semiconductor-based direct conversion detectors revolutionized radiation medical imaging since they allowed diagnostic capabilities not achievable with other detector approaches. the areas of highest impact are x-ray radiography and nuclear medicine. semiconductor detectors are also of a great significance to the field of x-ray computed tomography (ct) as they promise significant increase in intrinsic energy and spatial resolutions needed for better energy and material resolved ct imaging. cadmium zinc telluride (czt) is a material of choice for direct conversion ct detectors. recently, czt has been successfully employed in gamma cameras operating in ct-relevant energy range. however, for use in ct, czt has to demonstrate electronic properties that satisfy the requirement of high x-ray fluxes typical for ct; this includes prevention of possible buildup of space charge and related dynamic polarization of a detector material. therefore, the overall objective of this project is to investigate transport of photo-generated charge carriers in czt (i.e, electron and hole mobilities and their temperatures and field dependencies) and to evaluate the potential of czt photoconductor to be used in advanced ct detectors.

the post solid-state detectors for advanced ct appeared first on rezniklab and posted by pavlo karasyuk.

there is a great interest in utilization of non-crystalline photoconductors for direct conversion medical x-ray imaging detectors. currently, the only direct conversion detectors, available on the market, are amorphous selenium (a-se) based. unfortunately, a-se is a low z (atomic number) material and suffers from low x-ray stopping power. this limits the application of direct conversion detectors to high-dose and low x-ray energy procedures (mammography). for low dose and high-energy imaging (fluoroscopy), a-se must be replaced by high z material. potential candidates are: polycrystalline layers of hgi2, pbi2, tlbr, cdznte and pbo. poly-pbo holds a special place in this list: like a-se, it was previously successfully utilized in optical imaging (plumbicons pick up tubes) that suggests its appropriate photoconductive properties. a further advantage of pbo over other candidates is the absence of heavy absorption edges up to 88 kev, which inherently offers the higher spatial resolution. in 2005 simon et al showed a prototype of a pbo-based flat-panel x-ray detector characterized by very high spatial resolution and charge yield sufficient for low dose imaging. however, at that time, poly-pbo layers exhibited the residual signal after the end of x-ray exposure, called lag. reported signal lag restricts application of pbo to static imaging only and obscures full potential of pbo for medical imaging.
we have developed a practical approach that allows to combat the signal lag. the objective is achieved by advancing the deposition technology and provides a novel type of amorphous lead oxide (a-pbo). the results on temporal response of novel a-pbo samples were found to compare favorably to published results on poly-pbo and a-se films. our advances in pbo technology offer a-pbo films, suitable for real time x-ray imaging.

you can read more about the current work in our latest publications on the topic: “comparative analysis of multilayer lead oxide-based x-ray detector prototypes”, “dark current modeling for a polyimide—amorphous lead oxide-based direct conversion x-ray detector”

the post real-time low-dose x-ray imaging appeared first on rezniklab and posted by pavlo karasyuk.

breast cancer accounts for approximately 26% of all cancers diagnosed today. like other cancers, breast cancer is most successfully treated if the disease is diagnosed early. the major problem is distinguishing between benign and malignant masses. women are forced to contemplate prophylactic mastectomy because predictive power of current imaging is poor.
radialis corporation (a spin-off company of the tbrhri and 阿根廷vs墨西哥竞猜 ) is manufacturing an advanced positron emission mammography (pem) system for molecular (or functional) imaging of breast cancer. pem detects small cancerous breast lesions based on their increased glucose metabolism and such its imaging performance is inherently independent on breast tissue density.
the core technology of the pem system was developed in our research laboratory under the supervision of dr. alla reznik. radialis pem employs 2 planar high-resolution detector heads placed on both sides of gently steadied breast (see figure above). pem only requires breast immobilization rather than compression and hence completely eliminates pain. during image acquisition, detectors fully cover the entire breast that allows for improved sensitivity capable of significant radiation dose reduction in comparison with commercially available scanners. large field-of-view detector design enables high-resolution. tumors as small as 1.2 mm will be detectable by the initial results of radials’s pem system.
radialis’s pem technology can be used as an adjuvant technique for breast cancer detection, and an integral part of the surveillance protocol of women at high and intermediate lifetime risk of breast cancer. technological advances used will reduce manufacturing cost for pem devices, thus positively influence people health.

for more information, please see an article “using positron emission mammography to detect breast cancer” or our latest publication on the topic: “evaluation of a high-sensitivity organ-targeted pet camera”.

the post low-dose organ-targeted positron emission tomography appeared first on rezniklab and posted by pavlo karasyuk.