A new reconstruction strategy for image improvement in pinhole SPECT

Zeniya, Tsutomu; Watabe, Hiroshi; Aoi, Toshiyuki; Kim, Kyeong Min; Teramoto, Noboru; Hayashi, Takuya; Sohlberg, Antti; Kudo, Hiroyuki; Iida, Hidehiro

doi:10.1007/s00259-004-1510-4

Cited by 30 publications

(28 citation statements)

References 19 publications

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“…This non-uniformity of spatial resolution can be improved by complete data acquisition as demonstrated in our earlier study. 18 Besides high spatial resolution, the SPECT system has several advantages over PET as its operation is simple, and it does not require an on-site radiochemistry laboratory or a cyclotron for producing radiopharmaceuticals. Pinhole SPECT systems are often composed of clinically used SPECT cameras with pinhole collimator.…”

Section: Introductionmentioning

confidence: 99%

Use of a compact pixellated gamma camera for small animal pinhole SPECT imaging

et al. 2006

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Section: Introductionmentioning

confidence: 99%

Use of a compact pixellated gamma camera for small animal pinhole SPECT imaging

et al. 2006

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“…The transverse images of hot and cold regions were produced using a Filtered back projection (FBP) image reconstruction technique which is fast, easy to implement and most widely applied in SPECT [14]. Chang's attenuation correction technique was applied for compensation of the absorption of gamma photons within the phantom.…”

Section: Spect Image Reconstructionmentioning

confidence: 99%

Effect of Cut-Off Frequency of Butterworth Filter on Detectability and Contrast of Hot and Cold Regions in Tc-99m SPECT

Sayed¹,

Nasrudin²

2016

IJMPCERO

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In SPECT, noise is one of the major limitations that degrade image quality. To suppress the noisy signals in an image, digital filters are most commonly applied. However, in SPECT image reconstruction, selection of an appropriate filter and its functions has always remained a difficult task. In this work an attempt was made to investigate the effects of varying cut-off frequencies and in keeping the order of Butterworth filter constant on detectability and contrast of hot and cold regions images. A new insert simulating hot and cold regions which provides similar views in a reconstructed image was placed in the phantom's cylindrical source tank and imaged. Tc-99m radionuclide was distributed uniformly in the phantom. SPECT data were collected in a 20% energy window centered at 140 keV by a Philips ADAC Forte dual head gamma camera mounted with a LEHR collimator. Images were generated by using the filtered backprojection technique. A Butterworth filter of order 5 with cut-off frequencies 0.35 and 0.45 cycles•cm −1 was applied. Images were examined in terms of hot and cold regions, detectability and contrast. Results show that the hot and cold regions' detectability and contrast vary with the change of cut-off frequency. With a 0.45 cycles•cm −1 cut-off frequency, a significant enhancement in contrast of cold regions was achieved as compared to a 0.35 cycles•cm −1 cut-off frequency. Furthermore, the detectability of hot and cold regions improved with the use of a 0.45 cycles•cm −1 cut-off frequency. In conclusion, image quality of hot and cold regions affected in a different way with a change of cut-off frequency. Thus, care should be taken in selecting the filter cut-off frequency prior to reconstruction of images; particularly, when both types of regions are expected in the reconstructed image.

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“…In this case, the collection efficiency is minimal due to the fact that the system sensitivity and system spatial resolution operate as opposing magnitudes. 2,[6][7][8] The spatial resolution also depends on the source-collimator distance. As this distance increases, the spatial resolution severely worsens.…”

Section: Introductionmentioning

confidence: 99%

Stereoscopic full aperture imaging in nuclear medicine

Strocovsky

Otero

2011

AIP Advances

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Images of planar scintigraphy and single photon emission computerized tomography (SPECT) used in nuclear medicine are often low quality. They usually appear to be blurred and noisy. This problem is due to the low spatial resolution and poor sensitivity of the acquisition technique with the gamma camera (GC). Other techniques, such as coded aperture imaging (CAI) reach higher spatial resolutions than GC. However, CAI is not frequently used for imaging in nuclear medicine, due to the decoding complexity of some images and the difficulty in controlling the noise magnitude. Summing up, the images obtained through GC are low quality and it is still difficult to implement CAI technique. A novel technique, full aperture Imaging (FAI), also uses gamma ray-encoding to obtain images, but the coding system and the method of images reconstruction are simpler than those used in CAI. In addition, FAI also reaches higher spatial resolution than GC. In this work, the principles of FAI technique and the method of images reconstruction are explained in detail. The FAI technique is tested by means of Monte Carlo simulations with filiform and spherical sources. Spatial resolution tests of GC versus FAI were performed using two different sourcedetector distances. First, simulations were made without interposing any material between the sources and the detector. Then, other more realistic simulations were made. In these, the sources were placed in the centre of a rectangular prismatic region, filled with water. A rigorous comparison was made between GC and FAI images of the linear filiform sources, by means of two methods: mean fluence profile graphs and correlation tests. Finally, three-dimensional capacity of FAI was tested with two spherical sources. The results show that FAI technique has greater sensitivity (>100 times) and greater spatial resolution (>2.6 times) than that of GC with LEHR collimator, in both cases, with and without attenuating material and long and shortdistance configurations. The FAI decoding algorithm reconstructs simultaneously four different projections which are located in separate image fields on the detector plane, while GC produces only one projection per acquisition. Simulations have allowed comparison of both techniques under ideal identical conditions. Our results show it is possible to apply an extremely simple encoded imaging technique, and get three-dimensional radioactivity information for simplistic geometry sources. The results are promising enough to evaluate the possibility of future research with more complex sources typical of nuclear medicine imaging.

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A new reconstruction strategy for image improvement in pinhole SPECT

Cited by 30 publications

References 19 publications

Use of a compact pixellated gamma camera for small animal pinhole SPECT imaging

Use of a compact pixellated gamma camera for small animal pinhole SPECT imaging

Effect of Cut-Off Frequency of Butterworth Filter on Detectability and Contrast of Hot and Cold Regions in Tc-99m SPECT

Stereoscopic full aperture imaging in nuclear medicine

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