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Ding M, Stuhr K, Newman F, Hu A, Rice H, Miften M. SU-FF-J-73: Targeting Accuracy Using Exac-Trac® and Synergy® CBCT Image-Guided Radiotherapy Systems for Lung Stereotactic Body Radiotherapy. Med Phys 2009. [DOI: 10.1118/1.3181365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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102
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Ding M, Tong R, Liao SH, Dong J. An extension to 3D topological thinning method based on LUT for colon centerline extraction. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2009; 94:39-47. [PMID: 19046790 DOI: 10.1016/j.cmpb.2008.10.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Revised: 01/28/2008] [Accepted: 10/06/2008] [Indexed: 05/27/2023]
Abstract
Topological thinning is a valid but time-consuming method to calculate the centerline of human colon or other hollow organs accurately. An optimized 3D topological thinning method based on Look-up Table (LUT), which was proposed by Sadlier, proves to be effective in improving the efficiency on many occasions. However, it is still inefficient when processing some complex datasets. In this paper, we first analyze the reason causing the unstable performance, and then present an extension to Sadlier's method, which enables the rapid execution of the extraneous loops removing by avoiding unnecessary global connectivity testing. To reach this purpose, a min-heap structure is introduced to select a seed from the candidate voxels set of the final centerline, and region growing technique is used to find the voxels in the same branch with the seed. The comparison among the standard topological thinning, LUT method and the extension to LUT method indicates the extension achieves the most efficient performance.
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Xu L, Stoica P, Li J, Bressler SL, Shao X, Ding M. ASEO: A Method for the Simultaneous Estimation of Single-Trial Event-Related Potentials and Ongoing Brain Activities. IEEE Trans Biomed Eng 2009. [DOI: 10.1109/tbme.2007.901025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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104
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Yang D, Ding M, Mo Y, Zhang Q, Wang W, Li Y. The impact of chemotherapy on ovarian function in premenopausal patients with breast cancer. Fertil Steril 2008. [DOI: 10.1016/j.fertnstert.2008.07.879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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105
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Jiang W, Bai Z, Zhang D, Shi Y, Yong J, Chen S, Ding M, Deng H. Differentiation of mouse nuclear transfer embryonic stem cells into functional pancreatic beta cells. Diabetologia 2008; 51:1671-9. [PMID: 18581093 DOI: 10.1007/s00125-008-1065-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2008] [Accepted: 04/18/2008] [Indexed: 10/21/2022]
Abstract
AIMS/HYPOTHESIS Therapeutic cloning has been reported to have potential in the treatment of several degenerative diseases. However, it has yet to be determined whether mouse nuclear transfer-embryonic stem cells (NT-ESCs) can be differentiated into pancreatic beta cells and used to reverse diabetes in an animal model. METHODS We first used the somatic nuclear transfer technique to generate mouse NT-ESCs and then developed a chemically defined stepwise protocol to direct the NT-ESCs into functional pancreatic beta cells. We examined the gene expression pattern of the differentiated NT-ESCs and transplanted the NT-ESC-derived insulin-producing cells into recipient diabetic mice. RESULTS Four mouse NT-ESC lines were first established using an improved nuclear transfer technique and insulin-producing cells were efficiently generated from NT-ESCs by mimicking pancreatic in vivo development. Most of the insulin-producing cells that we generated co-produced pancreatic and duodenal homeobox 1, but not glucagon at the final stage of this differentiation method, which differed from the insulin and glucagon co-production reported by other groups. The differentiated NT-ESCs were able to release insulin in response to glucose stimuli and normalise the blood glucose level of diabetic mice for at least 2 months. CONCLUSIONS/INTERPRETATION These results demonstrate the potential of therapeutic cloning for cell therapy of type 1 diabetes in a mouse model.
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Zhang Y, Chen Y, Bressler SL, Ding M. Response preparation and inhibition: the role of the cortical sensorimotor beta rhythm. Neuroscience 2008; 156:238-46. [PMID: 18674598 DOI: 10.1016/j.neuroscience.2008.06.061] [Citation(s) in RCA: 187] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Revised: 06/23/2008] [Accepted: 06/24/2008] [Indexed: 10/21/2022]
Abstract
Paradigms requiring either a GO or a NO-GO response are often used to study the neural mechanisms of response inhibition. Here this issue is examined from the perspective of event-related beta (14-30 Hz) oscillatory activity. Two macaque monkeys performed a task that began with a self-initiated lever depression and maintenance (sustained motor output) and required a visual pattern discrimination followed by either a lever release (GO) or continued lever-holding (NO-GO) response. Analyzing simultaneous local field potentials (LFPs) from primary somatosensory, frontal motor, and posterior parietal cortices, we report two results. First, beta oscillation desynchronized shortly after stimulus presentation, the onset of which was approximately the same for both the GO and NO-GO conditions ( approximately 110 ms). Since it is well known that beta desynchronization is a reliable indicator of movement preparation, this result suggests that early motor preparation took place in both conditions. Second, following the GO/NO-GO decision ( approximately 190 ms), beta activity rebounded significantly ( approximately 300 ms) only in the NO-GO condition. Coherence and Granger causality measures revealed that the dynamical organization of the rebounded beta network was similar to that existing during the sustained motor output prior to stimulus onset. This finding suggests that response inhibition led to the restoration of the sensorimotor network to its prestimulus state.
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107
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Ding M, Newman F, Gaspar L, Kavanagh B, Stuhr K, Raben D, Li JS, Ma CM. A 4D treatment planning tool for the evaluation of motion effects on lung cancer treatments. ACTA ACUST UNITED AC 2008. [DOI: 10.1088/1742-6596/102/1/012008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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108
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Ding M, Lu L, Toth LA. Gene expression in lung and basal forebrain during influenza infection in mice. GENES BRAIN AND BEHAVIOR 2008; 7:173-83. [PMID: 17696998 DOI: 10.1111/j.1601-183x.2007.00335.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Inbred mice develop strain-dependent changes in sleep during the first few days after inoculation with influenza virus. To identify genes with the potential to differentially modulate sleep under this condition, we performed complementary DNA microarray analysis of both lung and basal forebrain (BF) of infected (I) and uninfected BALB/cByJ (C) and C57BL/6J (B6) mice. This analysis showed significant variation in the expression pattern of 667 and 1217 of the surveyed genes in BF and lung, respectively (P < 0.01). Applying the additional criterion of an effect size >or=2, 495 genes differed in expression in lung compared with 204 in BF. In BF, more genes were differentially expressed as a function of mouse strain, whereas in lung, more genes were differentially expressed as a function of health status. Significant alterations in expression after infection were more numerous and robust in BALB/cByJ vs. C57BL/6J mice. Some genes showed significant variation in both tissues as a function of strain or condition, but the changes in general were not parallel. Genes that showed significant and robust variation as a function of strain, health status or tissue included those related to immune function, metabolism, signal transduction, cell cycle regulation, apoptosis and other miscellaneous categories. Different patterns of gene expression in BF of uninfected mice suggest the possibility of fundamental mechanistic differences in pathways that modulate vigilance in these strains, whereas differences in expression of lung of infected mice suggests different peripherally generated sleep-modulatory stimuli in the two strains.
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Qing T, Liu H, Wei W, Ye X, Shen W, Zhang D, Song Z, Yang W, Ding M, Deng H. Mature oocytes derived from purified mouse fetal germ cells. Hum Reprod 2007; 23:54-61. [DOI: 10.1093/humrep/dem334] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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110
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Wang YH, Zhang ZK, He HP, Wang JS, Zhou H, Ding M, Hao XJ. Stilbene C-glucosides from Cissus repens. JOURNAL OF ASIAN NATURAL PRODUCTS RESEARCH 2007; 9:631-636. [PMID: 17943557 DOI: 10.1080/10286020600979548] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Four new stilbene C-glucosides, namely trans-3-O-methyl-resveratrol-2-C-beta-glucoside (1), cis-3-O-methyl-resveratrol-2-C-beta-glucoside (2), trans-3-O-methyl-resveratrol-2-(2-p-coumaric)-C-beta-glucoside (cissuside A) (3), and trans-3-O-methyl-resveratrol-2-(3-p-coumaric)-C-beta-glucoside (cissuside B) (4), were isolated from the aerial parts of Cissus repens, along with known trans-resveratrol (5), trans-resveratrol-2-C-beta-glucoside (6) and cis-resveratrol-2-C-beta-glucoside (7). Their structures were established by spectroscopic methods. Stilbene C-glucosides were found in the genus Cissus for the first time.
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Asadi-Zeydabadi M, Newman F, Stuhr K, Ding M, Durairaj V, Kavanagh B. TU-C-AUD-01: Visual Sensations During Megavoltage Radiotherapy to the Orbit Attributable to Cherenkov Radiation. Med Phys 2007. [DOI: 10.1118/1.2761350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Abstract
Abstract
Conventional capillary number theory predicts that residual oil will not be mobilized until a critical capillary number (2E - 5) is exceeded. This theory was tested to determine residual oil saturation mobilization after forced water imbibition. In the literature, high residual oil saturation was established from waterflooding at a certain pressure. Then gradually increasing pressure was applied for water injection until residual oil production was observed. It was confirmed that this critical capillary number is applicable when the initial residual oil saturation was estimated from spontaneous water imbibition tests. The same types of experiments were repeated for gas-liquid systems by creating the initial residual gas saturation through spontaneous oil or water imbibition tests on the same samples. The procedures, which included spontaneous imbibition tests followed by forced imbibition tests, were monitored by an on-line NMR system. Analysis of the experimental results produced an estimate of the critical capillary number for mobilizing residual gas from water imbibition or oil imbibition tests. In this research, we broadened the term of "imbibition" for both water and oil terms since, compared to gas, both water and oil are in the wetting phase. It was found that the critical capillary number for a gas-liquid system is very different from that of an oil-water system in the same type of rock.
Berea sandstone plugs were used in all the experiments. The reason for using Berea sandstone plugs is due to their relatively homogeneous pore structure. Additional Western Canadian sandstone plugs were used for testing gas-water systems to confirm the results obtained from the Berea sandstone plugs. Understanding the different mechanisms to produce discontinuous residual oil or residual gas is important for enhanced oil and gas recovery operations. Hopefully, this research can provide new insights into recovering additional gas from gas reservoirs with active aquifers.
Introduction
Increasing the capillary number has long been investigated as a strategy for improving oil recovery. Many methodologies around increasing the capillary number have been either tested in the laboratory or applied in the field. Capillary number is defined as the ratio of viscous forces to capillary forces. Evaluation of the capillary number can be used to describe the relative importance of viscous forces to capillary forces during immiscible displacements. There are various forms of the capillary number. The most common versions of capillary number are those by Saffman and Taylor(1):
Equation (1) (Available in full paper)
and Melrose and Brandner(2):
Equation (2) (Available in full paper)
When non-wetting phase oil is trapped in porous media, the pressure gradient required to move it through a capillary tube is much higher than what would be predicted by the pipe flow equation, due to the pressure discontinuity at the wetting/non-wetting interface. Because of the contact angle hysteresis, this discontinuity is not of the same magnitude on both sides of the discontinuous non-wetting phase. For example, in a water-wet medium, an oil droplet represents the discontinuous non-wetting phase. As the oil droplet is pushed through a pore throat, its downstream end gets squeezed into a much narrower segment making its radius of curvature much smaller than the upstream part.
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Ding M, Cui S, Li C, Jothy S, Haase V, Steer B, Marsden P, Pippin J, Shankland S, Rastaldi M, Cohen C, Kretzler M, Quaggin S. Faulty Podocyte Hypoxia Sensing—A Novel Pathway for Rapidly Progressive Glomerulonephritis. J Am Soc Nephrol 2006. [DOI: 10.1681/asn.2006101148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
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114
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Ding M, Xing L, Xiong W, Stuhr K, Newman F. 2797. Int J Radiat Oncol Biol Phys 2006. [DOI: 10.1016/j.ijrobp.2006.07.1215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Schwer A, Borges V, Ding M, Kavanagh B. 2698. Int J Radiat Oncol Biol Phys 2006. [DOI: 10.1016/j.ijrobp.2006.07.1114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Bridgland-Taylor MH, Hargreaves AC, Easter A, Orme A, Henthorn DC, Ding M, Davis AM, Small BG, Heapy CG, Abi-Gerges N, Persson F, Jacobson I, Sullivan M, Albertson N, Hammond TG, Sullivan E, Valentin JP, Pollard CE. Optimisation and validation of a medium-throughput electrophysiology-based hERG assay using IonWorks™ HT. J Pharmacol Toxicol Methods 2006; 54:189-99. [PMID: 16563806 DOI: 10.1016/j.vascn.2006.02.003] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2005] [Accepted: 02/12/2006] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Regulatory and competitive pressure to reduce the QT interval prolongation risk of potential new drugs has led to focus on methods to test for inhibition of the human ether-a-go-go-related gene (hERG)-encoded K+ channel, the primary molecular target underlying this safety issue. Here we describe the validation of a method that combines medium-throughput with direct assessment of channel function. METHODS The electrophysiological and pharmacological properties of hERG were compared using two methods: conventional, low-throughput electrophysiology and planar-array-based, medium-throughput electrophysiology (IonWorks HT). A pharmacological comparison was also made between IonWorks HT and an indirect assay (Rb+ efflux). RESULTS Basic electrophysiological properties of hERG were similar whether recorded conventionally (HEK cells) or using IonWorks HT (CHO cells): for example, tail current V1/2 -12.1+/-5.0 mV (32) for conventional and -9.5+/-6.0 mV (46) for IonWorks HT (mean+/-S.D. (n)). A key finding was that as the number of cells per well was increased in IonWorks HT, the potency reported for a given compound decreased. Using the lowest possible cell concentration (250,000 cells/ml) and 89 compounds spanning a broad potency range, the pIC50 values from IonWorks HT (CHO-hERG) were found to correlate well with those obtained using conventional methodology (HEK-hERG)(r=0.90; p<0.001). Further validation using CHO-hERG cells with both methods confirmed the correlation (r=0.94; p<0.001). In contrast, a comparison of IonWorks HT and Rb+ efflux data with 649 compounds using CHO-hERG cells showed that the indirect assay consistently reported compounds as being, on average, 6-fold less potent, though the differences varied depending on chemical series. DISCUSSION The main finding of this work is that providing a relatively low cell concentration is used in IonWorks HT, the potency information generated correlates well with that determined using conventional electrophysiology. The effect on potency of increasing cell concentration may relate to a reduced free concentration of test compound owing to partitioning into cell membranes. In summary, the IonWorks HT hERG assay can generate pIC50 values based on a direct assessment of channel function in a timeframe short enough to influence chemical design.
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Ding M, Stuhr K, Newman F, Johnson T, Kavanagh B. SU-FF-J-17: Accuracy and Dosimetric Advantage of Target Localization Using Stereoscopic Image-Guided Radiotherapy for Lung Cancer Treatment. Med Phys 2006. [DOI: 10.1118/1.2240796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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118
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Ding M, Xing L, Newman F. SU-FF-T-300: Investigation of Respiratory Motion Effect On Lung Tumor Radiotherapy Using 4D Monte Carlo Treatment Planning and 4D CT. Med Phys 2006. [DOI: 10.1118/1.2241217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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119
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Ding M, Danielsen CC, Hvid I. Age-related three-dimensional microarchitectural adaptations of subchondral bone tissues in guinea pig primary osteoarthrosis. Calcif Tissue Int 2006; 78:113-22. [PMID: 16397735 DOI: 10.1007/s00223-005-0028-5] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2005] [Accepted: 09/13/2005] [Indexed: 11/24/2022]
Abstract
We explored potential mechanisms of the microarchitectural adaptations of subchondral bone tissues in a guinea pig primary osteoarthrosis (OA) model. We harvested proximal tibiae of male Dunkin-Hartley (Charles River strain) guinea pigs at 3, 6, 9, 12, and 24 months of age (10 in each group). These proximal tibiae were scanned by micro-computed tomography to quantify the three-dimensional microarchitecture of the subchondral plate, cancellous bone, and cortical bone. Subsequently, the bones were compression-tested to determine their mechanical properties. Furthermore, bone collagen, bone mineral, and bone density were determined. Mankin's score corresponded to OA grading from absent or minimal cartilage degeneration in 3-month-old to severe degeneration in 24-month-old guinea pigs. In young guinea pigs, the volume fraction and thickness of the subchondral plate markedly increased from 3 to 6 months, whereas the volume fraction of the subchondral cancellous bone displayed an initial decline followed by an increase. With age, the trabeculae increased in thickness, changed from rod-like to plate-like, and became more axially oriented. An increasing ratio of bone collagen to mineral in subchondral bone indicated undermineralized bone tissues. In subchondral cancellous bone, Young's modulus was maximal at 6 months of age, whereas ultimate stress and failure energy showed a gradual increase with age. The findings show pronounced alterations of the microarchitecture and bone matrix composition of the subchondral bone. These alterations did not appear to follow the same pattern as in normal aging and may have different influences on the resulting mechanical properties.
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Ding M, Kananagh B, Schefter T, Stuhr K, Newman F. The Influence of Heterogeneity Corrections on Tumor and Normal Lung Dosimetry in Stereotactic Body Radiation Therapy for Lung Cancer Treatment. Int J Radiat Oncol Biol Phys 2005. [DOI: 10.1016/j.ijrobp.2005.07.867] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Eckardt H, Ding M, Lind M, Hansen ES, Christensen KS, Hvid I. Recombinant human vascular endothelial growth factor enhances bone healing in an experimental nonunion model. ACTA ACUST UNITED AC 2005; 87:1434-8. [PMID: 16189323 DOI: 10.1302/0301-620x.87b10.16226] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The re-establishment of vascularity is an early event in fracture healing; upregulation of angiogenesis may therefore promote the formation of bone. We have investigated the capacity of vascular endothelial growth factor (VEGF) to stimulate the formation of bone in an experimental atrophic nonunion model. Three groups of eight rabbits underwent a standard nonunion operation. This was followed by interfragmentary deposition of 100 μg VEGF, carrier alone or autograft. After seven weeks, torsional failure tests and callus size confirmed that VEGF-treated osteotomies had united whereas the carrier-treated osteotomies failed to unite. The biomechanical properties of the groups treated with VEGF and autograft were identical. There was no difference in bone blood flow. We considered that VEGF stimulated the formation of competent bone in an environment deprived of its normal vascularisation and osteoprogenitor cell supply. It could be used to enhance the healing of fractures predisposed to nonunion.
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Cormier JN, Xing Y, Ding M, Ross MI, Lee JE, Mansfield PF, Gershenwald JE, Du XL. Population based assessment of surgical treatment trends for melanoma patients. J Clin Oncol 2005. [DOI: 10.1200/jco.2005.23.16_suppl.7509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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123
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Ding M, Newman F, Stuhr K, Johnson T. SU-FF-T-350: A Comparative Dosimetric Study of Three-Dimensional Conformal, Dynamic Conformal Arc, and Intensity Modulated Radiation Therapy for Brain Tumor Treatment. Med Phys 2005. [DOI: 10.1118/1.1998079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Ding M, Newman F, Stuhr K. SU-FF-T-413: The Impact of Heterogeneity Correction On Tumor Dosimetry for Lung Cancer Stereotactic Body Radiation Therapy. Med Phys 2005. [DOI: 10.1118/1.1998212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Chen L, Price RA, Nguyen TB, Wang L, Li JS, Qin L, Ding M, Palacio E, Ma CM, Pollack A. Dosimetric evaluation of MRI-based treatment planning for prostate cancer. Phys Med Biol 2005; 49:5157-70. [PMID: 15609565 DOI: 10.1088/0031-9155/49/22/010] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The purpose of this study is to evaluate the dosimetric accuracy of MRI-based treatment planning for prostate cancer using a commercial radiotherapy treatment planning system. Three-dimensional conformal plans for 15 prostate patients were generated using the AcQPlan system. For each patient, dose distributions were calculated using patient CT data with and without heterogeneity correction, and using patient MRI data without heterogeneity correction. MR images were post-processed using the gradient distortion correction (GDC) software. The distortion corrected MR images were fused to the corresponding CT for each patient for target and structure delineation. The femoral heads were delineated based on CT. Other anatomic structures relevant to the treatment (i.e., prostate, seminal vesicles, lymph notes, rectum and bladder) were delineated based on MRI. The external contours were drawn separately on CT and MRI. The same internal contours were used in the dose calculation using CT- and MRI-based geometries by directly transferring them between MRI and CT as needed. Treatment plans were evaluated based on maximum dose, isodose distributions and dose-volume histograms. The results confirm previous investigations that there is no clinically significant dose difference between CT-based prostate plans with and without heterogeneity correction. The difference in the target dose between CT- and MRI-based plans using homogeneous geometry was within 2.5%. Our results suggest that MRI-based treatment planning is suitable for radiotherapy of prostate cancer.
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