Performance evaluation of computed tomography scanners in Indonesia: recommendation from a nation-wide study.

In this study, an evaluation of the compliance test data from 684 computed tomography (CT)-scanners in Indonesia for the 2019-22 test period was carried out. The study was aimed to describe the performance profile of CT-scanners in Indonesia and evaluate the testing protocol. A total of 87.8% of the CT-scanners unconditionally passed the tests, 8.8% passed the tests with conditions and 3.4% failed the tests. Of the devices conditionally passed the tests, the top two causes were water CT number accuracy (45.2%) and laser position accuracy (41.9%). Meanwhile, 75.0% of the failed devices were due to failing to meet the patient dose test criteria. The failure of the test for the water CT number accuracy parameter was caused by variations in the type of phantom used in the test, where several types of phantoms did not use water as material of the homogeneity module. Failures in laser position accuracy test were caused by the passing criteria that adjust to the minimum slice thickness, so that modern CT-scanner with small detector sizes and collimations tend not to pass. On the other hand, the failure on dose aspects was due to the frequent unavailability of baseline values for comparison. Of these top three failure causes, two of them, namely the CT number and dose test parameters, have been accommodated in the latest regulation (BAPETEN Regulation No. 2/2022) with a change in the evaluation method, while for the laser position accuracy test it is recommended to alter the passing criteria to an absolute value, namely 1 mm.

Performance evaluation of stationary and mobile radiography systems in Indonesia.

An analysis and evaluation has been carried out on each test parameter contained in the compliance test of 1016 stationary and 480 mobile radiography devices compiled by the Indonesian Nuclear Energy Regulatory Agency (Badan Pengawas Tenaga Nuklir, BAPETEN) from 2019 to 2020. The data were categorised and analysed based on the devices' age to observe the correlation of performance with the age of the X-ray machine. In addition, the implementation level of the Automatic Exposure Control (AEC) system test of the stationary radiography X-ray modality is also reviewed. The results of the evaluation showed that 89.9% of the stationary radiography devices unconditionally pass the test, 5.2% are in the status of 'conditional pass' and 4.9% fail the test. On the other hand, 84.8% of mobile radiography devices unconditionally pass the test, 2.1% are in the status of 'conditional pass' and 13.1% fail the test. From the evaluation conducted, there is no observable correlation between the age of the modality and the results of the compliance test. Overall, only 9.2% of stationary radiography X-ray compliance test reports have included the AEC test since it is not a mandatory requirement of the national protocol.

Development, Construction, and Evaluation of an Alternative Dosimetry Phantom for Computed Tomography.

This article aims to present the development, construction, and evaluation of an alternative computed tomography dose index (CTDI) phantom. Epoxy resin was mixed with an iodine-based contrast agent to produce radiological characteristics resembling polymethyl methacrylate (PMMA) as a standard CTDI phantom. As a preliminary study, testing was carried out using computed tomography images (80 and 120 kVp) on 12 variations of epoxy-iodine resin mixtures to obtain relative electron density (ρe) values and effective atomic numbers (Zeff) of the samples. The alternative CTDI phantoms were then constructed with a resin-iodine mixture using iodine concentrations that yield on closest ρe and Zeff values to those of PMMA. The evaluation was carried out by comparing dose measurement results at various energies between the alternative phantom and the International Electrotechnical Commission-standard CTDI phantom. At a concentration of 0.46%, the epoxy resin has ρe and Zeff with a deviation against PMMA of 0.12% and 1.58%, respectively, so that composition was chosen for the alternative CTDI phantom construction. The average dose discrepancy values were 5% and 1%, respectively, for the head and body phantoms in the tested tube voltages of 80 kVp, 100 kVp, 120 kVp, and 135 kVp. The Student's t-test result between the alternative and the standard phantoms also showed P < 0.05, indicating the comparability of the alternative CTDI phantom with the standard CTDI phantom.

Task-based phantom evaluation of cardiac catheterization imaging modes.

This study aimed to quantify the dose and quality of the preprogrammed imaging modes on two cardiac angiography devices (Philips Allura FD10 Clarity and Allura FD10) using a task-specific in-house phantom, and to discuss the appropriateness of the pre-programmed settings. A Figure of Merit (FOM), defined as the squared Signal Difference to Noise Ratio (SDNR) divided by Entrance Surface Air Kerma (ESAK), was calculated for phantom inserts with different sizes and concentrations of iodine, as well as tin foils. For the Allura FD10 Clarity device, the low dose fluoroscopic mode was found to be very dose efficient, while the available ciné modes should only be used for cases with high demand for contrast and temporal resolutions. For both devices, the basic beam spectrum of the low dose fluoroscopic mode should be explored for use on other imaging modes. Ciné modes for the Allura FD10 device differ only by their spatial resolution characteristics and have almost identical dose per frame. This study also found that tin may not be a suitable replacement for iodine for research purposes due to mismatching SDNR. The number of recommendations formulated for these two devices suggests that comparative dose and image quality tests of all routinely used imaging modes should be an obligatory part of the physicists' acceptance testing.

Optimization of dose and image quality of paediatric cardiac catheterization procedure.

The purpose of this study is to quantify the quality of the available imaging modes for various iodine-based contrast agent concentration in paediatric cardiology. The figure of merit (FOM) was defined as the squared signal to noise ratio divided by a patient dose related parameter. An in house constructed phantom simulated a series of vessel segments with iodine concentrations from 10% or 30 mg/cc to 16% or 48 mg/cc of iodine in a blood plasma solution, all within the dimensional constraints of a paediatric patient. The phantom also used test inserts of tin (Sn). Measurements of Entrance Surface Air Kerma (ESAK) and exit dose rate were performed along with calculations of the signal-to-noise ratio (SNR) of all the objects. A first result showed that it was favourable to employ low dose fluoroscopy mode and lower frame rate modes in cine acquisition if dynamic information is not critical. Normal fluoroscopy dose mode provided a considerably higher dose level (in comparison to low dose mode) with only a slight improvement in SNR. Higher frame rate cine modes should be used however when the clinical situation dictates so. This work also found that tin should not be intended as iodine replacement material for research purposes due to the mismatching SNR, particularly on small vessel sizes.