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Background: The purpose of the study was to discuss whether 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography/computed tomography (18F-FDG PET/CT) study protocol should include brain imaging. Materials and methods: Analysis of international societies recommendations compared with the original data obtained in over 1000 consecutive torso and brain 18F-FDG PET/CT studies collected in 2010. Results: According to the international societies recommendations, the 18F-FDG should not be the radiotracer of choice considering the brain region PET/CT study. However, it can be performed as an additional brain imaging tool. Based on at least a 3-year follow-up, we detected 8 cases of suspicious brain findings and no primary lesion among over 1000 consecutive torso and brain 18F-FDG PET/CT scans performed in 2010. However, in 5 out of 8 patients, the brain lesion was the only metastasis detected, affecting further therapy. Conclusions: The 18F-FDG PET/CT study may help detect malignant brain lesions and, therefore, including brain region imaging into the study protocol should be considered.
ABSTRACT
According to the international societies' recommendations, the 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography/computed tomography ([18F]FDG PET/CT) technique should not be used as the method of choice in brain tumour diagnosis. Therefore, the brain region can be omitted during standard [18F]FDG PET/CT scanning. We performed comprehensive literature research and analysed results from 14,222 brain and torso [18F]FDG PET/CT studies collected in 2010-2020. We found 131 clinically silent primary and metastatic brain tumours and 24 benign lesions. We concluded that the brain and torso [18F]FDG PET/CT study provides valuable data that may support therapeutic management by detecting clinically silent primary and metastatic brain tumours.
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BACKGROUND: Due to the lack of selectivity of ionizing radiation between normal and cancer cells, it is important to improve the existing radiation patterns. Lowering the risk of cancer recurrence and comfort during treatment are priorities in radiotherapy. MATERIALS AND METHODS: In the experiment we used dose verification to determine the irradiation time calculated by a treatment planning system for 6XFFF and 10XFFF beams. Cells cultured under standard conditions were irradiated with a dose of 2 Gy at different beam rates 400 MU/min, 600 MU/min, 800 MU/min, 1000 MU/min, 1400 MU/min, 1600 MU/min and 2400 MU/min using 6XFFF, 10XFFF and 6XFF beams. RESULTS: The experiment was aimed at comparing the biological response of normal prostate cells after clinically applied radiation patterns. No statistically significant differences in the cellular response were observed. The wide range of beam rates as well as the beam profiles did not significantly affect cell proliferation. CONCLUSIONS: High beam rates, without significantly affecting the clonogenic capacity of cells, have an impact on the quality of patient's treatment. With the increasing beam rate the irradiation time is shortened, which has an important impact on patients' health. This experiment can have a practical significance.
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PURPOSE: To evaluate the use of pseudo-monoenergetic reconstructions (PMR) from dual-energy computed tomography, combined with the iterative metal artefact reduction (iMAR) method. METHODS: Pseudo-monoenergetic CT images were obtained using the dual-energy mode on the Siemens Somatom Definition AS scanner. A range of PMR combinations (70-130 keV) were used with and without iMAR. A Virtual Water™ phantom was used for quantitative assessment of error in the presence of high density materials: titanium, alloys 330 and 600. The absolute values of CT number differences (AD) and normalised standard deviations (NSD) were calculated for different phantom positions. Image quality was assessed using an anthropomorphic pelvic phantom with an embedded hip prosthesis. Image quality was scored blindly by five observers. RESULTS: AD and NSD values revealed differences in CT number errors between tested sets. AD and NSD were reduced in the vicinity of metal for images with iMAR (p < 0.001 for AD/NSD). For ROIs away from metal, with and without iMAR, 70 keV PMR and pCT AD values were lower than for the other reconstructions (p = 0.039). Similarly, iMAR NSD values measured away from metal were lower for 130 keV and 70 keV PMR (p = 0.002). Image quality scores were higher for 70 keV and 130 keV PMR with iMAR (p = 0.034). CONCLUSION: The use of 70 keV PMR with iMAR allows for significant metal artefact reduction and low CT number errors observed in the vicinity of dense materials. It is therefore an attractive alternative to high keV imaging when imaging patients with metallic implants, especially in the context of radiotherapy planning.
Subject(s)
Algorithms , Artifacts , Humans , Metals , Phantoms, Imaging , Radiographic Image Interpretation, Computer-Assisted , Tomography, X-Ray ComputedABSTRACT
BACKGROUND: One of the most important test in every quality assurances process of medical linear accelerators is the Winston-Lutz test, allowing an evaluation of the treatment isocentre in the light of uncertainty of the position of the collimator, the gantry and the couch. AIM: The purpose of this work was analysis of the results of the Winston-Lutz test performed with three different phantoms for two different accelerators. MATERIALS AND METHODS: Measurements were performed on two Varian machines: TrueBeam equipped with aS1200 EPID and TrueBeam equipped with aS1000 EPID. During the study three different phantoms dedicated for verification of the radiation isocentre were used: PTW Isoball, AQUILAB Isocentre Phantom and Varian Isocentre Cube. Analysis of the DICOM images was performed in Artiscan software. RESULTS: For TrueBeam with as1200 EPID, gantry MV isocentre was about 0.18â¯mm larger for Varian Isocentre Cube than for two other phantoms used in this study. The largest variability of this parameter was observed for the couch. The results differed to 1.16â¯mm. For TrueBeam with as1000 EPID, results for collimator isocentre with PTW Isoball phantom were about 0.10â¯mm larger than for two other phantoms. For the gantry, results obtained with Varian Isocentre Cube were 0.21â¯mm larger. CONCLUSION: The obtained results for all three phantoms are within the accepted tolerance range. The largest differences were observed for treatment couch, which may be related to the phantom mobility during couch movement.
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PURPOSE: Quantification analysis for monoenergetic computed tomography (CT) images obtained from dual-energy CT scanning was performed in the light of their potential use for structures delineation during radiotherapy. METHODS: Parameters that describe the quality of the images are: linearity, low and high contrast resolution, uniformity, noise and signal to noise ratio (SNR). To evaluate these parameters, a Catphan phantom was scanned using a dual-energy mode at Somatom Definition AS. Based on the polyenergetic CT images, sixteen monoenergetic series (ranged from 40â¯keV to 190â¯keV) were created by CT scanner software and automatically analyzed using Artiscan software. RESULTS: Analysis of linearity shows that a potential use of any monoenergetic images in radiotherapy planning requires that individual calibration curves are implemented for each of them. While the results of the high contrast resolution analysis were comparable for each energy (5 lp/cm), the results of the analyses for uniformity, low contrast resolution, noise and SNR allowed us to select the best imaging energies. The highest relative uniformity was detected for images reconstructed for energies of 60â¯keV and 70â¯keV (98.54% and 98.61%). Similar results were observed for low contrast resolution, where the largest number of disks was detected for these energies, and the noise values (0.42% for 60â¯keV, 0.44% for 70â¯keV). The best SNR was observed for images reconstructed for energy of 60â¯keV. CONCLUSIONS: Taking into account these results, the energy of 70â¯keV was selected as potentially the best for reconstruction of monoenergetic images used for structures delineation during radiotherapy.
