فهرست مطالب

  • Volume:7 Issue: 2, 2020
  • تاریخ انتشار: 1399/06/04
  • تعداد عناوین: 8
|
  • Hossein Amiri, Bahador Makkiabadi* Pages 82-91

    Acoustic thermometry is one of non-invasive methods to measure the temperature inside tissue area. especially when using the thermal therapy techniques such as High Intensity Focused Ultrasound (HIFU) and other thermal based methods, thermal assessment of heated area seems to be necessary. Some of acoustic properties of medium are temperature dependent, therefore, evaluation of temperature dependent parameters will be an indirect and non-invasive approach in thermometry. In this paper some of thermometry methods based on changes in acoustic properties of medium has been reviewed.  The published methods are classified in two main categories:  passive and active thermometry. In the passive thermometry, the thermal measurement probes, induced no acoustic signals to the medium, but they receive the radiated signals from the heated medium. In active method, the thermometry probe transmits a signal into the heated region and receive the echoes, then the received RF signals are processed in order to measure the temperature.

  • Saman Dalvand, Hossein Rajabi *, Ameneh Omidi, Etesam Malekzadeh Pages 92-99
    Purpose

    Radiopharmaceutical Therapy (RPT) is one of the effective methods for pain palliation of bone metastases. Bone marrow is a critical organ in bone structure whose absorbed dose should be kept below a certain threshold. The purpose of this study was to calculate and compare absorbed doses of bone-seeking radiopharmaceuticals used in the palliative treatment of bone metastases.

    Materials and Methods

    In this study, the GATE Monte Carlo code was used to simulate a femur bone, which consists of bone marrow, endosteal layer, bone, and soft tissue phantom model. Absorbed doses of the 153Sm-EDTMP, 89SrCl2, 177Lu-EDTMP, 188Re-HEDP, and 223RaCl2 radiopharmaceuticals were calculated in the femur phantom compartments.

    Results

    bone absorbed doses per disintegration from alpha particles of 223RaCl2 is approximately 24 times higher than absorbed doses from beta particles of 89SrCl2. Also, absorbed dose per disintegration from beta particles of 89SrCl2 in the bone is approximately 12, 6 and 1.5 times higher than 177Lu-EDTMP, 153Sm-EDTMP, and 188Re-HEDP, respectively. Moreover, the bone and bone marrow absorbed dose from beta particles of 153Sm-EDTMP is 1.9 times higher than 177Lu-EDTMP. Besides, absorbed dose per disintegration from beta particles of 188Re-HEDP in the bone marrow is approximately 40, 30, 7, and 4 times higher than 223RaCl2, 89SrCl2, 177Lu-EDTMP and 153Sm-EDTMP, respectively.

    Conclusion

    Our results show that 223RaCl2 could be a more efficient radiopharmaceutical for radionuclide therapy of bone metastases. Also, 177Lu-EDTMP, due to low marrow toxicity and comparable bone absorbed dose with 153Sm-EDTMP, can be used for achieving bone pain palliation. Moreover, significantly high bone marrow absorbed dose of 188Re-HEDP should be considered for palliative therapy of metastatic bone patients.

    Keywords: Dosimetry, Bone Metastasis, Radiopharmaceutical Therapy, Monte Carlo Simulation
  • Hamid Ghaznavi* Pages 100-104
    Purpose

    Computed Tomography (CT) is a fundamental part of diagnosis of diseases. During CT examinations organs in and out of scanned volume are exposed to ionization radiation. The aim of this study was Estimation Thyroid cancer risk in Patients who Underwent 64 Slice brain and paranasal sinuses CT scan.

    Materials and Methods

    with permission from the authors and editor, data related to thyroid dose of 40 patients in Mazyar et al.'s paper was used and by using Biological Effects of Ionizing Radiation (BEIR)VII model thyroid cancer risk was calculated for different ages at exposure in male and female.

    Results

    In both brain and paranasal sinuses CT, ERR values in female patients were twice as many as those in male patients. At age range from 20 to 40 years, ERR was considerably more than at age range 40-60 years since young patients are more radiosensitive than old patients.

    Conclusion

    The calculations of ERR indicate that PNS and brain CT increase the theoretical risk of thyroid cancer incidence. Although the ERR values are low, impacts on the thyroid cancer incidence should not be disregarded.

    Keywords: Thyroid Cancer Risk, Biological Effects of Ionizing Radiation VII Model, Computed Tomography, Brain Computed Tomography, Paranasal Sinuses Computed Tomography
  • Elham Samadi*, Hessam Ahmadi, Fereidoun Nowshiravan Rahatabad Pages 105-111
    Purpose

    Parkinson's Disease (PD) is a neuro-degenerative interminable issue causing dynamic loss of dopamine-creating synapses, which is one of the most far reaching ailments after Alzheimer's infection. In this paper, a system for the classification of Parkinson’s disease tremor using noninvasive measurement and frequency domain features is represented.

    Materials and Methods

    Tremor time-series of Parkinson's disease patients were recorded via a smartphone’s accelerometer sensor. Short-Time Fourier Transform (STFT) was applied to transform the time-domain signal into the frequency domain with high time-frequency resolution. Several frequency features, including mean, max of power spectral density and side frequency have been extracted and by using the FDR algorithm combinations of features carried enough information to reliably assess the severity of tremor in Parkinson patients were determined.

    Results

    Four different classifiers were implemented to estimate the severity of tremors based on the Unified Parkinson's Disease Rating Scale (UPDRS) in Parkinson's disease patients.

    Conclusion

    Classifiers’ estimation was compared to clinical scores derived via neurologist UPDRS annotation on Parkinson's disease patients’ tremor. The best accuracy achieved was 95.91±1.51.

    Keywords: Accelerometer, Parkinson’s Tremor, Unified Parkinson's Disease Rating Scale, Classification, Evolutionary Algorithm
  • Gholamreza Fallah Mohammadi*, Ehsan Mihandoost Pages 112-117
    Purpose

    Point dose calculation in the Treatment Planning System (TPS) is performed using Computed Tomography (CT) images because CT images data have the tissue electron density information. The effect of CT imaging protocols on the calculation of point doses in TPS is one of the most important subjects that was evaluated in this study.

    Materials and Methods

    CT scan imaging was performed from cylindrical water phantom using three scanner systems and different imaging technical parameters. The CT images data were irradiated in TPS to delivering a 200 cGy radiation dose to the center of the phantom with 6 and 15MV X-Ray photon energy with multiple radiation fields and Monitor Unit (MU) were separately calculated. In the TPS, a virtual water phantom with the same characteristic as CT image phantom was simulated and irradiated with similar conditions. The difference in MU values obtained from two irradiation methods in TPS was compared with Wilcoxon nonparametric test.  

    Results

    Variations of mA, kV, Pitch, slice thickness, and kernel as CT imaging parameters have not significantly affected radiotherapy point dose calculation (<2%). CT imaging protocols as a thin slice, 80 kV, and sharp kernel have the greatest difference between CT image-based calculation and designed phantom calculation in TPS where wedge field and 6 MV photon energy were used.

    Conclusion

    The use of CT images obtained with multiple protocols can be used without having a significant effect on the dose calculations of the treatment planning system.

    Keywords: Computed Tomography Scan, Imaging Protocol, Point Dose, Radiotherapy
  • Hossein Amiri, Ali Khani, Yousef Moghimi Boldaji, Bahador Makkiabadi* Pages 118-124
    Purpose

    Internal temperature is a significant factor for medical diagnosis. There are several thermometric methods, including IR, MRI, and active ultrasonic thermometry, which have limitations for clinical applications. The new method in this field called Passive Acoustic Thermometry (PAT), which enhanced some of this limitation. PAT is a safe method for internal temperature estimation that works based on acoustic radiation of materials with a specific temperature. Several experimental studies have been carried out so far in the field of PAT. While, to the best of our knowledge, there is no simulation-based research for nonhomogeneous materials reported yet. In this article (for the first time) we proposed a simulation framework for evaluating the PAT methodologies in nonhomogeneous materials; also we proposed a new formulation for temperature estimation in PAT algorithm.

    Materials and Methods

    This framework supports the generation of acoustic radiation, signal processing, parameter estimation, and temperature reconstruction processes. At the moment the proposed framework estimates the temperature in the frequency domain and uses the frequency spectrum of the acquired ultrasound signals captured by a single transducer. Using the proposed framework, we tried to implement the previously practical experiments and the results of the simulation are consistent with those of the practical experiments. Also, we proposed the formulation that improves the error of temperature estimation.  

    Results

    We study 6 scenarios, including 2 environments with a target at 3 different temperatures. The average error of the proposed formulation in two different nonhomogeneous materials for three different temperatures is less than 0.25°C.

    Conclusion

    The results show that the proposed formulation is the best estimation in the formula that has been introduced until now and compare with the previous study the accuracy is enhanced 54% (from 0.79 to 0.36 deg.). Therefore, the proposed formula enhanced PAT accuracy for temperature estimation. Also, the results show that it is possible to use this framework to evaluate the PAT in different scenarios. Therefore, this method enhances the possibility of examination of different conditions and algorithms. It also reduces the cost of practical experiment.

    Keywords: Internal Temperature, Passive Acoustic Thermometer, Nonhomogeneous Materials
  • Parvaneh Darkhor, Jalil Pirayesh Islamian* Pages 125-133

    In single photon emission computed tomography, collimator selection, optimization, and also geometric calibration have a major impact on the acquired image quality and so on an accurate detectability and diagnosis. The collimator optimization phenomena consider some parameters such as field of view, resolution, sensitivity, resolution at depth, septal thickness and penetration for a specific application task. While the parallel hole collimator is usually used in SPECT and planar imaging but due to the limited solid angle covered by the collimator, the system sensitivity and resolution were highly reduced. Meanwhile other types of collimators such as pin-hole, multi-pin-hole, slant and slit-slat collimators were introduced with a trade-off between sensitivity and resolution. The slant collimator with a much larger solid angle potentially increase the low detection sensitivity from a thin crystal than a parallel hole. This article reviews improvements on collimators also by considering the geometry and geometric calibration methods for improving the image quality in single photon emission computed tomography.

    Keywords: Collimator, Resolution, Image Quality, Single Photon Emission Computed Tomography, Sensitivity
  • MohmmadReza Fouladi, Kamran Gholami, Hossein Ghadiri* Pages 134-137

    X-ray Computed Tomography (CT), e.g. clinical CT scanners, basically provide Linear Attenuation Coefficients (LACs) of objects under study by the means of algorithmic reconstruction of acquired views of attenuated X-ray passing through the samples in different angles around the imaged sample. Micro Computed Tomography (micro-CT) basically works the same as clinical CT. It provides volumetric information representing the inner structure of objects with a resolution in the micron range. LOTUS-inVivo is a micro-CT scanner dedicated for imaging of small animals and ex-vivo biological samples. In the present study the spatial resolution and Low Contrast Detectability (LCD) of LOTUS-inVivo scanner were evaluated using standard phantoms. We aimed to prove the capability of LOTUS-inVivo for small animal and ex-vivo biological samples imaging using the measured image quality parameters, i.e. spatial resolution and low contrast detectability. By the means of analysis of bar and LCD phantom images, the limiting resolution of LOTUS-inVivo micro-CT scanner was measured about 2.7 µm and has been shown that it’s capable of resolving sizes greater than 12.5 µm. Also, we concluded that LOTUS-inVivo is capable of discriminating tissues with 3% differences in contrast relative to the background, for 1 mm bar size. Thus, the provided technical characteristics in this study have made LOTUS-inVivo as a suitable tool for small animal imaging.

    Keywords: LOTUS-inVivo, Micro- Computed Tomography, Tomography, Small Animal Imaging, ImageQuality