Effects of cervical collar on entrance surface dose, exit surface dose and image quality in plain radiography: a phantom study

Introduction: Trauma patients presented to emergency department usually come with spinal immobilization device as a precaution and initial pre-management care by emergency medical personnel. These types of patients are at higher risk for suspected cervical fractures and internal injuries. The use of cervical collar raises some issues on radiation dose to the patient and image quality. Therefore, the use of cervical collar in routine trauma patients is questioned by researchers. The purpose of this paper was to investigate the effect of cervical collar on entrance surface dose, exit surface dose and image quality. Methods: Siemens Multix Top CR System and Kyoto Kagaku PBU-50 Body Phantom was used. The phantom was positioned supine on the table couch and was exposed with and without cervical collar. An Anteroposterior (AP) Axial cervical projection was performed and the phantom was also exposed with and without Automatic Exposure Control (AEC) to study the effects on radiation dose and image quality. The dose reading was recorded in all exposures and compared. Images obtained were analyzed for Signal to Noise Ratio (SNR). Results: Lower entrance dose was recorded with cervical collar when the AEC was disabled during the exposure and the results were vice versa when the AEC was enabled. Higher exit dose was calculated when cervical collar was applied to the phantom. Greater signal to noise ratio (SNR) was observed with cervical collar. Conclusions: This study concluded that cervical collar adds to exit dose and without any impact on image quality. The entrance surface dose recorded with cervical collar and AEC disabled was lower compared to when it was removed. The entrance dose recorded with collar and the AEC enabled was higher compared to when it was removed

Hybrid Imaging-SPECT/CT: making a difference

Abstract: With the technological advancements in the medical imaging field, the past decade has witnessed a dramatic evolution of multimodality imaging systems. Scientists, technologists and researchers have been able to bring systems in clinical practice, in which two or more standalone diagnostic imaging modalities have been combined. Some of those multimodality imaging systems are: PET/CT, SPECT/CT, PET/MRI and PET/SPECT/CT. With this technique a patient is scanned in a single session and the desired structural and functional information of the organ of interest is achieved. Recent clinical imaging studies in the areas of cardiology,endocrinology, infection, musculoskeletal and neurology has shown, that with multimodality diagnostic imaging, a significant increase in diagnostic accuracy is achieved, as compared to single diagnostic imaging modality. In this review, emphasis is given to the technical aspects and clinical applications of the SPECT/CT hybrid imaging modality

Allah’s wondrous creatures, the Holy Qur’an and technological inventions: ultrasound imaging

Allah (s.w.t) has created innumerable distinct creatures and mentioned to us about their special qualities through His revelation. The Qur’an is the ultimate source of guidance for its followers for all aspects of life including science. If one is to study nature scientifically there are countless observable facts that are parallel to the teachings of Islam. One of these facts is echolocation found in bats and dolphins. These animals generate ultrasonic signals and detect the echoes reflected back to them to map out their environment and catch prey. Modern health sciences have already adopted this phenomenon in the form of ultrasound imaging for diagnosis of certain diseases. However, there is room for improvement in the overall performance of this technique. This article highlights the technological developments directly inspired by nature i.e., crawfish/crayfish and relates echolocation characteristics of bats and dolphins with basic principles of ultrasound imaging. In-depth studies on the echolocation properties of these creatures can lead to further improvement in the current ultrasound imaging technique. Such as; the construction of a transducer which simultaneously generates multi-frequency ultrasound signals and development of new interpreting software. Moreover, reading verses of the Holy Qur’an heartily and enthusiastically will lead to the development of innovative ideas that can be translated into reality and applied for the betterment of humankind

Image quality enhancement by reducing scattered gamma photons with a flat sheet of Zinc 0.35 mm thick material filter in Tc-99m SPECT

One of the limitations of single photon emission computed tomography (SPECT) is the presence of signals of noise in image data which degrade image quality. There are different sources of noise and one of them is the detection of scattered gamma photons in the SPECT projection data. Therefore, Zinc (Zn) material filter of 0.35mm thickness was used to preferentially absorb scattered gamma photons from reaching the detector of gamma camera. SPECT data were acquired by using Phillips ADAC Forte dual head gamma camera with and without material filter. Standard energy window (20%) centered at 140 keV over the photopeak of Tc-99m was adjusted. For data acquisition 128×128 matrix was selected. The Tc-99m radioactivity of 22.5 mCi was injected into the Carlson’s phantom. An insert placed into the phantom consisting of various sizes of hot regions was scanned. Material filter was installed on the outer surface of the collimator of gamma camera. Images were reconstructed by using filtered back projection method. Butterworth filter of cut-off frequency 0.35 cycle/cm and order 5 was chosen. Chang’s attenuation correction on the data was applied. Hot region images were analyzed in terms of contour/visual, hot regions detectability, contrast and signal-to-noise ratio (SNR). Results of our work show enhancement in the detectability and contrast of smaller hot regions with material filter. Increase in SNR of both large and small size hot regions with material filter as compared to without material filter. It is concluded that, material filter technique can assist clinicians in making correct decisions in detecting smaller hot lesions in Tc-99m clinical SPECT. However, more studies are required to validate its utility by scanning organ phantoms. Index Terms – Scatter Correction, SPECT, Material Filter, Image Quality

Use of an Effective Attenuation Coefficient Value and Material Filter Technique for Scatter Correction in Tc-99m SPECT

Accuracy in the diagnosis of disease in Tc-99m Single Photon Emission Computed Tomography is reduced due to the presence of scattered gamma photons in the image data. A range of scatter correction techniques exist, however, none is considered as the standard. The objective of this study is to apply a flat sheet of Aluminum 0.3mm thick as an absorber for the removal of scattered gamma photons and compare the image quality with those images obtained by using effective attenuation coefficient value. Data were acquired with the gamma camera (Philip ADAC Forte dual head) installed with LEHR collimator. A cylindrical phantom with cold and hot regions insert was scanned. Tc-99m radioactive material was introduced into the phantom. Images were reconstructed by using filtered back projection method. Perceived image quality and contrast of cold and hot regions, whereas, count profile and standard deviation in the count density of uniform region was measured. Quantitative analysis of all image quality parameters investigated show fair improvement with material filter. In conclusion, 0.3mm thickness of aluminum material filter may have some advantage over the use of effective attenuation coefficient value for scatter compensation when applied by scanning other ECT phantoms using Tc-99m radionuclide

Comparison of low-pass filters for SPECT imaging

In single photon emission computed tomography (SPECT) imaging, the choice of a suitable filter and its parameters for noise reduction purposes is a big challenge. Adverse effects on image quality arise if an improper filter is selected. Filtered back projection (FBP) is the most popular technique for image reconstruction in SPECT. With this technique, different types of reconstruction filters are used, such as the Butterworth and the Hamming. In this study, the effects on the quality of reconstructed images of the Butterworth filter were compared with the ones of the Hamming filter. A Philips ADAC forte gamma camera was used. A low-energy, high-resolution collimator was installed on the gamma camera. SPECT data were acquired by scanning a phantom with an insert composed of hot and cold regions. A Technetium-99m radioactive solution was homogenously mixed into the phantom. Furthermore, a symmetrical energy window (20%) centered at 140 keV was adjusted. Images were reconstructed by the FBP method. Various cutoff frequency values, namely, 0.35, 0.40, 0.45, and 0.50 cycles/cm, were selected for both filters, whereas for the Butterworth filter, the order was set at 7. Images of hot and cold regions were analyzed in terms of detectability, contrast, and signal-to-noise ratio (SNR). The findings of our study indicate that the Butterworth filter was able to expose more hot and cold regions in reconstructed images. In addition, higher contrast values were recorded, as compared to the Hamming filter. However, with the Butterworth filter, the decrease in SNR for both types of regions with the increase in cutoff frequency as compared to the Hamming filter was obtained. Overall, the Butterworth filter under investigation provided superior results than the Hamming filter. Effects of both filters on the quality of hot and cold region images varied with the change in cutoff frequency

Effects of Copper 0.127 mm Thick Flat Sheet on Uniform and Hot Region Images as A Material Filter for Scatter Correction in Tc-99m SPECT

In the SPECT image data, presence of scatter component leads to poor image quality. Consequently, inaccuracy in the diagnosis of disease occurs. This study aims to improve the image quality by reducing some fraction of scattered gamma photons prior to detection using a material filter technique. Data were acquired by scanning a cylindrical source tank with hot/cold regions insert filled with water and uniformly distributed Tc-99m radionuclide. Philip ADAC Forte dual head gamma camera with LEHR collimator was used. Material filter, a flat sheet of Cu 0.127mm thick was attached on the outer surface of the collimator. SPECT data were acquired without and with material filter. Filtered back projection technique was applied. Images were visually examined in order to observe the improvement in image quality of uniform and hot regions as well as the detectability of hot regions. Standard deviation in the count density of uniform region and contrast of hot region images was calculated. Findings of the study reflect an overall enhancement in the image uniformity, hot regions detectability and contrast with material filter. It is concluded that, material filter technique need further investigations for applicability in clinical studies by scanning other phantoms mimicking human organs

A new technique for reduction of scattered Gamma photons in Tc-99m SPECT imaging

In healthcare, the prime objective prior to cure any disease is accurate diagnosis of abnormalities in humane. There are different diagnostic procedures and techniques. In this regard, imaging techniques play a potential role. Single Photon Emission Computed Tomography (SPECT) imaging is one among them. The technique uses some gamma photon emitting radionuclides and it is applied worldwide as an important diagnostic imaging tool. However, the technique has some limitations, e.g., equipment related, absorption and scattering of gamma photons within the patient body. Scattering of gamma photons degrade the system spatial resolution. Consequently, image quality is degraded and quantitative accuracy of radioactivity distribution is limited. This work attempts to reduce the effects of scattered gamma photons from SPECT images. There are some scatter correction techniques and each technique has limitations in one or another way. A unique technique has been introduced to absorb some fraction of scattered gamma photons from the image raw data before their registration. The technique uses thin sheets of materials; copper and aluminum as physical filters. SPECT data are acquired by using Toshiba GCA 901 A/HG gamma camera. Carlson’s phantom filled with water is used. Cold and hot regions inserts are placed in the phantom. Tc-99m radionuclide is uniformly distributed in the phantom. Either LEGP or LEHR collimators are used. Data acquisition parameters are chosen as those are selected for patient studies. Data are acquired with and without physical filters. Images are reconstructed by FBP reconstruction technique with Butterworth filter. Chang’s attenuation correction technique is applied for compensation of absorption of gamma photons. Images obtained with and without physical filtered data are analyzed and compared in terms of perceived image quality, hot and cold region detectability and image contrast. Results show that, perceived image quality, hot and cold region detectability and image contrast is improved when physical filters are used. This suggests that the technique may have potential applications in clinical studies

Flat sheet of zinc material as a filter for gamma photons in Tc-99m SPECT imaging

Purpose of the Study: Scattered gamma photons in single photon emission computed tomography (SPECT) is one of the main issues that degrade the image quality. There are several types of scatter correction methods. However, none of the technique is applied in routine clinical Tc-99m SPECT imaging. Therefore, Zinc (Zn) material filter was constructed for pre-filtration of scattered gamma photons in Tc-99m single photon emission computed tomography (SPECT). Materials and Methods: Tc-99m radioactivity was administered into the Carlson’s phantom. Planar and tomographic data were acquired with and without hot regions insert, respectively, with and without material filter. Scatter to non-scatter ratio was measured from the photopeak region of Tc-99m spectra. Tomographic images were generated using filtered back projection method. Contours on images were drawn with ImageJ software. Images obtained with and without material filter were analysed in terms of detectability of hot regions. Results: Remarkable decrease (≈ 21%) in the ratio of scattered to non-scattered gamma photons with material filter was achieved. Detectability of smaller hot regions with material filter was enhanced. In terms of sizes of all hot regions, material filter results appear closer to the original sizes. Conclusion: Material filter technique could be applied in Tc-99m clinical SPECT, while organ phantom studies are needed

Emission computed tomography test phantoms: a review

It is vital to assess the performance of emission computed tomography (ECT) systems prior to their use for clinical examinations. Generally, performance tests of ECT systems are time-consuming, expensive and require more than one phantom to scan and then analyse the data. There is non-availability of such type of phantoms that can provide all necessary data for performance of some quality control (QC) tests from a single scan data. In this paper, commercially available emission computed tomography (ECT) phantoms are thoroughly reviewed. Thus,designing and construction of a time-saving and cost-effective new compact ECT phantom has been suggested