rss_2.0Polish Journal of Medical Physics and Engineering FeedSciendo RSS Feed for Polish Journal of Medical Physics and Engineering Journal of Medical Physics and Engineering Feed stiffness in cold pressor test hyper-reactors<abstract> <title style='display:none'>Abstract</title> <p><italic>Background:</italic> The cold pressor test (CPT) is a sympathoexcitatory manoeuvre to measure cardiovascular hyperactivity which may be a sign of future hypertension development.</p> <p><italic>Aims and Objectives:</italic> To evaluate the vascular stiffness background among healthy CPT hyper-reactor (H-R) males and age and gender-matched normo-reactors (N-R).</p> <p><italic>Methods:</italic> The study was carried out in 34 healthy young males aged 19 years old. Five minutes of recordings of left middle fingertip digital pulse wave (DPW) signals (through a piezoelectric finger pulse transducer) were registered. This was followed by the application of a cold pressor. Blood pressure (BP) and heart rate (HR) during CPT were recorded, and the individuals were divided into N-Rs and H-Rs. Vascular stiffness indices like pulse wave velocity (PWV), B/A wave ratio, pulse rising time (PRT, or crest), large artery stiffness index (SI), and pulse width (PW) were compared between H-Rs and N-Rs.</p> <p><italic>Results:</italic> No significant differences were observed between the two groups across all studied parameters.</p> <p><italic>Conclusion:</italic> The results suggest there was no difference in the vascular stiffness background between CPT H-R and N-R individuals.</p> </abstract>ARTICLEtrue analysis of VMAT prostate plans: insights from dimensionality reduction and information theory techniques<abstract> <title style='display:none'>Abstract</title> <p><italic>Introduction:</italic> Volumetric Modulated Arc Therapy (VMAT) is a state-of-the-art prostate cancer treatment, defined by high dose gradients around targets. Its unique dose shaping incurs hidden complexity, impacting treatment deliverability, carcinogenesis, and machine strain. This study compares various aperture-based VMAT complexity indices in prostate cases using principal component and mutual information analyses. It suggests essential properties for an ideal complexity index from an information-theoretic viewpoint.</p> <p><italic>Material and methods:</italic> The following ten complexity indices were calculated in 217 VMAT prostate plans: circumference over area (CoA), edge metric (EM), equivalent square field (ESF), leaf travel (LT), leaf travel modulation complexity score for VMAT (LTMCSV), mean-field area (MFA), modulation complexity score (standard MCS and VMAT variant MCSV), plan irregularity (PI), and small aperture score (SAS<sub>5mm</sub>). Principal component analysis (PCA) was applied to explore the correlations between the metrics. The differential entropy of all metrics was also calculated, along with the mutual information for all 45 metric pairs.</p> <p><italic>Results:</italic> Whole-pelvis plans had greater complexity across all indices. The first three principal components explained 96.2% of the total variance. The complexity metrics formed three groups with similar conceptual characteristics, particularly ESF, LT, MFA, PI, and EM, SAS<sub>5mm</sub>. The differential entropy varied across the complexity metrics (PI having the smallest vs. EM the largest). Mutual information analysis (MIA) confirmed some metrics’ interdependence, although other pairs, such as LTMCSV/SAS<sub>5mm</sub>, LT/MCSV, and EM/SAS<sub>5mm</sub>, were found to share minimal MI.</p> <p><italic>Conclusions:</italic> There are many complexity indices for VMAT described in the literature. PCA and MIA analyses can uncover significant overlap among them. However, this is not entirely reducible through dimensionality reduction techniques, suggesting that there also exists some reciprocity. When designing predictive models of quality assurance metrics, PCA and MIA may prove useful for feature engineering.</p> </abstract>ARTICLEtrue properties of domestic bioactive calcium phosphate ceramics doped with silicon<abstract> <title style='display:none'>Abstract</title> <sec> <title style='display:none'>Introduction</title> <p>The relevance of this study lies in the fact, that today the search for biocompatible materials for the management of bone defects is of importance. Such materials could become an alternative to transplants. For the replacement of bone defects, two-phasic bioactive ceramics of hydroxyapatite and β-tricalcium phosphate is a very attractive biomaterial due to its excellent biocompatibility and osteoconductivity, but the results of its use are quite controversial due to insufficient bioactivity. The purpose of this work is to investigate the osseointegration properties of two-phase bioactive ceramics doped with silicon (HTdSi), both as a single component and a component in combination with platelet-rich fibrin, as well as in comparison with the well-known imported analogue – BIO, which consists of β-tricalcium phosphate, also as an independent component and a component in combination with platelet-rich fibrin. In the experiment, the rabbits of the New Zealand white breed at the age of 3 months and with an average weight of 2.5 kg were used. The terms of implantation are 30, 60, 90 and 180 days. The advantages of the domestic bio-composite are substantiated on the basis of clinical, radiological and histological studies.</p> </sec> <sec> <title style='display:none'>Material and methods</title> <p>In the experiment, the rabbits of the New Zealand white breed at the age of 3 months and with an average weight of 2.5 kg were used. The terms of implantation are 30, 60, 90 and 180 days.</p> </sec> <sec> <title style='display:none'>Results</title> <p>The osteointegration properties of two-phase bioactive ceramics doped with silicon (HTdSi), both as a single component and in combination with platelet fibrin, were investigated, as well as in comparison with the known imported analog - BIO, which contains β-tricalcium phosphate, both as a single component and in combination with platelet fibrin.</p> </sec> <sec> <title style='display:none'>Conclusions</title> <p>The advantages of domestic biocomposite are substantiated on the basis of clinical, radiological and histological studies.</p> </sec> </abstract>ARTICLEtrue of the Small Field of View and Imaging Parameters to Image Quality and Dose Calculation in Adaptive Radiotherapy<abstract> <title style='display:none'>Abstract</title> <sec> <title style='display:none'>Background</title> <p>The use of cone beam computed tomography (CBCT) for dose calculation in adaptive radiotherapy has been investigated in many studies. Proper acquisition and reconstruction of preset parameters could improve the accuracy of dose calculation based on CBCT images. This study evaluated the impact of the modified image acquisition and preset reconstruction parameter available in X-Ray Volumetric Imaging (XVI) to improve CBCT image quality and dose calculation accuracy.</p> </sec> <sec> <title style='display:none'>Materials and methods</title> <p>Calibration curves were generated by scanning the CIRS phantom using CBCT XVI Elekta 5.0.4 and Computed Tomography (CT) Simulator Somatom, which served as CT image reference. Rando and Catphan 503 phantoms were scanned with various acquisition and reconstruction parameters for dose accuracy and image quality tests. The image quality test is uniformity, low contrast visibility, spatial resolution, and geometrical scale test for each image by following the XVI image quality test module.</p> </sec> <sec> <title style='display:none'>Results</title> <p>Acquisition and reconstruction parameters have an impact on the Hounsfield Unit (HU) value that is used as the HU-Relative Electron Density (RED) calibration curve. The dose difference for all the calibration curves was within 1% and passed the gamma passing rate. Images acquired using 120 kVp, F1 (with Bowtie Filter), and 50 mA (F1-120-50-10) scored the highest Gamma Index (GI) of 98.5%. For the image quality test, it scored 1.20% on the uniformity test, 2.14% on the low contrast visibility test, and 11 lp/cm on the spatial resolution test. However, F1-120-50-10 reconstructed with different reconstructions scored 3.83% and 4 lp/cm in contrast and spatial resolution test, respectively.</p> </sec> <sec> <title style='display:none'>Conclusion</title> <p>CBCT reconstruction parameters work as a scatter correction. It could improve the dose accuracy and image quality. Nevertheless, without adequate CBCT acquisition protocols, it would produce an image with high uncertainty and cannot be fixed with reconstruction protocols. The F1-120-50-10 protocols generate the highest dose accuracy and image quality.</p> </sec> </abstract>ARTICLEtrue of noise-power spectrum and modulation-transfer function for CT images reconstructed with iterative and deep learning image reconstructions: An initial experience study<abstract> <title style='display:none'>Abstract</title> <sec> <title style='display:none'>Introduction</title> <p>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).</p> </sec> <sec> <title style='display:none'>Methods</title> <p>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 ASIR-V strengths (i.e. 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100%) and DLIRs (i.e. 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.</p> </sec> <sec> <title style='display:none'>Results</title> <p>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.</p> </sec> <sec> <title style='display:none'>Conclusions</title> <p>The noise in the DLIR images was more homogenous at high and low frequencies, while in the ASIR-V images, the noise was more concentrated at high frequencies. The MTF was similar for both reconstruction algorithms. The DLIR method showed a better noise reduction than the ASIR-V reconstruction.</p> </sec> </abstract>ARTICLEtrue resolution 2D plastic scintillator detectors for radiotherapy departments<abstract> <title style='display:none'>Abstract</title> <sec> <title style='display:none'>Introduction</title> <p>Plastic scintillation detectors (PSD) have been developed for over four decades and are widely used in a variety of fields, but one can find relatively few reports of their clinical use compared to other dosimetric solutions.</p> </sec> <sec> <title style='display:none'>Material and methods</title> <p>The inexpensive detector setup made of a Saint-Gobain BC-400 plastic scintillator and commercially available on the market CMOS-based DSLR Pentax camera was investigated. Build PSD detectors were irradiated with 6, 10 and 15 MV flattening filtered (FF) and 6 and 10 MV flattening filter free (FFF) photon beams using a clinical linear accelerator. Data were processed using Matlab software to remove background and artefacts. A comparison of the spatial resolution parameters to the Gafchromic EBT3 films was performed.</p> </sec> <sec> <title style='display:none'>Results</title> <p>Average dose difference between TPS and PSD was 1.1%. The measured spatial resolution was 0.29 mm, and it differed from the film by 1.1%. MTF50 for PSD was 0.57 mm higher than the Gafchromic film. Signal to dose fit function with an R-square equal to 0.999 was established. The standard deviation of mean pixels value for a series of measurements was below 0.1%, for variable dose rate dependence was below 0.6% and for different energies 1.1%.</p> <p>It was demonstrated that such a setup allows a satisfactory signal-to-dose dependence and provides high spatial resolution at an affordable price compared to a 2D ion chamber or a diode detector array. Moreover, PSDs are reusable and provide a simple readout compared to Gafchromic films commonly used in radiotherapy departments.</p> </sec> <sec> <title style='display:none'>Conclusions</title> <p>Variable parameters of the camera allow to select signal values at the optimal level. The system presented excellent signal stability, high image resolution and a simple signal-to-dose relationship which encourages further work to investigate PSDs for use in radiation therapy departments.</p> </sec> </abstract>ARTICLEtrue evaluation method using multiple image analyses for panoramic radiography improvement<abstract> <title style='display:none'>Abstract</title> <sec> <title style='display:none'>Introduction</title> <p>In the standardization of panoramic radiography quality, the education and training of beginners on panoramic radiographic imaging are important. We evaluated the relationship between positioning error factors and multiple image analysis results for reproducible panoramic radiography.</p> </sec> <sec> <title style='display:none'>Material and methods</title> <p>Using a panoramic radiography system and a dental phantom, reference images were acquired on the Frankfurt plane along the horizontal direction, midsagittal plane along the left–right direction, and for the canine on the forward–backward plane. Images with positioning errors were acquired with 1–5 mm shifts along the forward– backward direction and 2–10° rotations along the horizontal (chin tipped high/low) and vertical (left–right side tilt) directions on the Frankfurt plane. The cross-correlation coefficient and angle difference of the occlusion congruent plane profile between the reference and positioning error images, peak signal-to-noise ratio (PSNR), and deformation vector value by deformable image registration were compared and evaluated.</p> </sec> <sec> <title style='display:none'>Results</title> <p>The cross-correlation coefficients of the occlusal plane profiles showed the greatest change in the chin tipped high images and became negatively correlated from 6° image rotation (r = −0.29). The angle difference tended to shift substantially with increasing positioning error, with an angle difference of 8.9° for the 10° chin tipped low image. The PSNR was above 30 dB only for images with a 1-mm backward shift. The positioning error owing to the vertical rotation was the largest for the deformation vector value.</p> </sec> <sec> <title style='display:none'>Conclusions</title> <p>Multiple image analyses allow to determine factors contributing to positioning errors in panoramic radiography and may enable error correction. This study based on phantom imaging can support the education of beginners regarding panoramic radiography.</p> </sec> </abstract>ARTICLEtrue method for blood glucose monitoring using ECG signal<abstract> <title style='display:none'>Abstract</title> <p><italic>Introduction:</italic> Tight glucose monitoring is crucial for diabetic patients by using a Continuous Glucose Monitor (CGM). The existing CGMs measure the Blood Glucose Concentration (BGC) from the interstitial fluid. These technologies are quite expensive, and most of them are invasive. Previous studies have demonstrated that hypoglycemia and hyperglycemia episodes affect the electrophysiology of the heart. However, they did not determine a cohort relationship between BGC and ECG parameters.</p> <p><italic>Material and method:</italic> In this work, we propose a new method for determining the BGC using surface ECG signals. Recurrent Convolutional Neural Networks (RCNN) were applied to segment the ECG signals. Then, the extracted features were employed to determine the BGC using two mathematical equations. This method has been tested on 04 patients over multiple days from the D1namo dataset, using surface ECG signals instead of intracardiac signal.</p> <p><italic>Results:</italic> We were able to segment the ECG signals with an accuracy of 94% using the RCNN algorithm. According to the results, the proposed method was able to estimate the BGC with a Mean Absolute Error (MAE) of 0.0539, and a Mean Squared Error (MSE) of 0.1604. In addition, the linear relationship between BGC and ECG features has been confirmed in this paper.</p> <p><italic>Conclusion:</italic> In this paper, we propose the potential use of ECG features to determine the BGC. Additionally, we confirmed the linear relationship between BGC and ECG features. That fact will open new perspectives for further research, namely physiological models. Furthermore, the findings point to the possible application of ECG wearable devices for non-invasive continuous blood glucose monitoring via machine learning.</p> </abstract>ARTICLEtrue in-house step-wedge phantom for the calibration of pixel values in CT localizer radiographs for water-equivalent diameter measurement<abstract> <title style='display:none'>Abstract</title> <p><italic>Introduction:</italic> To develop an in-house acrylic-based step-wedge phantom with several thickness configurations for calibrating computed tomography (CT) localizer radiographs in order to measure the water-equivalent diameter (D<sub>w</sub>) and the size-specific dose estimate (SSDE).</p> <p><italic>Method:</italic> We developed an in-house step-wedge phantom using 3 mm thick acrylic, filled with water. The phantom had five steps with thicknesses of 6, 12, 18, 24, and 30 cm. The phantom was scanned using a 64-slice Siemens Definition AS CT scanner with tube currents of 50, 100, 150, 200, and 250 mA. The relationship between pixel value (PV) and water-equivalent thickness (t<sub>w</sub>) was obtained for the different step thicknesses. This was used to calibrate the CT localizer radiographs in order to measure D<sub>w</sub> and SSDE. The results of D<sub>w</sub> and SSDE from the radiographs were compared with those calculated from axial CT images.</p> <p><italic>Results:</italic> The relationship between PV and t<sub>w</sub> from CT localizer radiographs of the phantom step-wedge produced a linear relationship with R<sup>2</sup> &gt; 0.990. The linear relationships of the D<sub>w</sub> and SSDE values obtained from CT localizer radiographs and axial CT images had R<sup>2</sup> values &gt; 0.94 with a statistical test of <italic>p</italic>-value &gt; 0.05. The D<sub>w</sub> difference between those from CT localizer radiographs and axial CT images was 3.7% and the SSDE difference between both was 4.3%.</p> <p><italic>Conclusion:</italic> We have successfully developed a step-wedge phantom to calibrate the relationship between PV and t<sub>w</sub>. Our phantom can be easily used to calibrate CT localizer radiographs in order to measure D<sub>w</sub> and SSDE.</p> </abstract>ARTICLEtrue of virtual rhinomanometry<abstract> <title style='display:none'>Abstract</title> <p><italic>Introduction:</italic> This paper describes the results of research aimed at developing a method of otolaryngological diagnosis based on computational fluid dynamics, which has been called Virtual Rhinomanometry.</p> <p><italic>Material and methods:</italic> Laboratory studies of airflows through a 3D printed model of nasal cavities based on computed tomography image analysis have been performed. The CFD results have been compared with those of an examination of airflow through nasal cavities (rhinomanometry) of a group of 25 patients.</p> <p><italic>Results:</italic> The possibilities of simplifying model geometry for CFD calculations have been described, the impact of CT image segmentation on geometric model accuracy and CFD simulation errors have been analysed, and recommendations for future research have been described.</p> <p><italic>Conclusions:</italic> The measurement uncertainty of the nasal cavities’ walls has a significant impact on CFD simulations. The CFD simulations better approximate RMM results of patients after anemization, as the influence of the nasal mucosa on airflow is then reduced. A minor change in the geometry of the nasal cavities (within the range of reconstruction errors by CT image segmentation) has a major impact on the results of CFD simulations.</p> </abstract>ARTICLEtrue Changes of Elongation Index of erythrocytes caused by storage of blood at low temperature<abstract> <title style='display:none'>Abstract</title> <p><italic>Introduction:</italic> An important parameter characterizing the ability of erythrocytes to deform depending on the blood flow conditions is the Elongation Index (EI), and it is a parameter defined by the shape of the erythrocyte obtained as a diffraction pattern of erythrocytes at different values of shear stresses.</p> <p><italic>Material and methods:</italic> EI measurements at different shear stress were performed by Laser-assisted Optical Rotational Cell Analyzer (LORRCA) for erythrocytes derived from Tissue Bank in Katowice. Measurements were performed immediately after receiving them from Tissue Bank and after 2, 9, and 28 days of storage of samples at the temperature of 4°C in solution with the anticoagulant.</p> <p><italic>Results:</italic> An increase in the erythrocytes Elongation Index in the first 9 days of storing samples at low temperatures was observed in the entire range of applied shear stresses. This indicates an increase in the elasticity of erythrocytes during short-term storage at 4°C. In turn, on the 28th day of erythrocyte storage, a significant decrease in the Elongation Index for shear stresses greater than 1 Pa was observed, which indicates the stiffening of the erythrocyte membrane structure, reducing their elasticity. The relative decrease in the Elongation Index of erythrocytes stored for 28 days compared to erythrocytes measured at the beginning was similar and slightly greater than 30% for shear stresses greater than 3 Pa. For shear stresses lower than 3 Pa, the relative change in elongation index was smaller than for shear stresses greater than 3 Pa and increased with the increase in shear stress.</p> <p><italic>Conclusions:</italic> The elongation index of erythrocytes stored in the anticoagulant solution at 4°C, initially increases in the entire range of applied shear stresses in the first few days from the moment of blood collection and preparation at the Tissue Bank, and then decreases, but on the ninth day of storage the elongation index is still higher than for blood immediately after collection.</p> </abstract>ARTICLEtrue determination of virtual source position using convergent anti-trigonometric functions (arcCOS and arcSIN) method for scanning-passive scatter beam in carbon ion therapy<abstract> <title style='display:none'>Abstract</title> <p><italic>Introduction:</italic> We developed a convergent trigonometric functions technique (arcCOS, arcSIN) capable of dealing with the virtual source position delivered by different carbon ion energies from the pattern of scanning-passive scatter beam in this study.</p> <p><italic>Materials and Methods:</italic> A home-made large-format CMOS sensor and Gaf Chromic EBT3 films were used for the virtual source position measurement. The Gaf films were embedded in a self-designed rectangular plastic frame to tighten the films and set up on a treatment couch for irradiation in the air with the film perpendicular to the carbon ion beam at the nominal source-axis-distance (SAD) as well as upstream and downstream from the SAD. The horizontal carbon ion beam with 5 energies at a machine opening field size was carried out in this study. The virtual source position was determined with a convergent arcCOS and arcSIN methods and compared with the linear regression by back-projecting the FWHM to zero at a distance upstream from the various source-film-distance.</p> <p><italic>Results:</italic> The film FWHM measurement error of 0.5 mm (the large-format CMOS detectors was in pixel, a pixel equals 0.5 mm) leads to 1×10<sup>-3</sup>% deviation of α(cACOS and cASIN) at every assumed virtual source position. The overall uncertainty for the reproducibility of the calculated virtual source position by the assumed t in the vertical and horizontal directions amounts to 0.1%. The errors of calculated virtual source position by assumed t with back projecting FWHM to zero methods were within 1.1 ± 0.001, <italic>p</italic> = 0.033. The distance of virtual source positions is decreased from SAD with high to low energy.</p> <p><italic>Conclusion:</italic> We have developed a technique capable of dealing with the virtual source position with a convergent arcCOS and arcSIN methods to avoid any manual measurement mistakes in scanning-passive scatter carbon ion beam. The method for investigating the virtual source position in the carbon ion beam in this study can also be used for external electrons and the proton.</p> </abstract>ARTICLEtrue Software with a Graphical User Interface for GAMOS: Basic Training and an Educational Tool for Medical Physicists<abstract> <title style='display:none'>Abstract</title> <p><italic>Introduction:</italic> It is necessary to have special experience to perform the Monte Carlo calculation, commonly used in medical physics and accepted as the gold standard. In this study, we developed software to teach basic steps to medical physicists who were inexperienced in the medical linear accelerator Monte Carlo simulation.</p> <p><italic>Material and methods:</italic> For the design interface, a software called GamosLinacGUI was developed using Gnome Builder, Python, and GTK. The user, who wants to learn the basics of GAMOS and simulate a linear accelerator, can enter the values in the software, select some options and quickly create geometry and physics files.</p> <p><italic>Results:</italic> For proof that the software generates the correct inputs for GAMOS simulation in the same conditions for the measurements and calculations. Required files for GAMOS have been created and tested and run the simulation accordingly. This software was tested with Centos Linux.</p> <p><italic>Conclusions:</italic> GamosLinacGUI has been successfully developed, which creates the geometry and physics files required for the simulation with GAMOS as a training and learning tool.</p> </abstract>ARTICLEtrue of national diagnostic dose reference levels (DRLs) for routine computed tomography examinations in Jordan<abstract> <title style='display:none'>Abstract</title> <p><italic>Background:</italic> Dose reference levels (DRLs) are used as indicators as well as guidance for dose optimization and to ensure justification of appropriate dose for a given clinical indication. The main aims of this study were to establish local DRLs for each CT imaging protocol as a reference point to evaluate the radiation dose indices and to compare our DRLs with those established in other countries and against the internationally reported guidelines.</p> <p><italic>Materials and methods:</italic> 2000 CT dose reports of different adult imaging protocols from January 2021 until April 2022 were collected retrospectively at different hospitals in Jordan. Data were collected from CT scans that were performed using different types and models of CT scanners and included four adult non-enhanced, helical CT imaging protocols; Head, Chest, Abdomen-Pelvis, and Chest-Abdomen-Pelvis.</p> <p><italic>Results:</italic> The average doses of CTDI<sub>vol</sub>, DLP, and effective dose were (65.11 mGy, 1232.71 mGy·cm, 2.83 mSv) for the head scan, (16.6 mGy, 586.6 mGy·cm, 8.21 mSv) for the chest scan, (17.91 mGy, 929.9 mGy·cm, 13.9 mSv) for the abdomen-pelvis scan, and (19.3 mGy, 1152 mGy·cm, 17.25 mSv) for the chest-abdomen-pelvis scan. In comparison with results from different international studies, DLP values measured in the present study were lower for the chest-abdomen-pelvis and abdomen-pelvis CT scans, and higher for the head CT and chest CT scans.</p> <p><italic>Conclusions:</italic> It is very important that each country establishes its own DRLs and compares them with those reported by other countries, especially the developed ones. It is also important that these levels are regularly updated.</p> </abstract>ARTICLEtrue thermal imaging be useful in early diagnosis of lower extremities chronic venous disease?<abstract> <title style='display:none'>Abstract</title> <p><italic>Introduction:</italic> World statistics confirmed that about 40-50% of men and 50-55% of women suffer from chronic venous disease. Currently, the Duplex ultrasound is the leading diagnostic method for chronic venous disease (CVD), but it has some limitations. Therefore, it is important to find a new diagnostic technique that will provide additional parameters, describing not only structural but also early metabolic and functional changes.</p> <p><italic>Materials and Methods:</italic> This study aimed to demonstrate the usefulness of the thermal imaging technique in the diagnosis of chronic venous disease. Results were obtained for two groups: 61 patients suffering from the primary chronic venous disease (CVD group) and 30 healthy people (control group). The obtained results compared the thermal imaging parameters to data obtained from the ultrasound examination. Parameters such as the reflux duration and extent of the CEAP classification were correlated with the mean temperature of the limb, the mean temperature of the lesion (determined using two methods), and the thermal range. Based on data obtained during the study, correlation coefficients were calculated for individual parameters.</p> <p><italic>Results:</italic> The results obtained show that the mean limb temperature, and especially the mean temperature of a proposed isothermal area, is significantly correlated with the range of reflux. The conducted tests showed the correlation between some thermal and ultrasonic parameters determined by Spearman's coefficient is 0.4 (p &lt; 0.05).</p> <p><italic>Conclusions:</italic> Thus, parameters such as the isothermal area and the thermal range may be used as a preliminary quantitative diagnosis, similarly to those derived from the Duplex ultrasound.</p> </abstract>ARTICLEtrue diagnostic reference levels in diagnostic and therapeutic pediatric cardiology at a specialist pediatric hospital in South Africa<abstract> <title style='display:none'>Abstract</title> <p><italic>Introduction:</italic> Children may be at a higher risk of experiencing the detrimental effects of ionizing radiation arising from medical radiation imaging. Dose optimisation is therefore recommended to provide assurance that their exposure is as low as reasonably achievable. To this end, periodic assessment of dose levels and establishment of Local Diagnostic Reference Levels (LDRLs) in medical facilities is necessary. There is a general paucity in the literature of data pertaining to dose levels in pediatric interventional radiology. This study establishes LDRLs in diagnostic and therapeutic heart catheterization procedures at a specialist pediatric hospital in a resource constrained country.</p> <p><italic>Material and methods:</italic> Dose indicators from actual patient procedures were collected from the archive and analyzed retrospectively to determine the median, 25th, and 75th percentiles of the total Air Kerma Area Product (KAP), Cumulative Air Kerma (CAK), total Fluoroscopy Time (FT), and a total number of Cine Images (CI) of selected interventional procedures. The dose indicators were also age-stratified into five age groups defined by the International Commission on Radiation Protection publication 135. The results were compared to values available from similar studies in the literature to benchmark our dose levels. Local Dose Reference Levels were set as the 75th percentile values.</p> <p><italic>Results:</italic> For diagnostic procedures (n = 80), the 75th percentiles of KAP, CAK, FT, and CI were 4.0 Gy·cm<sup>2</sup>, 31.5 mGy, 14.3 min, and 315 frames, respectively and 3.2 Gy·cm<sup>2</sup>, 30.5 mGy, 17.5 min, and 606 frames, respectively for therapeutic procedures (n = 143).</p> <p><italic>Conclusions:</italic> The LDRLs from this study did not vary significantly from those published in the literature, suggesting that practices at our center were comparable to international norms. Regular reviews of the LDRLs must be conducted to check that the dose levels do not deviate considerably.</p> </abstract>ARTICLEtrue and pre-evaluation of an in-house cylindrical ionization chamber fabricated from locally available materials<abstract> <title style='display:none'>Abstract</title> <p><italic>Introduction:</italic> The objectives of this study were to construct a very robust in-house cylindrical ionization chamber from locally available materials to minimize cost, and to assess its suitability for use in a clinical setting.</p> <p><italic>Materials and Methods:</italic> The entire body of the constructed IC was composed of Perspex (PMMA). Other components of the IC were made from locally available materials, such as paper and discarded items. The in-house IC was made waterproof by passing the triaxial cable connecting its various electrodes through a plastic tube which once served as a drainage tube of a urine bag. This connection was made such that the chamber was vented to the environment. The completed in-house IC was evaluated for: polarity effect, ion recombination, ion collection efficiency, stability, dose linearity, stem effect, leakage current, angular, dose rate and energy dependences.</p> <p><italic>Results:</italic> Although the pre-evaluation results confirmed that the in-house IC satisfied the stipulated international standards for ICs, there was a need to enhance the stem effect and leakage current characteristics of the IC. The in-house IC was found to have an absorbed dose to water calibration coefficient of 4.475 x 10<sup>7</sup> Gy/C (uncertainty of 1.6%) for cobalt 60 through a cross-calibration with a commercial 0.6 cc cylindrical IC with traceability to the Germany National Dosimetry Laboratory. Using a Jaffé diagram, the in-house IC was also found to have a recombination correction factor of 1.0078 when operated at the calibration voltage of + 400 V. In terms of beam quality correction factors for megavoltage beams, the in-house IC was found to exhibit characteristics similar to those of Scanditronix-Wellhofer IC 70 Farmer type IC.</p> <p><italic>Conclusion:</italic> The constructed in-house Farmer-type IC was able to meet all the recommended characteristics for an IC, and therefore, the in-house IC is suitable for beam output calibration in external beam radiotherapy.</p> </abstract>ARTICLEtrue patient centering of computed tomography images and its implementation to evaluate clinical practices in three hospitals in Indonesia<abstract> <title style='display:none'>Abstract</title> <p><italic>Purpose:</italic> This study aims to develop a software tool for investigating patient centering profiles of axial CT images and to implement it to evaluate practices in three hospitals in Indonesia.</p> <p><italic>Methods:</italic> The evaluation of patient centering accuracy was conducted by comparing the center coordinate of the patient’s image to the center coordinates of the axial CT image. This process was iterated for all slices to yield an average patient mis-centering in both the x- and y-axis. We implemented the software to evaluate the profile of centering on 268 patient images from the head, thorax, and abdomen examinations taken from three hospitals.</p> <p><italic>Results:</italic> We found that 82% of patients were mis-centered in the y-axis (i.e., placed more than 5 mm from the iso-center), with 49% of patients placed 10–35 mm from the iso-center. Most of the patients had a tendency to be placed below the iso-centers. In head examinations, patients were more precisely positioned than in the other examinations. We did not find any significant difference in mis-centering between males and females. We found that there was a slight difference between mis-centering in adult and pediatric patients.</p> <p><italic>Conclusion:</italic> Software for automated patient centering was successfully developed. Patients in three hospitals in Indonesia had a tendency to be placed under the iso-center of the gantry.</p> </abstract>ARTICLEtrue of a commercial EPID-based in-vivo dosimetry and its feasibility and implementation for treatment verification in Malaysia<abstract> <title style='display:none'>Abstract</title> <p><italic>Introduction:</italic> In vivo dosimetry verification is currently a necessity in radiotherapy centres in Europe countries as one of the tools for patient-specific QA, and now its demand is currently rising in developed countries, such as Malaysia. The aim of this study is to characterize commercial EPID-based dosimetry and its implementation for radiotherapy treatment verification in Malaysia.</p> <p><italic>Materials and Methods:</italic> In this work, the sensitivity and performance of a commercially available in vivo dosimetry system, EPIgray® (DOSIsoft, Cachan, France), were qualitatively evaluated prior to its use at our centre. EPIgray response to dose linearity, field size, off-axis, position, and angle dependency tests were performed against TPS calculated dose for 6 MV and 10 MV photon beams. Relative deviations of the total dose were evaluated at isocentre and different depths in the water. EPIgray measured dose was validated by using IMRT and VMAT prostate plan. All calculation points were at the beam isocentre and at points suggested by TG-119 with accepted tolerance of ±10% dose threshold.</p> <p><italic>Results:</italic> EPIgray reported good agreement for linearity, field size, off-axis, and position dependency with TPS dose, being within 5% tolerance for both energy ranges. The average deviation was less than ±2% and ±7% in 6 MV and 10 MV photon beams, respectively, for the angle dependency test. A clinical evaluation performed for the IMRT prostate plan gave average agreement within ±3% at the plan isocentre for both energies. While for the VMAT plan, 95% and 100% of all points created lie below ±5% for 6 MV and 10 MV photon beam energy, respectively.</p> <p><italic>Conclusion:</italic> In summary, based on the results of preliminary characterization, EPID-based dosimetry is believed as an important tool and beneficial to be implemented for IMRT/VMAT plans verification in Malaysia, especially for in vivo verification, alongside existing pre-treatment verification.</p> </abstract>ARTICLEtrue