Choirul Anam

This study aims to develop a software for measuring the computed tomography (CT) number of multiple materials automatically and investigate the impact of tube voltage on the measured CT numbers. The software was specifically design to automatically measure CT number of multiple materials on images of an ACR 464 CT phantom (Gammex, Inc.). Automatic measurements were performed using the matching technique based on the centroids of the phantom and bone objects. The software was tested first on images of the phantom scanned using a GE Revolution EVO 128-slice with rotation variations from 1° to 10° to evaluate its accuracy against rotation. The software was then implemented on images of the phantom scanned with tube voltage variations of 80, 100, 120, and 140 kV. Results of automatic measurements were compared with manual measurements. Manual measurements were performed using a …

IntroductionSize-specific dose estimation (SSDE) is suggested for accurate measurement of CT dose. Various methods have been developed for SSDE calculation by both manual and automated methods. However, truncation artefact may affect the specific size determination and SSDE calculation. In this article, we evaluate how truncation affects measurements of SSDE and compare the manual SSDE measurement based on individual sizes (effective diameter, Deff and water equivalent diameter, DW) with the automated calculation using IndoseCT software on truncated CT images.MethodsA phantom study was conducted using Siemens SOMATOM Definition AS + CT scanner with two CTDI phantoms of different sizes, 22 cm and 32 cm. Phantom images were acquired by varying the phantom positioning to simulate truncation percentages (TP) of 5%, 10%, 15%, and 20%. The SSDE values were manually …

The quality control (QC) procedure of computed tomography (CT) is an important task to be regularly performed. It consists of daily, monthly, and annual tasks. Each procedure can be time-consuming. Manual QC can take many hours. Manual measurement of image quality parameters can also lead to a bias due to the subjectivity of examiners. IndoQCT answers these challenges by being automatic, fast, objective, and accurate. Unlike some existing software that can only be used on one type of phantom and with limited parameters, IndoQCT can be used to evaluate CT image quality using various phantoms and numerous parameters. In this report, the basic workflow of IndoQCT to automatically evaluate CT image quality on the American College of Radiology (ACR) phantom was assessed. IndoQCT provides a total of 9 main tabs, covering various image quality parameters, namely: CT number (water), CT number of multiple objects, noise, spatial resolution, low contrast, slice thickness, laser alignment, distance accuracy, and gantry tilt. As a tool for productive QC procedures in health facilities, IndoQCT can increase the efficiency of QC.

Background:The slice spacing has a crucial role in the accuracy of computed tomography (CT) images in sagittal and coronal planes. However, there is no practical method for measuring the accuracy of the slice spacing.Purpose:This study proposes a novel method to automatically measure the slice spacing using the American Association of Physicists in Medicine (AAPM) CT performance phantom.Methods:The AAPM CT performance phantom module 610-04 was used to measure slice spacing. The process of slice spacing measurement involves a pair of axial images of the module containing ramp aluminum objects located at adjacent slice positions. The middle aluminum plate of each image was automatically segmented. Next, the two segmented images were combined to produce one image with two stair objects. The centroid coordinates of two stair objects were automatically determined. Subsequently, the …

Purpose This study proposes a method for automatically measuring the thickness of thin slices on images of the Catphan phantom. Methods In the proposed method, the angle of the phantom's orientation was determined based on the relative coordinates of the four hole objects in the phantom. After the angle of the wires were determined, the profiles of pixel values across the wire objects were constructed. Finally, their full widths at half maximum (FWHMs) were determined and multiplied by tan 23o to obtain the slice thicknesses of the images. The results of the proposed method were compared to a previous method, which used the Hough transform to obtain the phantom’s orientation. We used slice thicknesses ranging from 0.8 mm to 5.0 mm, and phantom angles from 0o to 10o. Results Our proposed method detected the angle of the phantom accurately in the thin slice thickness, while a previous method did not …

Introduction A significant number of head computed tomography (CT) scans are performed annually. However, due to the close proximity of the thyroid gland to the radiation field, this procedure can expose the gland to ionising radiation. Consequently, this study aimed to estimate organ dose, effective dose (ED) and lifetime attributable risk (LAR) of thyroid cancer from head CT scans in adults. Methods Head CT scans of 74 patients (38 males and 36 females) were collected using three different CT scanners. Age, sex, and scanning parameters, including scan length, tube current–time product (mAs), pitch, CT dose index, and dose‐length product (DLP) were collected. CT‐Expo software was used to calculate thyroid dose and ED for each patient based on scan parameters. LARs were subsequently computed using the methodology presented in the Biologic Effects of Ionizing Radiation (BEIR) Phase VII report …

A free software for digital imaging and communications in medicine (DICOM) image anonymization is needed to protect patient information from third parties. This study aimed to develop a software for the anonymization of patient information in computed tomography (CT) image. There was a total of 17 informations to be anonymized, such as Patient’s Name, Other Patient Names, Patient’s ID, Patient’s Birth Date, Patient’s Sex, Patient’s Age, Study ID, Study Description, Series Description, Institution Name, Institution Adress, Referring Phisician’s Name, Consulting Physician’s Name, Performing Physician’s Name, Name of Physician (s) Reading Study, Operator’s Name, and Protocol Name. In every information, its initial value was replaced with a dummy value with the string value of" N/A". For testing, patient CT images from four different hospitals with different scanners were collected. It is found that each scanner had different information stored in DICOM information. However, the anonymization process in the four hospitals works well with accuracy of 100%. The developed software can anonymize DICOM images flexibly and successfully. This software can be used for anonymization of patient information in order to protect patient information.

This study aims to develop an automatic method for calculating slice thickness on an American College of Radiology (ACR) phantom and evaluate its accuracy at variations of orientation angle and slice thickness. The phantom was scanned using Siemens SOMATOM perspective, with variations of the slice thickness (ie 1.5, 3, 5, 6, 7, and 10 mm) and rotation angles (ie 0.0, 22.5, 45.0, and 67.5). The phantom rotation was based on the bone object as a reference. After determining the rotation angle, the phantom image was rotated by the angle. Next, profiles of pixel values across the wire objects for measuring slice thickness were developed from rotated phantom images. The slice thickness was measured automatically from the obtained profiles. The results of the automated method are 2.5, 4.1, 5.4, 5.8, 7.8, and 9.8 mm for all varied slice thicknesses. The differences between the automatic and manual methods are within 0.3 mm. The automatic method is capable of detecting slice thickness for various angles. The differences in slice thickness for various angles are within 0.1 mm for a slice thickness of 3 mm. These results are similar when compared to manual measurements. An algorithm for automated slice thickness measurement on ACR phantom has been successfully developed.

We investigated the accuracy of automatic measurements of the effective diameter (Deff) using IndoseCT software with axial computed tomography (CT) images of polyester-resin (PESR) phantoms of various diameters. The phantoms used PESR as the base material mixed with Methyl Ethyl Ketone Peroxide (MEKP) as the catalyst. The phantom diameters were 8, 16, 24, and 32 cm. The phantoms were scanned with a CT scanner from edge-to-edge position with field of views (FOVs) of 30, 35, 40, 45, and 50 cm. The Deff was measured from all slices along the z-axis. It was found that the automatic Deff measurements were very accurate. The Deff values were different by less than 0.02 cm for all diameters and all FOVs used. The maximum difference was obtained a ta diameter of 16 cm and FOV of 35 cm. We found that the precision of Deff measurements along the z-axis was very good with a maximum standard deviation of 0.01 cm. The relationships between phantom diameter and measured Deff for all FOVs had p-values< 0.001 and r2= 1.000. Therefore, the IndoseCT is able to accurately and precisely measure Deff to facilitate estimating the patient dose in the SSDE metric.

AMF filter can reduce the standard deviation compared to without AMF for some magnifications. However, caution should be considered when applying the AMF filter, as it can decrease the model performance in some cases.

The purpose of this study was to evaluate the effect of rectangular region of interest (ROI) size on modulation transfer function (MTF), to develop the radial ROI, and to compare both ROIs performances for MTF measurement using a cylindrical polymethyl methacrylate (PMMA) phantom. The PMMA phantom used in this study was rotated 45. Four rectangular ROIs and a radial ROI were created to measure the MTF value. The rectangular ROI sizes were 3× 41, 21× 41, 41× 41, and 61× 41 pixels; each was placed at upper phantom edge. The radial ROI’s length was 41 pixels and placed at several points in phantom edge. The MTF calculation was automatically conducted using MATLAB. The MTFs from rectangular ROIs and radial ROI were then compared. The comparison of the MTF measurement was also conducted using three different filters. The MTF which used radial ROI was smoother than those of rectangular ROI for all filters. This indicated that radial ROI was more resistant to noise than rectangular ROI. Rectangular ROI with the 41× 41 pixels had similar 50% and 10% MTF values with the radial ROI. The MTF value which was obtained using radial ROI is more accurate and robust than those obtained using rectangular ROI.

Purpose This study aims to compare the modulation transfer function (MTF) measured using IndoQCT and ImQuest software on GE CT phantom images with variations of slice thickness and reconstruction filter. Method This study compared MTFs measured using two software (ie, IndoQCT and ImQuest software) on GE CT phantom images. IndoQCT implemented automatic region of interest (ROI) determination, while ImQuest used manual ROI determination. Both software analysed images with three variations of slice thickness (ie, 2.5, 5, and 10 mm) and reconstruction filter (ie, standard, soft tissue, chest, and bone filters). Results IndoQCT provides automatic ROI selection and produces stable MTF curves, while ImQuest provides manual ROI selection and produces more fluctuating MTF curves. In slice thickness variation, IndoQCT showed that different slice thickness did not significantly affect spatial resolution as suggested, while ImQuest showed significant differences in spatial resolution for thickest slice thickness. In filter variation, IndoQCT produced high spatial resolution value in bone filter, while ImQuest produced the lower spatial resolution value. Overall, both software showed MTF differences within 15%, except in certain conditions, for example on a slice thickness of 10 mm. Conclusions We have compared MTFs measured using IndoQCT and ImQuest software. Both software can be used to measure MTFs on the GE phantom images with relatively accurate results. IndoQCT generally produces higher MTF values than those from ImQuest. However, the difference MTF is not statistically significant. This study found that at 10 mm slice …

Objective To develop an algorithm to measure slice thickness running on three types of Catphan phantoms with the ability to adapt to any misalignment and rotation of the phantoms. Method Images of Catphan 500, 504, and 604 phantoms were examined. In addition, images with various slice thicknesses ranging from 1.5 to 10.0 mm, distance to the iso-center and phantom rotations were also examined. The automatic slice thickness algorithm was carried out by processing only objects within a circle having a diameter of half the diameter of the phantom. A segmentation was performed within an inner circle with dynamic thresholds to produce binary images with wire and bead objects within it. Region properties were used to distinguish wire ramps and bead objects. At each identified wire ramp, the angle was detected using the Hough transform. Profile lines were then placed on each ramp based on the centroid …

Purpose The aim of this study is to develop software to automatically assess the laser alignment on the ACR CT phantom and evaluate its accuracy on sixteen CT scanners. Methods Software for an automated method of laser alignment assessment on the ACR CT phantom was developed. Laser alignment assessment was based on the positions of the ball-bearing markers at the edge of the ACR CT phantom. The automatic assessment was performed using several steps, including segmentation to acquire the coordinates of the ball-bearing markers and determination of the distances between lines connecting them with lines through the center of the image. A comparison of the results from the automatic method with those from the manual method was performed. The manual measurements were carried out using MicroDicom Viewer. A Mann–Whitney U test was performed to determine the statistical difference …

The aim of this study is to measure the volumetric computed tomography dose index (CTDIvol) for different tube voltages for a polyester-resin (PESR) phantom, and to compare it to values for a standard polymethyl methacrylate (PMMA) phantom. Both phantoms are head phantoms with a diameter of 16 cm. The phantoms were scanned by a CT scanner (GE Revolution EVO 64/128 slice) with tube voltages of 80, 100, 120, and 140 kV. The other scan parameters were constant (i.e. tube current of 100 mA, rotation time of 1 s, and collimation width of 10 mm). The CTDI100,c and CTDI100,p were obtained by measuring the dose with an ionization chamber inserted into five holes within the phantoms. The CTDIvol was calculated based on the CTDI100,c and CTDI100,p values. The measurements were repeated three times for each hole. It was found that the CTDIvol values for the PESR phantom were dependent on tube …

This study is to develop an automated method to determine the spatial resolution of computed tomography (CT) images on line-pair objects of the American College of Radiology (ACR) CT accreditation phantom. The ACR phantom was scanned using a GE Healthcare 128-slice CT scanner with seven different reconstruction filters of E1, E2, E3, LU, S1, S2, S3. The automated method involved building a standard deviation map (SDM), segmenting the line-pair objects within SDM images, determining the region of interest (ROI) within line pair object, and determining a resolvable line-pair object with dynamic threshold which is dependent on image noise. The scanning parameters were fixed at 120 kVp and 160 mAs. The results of automated method were compared with those from manual measurements performed by five human observers. The automatic method produced spatial resolution results of 0.7, 0.7, 0.7, 0.7, 0.6, 0.6, and 0.6 lp/mm for filters E1, E2, E3, LU, S1, S2, and S3, respectively, while the manual measurements yielded results of 0.6, 0.6, 0.6, 0.7, 0.6, 0.5, and 0.5 lp/mm. The differences between the manual and automatic measurement results were small, with a maximum difference of 0.1 lp/mm. Hence, the automatic measurement of spatial resolution on line-pair objects of the ACR CT accreditation phantom is a feasible and reliable method.

The gallbladder and pancreas are the organs exposed to primary radiation on abdominal computed tomography (CT). Up to now, organ dose estimation has been carried out by measuring it on Anthropomorphic phantoms with a thermoluminiscence detector (TLD), or using a Monte Carlo simulation. The radiation dose received by the patient is estimated using two parameters, namely the volume computed tomography dose index (CTDIvol) and the dose length product (DLP). However, both CTDIvol and DLP neglect the physical characteristics of patients, such as patient size and attenuation. Estimate of patient dose is more accurately conducted by the concept of size-specific dose estimate (SSDE). Currently, the SSDE concept is used for dose distribution estimation within patients, however it has not been used for organ dose estimation. Therefore, this study aimed to estimate doses of the gallbladder and pancreas …

Introduction: Deep learning image reconstruction (DLIR) is a very recent image reconstruction method that is already available for commercial use. We evaluated the quality of DLIR images and compared it to the quality of images from the latest adaptive statistical iterative reconstruction (ASIR-V) algorithm in terms of noise-power spectrum (NPS) and modulation-transfer function (MTF).Methods: We scanned a Revolution QA phantom (GE Healthcare, USA) and a 20 cm water phantom (GE Healthcare, USA) with our 512 multi-slice computed tomography (CT) scanner. Images of the tungsten wire within the Revolution QA phantom were reconstructed with a 50 mm field of view (FOV). The images were reconstructed with various ASIRV strengths (ie 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100%) and DLIRs (ie low, medium, and high) to assess the MTF. The images from the 20 cm water phantom were reconstructed with the same configuration to assess the NPS. Results: The MTF was similar for both reconstruction algorithms of DLIR and ASiR-V. The peak frequency (fp) of the DLIR low was comparable to that from ASIR-V at 50, 60, 70%; the DLIR medium was comparable to ASIR-V at 80%; and the DLIR high was comparable to ASIR-V at 100%. The average frequency (fA) of the DLIR low was comparable to that from ASIR-V at 40%; the DLIR medium was comparable to ASIR-V at 50%; and the DLIR high was comparable to ASIR-V at 70%. Both the DLIR and ASIR-V were able to reduce noise, but they had a different texture. Conclusions: The noise in the DLIR images was more homogenous at high and low frequencies, while in the ASIR-V images, the …

Background:Methods for segmentation, ie, Full-segmentation (FS) and Segmentation-rotation (SR), are proposed for maintaining Computed Tomography (CT) number linearity. However, their effectiveness has not yet been tested against noise.Objective:This study aimed to evaluate the influence of noise on the accuracy of CT number linearity of the FS and SR methods on American College of Radiology (ACR) CT and computational phantoms.Material and Methods:This experimental study utilized two phantoms, ACR CT and computational phantoms. An ACR CT phantom was scanned by a 128-slice CT scanner with various tube currents from 80 to 200 mA to acquire various noises, with other constant parameters. The computational phantom was added by different Gaussian noises between 20 and 120 Hounsfield Units (HU). The CT number linearity was measured by the FS and SR methods, and the accuracy of …

The purpose of this study to develop software to extract and investigate the profiles of the tube current and volume computed tomography dose index (CTDIvol) along the longitudinal axis (z-axis). The tube current and CTDIvol were extracted from the Digital Imaging and Communications in Medicine (DICOM) header of every image along the longitudinal axis. We evaluated the profiles of the tube current and CTDIvol from eight computed tomography (CT) scanners. If the CTDIvol did not fluctuate along the fluctuation of the tube currents, then the system will adjust the CTDIvol with tube currents. It is found that TCM is not always activated. If TCM is activated, the profiles of TCM vary from one scanner to another. The Siemens and Philip scanners have adjusted the CTDIvol profile with tube current, but the Toshiba scanner has not. By developed software, CTDIvol profile of the Toshiba can be easily adjusted. In conclusion, software to investigate the profile pattern of CTDIvol along the longitudinal axis has been successfully developed. The software is easy to use and works quickly. From this study, medical staff must be careful when using the CTDIvol along longitudinal axis contained in each DICOM header.