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Ming Chao

Publications and source records attributed to Ming Chao.

6 recordsLinked to original sources
PubMed2006

Four-dimensional cone-beam computed tomography using an on-board imager.

On-board cone-beam computed tomography (CBCT) has recently become available to provide volumetric information of a patient in the treatment position, and holds promises for improved target localization and irradiation dose verification. The design of currently available on-board CBCT, however, is far from optimal. Its quality is adversely influenced by many factors, such as scatter, beam hardening, and intra-scanning organ motion. In this work we quantitatively study the influence of organ motion on CBCT imaging and investigate a strategy to acquire high quality phase-resolved [four-dimensional (4D)] CBCT images based on phase binning of the CBCT projection data. An efficient and robust method for binning CBCT data according to the patient's respiratory phase derived in the projection space was developed. The phase-binned projections were reconstructed using the conventional Feldkamp algorithm to yield 4D CBCT images. Both phantom and patient studies were carried out to validate the technique and to optimize the 4D CBCT data acquisition protocol. Several factors that are important to the clinical implementation of the technique, such as the image quality, scanning time, number of projections, and radiation dose, were analyzed for various scanning schemes. The general references drawn from this study are: (i) reliable phase binning of CBCT projections is accomplishable with the aid of external or internal marker and simple analysis of its trace in the projection space, and (ii) artifact-free 4D CBCT images can be obtained without increasing the patient radiation dose as compared to the current 3D CBCT scan.

Algorithms↗
PubMed2004

[Magnetic resonance behavior of lipiodol--an experimental study].

OBJECTIVE: To describe the characteristics of magnetic resonance (MR) signals generated by lipiodol and to assess the influence on MR imaging of hepatoma nodule. METHODS: Pure lipiodol and lipiodol emulsions mixed with 76% urografin in different ratio were imaged by both CT and MR; quantitative T(1) and T(2) measurements of lipiodol were performed. Fourty-one SD rats with transplanted walker-256 sarcoma in liver were randomly divided into six groups: 0.4-0.6 ml lipiodol emulsion was infused via hepatic artery in experimental groups by means of laparotomy under celiac anesthesia. The changes in MRI signal of hepatoma nodule were observed. RESULT: In vitro, iodized oil demonstrated high signal on T(1)-weighted images when performed at 37 degree, but all could be suppressed by the fat saturation sequence, and showed very low signal on T(2)-weighted images. The characteristic of MR signal with ultra fluid lipiodol was different from that of iodized oil (P<0.01), showing short T(1) and long T(2) signal; the high signal on T(1)-weighted images was only partially suppressed by the fat saturation sequence. With descending ratio of lipiodol in emulsion, the signal behavior was gradually similar to urografin (r -0.958, P<0.01). When rats were transarterially infused with emulsion, the intensity of the signal on MRI was nearly the same as that in the control rats, but when lipiodol was injected out of the hepatic artery and accumulated in lymphadenopathy, it demonstrated a signal similar to fat; the high intensity signal was maintained on T(1)-weighted images and T(2)-weighted images. CONCLUSION: There are little changes in MR signal intensity when the lipiodol is accumulated in the tumor nodules. MR behavior of lipiodol is determined by its deposit area.

Animals↗
PubMed2004

[Histopathological changes in rat transplanted hepatoma after lipiodol transarterial embolization].

OBJECTIVE: To study the histopathological effect of hepatic arterial infusion of lipiodol on transplanted hepatoma in rats. METHODS: Fourty-one rats bearing Walker-256 transplanted hepatoma were randomly divided into embolization group (n = 35, divided in 5 subgroups, with 7 rats in each) and control group (n = 6). Lipiodol (0.5 ml/kg)emulsified with 0.2 - 0.3 ml of 76% urografin (v:v = 1:1) was infused via gastroduodenal artery into hepatic artery in embolization group. Rats in the control group were given via the same route urografin only. Histopathological changes of the treated tumors were examined by light and transmission electron microscopy. RESULTS: In the control rats treated with urografin alone, the average tumor size increased 2.8 fold on day 3, while that in the lipiodol treated rats increased 1.7 fold (P < 0.01). Compared with the control group, on day 3, 5, 10 after embolization treatment, tumor necrosis was more extensive (P < 0.01). In one of the treated rats, the tumor was completely necrotic on day 10. Inflammatory reaction was marked in the early post-embolic period, but it was replaced by fibrous tissue encapsulation. From day 1 on, in 17 of the 18 treated rats, apoptotic cells, identified by typical morphology under light and electronic microscopes, were observed, mainly in the tumor periphery. CONCLUSION: In addition to cellular necrosis, apoptosis may be another important mechanism leading to cell death in hepatoma treated with transarterial embolization.

Animals↗
PubMed2003

[Three-dimensional CT angiography with volume rendering for the detection of intracranial aneurysms].

OBJECTIVE: To evaluate the value of three-dimensional CT angiography (3D-CTA) with volume rendering (VR) for the detection of intracranial aneurysm. METHODS: Axial CT images were obtained by helical CT scanning on 45 patients with intracranial aneurysms, 15 males and 30 females, aged 63.9 (33-79 years). The primitive data were entered into the Silicon Graphics O2 board to be treated. VR technique was adopted to reconstruct 3D-CTA imaging, aided by multiplanar reformation to obtain the total volume of aneurysm. Among the 45 patients 25 underwent DSA simultaneously, 21 underwent clamping of aneurysm, and 3 underwent GDC thrombosis. RESULTS: Fifty-nine intracranial aneurysms were detected in 45 patients by 3D-CTA, including 32 small aneurysms (< or = 5 mm). 3D-CTA with VR well demonstrated aneurysms and provided useful information including the site, shape, size and spatial relationship to the surrounding vessels and bony structures. CONCLUSION: A quick, reliable, and relatively noninvasive diagnostic tool for intracranial aneurysms, 3D-CTA with VR delineates the aneurysmal morphology in detail, and provides useful information for choosing and planning microsurgical or endovascular treatment.

Adult↗