Journal of Biomedical Physics and Engineering最新文献

The relationship between breast size and breast cancer risk is complex and not fully understood. This study investigates how breast size, categorized by cup size, correlates with age-standardized rates (ASR) of breast cancer incidence. Data were collected from two sources: breast cancer incidence rates from the Global Cancer Observatory (GCO) and breast size data from "Data Pandas," an open-access database. This allowed for a cross-country analysis of breast cancer incidence and breast size characteristics. Descriptive statistics indicated that ASR increased with larger cup sizes, ranging from 34.72 (AA) to 90.17 (C). An ANOVA test revealed significant differences in mean ASR among cup size groups (F=14.416, P<0.001), with Bonferroni comparisons showing distinct clusters: smaller sizes (AA, AA-A, A) differed significantly from larger sizes (A-B, B, B-C, C).The largest mean ASR difference was between groups A and C (-42.93, P=0.001), highlighting higher ASR in larger cup sizes. This suggests a significant association between breast cup size and breast cancer ASR, potentially linked to physiological or hormonal factors.Despite limitations, these findings prompt further investigation. The next phase will focus on breast cancer patients, addressing relevant risk factors for a more comprehensive understanding of the associations observed.

Background: In radiotherapy, the accuracy of dose calculation systems plays a key role in the treatment of cancer patients.

Objective: The current research aimed to evaluate the dose calculation accuracy of Monaco Treatment Planning System (TPS) in estimating the Effective Wedge Angle (EWA) using two different mathematical methods: Elekta formula and ICRU-24 formula.

Material and methods: In this experimental study, EWAs for different field sizes (5×5, 10×10, 15×15, 20×20, 25×25, and 30×30 cm²) at standard angles (15°, 30°, 45°, and 60°) were computed by the Monaco TPS using two different analytical methods. The practical EWAs were measured according to the conditions outlined in the Elekta formula and the ICRU-24 formula, and these measurements were compared with the results derived from the TPS.

Results: The planned and measured EWAs are consistent with the Elekta formula, and the error value was less than ±0.5 in all radiation fields and EWAs. In the ICRU-24 formula, the maximum deviation was ±2.6° between the computational and practical EWAs.

Conclusion: The Elekta-based analytical method demonstrates a good agreement between planned and measured EWAs, while the ICRU-24 formula exhibited the greatest discrepancies.

Background: The biomechanical impacts of Conventional Open Surgery (COS) versus Minimally Invasive Surgery (MIS) fusion techniques on adjacent segments and their potential role in developing Adjacent Segment Disease (ASD) remain uncertain for spondylolisthesis.

Objective: This study aimed to investigate the impact of MIS and COS fusion surgeries on adjacent spinal segments for spondylolisthesis, through on muscle injury and developing ASD.

Material and methods: This prospective and non-randomized controls study used a validated musculoskeletal model to compare the biomechanical effects of COS and MIS L₄/L₅ fusion surgery on patients with spondylolisthesis. The model incorporated kinematic data from 30 patients who underwent each surgery. A sitting task was simulated to model post-operative muscle atrophy, and the analysis focused on changes in biomechanics of adjacent spinal segments.

Results: Lumbar flexion was significantly greater (201%) in MIS vs. COS, despite similar pelvic tilt. Consequently, Lumbopelvic Rhythm (LPR) also increased in MIS (133%). Both techniques altered inter-segmental moments. While inter-joint load was higher in COS, only the lower joint's compressive load was significantly greater (67%). Additionally, MIS required lower overall muscle force with reduced loads and passive moment on spinal joints compared to COS.

Conclusion: This study demonstrates that MIS fusion preserves physiological LPR better than COS. MIS maintains normal spinal curvature and maintains lumbar lordosis. While open surgery can lead to abnormal curvature and increased muscle forces to compensate for spinal stability. The study emphasizes the importance of paraspinal muscles in influencing spinal load distribution during MIS compare to COS.

Background: The evaluation of treatment-associated errors is important in the radiotherapy process, particularly those resulting related to patient setup.

Objective: This research aimed to assess the interfractional setup errors and determine the Clinical Target Volume to Planning Target Volume (CTV to PTV) margin in patients undergoing 3-Dimensional Conformal Radiation Therapy (3DCRT) for head and neck cancer by means of electronic portal imaging device.

Material and methods: In this analytical study, 300 portal images were acquired from 50 patients undergoing 3DCRT for head and neck cancer. Using the portal images of Lateral (LAT) and Antero-Posterior (AP) fields, population systematic (∑) and random (σ) errors were obtained in the lateral, longitudinal, and vertical directions. Finally, based on the International Commission on Radiation Units and Measurements (ICRU) Report 62's, Stroom's and Van Herk's methods, Planning target volume margins were determined.

Results: The translational shift ranges were 0-8.1 mm in the ML, 0-9 mm in the SI (AP), 0-8.8 mm in the SI (LAT), and 0-10 mm in the AP directions. The population systematic and random errors were respectively 3.230, 2.753, and 2.997 mm, and 1.476, 1.853, and 1.715 mm in X, Y, and Z directions. The calculated PTV margins using the ICRU-62, Stroom's, and Van Herk's formulae were ranging from 3.236-3.551, 6.605-7.493, and 7.932-9.108 mm, respectively.

Conclusion: A PTV margin of 7.5-9.5 mm seems safe for ensuring adequate treatment volume coverage. In addition, the EPID is an effective equipment for verifying patient positioning and reducing treatment setup errors.

Background: The development of a standard motion capture system is needed since the measurement of temporomandibular disorders is time-consuming and costly using laboratory tools.

Objective: The current study aimed to investigate the mandibular kinematic variables using a regular mobile phone and the motion analysis system.

Material and methods: In this quasi-laboratory and comparative study, ten healthy individuals participated, and three mobile cameras, nine red markers, and Kinovea software were also used to investigate the mandibular kinematic variables. Nine light reflective markers were used to check the sensitivity, accuracy, and reliability of the proposed system. The motion was analyzed using seven motion analysis infrared cameras and Qualisys Track Manager (QTM) software. Two other raters analyzed the kinematic variables obtained from the mobile to measure intra- and inter-rater reliability.

Results: Pearson's correlation coefficient was obtained at 0.98, 0.75, 0.98, and 0.96, showing a high correlation. The accuracy and reliability validation tests showed an average error and an accuracy of 0.156 mm and 95%, respectively, with a mobile phone. The Intra Class Correlation coefficient showed a high internal correlation in the mentioned confidence interval (0.98 and 0.81, and 0.96 and 0.97). The intraclass correlation coefficient method also showed 97% inter-raster reliability.

Conclusion: Mobile phones as a new system can evaluate the kinematic variables of mandibular disorders with appropriate accuracy and reliability.

Background: Cardiovascular Diseases (CVD) requires precise and efficient diagnostic tools. The manual analysis of Electrocardiograms (ECGs) is labor-intensive, necessitating the development of automated methods to enhance diagnostic accuracy and efficiency.

Objective: This research aimed to develop an automated ECG classification using Continuous Wavelet Transform (CWT) and Deep Convolutional Neural Network (DCNN), and transform 1D ECG signals into 2D spectrograms using CWT and train a DCNN to accurately detect abnormalities associated with CVD. The DCNN is trained on datasets from PhysioNet and the MIT-BIH and the MIT-BIH arrhythmia dataset. The integrated CWT and DCNN enable simultaneous classification of multiple ECG abnormalities alongside normal signals.

Material and methods: This analytical observational research employed CWT to generate spectrograms from 1D ECG signals, as input to a DCNN trained on diverse datasets. The model is evaluated using performance metrics, such as precision, specificity, recall, overall accuracy, and F1-score.

Results: The proposed algorithm demonstrates remarkable performance metrics with a precision of 100% for normal signals, an average specificity of 100%, an average recall of 97.65%, an average overall accuracy of 98.67%, and an average F1-score of 98.81%. This model achieves an approximate average overall accuracy of 98.67%, highlighting its effectiveness in detecting CVD.

Conclusion: The integration of CWT and DCNN in ECG classification improves accuracy and classification capabilities, addressing the challenges with manual analysis. This algorithm can reduce misdiagnoses in primary care and enhance efficiency in larger medical institutions. By contributing to automated diagnostic tools for cardiovascular disorders, it can significantly improve healthcare practices in the field of CVD detection.

Background: Photothermal therapy (PTT) is one of the effective and non-invasive strategies which hold great promise for improving the treatment of cancer cells. PTT is based on activating a photosensitizer by infrared light irradiation and producing heat and reactive species and apoptosis in the tumor area.

Objective: The aim of this study was to investigate the effect of photothermal/chemotherapy on melanoma cancer cells using poly (2-amino phenol)/gold (P2AO/AuNPs) and doxorubicin (DOX).

Material and methods: In this experimental study, nanoparticles of P2AO/AuNPs were synthesized, and their mixture with DOX was applied as a photosensitizer for photothermal/chemotherapy of a C540 (B16-F10) melanoma cell line.

Results: P2AO/AuNPs generated heat and cytotoxic responsive oxygen species (ROS) upon 808-nm light irradiation with simultaneous intensifying DOX therapeutic effect under domination of synergism effects between light irradiation, P2AO/AuNPs, and doxorubicin. Cell treatment with both P2AO/AuNPs and DOX resulted in a considerable increase in necroptotic cells to 61% with a significant decrease in the living cells (39%).

Conclusion: P2AO/AuNPs provided a platform for light absorption and intensifying DOX therapeutic effect. This study approved the applicability of a new photothermal/chemotherapy by domination of synergistic effects attained by combination of laser light, P2AO, AuNPs, and DOX.

Background: T₁ thermometry is considered a straight method for the safety monitoring of patients with deep brain stimulation (DBS) electrodes against radiofrequency-induced heating during Magnetic Resonance Imaging (MRI), requiring different sequences and methods.

Objective: This study aimed to compare two T₁ thermometry methods and two low specific absorption rate (SAR) imaging sequences in terms of the output image quality.

Material and methods: In this experimental study, a gel phantom was prepared, resembling the brain tissue properties with a copper wire inside. Two types of rapid gradient echo sequences, namely radiofrequency-spoiled and balanced steady-state free precession (bSSFP) sequences, were used. T₁ thermometry was performed by either T₁-weighted images with a high SAR sequence to increase heating around the wire or T₁ mapping methods.

Results: The balanced steady-state free precession (bSSFP) sequence provided higher image quality in terms of spatial resolution (1×1×1.5 mm³ compared with 1×1×3 mm³) at a shorter acquisition time. The susceptibility artifact was also less pronounced for the bSSFP sequence compared with the radiofrequency-spoiled sequence. A temperature increase, of up to 8 ℃, was estimated using a high SAR sequence. The estimated change in temperature was reduced when using the T₁ mapping method.

Conclusion: Heating induced during MRI of implanted electrodes could be estimated using high-resolution T₁ maps obtained from inversion recovery bSSFP sequence. Such a method gives a direct estimation of heating during the imaging sequence, which is highly desirable for safe MRI of DBS patients.

In diagnostic radiology, entrance surface air kerma (ESAK) is one of the patient radiation dose quantities, and the effective dose is used as an estimator of possible risk for radiation exposure level. Calculation of the ESAK and effective dose requires both X-ray machine parameters and patient exposure parameters. Due to the high performance of smartphones and the increase in mobile applications, this study aimed to develop a mobile application to estimate the ESAK and effective dose in general radiography. The ESAK calculator was then developed using Android studio software, which is a standalone application operating on Android operating system version 5.0 or higher. X-ray machine parameters are initially required for calculating X-ray output. For the ESAK and effective dose calculation, exposure parameters for each examination are needed. The results showed that the average score of satisfaction was 4.64±0.13, which was very satisfactory. In conclusion, the ESAK calculator could be used for estimating ESAK and effective dose for individual radiographic examination.