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In-Room Imaging Devices Used for Treatment
Published in W. P. M. Mayles, A. E. Nahum, J.-C. Rosenwald, Handbook of Radiotherapy Physics, 2021
A method based on the photo-stimulable phosphor plate, the Fuji system (Sonoda et al. 1983), was further described by Wilenzick et al. (1987). The image receptor was a flexible plate supporting a 1 mm thick layer containing europium-doped barium fluoro-halide. This is called computed radiography (CR). The phosphor contains electron energy traps that are filled when the plate is exposed to ionising radiation. The plate is read out in a separate reader, where a red, scanning laser beam releases the stored energy in the form of visible photons that are then transmitted to a photomultiplier via a light guide. The system gave very high-quality images that could be digitally stored and processed in all the usual ways. It gained wide acceptance in radiology as a replacement for film with the double advantage of eliminating the need for chemical processing and producing images directly in digital form.
Factors affecting image quality
Published in Damian Tolan, Rachel Hyland, Christopher Taylor, Arnold Cowen, Get Through, 2020
Damian Tolan, Rachel Hyland, Christopher Taylor, Arnold Cowen
False – a pinhole can measure focal spot size, which is related to resolution, but it will not measure resolution itself. A line pair test object is used for this purpose.True – increasing the geometric magnification requires either a smaller focus–object distance or a larger object–film distance. either of these changes will increase the size of the penumbra.True – this may then be used for comparison of different imaging systems.False – spatial resolution is comparable in modern computed radiography.True – and by the number of lines on the monitor. These two factors determine the pixel size.
X-ray Vision: Diagnostic X-rays and CT Scans
Published in Suzanne Amador Kane, Boris A. Gelman, Introduction to Physics in Modern Medicine, 2020
Suzanne Amador Kane, Boris A. Gelman
Radiography that produces digital images that can be processed, stored and displayed on computers is called digital radiography. Several technologies are used in digital radiography. One is computed radiography (CR), not to be confused with computed tomography discussed in Section 5.11. In CR a latent image is created on plates coated with so-called storage phosphors, materials such as europium-doped barium fluoride, which exhibit photo-stimulated luminescence. Absorbed x-ray photons excite electrons that are trapped in impurities within the storage phosphor. The distribution of these trapped electrons represents the stored latent image. To convert the latent image into a digital image a scanning laser is used to illuminate the storage phosphor plate. The laser beam causes the trapped electron to escape and emit visible photons, which are guided into a photomultiplier tube.
Age, creatinine, and ejection fraction (ACEF) score as predictive values for late non-valvular atrial fibrillation recurrence after radiofrequency ablation
Published in Clinical and Experimental Hypertension, 2023
Yan Luo, Yan Tang, Wenchao Huang, Shiqiang Xiong, Yu Long, Hanxiong Liu
Ablation was performed by pressure sensing with the catheter and cold saline, (50 w, 15 mL/min) leading to left atrial matrix improvement (e.g., anterior and posterior pulmonary vein, BOX). If the AF changed to atrial flutter or auricular tachycardia during ablation, the ablation area was electroisolated. If AF changed to SR during ablation, the operation was completed. A temporary pacemaker was implanted in the postoperative period, if needed. The operation was performed under X-ray fluoroscopy, computed radiography digital photography, continuous invasive blood pressure monitoring, postoperative sterile dressing, and wound dressing. The patient’s consciousness and vital signs were monitored intraoperatively and recorded. Heparin sodium and contrast agent were used intraoperatively.
Effective radiation dose in radiostereometric analysis of the hip
Published in Acta Orthopaedica, 2020
Ian F Blom, Lennard A Koster, Bart Ten Brinke, Nina M C Mathijssen
In general, a combination of increasing kiloVoltage (kV) and decreasing milliAmpere-seconds (mAs) results in a decrease in radiation dose. However, decreasing the radiation dose results in a lower image quality (Bushong 1975, Fauber et al. 2011, Carroll 2014, Ma et al. 2014). Decreasing radiation dose, while the image quality remains acceptable for the purpose, is called the As Low As Reasonably Achievable (ALARA) principle (ICRP 1955). According to Teeuwisse et al. (1998) an RSA radiograph of the hip, using computed radiography (CR) roentgen detectors, has an effective radiation dose (ED) of 0.150 miliSievert (mSv) (Valstar 2001). However, most RSA studies do not provide the ED of the applied roentgen technique and thus the actual radiation dose remains unknown.
In Asian women undergoing total knee arthroplasty, lower leg morphology in those with rheumatoid arthritis differed from those with osteoarthritis
Published in Modern Rheumatology, 2020
Shu Takagawa, Naoto Mitsugi, Yuichi Mochida, Naoya Taki, Kengo Harigane, Yohei Yukizawa, Yohei Sasaki, Masaki Tsuji, Kagayaki Sahara, Yutaka Inaba
Anteroposterior full-length lower limb radiographs in the standing position were obtained preoperatively. Radiographs were projected using the Fuji computed radiography system, and various parameters were measured using Fujifilm OP-A software (Fujifilm, Co., Ltd, Tokyo, Japan). The hip-knee-ankle angle (HKA), femorotibial angle (FTA), VCA, and coronal bowing of both femur and tibia, using the method of Yau et al. [13], were measured (Figure 1). HKA was defined as the angle between the mechanical axis of the femur and the tibia. FTA was defined as the lateral angle between the anatomical axis of the femur and the tibia. VCA was defined as the angle between the mechanical axis of the femur and the anatomical axis of the femur. Coronal femoral bowing was measured by dividing the femoral diaphysis into four equal parts. A line that described the midpoint of the intramedullary canal was drawn in each quarter. Femoral bowing was defined as the angulation between the proximal and distal quarters of femoral diaphysis. Coronal tibial bowing was measured by dividing the tibial diaphysis into three equal parts. A line that described the midpoint of the intramedullary canal was drawn in each third. Tibial bowing was defined as the angulation between the proximal and distal thirds of the tibial diaphysis. Positive values meant femoral/tibial lateral bowing and negative values meant medial bowing. The frequency distributions of HKA, FTA, VCA, and femoral/tibial bowing angles were analyzed. In RA and OA patients, the percentages of limbs were calculated in the six different range subgroups of HKA (from under –20° to successive 10° increments up to over 20°), six different range subgroups of FTA (from under 160° to successive 10° increments up to over 200°), five different range subgroups of VCA (from under 5° to successive 1° increments up to over 8°), six different range subgroups of femoral bowing angle (from under –6° to successive 3° increments up to over 6°), and five different range subgroups of tibial bowing angle (from under –4° to successive 2° increments up to 4°).