Biplane Flat Detector System for Surgical Angiography - Report Example

BIPLANE FLAT DETECTOR SYSTEM FOR SURGICAL ANGIOGRAPHY Department Table of Contents Table of Contents 2 0 Introduction 32.0 Radiation Protection 4 3.0 Safeguarding Electro-Mechanical Safety 5 4.0 Ways to Maximize Clinical Use 7 5.0 Quality Assurance 8 6.0 Constancy Checking 9 Conclusions 9 References 11 1.0 Introduction The rising demand for high-end imaging for reduced invasive angiography has called for the design of advanced equipment and machines in the healthcare industry. One of the latest technologies for this purpose is the Artis zee biplane system (VC 14), a flat detector system for surgical angiography. This machine was released by Global Siemens Company in 2009 through their Siemens Healthcare affiliate. This machine is equipped by microprocessor controlled 30x40 flat detectors, automated high frequency X-ray generator for fluoroscopy controlled dose rate together with acquisition. Artis zee’s X-ray tube is characterized by “MEGALIX Cat 125/15/40/80-121GW, MEGALIX Cat 125/15/40/80-122GW and has a 0.3mm/ 0.6mm/ 1.0mm focal spot size, 12° anode angle with a 1,400,000 J heat storage capacity, 150 Hz (three-phase current) anode rotation and a total filtration of ≥ 2.5 mm AI” (Siemens Healthcare 2010). The Artis zee biplane system may be harmful to both the patient and the radiographer due to the fact that it deals with invasive procedures that demands for long fluoroscopy time. The skills and full knowledge of safe operational protocol of this machine is therefore important for trained radiographer. It is also important to ensure that the person in charge of the medical staff as well as the working team follow clear documented procedures. These documented guidelines should include the best way on how to use The Artis zee biplane system in the manner that conforms to the principle of as low as reasonably achievable (ALARA). This paper aims to explore the Artis zee biplane system, explaining radiation protection, electromagnetic safety, ways to maximize clinical use and quality assurance for angiography machines. 2.0 Radiation Protection The safety of both the staff and patient rely mostly on the availability of radiation protection tools. According to Siemens Healthcare 2010, the manufacturer of Artis zee recommends the following as the best radiation protection measures. The first method is beam collimation and it is important in reducing scattered radiation and consequently improves image contrast quality. More safety can be enhanced through the graphic display in the last image hold (LIH) on the display of image by performance of a radiation free positioning of collimators and semi-transparent filter parameters. The second method of radiation protection is choosing the right organ program by the use of fluoro loop and low dosing acquisition to review the changing processes. Artis zee’s dose area product and dose rate can be minimized through the use of foot operated switch since there is a live display of their interventional reference point in the examination room. The use of the lead shields such as gloves, neck collars aprons and goggles to protect sensitive organs form the third protection measures. Research shows that operators can protect themselves more than ten times by wearing shields than when they don’t. This is so because the interventional reference point is proportional to the source image distance (SID) thus reducing SID will reduce dose proportionally (Furlow 2011, 421). This ensures positioning of the patients as far as possible and whiles the receptor and X-tray tubes placed closer. Moreover, central the beam’s graphic display and the image edges in LIH allows for the visual positioning of the object without radiation. In addition to this, image magnification and image zooming decrease patient dose rate and increase image quality respectively. Using earlier stored images or variable frame rates in digital subtraction angiography help in reduces dose rate for skin by minimizing the number of fluorographic images. The radiation protection can also be enhanced by using the available dose rate reduction techniques like spectral beam filtration, catheters with highly radiopaque tips and fluoroscopy dose rate settings (Guo et al 2013, 129). In this respect, Artis zee biplane system is fitted with a five level adaptive Cu pre-filtration which helps in reducing skin doses since it is automatically set depending on the C-arm angulation and the current object transparency. Late but not least, keeping a reasonable distance between the tube side and the patient as much as possible is important in reducing the dose because the scattered radiation attenuates with the distance squared. Operator should also ensure that the X-ray tube is on his or her opposite side as much as possible to limit scattered radiation. 3.0 Safeguarding Electro-Mechanical Safety All medical electrical installations must consider electromechanical safety during installation. Artis zee biplane system is equipped with three emergency power supply systems: imaging system for >90 seconds power failure, for the while system including imaging system and table movements for > 10 minutes power failure and the entire system emergency fluoroscopy inclusive (Siemens Healthcare 2010). Electromechanical safety of the patient is enhanced by ensuring that X-ray generator is kept away from the monitoring area and is fully integrated into the system control during installation. It is also important to ensure that cables are double insulated, armored or enclosed to provide safety. Before designing electrical installation for Artis zee biplane system, it is important to obtain its supply parameters at the design stage so as to ensure the proper functioning and reliability (Tsapaaki et al 2004, 297). It is important to note that the Artis zee biplane system is likely to fail if its power supply does not conform to the parameters for which it was designed and the electrical system should be designed constructed in such a way that it meets the worst case scenario. Rating of the Artis zee must also be considered to ensure quality and quantity of power supplied meets all specifications. Artis zee is supplied by three phase power via a contactor that is mainly operated by a green momentary push button with the aid of a self-holding circuit. The disconnection is through either failure of the incoming power or red push button. The machine also provides for an emergency button which may be important for emergency stop. Moreover, there are also provision for other emergency stops within the circuit and can be added as may be deemed fit by a technician or an engineer. The buttons are designed in a way such that there is prevention of accidental activation by incorporating a twist-to-release mechanism and protective shrouds. The emergency red off button which is part of self-holding button is maintained closed. Additional contacts may also be supplied with regards to specifications of the supplier of the medical equipment. Intelligent collision protection (ICP) technology combined with a highly flexible C-arm not only provides a quick position but also integrate collision monitoring through a computerized system (Tsapaki 2004, 297). The ICP is very crucial in stopping arm movement especially if it touches on the object or patients thus prevent any damage. Solid state amorphous silicon, the flat detector materials enables it to integrate temperature stabilization and the high-speed fiber optic connection to the imaging system play a key role in protection of collision (Dragusin et al2008, 91). It is also important to ensure that that there is protection for over-pressure for the X-ray tube assemblies. In this respect, Artis zee biplane system comprises of a high-performance which provide excellent heat dissipation when utilizing large zoom and during long procedures. 4.0 Ways to Maximize Clinical Use Artis zee biplane system is manufactured with several features to enhance its efficiency in the medical healthcare. In order to enhance image quality, Siemens Healthcare has ensured this machine has 56’’ full color medical screen that enhance clarity of both roadmap images and live fluoroscopy. This has also improved the visualization of stents, their coils, meshes as well as guiding wires at the least acceptable dose levels. Interventional procedures as well as diagnostic flexibility have been improved to a great level by the 30x40 flat detectors (Siemens Healthcare 2010). Viewing of fine images before and after procedure is made efficient by the high resolution coupled by micro-focus thus able to deliver images with the finest details resolution which is critically needed by radiologists during diagnosis. The Artis zee biplane system is also equipped with imaging chain for advanced 3D applications thus allow accuracy and speed of not only the diagnosis but also treatment. This is because the 3D data sets are gotten faster and with ease by use of screen workflow guidance. The availability of Syngo Dyna CT, an advanced soft tissue program, improves the diagnostic capabilities by making angiographic computed tomography (ACT) procedure possible hence reducing doses and saving time since there is no time wasted in sending patients for CT (Dragusin et al 2008, 91). Artis zee biplane system also maximizes clinical use through the tableside control which has provision for pre-examination, vascular quantification and post processing thus enhancing comfort. This machine also provides effective patient access and unique flexible positions for biplane and single plane. The required full range of biplane angulations can be covered easily by availability of second isocentric work position. 5.0 Quality Assurance Quality Assurance (QA) refers to the “set of activities intended to establish a confidence that quality requirements will be met and that a system, structure, procedure or components will work accordingly and that they shall comply with the established standards” (Zoetelief et al 2010, 237). In this respect, the QA plays an important role in radiology department by ensuring that clarity of image quality is achieved at minimum acceptable doses. It is therefore recommended that the following tests be done by qualified physicist. First, it is important to check tube and generator performance before doing a test on intensifier fluoroscopy system to ensure the right quality of X-ray beam. Second test is done on the automatic exposure control performance to ensure it is adheres to ALARA principle by taking measurements of patience and intensifier entrance dose rates. The third step is to adjust the X-ray beam so that it is only restricted to the useful area of the input phosphor to prevent interference with image quality. And the system noise will be dominated by X-ray quantum noise and not the system electronic noise due to low exposure. The fourth step is to measure the system dynamic range in order to ensure that radiation range of intensities accommodated by digital fluorography system is acceptable due to entrance and intensity skin exposure (Zoetelief et al 2008, 237). It is also important to evaluate the extent to which video monitor displays details which is affected by focusing and noise generation as a result of deteriorating performance. Threshold contrast detail delectability test is necessary to evaluate this phenomenon. The sixth test to be conducted is acquisition stability test which examines sequence of images to confirm stability of exposure during digital substations. Last step is the assessment of pixel misregistration so as not to obscure an opacified visibility which may be as a result of electronic jitter between the mask image and the contrast. 6.0 Constancy Checking Constancy checking refers to the checks that are undertaken after maintenance operations have been done on the machine. These tests are done to ascertain that the machine is still working as specified and if there are changes in the machine what they are and how they can be corrected. Corrective actions are often originated from the quality assurance tests mentioned above and can be done by technician or a radiographer. Checking of the following parameters after every one or two months is therefore recommended. The first test is to confirm the functioning of the automatic exposure control system by examining the entrance surface and patient entrance dose rates (Zoetelief et al 2008, 237). The spatial resolution limit is also done to ascertain the image sharpness which is a measure of the sensitivity of the state of focusing system. The fourth test to be done after repair or maintenance is the low contrast resolution test. Low contrast resolution may result from contrast loss in the intensifier system or noise and can be measured. Conclusions The discussion presented above demonstrate that Artis zee biplane system (VC 14), a flat detector system for surgical angiography is a highly effective, efficient and conform to the principle of as low as reasonably achievable (ALARA). With the availability of a comprehensive beam protection tools, Artis zee biplane system (VC 14) reduces patient and operator radiation dose rates. This equipment is also designed with several proactive safety devices to ensure not only the safety of the patient but also that of the operator, staff and provides comfort as well. In order to optimize the clinical use of the equipment, Siemens have incorporated several features that enhance image quality and increase the diverse features of pre and post imaging procedures. In order to enhance usability of Artis zee biplane system (VC 14) in healthcare, it is important to follow all the safety precautions such as electromechanical safety, radiation protection measures, established Quality Assurance and constancy checking in order to maximize usability. References Dragusin, O., M. Gewillig, W. Desmet, K. Srnans, L. Struelens, and H. Bosmans. 2008. "Radiation Dose Survey In A Paediatric Cardiac Catheterizations Laboratory Equipped With Flat-Panel Detectors." Radiation Protection Dosimetry 129, no. 1-3: 91 Furlow, Bryant. 2011. "Radiation Protection in Pediatric Imaging." Radiologic Technology 82, no. 5: 421 Guo, Hui, Wen-Ya Liu, Xiao-Ye He, Xiao-Shan Zhou, Qun-Li Zeng, and Bai-Yan Li. 2013. "Optimizing imaging quality and radiation dose by the age-dependent setting of tube voltage in pediatric chest digital radiography." Korean Journal Of Radiology: Official Journal Of The Korean Radiological Society 14, no. 1: 126-131. Siemens Healthcare. 2010. Additional Features and benefits of Artis zee biplane system. Accessed March 26, 2014. http://www.healthcare.siemens.com/medical-imaging/angio/artis-zee/artis-zee/features Siemens Healthcare. 2011 “Artis zee for Interventional Radiology: There is so much more to zee. Accessed March 27, 2014. http://usa.healthcare.siemens.com/siemens_hwem-hwem_ssxa_websites-context-root/wcm/idc/siemens_hwem-hwem_ssxa_websites-contextroot/wcm/idc/groups/public/@us/documents/download/mdaw/odm0/~edisp/artis_zee_for_interv_radiology-00552879.pdf Tsapaki, Virginia, Sophia Kottou, Nikolaos Kollaros, Paraskevi Dafnomili, Zinon Kyriakidis, and Vassiliki Neofotistou. 2004. "Dose performance evaluation of a charge coupled device and a flat-panel digital fluoroscopy system recently installed in an interventional cardiology laboratory." Radiation Protection Dosimetry 111, no. 3: 297 Zoetelief, J., F. W. Schultz, S. Kottou, L. Gray, U. Oconnor, D. Salat, and J. Vassileva, et al. 2008. "Quality Control Measurements for Fluoroscopy Systems in Eight Countries Participating En the Sentinel Eu Coordination Action." Radiation Protection Dosimetry 129, no. 1-3: 237. Read More