A dynamic micro-CT scanner based on a carbon nanotube field emission x-ray source

Cao, Guohua; Lee, Yueh Z.; Peng, Rui; Liu, Z; Rajaram, Ramya; Calderón‐Colón, Xiomara; An, Li; Wang, P; Phan, Thanh T.N.; Sultana, Shabana; Lalush, David S.; Lü, Jianping; Zhou, Otto

doi:10.1088/0031-9155/54/8/005

Cited by 111 publications

(70 citation statements)

References 32 publications

(43 reference statements)

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“…The respiration signal is obtained from a sensor pad placed on the surface of the animal under the abdomen to monitor chest cavity motion. 23,24,26 The respiration sensor is a foam pad encased in a rubber shell attached to thin tubing running into the sensor processor. The signal measures the pressure change in the tubing caused by the compression of the foam.…”

Section: B Physiological Motion Monitoringmentioning

confidence: 99%

Physiologically gated microbeam radiation using a field emission x‐ray source array

et al. 2014

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Purpose: Microbeam radiation therapy (MRT) uses narrow planes of high dose radiation beams to treat cancerous tumors. This experimental therapy method based on synchrotron radiation has been shown to spare normal tissue at up to 1000 Gy of peak entrance dose while still being effective in tumor eradication and extending the lifetime of tumor-bearing small animal models. Motion during treatment can lead to significant movement of microbeam positions resulting in broader beam width and lower peak to valley dose ratio (PVDR), which reduces the effectiveness of MRT. Recently, the authors have demonstrated the feasibility of generating microbeam radiation for small animal treatment using a carbon nanotube (CNT) x-ray source array. The purpose of this study is to incorporate physiological gating to the CNT microbeam irradiator to minimize motion-induced microbeam blurring. Methods: The CNT field emission x-ray source array with a narrow line focal track was operated at 160 kVp. The x-ray radiation was collimated to a single 280 μm wide microbeam at entrance. The microbeam beam pattern was recorded using EBT2 Gafchromic c films. For the feasibility study, a strip of EBT2 film was attached to an oscillating mechanical phantom mimicking mouse chest respiratory motion. The servo arm was put against a pressure sensor to monitor the motion. The film was irradiated with three microbeams under gated and nongated conditions and the full width at half maximums and PVDRs were compared. An in vivo study was also performed with adult male athymic mice. The liver was chosen as the target organ for proof of concept due to its large motion during respiration compared to other organs. The mouse was immobilized in a specialized mouse bed and anesthetized using isoflurane. A pressure sensor was attached to a mouse's chest to monitor its respiration. The output signal triggered the electron extraction voltage of the field emission source such that x-ray was generated only during a portion of the mouse respiratory cycle when there was minimum motion. Parallel planes of microbeams with 12.4 Gy/plane dose and 900 μm pitch were delivered. The microbeam profiles with and without gating were analyzed using γ -H2Ax immunofluorescence staining. Results: The phantom study showed that the respiratory motion caused a 50% drop in PVDR from 11.5 when there is no motion to 5.4, whereas there was only a 5.5% decrease in PVDR for gated irradiation compared to the no motion case. In the in vivo study, the histology result showed gating increased PVDR by a factor of 2.4 compared to the nongated case, similar to the result from the phantom study. The full width at tenth maximum of the microbeam decreased by 40% in gating in vivo and close to 38% with phantom studies. Conclusions:The CNT field emission x-ray source array can be synchronized to physiological signals for gated delivery of x-ray radiation to minimize motion-induced beam blurring. Gated MRT reduces valley dose between lines during long-time radiation of a moving object. The technique allows for...

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Section: B Physiological Motion Monitoringmentioning

confidence: 99%

Physiologically gated microbeam radiation using a field emission x‐ray source array

et al. 2014

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“…This type of imaging can be done also with sources operating in continuous mode by using external shutters with open time windows > 30 ms; nevertheless, the total number of photons emitted in each pulse is very low in this second case, and the x-ray transmission through the closed shutter must be taken into account for proper raw data calibration. More recently, Cao et al have investigated the use of a compact field emission microfocus x-ray source based on carbon nanotube (Cao et al, 2009(Cao et al, , 2010. In this type of source, the metal filament cathode is replaced by a field emission cathode that is capable of emitting electrons at room temperature with voltage-controlled output current (Yue et al, 2002).…”

Section: X-ray Sourcesmentioning

confidence: 99%

High-Resolution CT for Small-Animal Imaging Research

Badea

Panetta²

2014

Comprehensive Biomedical Physics

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“…ϫ 0.5 mm 2 cathode has been reported previously. 29 The beam-to-beam variation among the 25 x-ray beams is ϳ20 m.…”

Section: Fig 12mentioning

confidence: 99%

“…27,28 The technology enables the design of tomography systems with great flexibility in source configuration and imaging sequence. It is now being actively investigated for both preclinical 29 and clinical 30 imaging applications. Based on this MBFEX technology, we recently proposed the concept of a stationary DBT ͑s-DBT͒ scanner.…”

Section: Introductionmentioning

confidence: 99%

Design and characterization of a spatially distributed multibeam field emission x‐ray source for stationary digital breast tomosynthesis

et al. 2009

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Digital breast tomosynthesis ͑DBT͒ is a limited angle computed tomography technique that can distinguish tumors from its overlying breast tissues and has potentials for detection of cancers at a smaller size and earlier stage. Current prototype DBT scanners are based on the regular full-field digital mammography systems and require partial isocentric motion of an x-ray tube over certain angular range to record the projection views. This prolongs the scanning time and, in turn, degrades the imaging quality due to motion blur. To mitigate the above limitations, the concept of a stationary DBT ͑s-DBT͒ scanner has been recently proposed based on the newly developed spatially distributed multibeam field emission x-ray ͑MBFEX͒ source technique using the carbon nanotube. The purpose of this article is to evaluate the performance of the 25-beam MBFEX source array that has been designed and fabricated for the s-DBT system. The s-DBT system records all the projection images by electronically activating the multiple x-ray beams from different viewing angles without any mechanical motion. The configuration of the MBFEX source is close to the published values from the Siemens Mammomat system. The key issues including the x-ray flux, focal spot size, spatial resolution, scanning time, beam-to-beam consistency, and reliability are evaluated using the standard procedures. In this article, the authors describe the design and performance of a distributed x-ray source array specifically designed for the s-DBT system. They evaluate the emission current, current variation, lifetime, and focal spot sizes of the source array. An emission current of up to 18 mA was obtained at 0.5ϫ 0.3 mm effective focal spot size. The experimentally measured focal spot sizes are comparable to that of a typical commercial mammography tube without motion blurring. Trade-off between the system spatial resolution, x-ray flux, and scanning time are also discussed. Projection images of a breast phantom were collected using the x-ray source array from 25 different viewing angles without motion. These preliminary results demonstrate the feasibility of the proposed s-DBT scanner. The technology has the potential to increase the resolution and reduce the imaging time for DBT. experimentally the feasibility of achieving 11 s scanning time at full detector resolution with 0.5 ϫ 0.3 mm source resolution without motion blur. The flexibility in configuration of the x-ray source array will also allow system designers to consider imaging geometries that are difficult to achieve with the conventional single-source rotating approach.

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A dynamic micro-CT scanner based on a carbon nanotube field emission x-ray source

Cited by 111 publications

References 32 publications

Physiologically gated microbeam radiation using a field emission x‐ray source array

Physiologically gated microbeam radiation using a field emission x‐ray source array

High-Resolution CT for Small-Animal Imaging Research

Design and characterization of a spatially distributed multibeam field emission x‐ray source for stationary digital breast tomosynthesis

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