OBJECTIVE: In this study, we evaluated image quality and radiation dose reduction when a Copper (Cu) filter was added to hip joint X-ray imaging.
METHODS: We measured effective energy without (0 mm) and with (0.1/0.2 mm) Cu-added filter at 70 kV, and we calculated soft tissue-bone contrast and signal-difference-to-noise-ratio (SDNR) under constant entrance surface dose. After that, we estimated the dose reduction rate.
RESULTS: The effective energy was 32.07 keV for 0 mm Cu, 37.59 keV for 0.1 mm Cu, and 40.91 keV for 0.2 mm Cu. As the thickness of the Cu-added filter was increased, contrast decreased, but SDNR increased. The dose reduction rate in bone calculated measuring SDNR was 34% for 0.1 mm Cu and 47% for 0.2 mm Cu in max.
CONCLUSIONS: It was suggested that adding Cu filter to hip-joint X-ray imaging could reduce entrance surface dose while maintaining the image quality based on SDNR.

BACKGROUND: Breathing signal-guided 4D CT sequence scanning such as the intelligent 4D CT (i4DCT) approach reduces imaging artifacts compared to conventional 4D CT. By design, i4DCT captures entire breathing cycles during beam-on periods, leading to redundant projection data and increased radiation exposure to patients exhibiting prolonged exhalation phases. A recently proposed breathing-guided dose modulation (DM) algorithm promises to lower the imaging dose by temporarily reducing the CT tube current, but the impact on image reconstruction and the resulting images have not been investigated.
OBJECTIVE: We evaluate the impact of breathing signal-guided DM on 4D CT image reconstruction and corresponding images.
METHODS: This study is designed as a comparative and retrospective analysis based on 104 4D CT datasets. Each dataset underwent retrospective reconstruction twice: (a) utilizing the acquired clinical projection data for reconstruction, which yields reference image data, and (b) excluding projections acquired during potential DM phases from image reconstruction, resulting in DM-affected image data. Resulting images underwent automatic organ segmentation (lung/liver). (Dis)Similarity of reference and DM-affected images were quantified by the Dice coefficient of the entire organ masks and the organ overlaps within the DM-affected slices. Further, for lung cases, (a) and (b) were deformably registered and median magnitudes of the obtained displacement field were computed. Eventually, for 17 lung cases, gross tumor volumes (GTV) were recontoured on both (a) and (b). Target volume similarity was quantified by the Hausdorff distance.
RESULTS: DM resulted in a median imaging dose reduction of 15.4% (interquartile range [IQR]: 11.3%-19.9%) for the present patient cohort. Dice coefficients for lung ( n = 73 $n=73$ ) and liver ( n = 31 $n=31$ ) patients were consistently high for both the entire organs and the DM-affected slices (IQR lung: 0.985 / 0.982 $0.985/0.982$ [entire lung/DM-affected slices only] to 0.992 / 0.989 $0.992/0.989$ ; IQR liver: 0.977 / 0.972 $0.977/0.972$ to 0.986 / 0.986 $0.986/0.986$ ), demonstrating that DM did not cause organ distortions or alterations. Median displacements for DM-affected to reference image registration varied; however, only two out of 73 cases exhibited a median displacement larger than one isotropic 1 mm 3 ${\\rm mm}^3$ voxel size. The impact on GTV definition for the end-exhalation phase was also minor (median Hausdorff distance: 0.38 mm, IQR: 0.15-0.46 mm).
CONCLUSIONS: This study demonstrates that breathing signal-guided DM has a minimal impact on image reconstruction and image appearance while improving patient safety by reducing dose exposure.

Neutropenia is a common chemotherapy-associated adverse event (AE) in dogs and a significant cause of decreased relative dose intensity. Dose reductions (DRs) and treatment delays (TDs) are frequently applied to decrease the risk of further neutropenic events (NEs) and AEs, but there is no standardised approach. The two main objectives of this retrospective study were to determine: (1) the failure rate of a 10% DR to prevent a subsequent inadequate absolute neutrophil count (ANC), defined as a nadir ANC <0.75 × 109/L or pretreatment ANC <1.5 × 109/L; and (2) if the duration of TDs due to pretreatment neutropenia affects the occurrence of subsequent NEs. A total of 1056 chemotherapy treatments were recorded for 128 dogs that developed at least one NE. In 75 of 124 (60.5%, 95% CI: 51.2%-69%) evaluable NEs, a nadir ANC of ≥0.75 × 109/L and pretreatment ANC of ≥1.5 × 109/L were achieved after a single 10% chemotherapy DR, while a 10% DR failed to prevent a subsequent inadequate ANC in the remaining 49/124 (39.5%, 95% CI: 30.1%-48.3%). The only variable associated with failure was the drug prescribed. DR failure occurred in 22/39 (56.4%, 95% CI: 40.9%-70.6%) lomustine DRs, 14/27 (51.9%, 95% CI: 33.9%-69.2%) cyclophosphamide DRs, but only 2/22 (9.1%, 95% CI: 2.5%-27.8%) doxorubicin DRs and 2/24 (8.3%, 95% CI: 2.3%-25.8%) vincristine DRs. Seventy-three evaluable TDs (mean: 5 days, SD ± 2.2 days) were prescribed. There was no association between TD duration and subsequent NEs (p = 0.11).

UNASSIGNED: Abdominal radiographs remain useful in newborns. Given the high radiation sensitivity of this population, it is necessary to optimize acquisition techniques to minimize radiation exposure.
UNASSIGNED: Evaluate the effects of three additional filtrations on radiation dose and image quality in abdominal X-rays of newborns using an anthropomorphic phantom.
UNASSIGNED: Abdominal radiographs of an anthropomorphic newborn phantom were performed using acquisition parameters ranging from 55 to 70 kV and from 0.4 to 2.5 mAs, without and with three different additional filtrations: 0.1 mm copper (Cu) + 1 mm aluminum (Al), 0.2 mm copper + 1 mm aluminum, and 2 mm aluminum. For each X-ray the dose area product (DAP) was measured, the signal-to-noise ratio (SNR) was calculated, and image quality (IQ) was evaluated by two blinded radiologists using the absolute visual grading analysis (VGA) method.
UNASSIGNED: Adding an additional filtration resulted in a significant reduction in DAP, with a decrease of 42% using 2 mm Al filtration, 65% with 0.1 mm Cu + 1 mm Al filtration, and 78% with 0.2 mm Cu + 1 mm Al filtration (p < 0.01). The addition of 2 mm aluminum filtration does not significantly decrease the SNR (p = 0.31), CNR (p = 0.52) or the IQ (p = 0.12 and 0.401 for reader 1 and 2, respectively). However, adding copper-containing filtration leads to a significant decrease in, SNR, CNR and IQ.
UNASSIGNED: Adding a 2 mm Al additional filtration for abdominal radiographs in newborns can significantly reduce the radiation dose without causing a significant decrease in image quality.

暂无摘要。

OBJECTIVE: Clinical radiographic imaging is seated upon the principle of differential keV photon transmission through an object. At clinical x-ray energies the scattering of photons causes signal noise and is utilized solely for transmission measurements. However, scatter - particularly Compton scatter, is characterizable. In this work we hypothesized that modern radiation sources and detectors paired with deep learning techniques can use scattered photon information constructively to resolve superimposed attenuators in planar x-ray imaging.
METHODS: We simulated a monoenergetic x-ray imaging system consisting of a pencil beam x-ray source directed at an imaging target positioned in front of a high spatial- and energy-resolution detector array. The setup maximizes information capture of transmitted photons by measuring off-axis scatter location and energy. The signal was analyzed by a convolutional neural network, and a description of scattering material along the axis of the beam was derived. The system was virtually designed/tested using Monte Carlo processing of simple phantoms consisting of 10 pseudo-randomly stacked air/bone/water materials, and the network was trained by solving a classification problem.
RESULTS: From our simulations we were able to resolve traversed material depth information to a high degree, within our simple imaging task. The average accuracy of the material identification along the beam was 0.91±0.01, with slightly higher accuracy towards the entrance/exit peripheral surfaces of the object. The average sensitivity and specificity was 0.91 and 0.95, respectively.
CONCLUSIONS: Our work provides proof of principle that deep learning techniques can be used to analyze scattered photon patterns which can constructively contribute to the information content in radiography, here used to infer depth information in a traditional 2D planar setup. This principle, and our results, demonstrate that the information in Compton scattered photons may provide a basis for further development. The work was limited by simple testing scenarios and without yet integrating complexities or optimizations. The ability to scale performance to the clinic remains unexplored and requires further study.

We propose a sitting position that achieves both high image quality and a reduced radiation dose in elbow joint imaging by area detector computed tomography (ADCT), and we compared it with the \'superman\' and supine positions. The volumetric CT dose index (CTDIvol) for the sitting, superman, and supine positions were 2.7, 8.0, and 20.0 mGy and the dose length products (DLPs) were 43.4, 204.7, and 584.8 mGy • cm, respectively. In the task-based transfer function (TTF), the highest value was obtained for the sitting position in both bone and soft tissue images. The noise power spectrum (NPS) of bone images showed that the superman position had the lowest value up to approx. 1.1 cycles/mm or lower, whereas the sitting position had the lowest value when the NPS was greater than approx. 1.1 cycles/mm. The overall image quality in an observer study resulted in the following median Likert scores for Readers 1 and 2: 5.0 and 5.0 for the sitting position, 4.0 and 3.5 for the superman position, and 4.0 and 2.0 for the supine position. These results indicate that our proposed sitting position with ADCT of the elbow joint can provide superior image quality and allow lower radiation doses compared to the superman and supine positions.

OBJECTIVE: Target positions should be acquired during beam delivery for accurate lung stereotactic body radiotherapy. We aimed to perform kilovoltage (kV) imaging during beam irradiation (intra-irradiation imaging) under phase-gated conditions and evaluate its performance.
METHODS: Catphan 504 and QUASAR respiratory motion phantoms were used to evaluate image quality and target detectability, respectively. TrueBeam STx linac and the Developer Mode was used. The imaging parameters were 125 kVp and 1.2 mAs/projection. Flattened megavoltage (MV) X-ray beam energies 6, 10 and 15 MV and un-flattened beam energies 6 and 10 MV were used with field sizes of 5 × 5 and 15 × 15 cm2 and various frame rates for intra-irradiation imaging. In addition, using a QUASAR phantom, intra-irradiation imaging was performed during intensity-modulated plan delivery. The root-mean-square error (RMSE) of the CT-number for the inserted rods, image noise, visual assessment, and contrast-to-noise ratio (CNR) were evaluated.
RESULTS: The RMSEs of intra-irradiation cone-beam computed tomography (CBCT) images under gated conditions were 50-230 Hounsfield Unit (HU) (static < 30 HU). The noise of the intra-irradiation CBCT images under gated conditions was 15-35 HU, whereas that of the standard CBCT images was 8.8-27.2 HU. Lower frame rates exhibited large RMSEs and noise; however, the iterative reconstruction algorithm (IR) was effective at improving these values. Approximately 7 fps with the IR showed an equivalent CNR of 15 fps without the IR. The target was visible on all the gated intra-irradiation CBCT images.
CONCLUSIONS: Several image quality improvements are required; however, intra-irradiated CBCT images showed good visual target detection.

Deep learning CT reconstruction (DLR) has become increasingly popular as a method for improving image quality and reducing radiation exposure. Due to their nonlinear nature, these algorithms result in resolution and noise performance which are object-dependent. Therefore, traditional CT phantoms, which lack realistic tissue morphology, have become inadequate for assessing clinical imaging performance. We propose to utilize 3D-printed PixelPrint phantoms, which exhibit lifelike attenuation profiles, textures, and structures, as a better tool for evaluating DLR performance. In this study, we evaluate a DLR algorithm (Precise Image (PI), Philips Healthcare) using a custom PixelPrint lung phantom and perform head-to-head comparisons between DLR, iterative reconstruction, and filtered back projection (FBP) with scans acquired at a broad range of radiation exposures (CTDIvol: 0.5, 1, 2, 4, 6, 9, 12, 15, 19, and 20 mGy). We compared the performance of each resultant image using noise, peak signal to noise ratio (PSNR), structural similarity index (SSIM), feature-based similarity index (FSIM), information theoretic-based statistic similarity measure (ISSM) and universal image quality index (UIQ). Iterative reconstruction at 9 mGy matches the image quality of FBP at 12 mGy (diagnostic reference level) for all metrics, demonstrating a dose reduction capability of 25%. Meanwhile, DLR matches the image quality of diagnostic reference level FBP images at doses between 4 - 9 mGy, demonstrating dose reduction capabilities between 25% and 67%. This study shows that DLR allows for reduced radiation dose compared to both FBP and iterative reconstruction without compromising image quality. Furthermore, PixelPrint phantoms offer more realistic testing conditions compared to traditional phantoms in the evaluation of novel CT technologies. This, in turn, promotes the translation of new technologies, such as DLR, into clinical practice.

BACKGROUND: Clinical guidelines for the treatment of rheumatoid arthritis (RA) recommend reducing the use of glucocorticoids (GCs) due to the high risk of associated complications.
OBJECTIVE: To determine the frequency of GC cancellations and dose reductions in real clinical practice, while taking into account active RA therapy.
METHODS: The study group consisted of 303 patients with RA reliable according to ACR/EULAR criteria (women 79.9%, age 52.8±13.3, disease duration 9 [4; 16] years, DAS-28-CRP 4.9±1.0, RF seropositivity 77.4%, ACPA seropositivity 70.3%), who were prescribed or changed therapy with disease-modifying antirheumatic drugs (DMARDs), biologic disease-modifying antirheumatic drugs (bDMARDs) or Janus kinase inhibitors (iJAK) due to disease exacerbation and ineffectiveness of previous treatment. All patients initially received GC (7.7±3.8 mg/day equivalent of prednisolone). After adjustment of therapy, 42.9% of patients received methotrexate, 27.6% leflunomide, 2.5% sulfasalazine, hydroxychloroquine, or a combination with an Non-steroidal anti-inflammatory drugs, 63.7% bDMARDs, and 7.2% iJAK. The need for GC intake was assessed by a telephone survey conducted 6 months after the start of follow-up.
RESULTS: Telephone survey was possible in 274 (90.4%) persons. There was a significant decrease in pain intensity (numerical rating scale, NRS 0-10) from 6.3±1.4 to 4.3±2.4 (p<0.001), fatigue (NRS) from 6.7±2.3 to 5.2±2.1 (p<0.001), and functional impairment (NRS) from 5.4±2.1 to 3.9±2.0 (p<0.001). A positive PASS index (symptom status acceptable to patients) was noted in 139 (50.7%) patients. GC cancellation was noted in 19.7%, dose reduction in 25.9%, maintaining the same dose in 42.7%, and dose increase in 11.7%.
CONCLUSIONS: Against the background of intensive RA therapy, including combination of DMARDs with bDMARDs or iJAK, complete withdrawal or reduction of GC dose was achieved in less than half (45.6%) of patients after 6 months.
Обоснование. Актуальные клинические рекомендации по лечению ревматоидного артрита (РА) указывают на необходимость снижения использования глюкокортикоидов (ГК) в связи с высоким риском осложнений на фоне приема этих препаратов. Цель. Определить частоту отмен и снижения дозы ГК на фоне активной терапии РА в реальной клинической практике. Материалы и методы. Исследуемую группу составили 303 пациента с РА, достоверным по критериям ACR/EULAR (женщины – 79,9%, возраст – 52,8±13,3 года, длительность болезни – 9 [4; 16] лет, DAS-28-СРБ – 4,9±1,0, серопозитивность по ревматоидному фактору – 77,4%, по антителам к циклическому цитруллиновому пептиду – 70,3%), которым в связи с обострением заболевания и неэффективностью предшествующего лечения назначена или изменена терапия синтетическими базисными противовоспалительными препаратами (сБПВП), генно-инженерными биологическими препаратами (ГИБП) или ингибиторами янус-киназ (иJAK). Все пациенты исходно получали ГК (7,7±3,8 мг/сут в эквиваленте преднизолона). После коррекции терапии 42,9% пациентов получали метотрексат, 27,6% – лефлуномид, 29,5% – сульфасалазин, гидроксихлорохин или комбинацию сБПВП, 63,7% – ГИБП, 7,2% – иJAK. Оценивалась потребность в приеме ГК по данным телефонного опроса, проведенного через 6 мес после начала наблюдения. Результаты. Телефонный опрос удалось провести у 274 (90,4%) лиц. Отмечено достоверное снижение интенсивности боли (числовая рейтинговая шкала – ЧРШ 0–10) с 6,3±1,4 до 4,3±2,4 (p<0,001), усталости (ЧРШ) – с 6,7±2,3 до 5,2±2,1 (p<0,001), функциональных нарушений (ЧРШ) – с 5,4±2,1 до 3,9±2,0 (p<0,001). Положительный индекс PASS (состояние симптомов, приемлемое для пациентов) отмечен у 139 (50,7%) пациентов. Отмена ГК наблюдалась у 19,7%, снижение дозы – у 25,9%, сохранение прежней дозы – у 42,7%, повышение дозы – у 11,7%. Заключение. На фоне активной терапии РА, включающей комбинацию сБПВП с ГИБП или иJAK, через 6 мес удалось добиться полной отмены или снижения дозы ГК менее чем у 1/2 (45,6%) пациентов.