Computed Radiography Cassettes Research Articles

PyDAP: Automated dental OPG beam area measurement using python and raspberry Pi camera

IntroductionThis study investigates if inexpensive computer hardware, open-source computer vision and a phosphor screen from disused CR (computed radiography) Cassette can be used to quantitatively assess beam shape and area. Materials and MethodsThe phosphor screen was affixed to a Carestream CS 8100 dental OPG system and the camera was mounted above the X-ray tube. Videos were acquired of the green light emissions during the tomographic irradiation. Images of a chessboard pattern, attached to the detector were used to correct for camera angulation and provide image pixel size calibration. K-Means colour clustering was used to define beam area. The effect of light conditions on beam dimension measurement was also investigated. The beam width measurement from optimised methodology was compared with that determined from dose calibrated GAFChromicTM XR-SP2film. ResultsVideos in dark conditions provided the most reproducible results. FW20M gained from initial sampling matched that obtained using the GAFChromicTM film within the errors of the measurements,6.41 ± 0.09 mm FW20M from this methodology,compared with FW20M (full width at 20 % of maximum) 6.4 ± 0.1 mm from film. The height and area were 126 ± 0.22 mm and 807 ± 11 mm2 respectively. The chess pattern imaging provided a robust means of perspective correction and pixel calibration. There is potential for this methodology to be employed using any digital camera, provided the camera acquisition settings remain constant, the sensor pixels are square, and the camera position is fixed. ConclusionThe potential of this low-cost open-source method of beam area measurement using computer vision is thus proven.

Abdomen Radiography with Atresia Ani Specifications at Bhayangkara Hospital Medan

Abdominal plain radiology examination Anal atresia aims to obtain a radiographic picture of congenital abnormalities in the anus which cause the anus to form imperfectly. The projections carried out in this radiological examination are Antero-Posterior Supine (AP), and Lateral Knee Chest (L) projections. This research uses descriptive research. Atresia ani radiology examination research time This was carried out in May-J 2021 at Bhayangkara Hospital, Medan. The X-ray aircraft used in this examination is a conventional Toshiba-DK Medical System brand aircraft with a capacity of 20 0 Kv and a maximum mA of 300 mA. Radiographic image processing uses CR (Computed Radiography). The cassette used during this examination was a CR cassette measuring 35 cm x 35 cm. The results of the research obtained from an abdominal examination with the suspicion of Atresia ani with the results of the interpretation from the radiologist being correct Atresia ani with the distance of the most distal intestinal air to the anal dimple (marker) being ± 2.6 cm.

PENGARUH LAMA WAKTU PEMAKAIAN (USIA) DAN BENTURAN FISIK PADA KASET COMPUTER RADIOGRAPHY (CR)TERHADAP CITRA RADIOGRAFI

Background: Computed Radiography (CR)is a radiographic image processing computer acquisition technology. In CR, the radiographic image results are stored in a special film cassette and expressed in the form of the gray level of the image pixels. The results of the radiographic image on the film cassette are then read by a scanner and then can be saved in the form of an image file, which can be a special digital film format called DICOM (Digital Imaging and Communication in Medicine). One of the disturbances that occur in the resulting CR image is artifact. The length of time used (age) of CR cassette can cause interference with the results of radiographic images. The longer the life of the CR cassette and the more frequent use of the CR cassette, the noise may appear in the radiographic image results. The condition of the CR cassette has a big effect on the formation od the image so that physical collision such as falling, regardless of grip or impact should be avoided when inserted into the CR reader.
 Methods: This type of research uses quantitative research with an experimental approach. The CR cassettes studied were 4 CR cassette with different sizes but the length of time used (age) was the same. All 4 CR cassette were exposes to the same exposure factor. The object used is the step wedge. The results of the radiographic images are evaluated subjectively by 5 respondents (radiographers) to draw conclusions.
 Results: The duration of use (age) of CR cassette is done properly and does not often occur, it will produce good radiographic image results and can be used to establish diagnoses. Physical impact on the CR cassette can results in artifact. Artifact contained in the results of CR images can interfere with diagnosis.

Measurement Accuracy of CT Beam Width with a Portable Flat-panel Detector

X-ray film or computed radiography (CR) system has been employed in clinical setting, and these devices are gradually replaced by portable flat-panel detector (FPD) systems. They may be employed to measure the beam width instead of the traditional CR system. In this study, we estimated the accuracy of beam width measured by the portable FPD system. A CR cassette and FPD were placed at the isocenter, and the pixel values were measured in a single axial CT scanning at a tube potential of 80 kVp, tube currents of 10-40 mA (5 mA steps), and tube rotation time of 0.5 s. Then, the FPD was sandwiched between 0.5 mm copper plate and 2 mm lead plate to avoid the pixel saturation and artifact from the FPD electronic substrates. The beam widths were measured at selected nominal beam widths (40, 80, 120 and 160 mm) using a double exposure technique (tube currents of 10 and 20 mA). Log-linear relationships for two systems were obtained between the pixel value and radiation exposure for parameters less than or equal to 12.5 mAs. A test for the equivalence with confidence intervals showed that the measurement accuracy of the CR and FPD systems was equivalent. The portable FPD system could be utilized for the measurement of the CT beam width as well as CR system.

Evaluation of the Image Registration Program for Portal Images Using CR and DRR Images in Radiation Therapy

In this study, computer simulations and experiments were used to verify the accuracy of a two-dimensional image registration program (program) for portal images that we previously developed. The program used a computed radiography cassette system and digitally reconstructed radiography images as planning images for external beam radiation therapy. Using this program, we also investigated the reason two-dimensional automatic image registration images experienced large misregistration in clinical practice using commercial image registration systems. Mutual information and normalized mutual information were used as the registration criteria. To investigate the influence of image background with or without a region of interest (ROI), results of image registrations were compared. Parameters of image registration were defined as translation in the horizontal and vertical directions (x and y, respectively) and rotation (θ) around the axis perpendicular to the x-y plane. There was no significant difference in image registration arising from the difference between mutual information and normalized mutual information. Image registration was improved with a ROI. Regardless of the registration criteria, errors in image registration with a ROI in the experimental study were ≤1.2 mm in directions x and y and ≤1.0 degree in rotation θ. We found that image registration required setting up as close to the planned position as possible.

RADIOGRAPHY IN THE FIELD: ASSESSING A LIGHTWEIGHT, HANDHELD, BATTERY-POWERED DENTISTRY UNIT FOR FIELD DIAGNOSTIC APPLICATIONS.

Radiography units are not used commonly in wildlife medicine field settings, primarily because of their weight and requirement for a power supply. In this study, a portable, battery-powered, and lightweight radiography unit, originally developed for dentistry, was assessed for its potential field applications. Radiographs of various animal species (ranging in weight from 14 g to 1,000 kg) were imaged using varying source image distance (SID) and exposure time. The quality of these images was evaluated for their resolution, image noise, and motion blur. When required, image resolutions were further enhanced using computed radiography postprocessing. Other parameters evaluated were the freehand use of the device, its battery durability, the maximum obtainable image size, and multiple use of a single computed radiography cassette. Using an SID of 60 cm, radiographs delivered adequate image quality. The quality, however, was found deteriorated in images of larger animals (>50 kg) or thicker tissues (>15 cm). The use of a tripod proved unnecessary in most cases, and its exclusion greatly facilitated equipment handling. Under field conditions, the battery was depleted after a total running time of 1.6 hr or 36 radiographs. The maximum size of a radiographic image reached a diameter of 40 cm, and radiation shielding allowed the multiple use of a single computed radiography cassette. Taken together, the radiography unit evaluated in this study presented a balanced compromise between portability and radiograph quality for field use. However, the unit image resolution cannot replace those of the fixed standard radiography units commonly used in veterinary medicine.

Background ionising radiation: a pictorial perspective.

Ionising radiation from natural sources, known as background radiation, has existed on earth since the earth's formation. The exposure of humans and other living creatures to this radiation is a feature of the earth's environment which is continuing and inescapable. The word "radiation" brings fear to many people: a fear of the unknown, as human's senses cannot detect the presence of ionising radiation. In this study, a catalogue of images of the distribution of radioactivity in every day objects and foods has been produced using an imaging plate from a computed radiography cassette. The aim of the study is that by visually demonstrating that every day objects and foods are radioactive would alleviate the fear of "radiation" by becoming aware that we live in a radioactive environment and even our body is radioactive.

Portable Wireless Digital Detectors: Advantages and Challenges

Wireless digital detectors are gaining increased use in mobile unit medical imaging. These detectors allow rapid, high-quality imaging anywhere, anytime in a hospital, allowing physicians in many instances to make fast decisions at the bedside. Medical imaging manufacturers are rolling out wireless digital detectors that are increasingly efficient and rugged. Most wireless digital detectors weigh about 3 to 4 kg and are comparatively heavier than film-screen cassettes or computed radiography cassettes, yet they are increasingly embraced because of efficiency in speed and convenience of delivering images [1]. Portable unit wireless digital detectors that are currently in use are amorphous siliconebased thin-film transistor arrayswith scintillator (mostly cesium iodide or gadolinium oxysulfide) deposited on top that converts x-rays into light photons [1,2]. These detectors have the potential to deliver patient care efficiently and improve workflow. Yet the efficiency and convenience offered by these detectors are introducing new challenges to workflow and to some extent to the radiation dose burden for patients in cases such as central venous catheter (CVC) placement. More than 5 million CVCs or central linesareplacedeachyear in the United States [3]. Most line placements are performed in surgical suites, often fluoroscopic or ultrasound guidance. Often, placement is verified by acquiring a radiograph. Although the need for such postoperative radiography is indebate [4], inmost cases, an image is acquired for verification of position before catheter use. In fact, the FDA recommends obtaining such radiographs

Key Performance Indicators for Comparing the Performance of Portable Radiography: Direct Digital Radiography versus Conventional Machine Computed Radiography—A Study in a Nonacute Hospital

IntroductionPortable radiography traditionally has been performed with a conventional portable x-ray unit with computed radiography (CR) system (conventional-CR combo), and off-site processing of the exposed CR cassettes was time-consuming. The direct digital radiography (DDR) portable x-ray system, with the digital image immediately available for review and wireless transmission as the key merits, is newly installed for portable radiography. Thus, the work flow of portable radiography is changed. This study was performed to quantitatively investigate the performance of portable radiography using the DDR portable x-ray system and conventional-CR combo in terms of efficiency and work flow enhancement. MethodsOne hundred ninety portable x-ray examinations were timed for each procedural step using conventional-CR combo (n=97) and the DDR portable x-ray system. The following key performance indicators were designed for measuring the performance of portable radiography quantitatively: “examination duration,” “time for image becoming available in PACS,” “postacquisition processing time,” and “manpower deployment time.” ResultsProductivity was raised by 96% using the DDR portable x-ray system. “Examination duration” using the DDR portable system was significantly faster (P < .0001), with a mean calculated time of 13.4 ± 7.6 minutes for the DDR portable system and 25.2 ± 10.9 minutes for conventional-CR combo. The “time for image becoming available in PACS” was significantly shorter than that of conventional-CR combo (P < .0001), with a mean time of 6.8 ± 2.6 minutes for the DDR portable system and 19.2 ± 9.7 minutes for conventional-CR combo. The “postacquisition processing time” was measured with slight differences, with a mean time of 2.2 ± 1.1 minutes for the DDR portable system and 1.9 ± 1.0 minutes for conventional-CR combo (P = .1064). Because more portable x-ray examinations could be performed when using the DDR portable x-ray system in each round of service, the mean “manpower deployment time” when using the DDR portable x-ray system was longer (ie, 82.6 ± 46.8 minutes for the DDR portable system and 24.5 ± 11.9 minutes for conventional-CR combo). ConclusionsBy using the new DDR portable x-ray system with work flow changes, the performance of portable radiography was improved in efficiency and work flow was enhanced. Furthermore, the four defined key performance indicators in this study may help provide a framework for measuring the performance of portable radiography in other institutions.

Physical evaluation of a needle photostimulable phosphor based CR mammography system

Needle phosphor based computed radiography (CR) systems promise improved image quality compared to powder phosphor based CR units for x-ray screening mammography. This paper compares the imaging performance of needle CR cassettes, powder based CR cassettes and a well established amorphous selenium (a-Se) based flat panel based mammography system, using consistent beam qualities. Detector performance was assessed using modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE). Mammography system performance was assessed against levels from the European Guidelines, including threshold gold thickness (c-d), relative signal difference to noise (SdNR) and mean glandular dose, for automatic exposure control settings suggested by the manufacturers. The needle based Agfa HM5.0 CR detector was compared against the single sided readout Agfa MM3.0R and dual sided readout Fuji Profect CS powder CR plates using a 28 kV Mo/Rh spectrum, while a 28 kV W/Rh spectrum was used to compare the Agfa HM5.0 against the Siemens MAMMOMAT Inspiration a-Se based system. MTF at 5 mm(-1) was 0.16 and 0.24 for the needle CR detector in the fast and slow scan directions, respectively, indicating a slight improvement (∼20%) over the two powder CR systems but remained 50% lower than the result at 5 mm(-1) for the a-Se detector (∼0.55). Structured screen noise was lower for the needle phosphor compared to the powder plates. CR system gain, estimated from the measured absorption fraction and NNPS results, was 6.3 for the (single sided) needle phosphor and 5.1 and 7.2 for the single sided and dual sided powder phosphor systems. Peak DQE at ∼100 μGy was 0.47 for the needle system compared to peak DQE figures of 0.33 and 0.46 for the single sided readout powder plates and dual sided readout plates. The high frequency DQE (at 5 mm(-1)) was 0.19 for the needle CR plates, a factor of approximately 3 greater than for the powder CR plates. At 28 kV W/Rh, 2 mm Al, peak DQE for the needle CR system was 0.45 against a value of 0.50 for the a-Se detector. The needle CR detector reached the Acceptable limit for 0.1 mm details in the European Guidelines at a mean glandular dose (MGD) of approximately 1.31 mGy imaged at 28 kV Mo/Rh, compared to figures of 2.19 and 1.43 mGy for the single sided and dual sided readout powder CR systems. The a-Se detector could reach the limit at 0.65 mGy using a 28 kV W/Rh spectrum, while the needle CR system required 1.09 mGy for the same spectrum. Imaging performance for the needle CR phosphor technology, characterized using MTF and DQE and threshold gold thickness demonstrated a clear improvement compared to both single and dual sided reading powder phosphor based CR systems.

SU-GG-T-54: A Phantom for Physics QA to Check the Accuracy of an Ir-192 Stepping Source Dwell Position and Reproducibility of Dwell Time in HDR Brachytherapy

Purpose: To determine the accuracy of dwell position, reproducibility of dwell time and effect of bending a transfer tube for Ir‐192 high‐dose rate (HDR) brachytherapy stepping source using an in‐house made phantom. Method and Materials: Experiments were performed using a Nucletron microselectron V3 (30) HDR after loading device with Ir‐192 single stepping source, Fuji Capusla XL computed radiography(CR) cassette and its reader and an in‐house made phantom. The central part of the phantom, which has alternating strips of lead and Perspex was used to check the accuracy of dwell positions while the outer part of the phantom, which consists of four different materials, namely perspex, copper,aluminium and Styro‐foam, was used to measure reproducibility of dwell time. Images were exported via network as DICOM images for further analysis by ImageJ.Results: Positional error of an HDR source smaller than 1.0 mm can be detected. Hence, it is possible to regularly check dwell positions for selected transfer tubes of a treatment plan as a quick verification of dwell positions. Reproducibility of dwell time within 0.1 second could be verified. No effect of bending a transfer tube was observed for normal clinical situations. However, under extreme cases in which the transfer tube was highly bent, the source dwell position was changed by less than 0.5mm. Conclusion: The phantom was capable of detecting dwell positional error of 1.0 mm and reproducibility of dwell time of 0.1 second. For typical clinical scenarios in which transfer tubes are bent, no effect on dwell position was observed. The phantom can be used with radiographic films or CR cassette with the latter being a preferred tool, as hospitals are phasing out film processors in favour of digital technology. The method is simple and robust for routine use.

Detection of electron beam energy variations using a computed radiography system

A method to evaluate the electron beam energy constancy by employing the computed radiography (CR) system has been developed. In this method, a right triangular plastic wedge is used to produce a curve of the CR storage phosphor plate signal versus the wedge thickness. The curve, which resembles the percentage depth ionization curve of the clinical electron beams, can be used to derive the energy constancy metric EC50. The sensitivity of the method was tested using polystyrene sheets of variable thicknesses. For electron energies up to 12 MeV, energy changes induced by 1.5 mm thick polystyrene can be detected, while a 2.3 mm thick polystyrene sheet is required for higher energies. The measurements were carried out over a two‐year period. The results showed a good reproducibility with the use of the same CR plate and cassette, and without the requirement of calibration procedures. The two‐year range of the EC50 was within the 99% confidence intervals, and the standard deviation of the EC50 was measured to be from 0.3 to 0.4 mm for different beam energies. This technique provides an efficient and accurate method to perform the electron beam energy check and could be used by centers equipped with the CR system without requiring additional detection devices.PACS number: 87.56.Fc

An investigation of the shielding characteristics of computed radiography cassettes

Computed radiography (CR) systems are rapidly replacing film screen techniques. Previous estimates have been made of the degree of attenuation that occurs as a primary diagnostic X-ray beam passes through a film-screen cassette at different tube potentials. Cassette attenuation is commonly stated in terms of equivalent thickness of lead, which can be calculated using lead attenuation curves. These values can then be subtracted from the shielding requirements calculated for diagnostic X-ray rooms. Since the introduction of CR, no comparison has been made between the attenuation of the old film-screen and the new CR cassettes. In order to perform such a comparison, transmission factors for two CR cassettes and one film-screen cassette were measured, in addition to experimental lead attenuation curves. Lead equivalent thickness values were calculated for all three cassettes using both a semi-theoretical model and measured data. Although there was some discrepancy between the two methods, both found that the new cassettes provided a similar or greater degree of attenuation as the film screen cassette.

TU‐C‐L100J‐05: A Practical Filmless Technique of Determining CT Beam Width

Purpose: To develop a filmless technique for the measurement of CT beam width for QA. Method and Materials: Images of pre‐patient collimated CT beams were acquired using Fuji computed radiography (CR) cassettes and direct‐exposure film (DF). CR cassettes were exposed using 80kV, 10mAs to avoid signal saturation. The DF was exposed at 80kV, 30mAs to achieve a proper optical density. The DF image was digitized then linearized. To achieve a proper signal range for CR, various plate‐reading protocols were evaluated. An IDL program was developed to automatically handle both the digitized film and a variety of CR image sizes. “Unprocessed” logarithmic CR data were linearized, which is critical to validate the FWHM. The program executes in an interactive fashion, whereby the user selects the beam to analyze. The program determines the background signal for subtraction then samples multiple cross‐beam profiles to form an averaged profile. The profile is smoothed and the FWHM is determined. Results: Under proper conditions of image acquisition, results show both DF and CR are appropriate techniques for beam width measurements. The CR technique demonstrated a high level of reproducibility with a coefficient of variation below 0.5%. Also, the CR results were within 0.3mm of specifications. Using various sizes of CR cassettes had a minimal effect on the results. However, if the properly exposed image is saturated due to an inappropriate CR plate reading protocol, the inaccuracy is substantial (&gt;1mm). The technique worked well for annual tests of six GE scanners. Over a wide range of beam width configurations, all measurements were within 0.9mm of specifications. Conclusion: A technique for determination of CT beam width in a filmless environment was developed and tested. The results obtained using CR yield accurate measurements of CT beam profile width. The technique is effective, practical, and has proven to be robust.

Recognition and Prevention of Computed Radiography Image Artifacts

Initiated by complaints of image artifacts, a thorough visual and radiographic investigation of 197 Fuji, 35 Agfa, and 37 Kodak computed radiography (CR) cassettes with imaging plates (IPs) in clinical use at four radiology departments was performed. The investigation revealed that the physical deterioration of the cassettes and IPs was more extensive than previously believed. It appeared that many of the image artifacts were the direct result of premature wear of the cassettes and imaging plates. The results indicate that a quality control program for CR cassettes and IPs is essential and should include not only cleaning of the cassettes and imaging plates on a regular basis, but also visual and radiographic image inspection to limit the occurrence of image artifacts and to prolong the life cycle of the CR equipment.

SU‐FF‐T‐207: Linac QA Using a Computed Radiography System

Purpose: The computed radiography (CR) is replacing film for linac quality assurance (QA) checks in our clinic. A few tools and methods were developed to facilitate this transition. Method, Materials and Results: A right‐triangular prism phantom was used for electron beam quality verification. The phantom was centered along the beam axis, and placed on top of a CR cassette with 110 cm source to image distance (SID). The image was processed to obtain a percentage exposure vs. wedge thickness curve, which was sensitive to electron energy changes. This method demonstrated good reproducibility. A method using a diamond‐shaped template for the light and radiation field congruence test had been previously developed. This method was analyzed and modified. In the modified version, the template was put right above the CR cassette to reduce the systematic error due to the penumbra effect. An IDL program was developed to compute the discrepancies between the light field and the radiation field. The jaw alignment was checked with a device similar to that of Lutz et al: a CR cassette sandwiched between two pairs of L‐shaped Cerrobend blocks. Each pair was embedded diagonally in a piece of foam. The pair above the cassette was at an angle of 90 degrees to the pair beneath the cassette. The radiation was delivered at collimator angles of 0 and 90 degrees to verify the x‐jaw and y‐jaw alignment, respectively. For each collimator angle, two gantry rotations ‐ 0 and 180 degrees ‐ were used, with equal monitor units delivered at an SID of 100 cm. The radiation field flatness, symmetry and penumbra were tested using CR combined with the RIT software solution. The results were consistent with those collected using films. Conclusion: QA checks using CR systems are more convenient and yield results comparable to those from film.

Scatter in computed radiography.

The effects of scatter radiation on images obtained with storage phosphor computed radiography (CR) were evaluated. The scatter degradation factor was extended to account separately for forward scatter and backscatter. Values for the ratios of forward scatter to primary radiation (sf/p) and backscatter to primary radiation (sb/p) were measured for various x-ray tube potentials, phantom thicknesses, and field sizes for CR imaging plates (IPs). Similar measurements were made for a common screen-film system. The sb/p values for the IPs were 0.05-3.80. Standard CR cassettes do not have lead foil behind the IP to control backscatter; the results of this study indicate that such control is needed. The sf/p values were 40%-70% higher in IPs (50%-120% higher when backscatter was included) than those in the conventional screen-film system. This difference is attributed to the differences in the K-absorption edges of barium and gadolinium and the fact that scatter has lower effective energy than the primary beam as they exit the patient.