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Dosimetry of Imaging Modalities in Radiotherapy
Published in Arash Darafsheh, Radiation Therapy Dosimetry: A Practical Handbook, 2021
Although kV imaging is commonly used in the IGRT, it is relatively challenging to measure or to calculate kV imaging doses to the patient in a radiotherapy clinic. This is because measuring dose from kV beams requires specific detectors and expertise. AAPM TG-180 recommended two methods that can be used to estimate dose resulting from imaging procedures. One requires patient-specific dose calculations while the other makes use of tabulated values to estimate organ doses from a specific imaging procedure referred to as non-patient-specific imaging dose estimation [1].
Introduction
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
The significant features of a CT system that have made volume CT possible include the high-powered X-ray tube, slip ring technology, advanced detector design and interpolation algorithms. Contemporary X-ray tube and generators can produce a range of voltages (kV) appropriate for different clinical applications. The capability to produce a variety of X-ray spectra facilitates a balance between image quality, highest SNR ratio and lowest possible patient dose.
Imaging: The key to success
Published in Peter A. Schneider, Endovascular Skills: Guidewire and Catheter Skills for Endovascular Surgery, 2019
kV. Kilovoltage is a measure of the penetrability of the X-ray beam and affects image contrast. It represents the electrical potential across the X-ray tube. The higher the voltage is across the X-ray tube, the greater the penetrating power of the beam and the better the contrast. Cerebral, thoracic, and abdominal arteriography usually requires 65–75 kV. Imaging these structures requires penetration of the skull, thoracic cage, and abdominal cavities, respectively. Extremity arteriography is performed with 55–65 kV.
LDR-adapted liver-derived cytokines have potential to induce atherosclerosis
Published in International Journal of Radiation Biology, 2023
Eunguk Shin, Dahye Kim, You Yeon Choi, HyeSook Youn, Ki Moon Seong, BuHyun Youn
It should be noted that there is a potential difference in biological effectiveness in our in vivo and in vitro experimental data using different types of radiation, gamma ray and X-ray. RBE (Relative Biological Effectiveness) has been used to describe the effectiveness of different types of radiation on the same specified end-point as cancer development or other health effects. Although gamma ray and x-ray are usually regarded as the same type of radiation, low energy photons with a weighting factor (wR) of 1 for simple comparison to other higher LET radiation, the biological effectiveness of lower-energy of low LET radiation may be more than two times greater than for higher-energy of low-LET (ICRP publication 92 and NCRP Report No.181). Also, RBE generally increases with decreasing dose and dose rate (Barendsen 1992; Sørensen et al. 2021). Conventional 200kV x-rays are considered to be about twice as effective at low doses compared to gamma rays in some in vitro studies, including chromosomal aberrations in human lymphocytes, and killing of mouse oocytes (National Research Council Board on Radiation Effects R 1998). Therefore, our mechanistic results in the irradiated cells should be carefully interpreted for the enhanced understanding of physiological response in the radiation-exposed mice, considering dose rate, fractionation and energy quantity of radiation.
The inhibitory effects of pimozide, an antipsychotic drug, on voltage-gated K+ channels in rabbit coronary arterial smooth muscle cells
Published in Drug and Chemical Toxicology, 2023
Mi Seon Seo, Jin Ryeol An, Ryeon Heo, Minji Kang, Seojin Park, Seo-Yeong Mun, Hongzoo Park, Eun-Taek Han, Jin-Hee Han, Wanjoo Chun, Geehyun Song, Won Sun Park
The whole-cell patch-clamp technique was adapted to record the Kv currents. Kv currents were measured using the NI-DAQ-8.0 digital interface (National Instruments, Union, CA, USA) and an EPC-800 amplifier (Medical System Corp., Darmstadt, Germany). Patch pipettes were pulled from borosilicate micro-capillaries (Clark Electromedical Instruments, Pangboune, UK) on a two-stage vertical puller (model PP-830; Narishige Scientific Instrument Laboratory, Tokyo, Japan). The resistance of the patch pipettes was 3–4 MΩ when filled with pipette solution. Current signals were digitized with Pathpro software at a sampling rate of 1–2 kHz and filtered at 0.5–1.0 kHz. The average cell capacitance was 17.34 ± 1.46 pF (n = 26). All experiments were carried out at room temperature (22–25 °C). The perforated-patch clamp technique was used to measure membrane potential. Nystatin was added to the internal pipette solution at 130 μg/mL. The success of the perforated-patch configuration was confirmed by the appearance of a slow capacitive current.
A New Imaging Technique for the Diagnosis of Thyroid Cancer: Thyroidography
Published in Journal of Investigative Surgery, 2021
Erhan Aysan, Ozan Aydin, Merve Ercivan, Direnc Aksoy, Alp Erdem Yavuz
The mammography device automatically adjusted the shot dose as it was in mammographic imaging mode. The kv and mas values were determined by the radiologist in cases where the device could not find an appropriate dose. First, raw (DICOM) images were obtained for each case. Subsequently, an algorithm was developed by a biomedical engineer specializing in medical imaging for the project. Aiming to display only microcalcifications in accordance with the radiological properties of thyroid tissue, raw images were transformed into new images (thyroidography) generated by this algorithm. In order for this algorithm to be optimized, an apparatus was designed in which imaging plates could be placed in accordance with the anatomy of the human neck and an international patent application was filed with the name “a new x-ray based thyroid imaging device” (patent application no. TPE 2016/00828, Figure 1).