Design and construction of a laser-based respiratory gating system for implementation of deep inspiration breathe hold technique in radiotherapy clinics

Background: Deep inspiration breath-hold (DIBH) is known as a radiotherapy method for the treatment of patients with left-sided breast cancer. In this method, patient is under exposure only while he/she is at the end of a deep inspiration cycle and holds his/her breath. In this situation, the volume of the lung tissue is enhanced and the heart tissue is pushed away from the treating breast. Therefore, heart dose of these patients, using DIBH, experiences a considerable decline compared to free breathing treatment. There are a few commercialized systems for implementation of DIBH in invasive or noninvasive manners. Methods: We present a novel constructed noninvasive DIBH device relied on a manufacturing near-field laser distance meter. This in-house constructed system is composed of a CD22-100AM122 laser sensor combined with a data acquisition system for monitoring the breathing curve. Qt Creator (a cross-platform JavaScript, QML, and C++-integrated development environment that is part of the SDK for development of the Qt Graphical User Interface application framework) and Keil MDK-ARM (a programming software where users can write in C and C++ and assemble for ARM-based microcontrollers) are used for composing computer and microcontroller programs, respectively. Results: This system could be mounted in treatment or computed tomography (CT) room at suitable cost; it is also easy to use and needs a little training for personnel and patients. The system can assess the location of chest wall or abdomen in real time with high precision and frequency. The performance of CD22-100AM122 demonstrates promise for respiratory monitoring for its fast sampling rate as well as high precision. It can also deliver reasonable spatial and temporal accuracy. The patient observes his/her breathing waveform through a 7” 1024 × 600 liquid crystal display and gets some instructions during treatment and CT sessions by an exploited algorithm called “interaction scenario” in this study. The system is also noninvasive and well sustainable for patients. Conclusions: The constructed system has true real-time operation and is rapid enough for delivering clear contiguous monitoring. In addition, in this system, we have provided an interaction scenario option between patient and CT or Linac operator. In addition, the constructed system has the capability of sending triggers for turning on and off CT or Linac facilities. In this concern, the system has the superiority of combining a plenty of characteristics

Simulation of a Quality Control Jaszczak Phantom with SIMIND Monte Carlo and Adding the Phantom as an Accessory to the Program

Introduction Quality control is an important phenomenon in nuclear medicine imaging. A Jaszczak SPECT Phantom provides consistent performance information for any SPECT or PET system. This article describes the simulation of a Jaszczak phantom and creating an executable phantom file for comparing assessment of SPECT cameras using SIMIND Monte Carlo simulation program which is well-established for SPECT. Materials and Methods The simulation was based on a Deluxe model of Jaszczak Phantom with defined geometry. Quality control tests were provided together with initial imaging example and suggested use for the assessment of parameters such as spatial resolution, limits of lesion detection, and contrast comparing with a Siemens E.Cam SPECT system. Results The phantom simulation was verified by matching tomographic spatial resolution, image contrast, and also uniformity compared with the experiment SPECT of the phantom from filtered backprojection reconstructed images of the spheres and rods. The calculated contrasts of the rods were 0.774, 0.627, 0.575, 0.372, 0.191, and 0.132 for an experiment with the rods diameters of 31.8, 25.4, 19.1, 15.9, 12.7, and 9.5 mm, respectively. The calculated contrasts of simulated rods were 0.661, 0.527, 0.487, 0.400, 0.23, and 0.2 for cold rods and also 0.92, 0.91, 0.88, 0.81, 0.76, and 0.56 for hot rods. Reconstructed spatial tomographic resolution of both experiment and simulated SPECTs of the phantom obtained about 9.5 mm. An executable phantom file and an input phantom file were created for the SIMIND Monte Carlo program. Conclusion This phantom may be used for simulated SPECT systems and would be ideal for verification of the simulated systems with real ones by comparing the results of quality control and image evaluation. It is also envisaged that this phantom could be used with a range of radionuclide doses in simulation situations such as cold, hot, and background uptakes for the assessment of detection characteristics when a new similar clinical SPECT procedure is being simulated

Evaluation of Personal Shields Used in Selected Radiology Departments

Introduction The purpose of this study was to evaluate personal shields in radiation departments of hospitals affiliated to Mashhad University of Medical Sciences. Materials and Methods First, the information related to 109 personal shields was recorded and evaluated by imaging equipment. Afterwards, the equivalent lead thickness (ELT) of 62 personal shields was assessed, using dosimeter and standard lead layers at 100 kVp. Results In this study, 109 personal shields were assessed in terms of tears, holes and cracks. The results showed that 18 shields were damaged. Moreover, ELT was evaluated in 62 shields. As the results indicated, ELT was unacceptable in 8 personal shields and lower than expected in 9 shields. Conclusion According to the results, 16.5% of personal shields had defects (tears, holes and cracks) and 13% of them were unacceptable in terms of ELT and needed to be replaced. Therefore, regular quality control of personal shields and evaluation of new shields are necessary at any radiation department

Evaluation of application of EPID for rapid QC testing of linear accelerator

AimEvaluation of application of EPID for rapid QC testing of linear accelerator.BackgroundQuality control of a linear accelerator device is a time and energy intensive process. In this study, attempts have been made to perform the linear accelerator quality control using electronic portal imaging device (EPID), which is mounted on most accelerators.Materials and methodsFirst, quality control and dosimetry parameters of the device were determined and measured based on standard protocols to ensure full calibration of the accelerator. Then, various features of EPID including spatial resolution and contrast resolution, the effect of buildup region, dose response and image uniformity were evaluated. In the next step, consistent with the parameters of linear accelerator quality control including field size, field flatness and symmetry, the light field coincidence with X-ray field, mechanical stability and multileaf collimator position accuracy test, the output images of device were obtained.After feeding images to the MATLAB software, their pixel content was analyzed. All measurements of the three photon beams were repeated three times.ResultsThe EPID image had a desirable resolution, contrast and uniformity and displayed high sensitivity to dose changes with linear dose response. Seven qualitative parameters of the linear accelerator were then controlled by EPID.ConclusionsThe results of the linear accelerator quality control using the EPID were consistent with practice. Quality control using the EPID was more convenient and faster than conventional methods

Evaluation of Personal Shields Used in Selected Radiology Departments

Introduction The purpose of this study was to evaluate personal shields in radiation departments of hospitals affiliated to Mashhad University of Medical Sciences. Materials and Methods First, the information related to 109 personal shields was recorded and evaluated by imaging equipment. Afterwards, the equivalent lead thickness (ELT) of 62 personal shields was assessed, using dosimeter and standard lead layers at 100 kVp. Results In this study, 109 personal shields were assessed in terms of tears, holes and cracks. The results showed that 18 shields were damaged. Moreover, ELT was evaluated in 62 shields. As the results indicated, ELT was unacceptable in 8 personal shields and lower than expected in 9 shields. Conclusion According to the results, 16.5% of personal shields had defects (tears, holes and cracks) and 13% of them were unacceptable in terms of ELT and needed to be replaced. Therefore, regular quality control of personal shields and evaluation of new shields are necessary at any radiation department

Specific absorbed fractions of internal photon and electron emitters in a human voxel-based phantom: A monte carlo study

The specific absorbed fraction (SAF) of energy is an essential element of internal dose assessment. Here reported a set of SAFs calculated for selected organs of a human voxel-based phantom. The Monte Carlo transport code GATE version 6.1 was used to simulate monoenergetic photons and electrons with energies ranging from 10 keV to 2 MeV. The particles were emitted from three source organs: kidneys, liver, and spleen. SAFs were calculated for three target regions in the body (kidneys, liver, and spleen) and compared with the results obtained using the MCNP4B and GATE/GEANT4 Monte Carlo codes. For most photon energies, the self-irradiation is higher, and the cross-irradiation is lower in the GATE results compared to the MCNP4B. The results show generally good agreement for photons and high-energy electrons with discrepancies within − 2% ±3%. Nevertheless, significant differences were found for cross-irradiation of photons of lower energy and electrons of higher energy due to statistical uncertainties larger than 10%. The comparisons of the SAF values for the human voxel phantom do not show significant differences, and the results also demonstrated the usefulness and applicability of GATE Monte Carlo package for voxel level dose calculations in nonuniform media. The present SAFs calculation for the Zubal voxel phantom is validated by the intercomparison of the results obtained by other Monte Carlo codes

Deep learning-guided attenuation correction in the image domain for myocardial perfusion SPECT imaging

We investigate the accuracy of direct attenuation correction (AC) in the image domain for myocardial perfusion SPECT (single-photon emission computed tomography) imaging (MPI-SPECT) using residual (ResNet) and UNet deep convolutional neural networks. MPI-SPECT 99mTc-sestamibi images of 99 patients were retrospectively included. UNet and ResNet networks were trained using non-attenuation-corrected SPECT images as input, whereas CT-based attenuation-corrected (CT-AC) SPECT images served as reference. Chang’s calculated AC approach considering a uniform attenuation coefficient within the body contour was also implemented. Clinical and quantitative evaluations of the proposed methods were performed considering SPECT CT-AC images of 19 subjects (external validation set) as reference. Image-derived metrics, including the voxel-wise mean error (ME), mean absolute error, relative error, structural similarity index (SSI), and peak signal-to-noise ratio, as well as clinical relevant indices, such as total perfusion deficit (TPD), were utilized. Overall, AC SPECT images generated using the deep learning networks exhibited good agreement with SPECT CT-AC images, substantially outperforming Chang’s method. The ResNet and UNet models resulted in an ME of −6.99 ± 16.72 and −4.41 ± 11.8 and an SSI of 0.99 ± 0.04 and 0.98 ± 0.05, respectively. Chang’s approach led to ME and SSI of 25.52 ± 33.98 and 0.93 ± 0.09, respectively. Similarly, the clinical evaluation revealed a mean TPD of 12.78 ± 9.22% and 12.57 ± 8.93% for ResNet and UNet models, respectively, compared to 12.84 ± 8.63% obtained from SPECT CT-AC images. Conversely, Chang’s approach led to a mean TPD of 16.68 ± 11.24%. The deep learning AC methods have the potential to achieve reliable AC in MPI-SPECT imaging