brian E. | Zhuang, Ting-Liang | Leng, Shuai | Chen, Guang-Hong

Article Type: Research Article

Abstract: Conventionally, the FDK algorithm is used to reconstruct images in many imaging systems where cone-beam projections are acquired from a single circular scanning path in a 2π angular range (full scan mode) and has been heuristically extended to a π+fan angle angular range (short-scan mode). In this paper, a new cone-beam reconstruction algorithm is derived for a single arc source trajectory with an equal weighting scheme. This algorithm is derived in the Katsevich framework. Since the …single arc does not satisfy Tuy's data sufficiency condition, the resulting algorithm is an approximate reconstruction algorithm. The feature of one-dimensional (1D) shift-invariant filtering in the conventional FDK algorithm is nicely preserved. The new algorithm includes a voxel dependent backprojection step of weighted combinations of 1D Hilbert filtered data, after an initial differentiation operation. In comparing the new algorithm with the standard FDK: the new algorithm intrinsically handles full scan, short scan and super-short scan modes. Numerical simulations have been performed to validate the algorithm, and demonstrate more quantitatively correct density values when reconstructing points away from the central slice. Noise performance was assessed for both the new algorithm and the FDK algorithm using simulated Poisson noise. Show more

Keywords: Cone-beam, reconstruction, shift-invariance, approximate, circular trajectory, FDK

Citation: Journal of X-Ray Science and Technology, vol. 15, no. 1, pp. 19-48, 2007

Authors: Zhong, Yubin | Li, Jiamin

Article Type: Research Article

Abstract: Proton therapy is a new and advanced external beam radiotherapy technique where the energetic ionizing particles, protons, are directed to the target turmors. This report reviews the basic principle and the advantages of proton therapy in terms superior dose distribution as compared to photon therapy. The suitable clinical application of this new technique is also described based on the experiences at Wanjie Hospital in China. It is reasonable to expect that, with the rapid advancements in …equipment and planning methods, proton therapy will become an important clinical choice in cancer treatments in near future. Show more

Keywords: Proton therapy, radiation, cancer treatment

Citation: Journal of X-Ray Science and Technology, vol. 15, no. 1, pp. 49-56, 2007

Authors: Rahimi, Seyed Ali

Article Type: Research Article

Abstract: Background and purpose: Access to health care is the basic right of people. Diagnostic radiology is one of the main procedures which appropriate planning and management are essential. Maintenance and supervision of the operating conditions following the recommended standards play a key role in ensuring the benefit of the instruments. Data show that more than 80% of patients referred to hospitals need radiology image. Improper service causes unnecessary duplications of radiation and even wrong diagnosis, as …a results threatening health of the patients. Lack of protective barrier leads to the hazardous radiation exposure to the staff and patients. Improper use of radiation instrumentation, such as asymmetry of X-ray field, defects in collimators, lack of adjusting ray field, low quality or defective developing machine, lack of proper protective barrier, low quality film and drugs, can cause severe damage. The purpose of this study was to assess the conditions of radiology units at Mazandaran University hospitals and compare them with the standards of ICRU NCRP and ICRP. Materials and methods: The following six categories of conditions of radiography centers affiliated to the Mazandaran University of Medical Sciences were studied for the types and the rates of deficiency. (1) Conditions of radiography room; (2) Conditions of radiography instruments; (3) Conditions of control room; (4) Conditions of dark room; (5) Conditions of installation; and (6) Conditions of the other facilities. Results: The results showed that, none of the dark rooms are standard, and do not have proper alarm signal. In 63% of these units there was no tiling system for staff protection from radiation. Defects in radiography room, protective barrier and lack looking rays were 60%, 51% and 47% respectively. Referring to the obtained data, periodic supervision, and obeying of the standards are necessary. Data were collected through, observation, interviewing and questionnaire. The data show that the radiology units are far from the international standards; only about 50% of the conditions on average are satisfactory. Conclusion: Overall, about 50% of the units are deficient in the six categories, comparing with international standards. The improvement of the conditions is needed. Show more

Keywords: Diagnostic radiology, dosimeter, radiology standards, protective barrier, ionized ray

Citation: Journal of X-Ray Science and Technology, vol. 15, no. 1, pp. 57-63, 2007