presentation about x ray machine

Basics of X-ray Physics X-ray production

• X-rays are produced by interaction of accelerated electrons with tungsten nuclei within the tube anode
• Two types of radiation are generated: characteristic radiation and bremsstrahlung (braking) radiation
• Changing the X-ray machine current or voltage settings alters the properties of the X-ray beam

X-rays are produced within the X-ray machine, also known as an X-ray tube. No external radioactive material is involved.

Radiographers can change the current and voltage settings on the X-ray machine in order to manipulate the properties of the X-ray beam produced. Different X-ray beam spectra are applied to different body parts.

The X-ray tube

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• A small increase in the filament voltage ( 1 ) results in a large increase in tube current ( 2 ), which accelerates high speed electrons from the very high temperature filament negative cathode ( 3 ) within a vacuum, towards a positive tungsten target anode ( 4 ). This anode rotates to dissipate heat generated. X-rays are generated within the tungsten anode and an X-ray beam ( 5 ) is directed towards the patient.

X-rays are generated via interactions of the accelerated electrons with electrons of tungsten nuclei within the tube anode. There are two types of X-ray generated: characteristic radiation and bremsstrahlung radiation.

Characteristic X-ray generation

• When a high energy electron ( 1 ) collides with an inner shell electron ( 2 ) both are ejected from the tungsten atom leaving a 'hole' in the inner layer. This is filled by an outer shell electron ( 3 ) with a loss of energy emitted as an X-ray photon ( 4 ).

Bremsstrahlung/Braking X-ray generation

• When an electron passes near the nucleus it is slowed and its path is deflected. Energy lost is emitted as a bremsstrahlung X-ray photon.
• Bremsstrahlung = Braking radiation
• Approximately 80% of the population of X-rays within the X-ray beam consists of X-rays generated in this way.

The X-ray spectrum

• As a result of characteristic and bremsstrahlung radiation generation a spectrum of X-ray energy is produced within the X-ray beam.
• This spectrum can be manipulated by changing the X-ray tube current or voltage settings, or by adding filters to select out low energy X-rays. In these ways radiographers are able to apply different spectra of X-ray beams to different body parts.

Page author: Dr Graham Lloyd-Jones BA MBBS MRCP FRCR - Consultant Radiologist - Salisbury NHS Foundation Trust UK ( Read bio )

Last reviewed: February 2016

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Chapter 9 The X-ray Machine

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Presentation on theme: "Chapter 9 The X-ray Machine"— Presentation transcript:

Producing an X-ray Exposure

Advanced Biomedical Imaging Lecture 3

Mobile Radiographic Equipment. Introduction In-patients who could not leave their beds In-patients who could not leave their beds Surgeons who required.

Wilhelm Conrad Röntgen

Line focus principle Heal effect Ratings Tube failure

X-ray tube.

X-RAY TUBE.

Chapter 11 Prime Factors.

CHAPTER 6 THE X-RAY BEAM SPECIFIC OBJECTIVES NOTED IN THIS POWER POINT BEGIN ON PAGE

The Generation of X-ray:

The X-Ray Tube Bushong Ch 7.

Chapter’s 2, 3. & 4 By Garland Fisher

Chapter 17 The Grid So far we have discussed how kVp, patient size and collimation impact scatter radiation. As the part size and kVp increase, scatter.

X-ray tube and detection of X-rays Lecture 5. Reminder: The rough schematics of an X-ray tube filament cathod target anode photon flux e-e- electron kinetic.

Electrons The discovery of the electron was a landmark

ACVR Artifacts Artifacts of Diagnostic Radiology

RADIATION PROTECTION IN DIAGNOSTIC AND INTERVENTIONAL RADIOLOGY

354 Chapt. 6 X-ray Tube TWO Primary components – cathode and anode Tube must be supported: Ceiling/floor mounted/C-arm, etc. – SID’s – Detents (center.

ENTC 4390 PRODUCTION OF X RAYS.

Resident Physics Lectures

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X-Ray Machine Operation The X-Ray Circuit - PowerPoint PPT Presentation

X-Ray Machine Operation The X-Ray Circuit

Xray machine operation the xray circuit – powerpoint ppt presentation.

• Kyle Thornton
• Diagnostic x-ray machines generally operate at 25 - 150 kVp and 100 - 1200 mA
• Most general purpose rooms contain a radiographic unit and a fluoroscopic w/image intensification capabilities
• X-ray tables must be of the radiolucent material possible
• Most table tops are floating
• All contain a cassette tray
• Operating Console
• High Voltage Generator
• On/off switch
• mAs selection
• kVp selection
• Exposure switch
• Table/wall unit activator
• Automatic exposure control - if available
• Adjustment of line compensation - older units
• Two Major Subcircuits
• Filament Circuit
• Allows the radiographer to adjust filament current
• Regulates electron emission
• Regulates tube current
• Regulates subsequent x-ray production
• High Voltage Circuit
• Steps up incoming voltage for x-ray production
• Timing circuit
• Monitor and compensate for fluctuations in incoming line voltage
• High voltage rectifiers
• Ammeters and voltmeters
• The components and circuitry that supply power to the X-ray tube
• Source of electrical power
• Line voltage compensation
• High voltage circuit
• Timer circuit
• Filament circuit
• Generator components can be found in the operating console and transformer assembly
• Supplied from local power in AC
• Commercial electric power commonly supplied in three-phase, 60 Hz. AC
• A simple generator supplies single-phase, 60 Hz. AC
• In a three-phase AC the voltage never drops to zero
• Line voltage is the voltage supplied by the power company
• This voltage is subject to fluctuations
• A compensator is used in the x-ray machine to monitor incoming voltage and keep it at a constant value
• On older units this can be done manually
• Newer units accomplish this automatically
• Converts incoming voltage to kilovoltage
• Allows for kVp selection
• Accomplished via the autotransformer and high voltage step-up transformer
• After increase voltage is then rectified
• Contains a timing circuit
• Determines when the exposure will be terminated
• Production of x-rays is controlled by regulating the voltage across the cathode and anode
• The first major circuit component encountered by incoming line voltage
• Has only one core with a single winding
• Has a variable turns ratio
• Can be used as a step-up or step-down transformer
• The autotransformers turns ratio is adjusted by major or minor kVp selection
• The output voltage of the autotransformer becomes the input voltage of the high voltage transformer
• This transformer brings line voltage to kilovoltage levels
• The turns ratio is generally 500-600
• The turns ratio is fixed - cannot be varied
• A voltmeter is connected to the primary side
• This value can be read prior to the exposure
• Located on secondary side of high voltage transformer
• This provides an average value of the tube current
• This cannot be read prior to exposure
• To operate efficiently, AC must be changed to DC prior to moving through the tube
• This process is known as rectification
• Accomplished via rectifiers
• Solid state rectifiers are generally used in modern x-ray equipment
• The resulting wave form depends on the number of rectifiers used
• Rectifiers are also used to measure current through the mA meter
• Half wave requires 0 - 2 rectifiers
• Uses only the positive half of the AC cycle
• The negative half is omitted
• Produces 60 DC pulses
• Full-wave requires 4 rectifiers
• Makes the most efficient use of both halves of the AC cycle
• The negative half is inverted to the positive half of the cycle
• 120 DC pulses are produced
• Terminates the exposure at a preset time
• Types of timers
• Mechanical timers
• Synchronous timers
• Impulse timers
• Electronic timers
• Automatic timers
• Least complex, least used
• Similar to an egg timer
• Accurate to app. 1/4 sec. , .25 s. or 250 ms.
• Uses a synchronous motor
• Turns in synch with incoming AC current
• Shortest time possible is 1/60 sec.
• Can only use multiples of 60
• Impulse Timers
• Works on the principles of voltage pulses
• Shortest possible time is 1/120 sec.
• Accurate to ms.
• Electronic Timers
• Provide very short exposure times
• Capable of exposures as short as 1 ms.
• Can be used for rapid serial exposures
• Uses the current passing through the tube
• Designed to provide the highest tube current at the shortest exposure time
• Automatic exposure controls
• Terminates the exposure when a certain amount of radiation reaches film
• Uses an ionization chamber, photomultiplier tube or solid state detector
• Spinning top test
• A special type of top is x-rayed while it is spinning
• The top has a small hole in it
• A certain time will have a corresponding number of dots on the film
• Calculating the number of dots
• 120 pulses/sec.in full-wave rectified circuit
• Multiply time X 120
• Must use a motorized spinning top
• Produce an arc image
• Solid state radiation detectors are generally used to check timers more accurately
• Produces electrons by heating the cathode to incandescense
• Voltages of 5-10 are needed to produce this heating capacity
• A step down transformer is necessary
• The primary voltage is supplied by the autotransformer
• The resulting output voltage is less
• This voltage is then supplied to the filament of the cathode
• Half and full-wave rectification result in a pulsed x-ray beam
• The output is single-phase power
• This causes voltage to swing from zero to maximum potential 120 times/sec for full-wave rectification
• During single phase the x-rays emitted are too low energy to be of use during the omitted negative half of the cycle
• Multiple voltage waveforms are initiated
• This happens with full-wave rectification only
• Three coils of wire are in a magnetic field
• Each current is slightly out of step with the other
• The resulting waveform never drops to zero
• Minimize voltage fluctuation
• Provide a more constant voltage waveform
• More efficient means of x-ray production
• Shorter exposure times are available
• Higher mA stations are available
• Higher energy x-rays are available
• Results in somewhat of a lower patient dose
• Results in a higher initial cost
• Three Phase Six Pulse
• 3 60 Hz AC voltage waveforms, 120 degrees out of step with each other
• Requires 3 phase power
• Uses 3 phase transformer with 6 - 12 rectifiers
• Three Phase Twelve Pulse
• Uses 3 phase transformer with slight variation in design from 3-phase, six-pulse
• Has 12 rectifiers
• Full-wave rectified power at 60 Hz is converted to a higher frequency (MHz)
• Uses a DC chopper
• The resulting beam has almost zero voltage ripple
• The generators are much smaller
• Image quality is improved with a lower patient dose
• Mobile x-ray machines were the first to use this technology
• The amount of voltage peak and trough between waves
• Single phase has 100 voltage ripple
• 3-phase, 6-pulse has 13
• 3-phase, 12-pulse has 4
• High-frequency has lt 1

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Michigan Engineering News

X-ray vision

One of the first experimenters at the new flagship US laser, Michigan alum Franklin Dollar’s mission is bigger than research.

Kate McAlpine

When the first beam of light ran through a laser system that will be the most powerful in the U.S., it was delivered to an experiment designed by an old hand at U-M’s Center for Ultrafast Optical Sciences.

As a graduate student in the late 2000s, Franklin Dollar (MSE Electrical Engineering ’10, PhD Applied Physics ’12) built experiments at HERCULES, the most intense laser in the world at the time. HERCULES has now been upcycled into ZEUS, the Zetawatt-Equivalent Ultra-short laser pulse System—which will offer triple the power of the next largest US lasers. Its peak power is three petawatts, or more than 100 times global electricity production, but only for a few quintillionths of a second.

Dollar has stayed connected with the lab, leading experiments in late 2022, early 2023 and January this year that the ZEUS team used to work out the bugs in the system. Then earlier this month, he led ZEUS’s first official experiment in the flagship target area, where the signature zetawatt-equivalent experiments will take place.

There’s an animated joy to the way Dollar describes his field—like he can’t help smiling about the questions, the laser experiments that help answer them, the technologies that spun out of it already and those that are coming in the future.

“In my field right now, which… It doesn’t even have a consistent name. I can call it high energy density science, I can call it advanced accelerators, I can call it fusion energy. I can just wave my hand and say ‘plasma physics.’ But what’s really exciting is that we’re using these great tools that are able to create some of the most extreme conditions in the known universe,” he said.

Few fields offer the breadth of laser plasma physics. As intense, powerful but very short pulses of light strike a target, whether it’s a gas in a chamber or a solid like a metal foil, they turn atoms into a hot soup of ions and free electrons—which the strong light waves can then accelerate. Although they take up a tiny amount of space, those experiments become a microcosm of some of the most extreme dynamics in the universe, enabling researchers to explore processes that previously could only be observed with a powerful telescope.

“It wasn’t that long ago that you could only get these answers from the middle of galactic nuclei or some crazy astrophysical process. And now we’re making these plasmas on lasers that fit in a university lab. A PhD student in a basement can see these types of events unfold and tease out these secrets of the cosmos,” he said.

Dollar’s own work is very fundamental—making the plasmas and seeing what they do, and optimizing experiments to produce X-rays or particle beams. These have applications in medicine, semiconductor engineering, basic research and more. Even before adding in special relativity, which crops up as the electrons and ions in the plasma are accelerated to near the speed of light, the extreme electric and magnetic fields already produce a complex behavior that is hard to describe mathematically. 

He is most motivated by the unknown, untangling these challenging dynamics. But he is also excited about the future applications coming out of the laser plasma physics field that brought us LASIK surgery to correct vision , and the miniature particle accelerators and X-ray sources that he is investigating. The ability to accelerate particles on the scale of a room rather than over miles of magnets could change the way semiconductors are manufactured, help more hospitals produce their own radioactive (or nuclear) medicines for targeting cancer, and enable a new kind of low-dose X-ray that can image soft tissues like organs.

His first official experiment at ZEUS explores extreme ultraviolet light, a step down in energy from those “soft” X-rays of interest for medical imaging. 

“The experiment that we are undertaking is to look at extreme ultraviolet light, the same light that is used to make state-of-the-art computer chips,” said Dollar. “While we understand how to use laser interactions to make bright X-rays, we actually don’t really know what happens in this wavelength region, which has applications across medicine, chemistry and nanofabrication.”

He’s recognized as a trail-blazer, a member of the Department of Energy’s Fusion Energy Sciences Advisory Committee and a fellow of the American Physical Society. Last year, he was named a co-lead of a project prototyping a 25-petawatt laser , which could re-launch the US as a leader in high peak power lasers. At present, the most powerful in the world is located in Romania, a 10-petawatt machine that is part of Europe’s Extreme Light Infrastructure.

But if Dollar had been judged by his early undergraduate grades, he would have been considered unlikely to make a career in plasma physics. He faced challenges that weren’t on the radar of most college recruiters and administrators, and he knows what it took to overcome them. Now, as the associate dean for graduate studies at the University of California, Irvine’s School of Physical Sciences, Dollar uses that knowledge to provide better access and support for students from historically excluded backgrounds. 

Dollar is likely the third American Indian to be hired as a faculty member to a top-100 physics program. A member of the Dry Creek Band of Pomo Indians, he is well aware of stereotypes that freeze Indigenous cultures in the past and lead some to view his high-tech career as a contradiction. But his identity as an American Indian is intertwined with his identity as a scientist.

“All societies have looked out at the world and wondered,” said Dollar. “Being a scientist and being an explorer isn’t just from the last few hundred years of history, but something that’s embedded in all societies, for thousands of years since these cultures began.”

Not the Sonoma on the wine labels

Dollar knows more than most about the many ways this country leaves talent on the table. Growing up in Sonoma County, he saw the stark contrast between the wealth of some of California’s richest wineries and the poverty of the migrant workers and his own life on the reservation run by his tribe.

Like many reservations, the Dry Creek Rancheria is on land deemed less suitable for agriculture—rockier and hillier than the surrounding vineyards, Dollar observed. Without the history of displacement by the U.S. government, he might have been raised on ancestral Pomo land, in a once-fertile valley that is now the bottom of the Lake Sonoma reservoir. Instead, he lived where resources sometimes didn’t stretch beyond basic survival.

“All the housing was temporary,” said Dollar. “The Dry Creek Rancheria is land held in trust by the federal government. While the tribe can enforce its own laws, it does not have ownership over the land and thus cannot use it as collateral.”

Without collateral, neither the tribe nor individuals can get a loan for building houses, businesses and more. Even if they could, Dollar pointed out that some banks choose not to do business on reservations because of the complexities around jurisdiction. 

Still, the Dry Creek Rancheria provided land for tribe members to live on. When Dollar was in seventh grade, his parents were able to buy a trailer home that the state of California considered scrap—the wiring wasn’t to code. But the reservation isn’t subject to California’s building codes, and it was a step up for his family, which had been homeless. 

They made trips to the storage tank of the reservation’s well to bring water back home, although they sometimes had access via a hose. And everyone on the reservation relied on water trucked in during the dry season. When Dollar was in high school, his family’s home got electricity, later than many families in the US went online with dial-up internet. The hardships didn’t seem exceptional to him at the time—he figured most Americans’ lives were more similar to his own than to the affluent vineyard owners on the land surrounding the reservation. 

As a teen and into college, Dollar worked at Longs Drugs stores, which have since been acquired by CVS. But it was his time in the tribe’s offices that gave him a taste for serving others and solving problems that affect people—an interest that eventually led him to go for a position in his college’s administration.

Dollar is aware of the many gaps that stood between his teenage self and the science and engineering work he excels at and enjoys. The associate dean position enables him to address some of those gaps for others. 

The route to science and engineering

On his own journey, Dollar was fortunate to have a science teacher who believed in his potential. Well-resourced schools may offer upwards of 10 advanced placement courses, but Geyserville New Tech Academy, with 150 students, had only a few. 

Brad Goodhart , the science teacher, supervised Dollar’s independent study in Advanced Placement Physics. He also introduced Dollar to some of the skills he would need as a scientist, hiring him to help assemble earthquake detectors. 

“I didn’t quite realize that I was doing science at the time,” said Dollar. “My idea of a scientist was whatever I saw on TV. And there were these people who knew everything and could do anything. And I’m like, well, I’m not that. I’m just gonna do this little thing here.”

If he hadn’t been able to get a ride to the SAT testing site an hour away, Dollar says his potential as a scientist might have ended there. This is one of the binds in college recruiting, he says: even looking at the top 10% of each school still selects for the students with resources that enable them to succeed rather than truly measuring each student’s potential. Recruiters often lack the resources and bandwidth to look any deeper, to really see students locked out of transportation and, these days, internet access.

Dollar’s academic talent wouldn’t have been enough on its own, but with social resources in the forms of mentorship and that crucial ride, Dollar had a solid application. Goodhart encouraged him to apply to the University of California, Berkeley.

College was a shock in many ways. Dollar was far from home and among peers who came from privileged backgrounds, who had parents, siblings and family friends who could advise on the everyday challenges of college. But perhaps the deeper shock was realizing that he needed to learn how to learn. He’d been a top student in high school. While his GPA at Berkeley was near a 3.0 first semester, it was 1.8 after his second.

“They gave me a ‘one more of these you’re out of here’ letter. And so that was very terrifying,” said Dollar.

“The strategies that got me through high school were clearly not the strategies that were going to get me through college, and I didn’t even understand that there would be new strategies. It hadn’t occurred to me that my idea of what it meant to learn was wrong.”

Without people to reach out to about this challenge and how to overcome it, Dollar internalized it at first, believing the problem was him. But in this place where the enrollment for introductory chemistry outnumbered his entire tribe, he found support in the Native American Recruitment and Retention Center, now the Indigenous and Native Coalition . It became a home away from home.

Discovering research

Around that time, a friend he’d met at Berkeley mentioned free pizza at an information session for UC-LEADS, a program that helps students from diverse backgrounds find opportunities to pursue experiences relevant to their goals . Dollar laughs about being motivated by the food when the program ended up changing the course of his life, connecting him with a research opportunity at Lawrence Berkeley National Laboratory.

Here, working among graduate students who problem-solved together on whiteboards, Dollar had a model for what learning looked like at the university level. And he was competent, measuring how materials transmit and reflect X-rays, and other optical properties. Collaborating with microelectronics and semiconductor manufacturers as well as a solar observatory project, his successes in the lab had real-world impacts. 

As he found community and built his technical skills, Dollar turned his talents to building his community in science and engineering. He’d been involved with the American Indian Science and Engineering Society (AISES) from his first year at Berkeley, although Berkeley no longer had its own chapter. After attending his first conference in Alaska in 2004, he decided to restart the Berkeley group. This led him to become Region 2 representative covering California, Nevada and Hawaii. 

“I participated in numerous workshops and conferences, and continued this work at Michigan and beyond,” said Dollar.

“I still have many friends from those early days in AISES. Having a professional group from the diverse tribes across the nation has been an incredible support network, as well as a great resource for advancing higher education policies to better accommodate Native students.”

While he was reluctant at first to take the next step with a multicultural summer program in engineering at faraway Harvard University, he went with encouragement from his mentors at UC Berkeley.

“When I left and went there, all of the years of failure and insecurities that I’d been building up didn’t come with me. I could just show up as a new person and start over and do good work,” said Dollar. “And that was really refreshing.”

It turned out he enjoyed living in a new city. This, along with the knowledge that two friends were heading for the University of Michigan, gave him the courage to apply for a longer stay at another university far from home.

A different physics experience

Dollar had initially chosen engineering because his friends from high school who were going into UC Berkeley chose engineering degrees. Asked to specialize further, he went with engineering physics because of the experience he had built up in high school. For a PhD, after working at Lawrence Berkeley’s Advanced Light Source, he leaned further into science with a degree in applied physics. Michigan’s Applied Physics Program turned out to be a great fit.

“They just felt like a family, in a sense, with a strong sense of community,” said Dollar. “People cared about you and wanted you to succeed.”

He’d also heard that the program was turning out 10% of the nation’s Black and African American physics PhD graduates and had assumed it must be a huge program. When he arrived, he realized it was the culture of the program rather than the size—and also the dismal fact that with the number of Black physics PhDs in the US running less than 20 most years, it only takes 1-2 graduates per year to make a program nationally significant.

Meanwhile, US universities award physics PhDs to just one or two American Indians in any given year, so Dollar took it as a good sign when there was already another American Indian in the program.

“They really are a massive force for good, and I learned a lot about inclusive administration based on how Roy Clarke, Brad Orr and Cagliyan Kurdak ran the program,” he said.

Applied Physics emphasized support and inclusion from its beginning in 1987, starting with the assumption anyone who got in should be able to graduate. They also did admissions differently. For instance, Dollar didn’t need to take the physics GRE, which would have tested him on a few topics he didn’t cover in engineering physics—and that he didn’t need or could learn on the fly during his studies. In addition, the leaders held meetings to check in about the department climate and provide a forum for students to get advice on how to succeed.

And importantly, the way learning is structured in the first year of graduate school suited Dollar as well, with a cohort of students essentially on the same schedule, sharing an office and working together.

“Steve Yalisove was my first introduction to active learning. I had never seen anything in my classes, let alone heard about it before. Along with Tim McKay in physics, who leads a lot of physics education work at Michigan, this would be my first exposure to modern pedagogy, and they remain excellent examples of how learning and teaching should take place in the classroom,” he said.

“Now that I am a faculty member and look at best practices, we see that this is the way that people learn best. We give it fancy names like active learning, but really it’s just learning.”

The way applied physics PhD students at U-M are funded is another factor that helps the program achieve a graduation rate of 80%, 20 points higher than the national average. The two years of funding, untethered from any particular faculty member, provides time to find the right lab. 

“This is 5 to 7 years, right? Every day in the lab is going to be a failure except for 3 or 4 days. And then you have a success, and you write that up in a paper, and that’s a magic moment. But every other day is a failure, and the only way to get through this is to persevere,” said Dollar. “That’s a very punishing existence. And to get through that, you need to be in a place where you can feel like you’re making a contribution even when nothing works that day.”

In a lab with complex, shared equipment, Dollar could work on problems that moved his colleagues’ projects forward, as well as his own, and celebrate each win with them. That’s how he ended up in the Center for Ultrafast Optical Science, working under Karl Krushelnick , now the Henry J. Gomberg Collegiate Professor of Engineering. Krushelnick had recently arrived from Imperial College London, and Dollar was his second PhD student. 

Experiments on HERCULES were group projects involving graduate students, post-doctoral researchers and staff scientists as well as research faculty.

“Often you can take simultaneous measurements on the same sequence of laser shots, so everyone can get data at the same time for their own theses and also be coauthors on each other’s papers. Having other experiments work out, getting everything working correctly, it fosters collaboration that way,” said Krushelnick.

While there was no particular training to become a faculty member for the applied physics program, Krushelnick understood that the program was making an effort to graduate PhD cohorts that better represent the diversity of the US. For his part, he tried to cultivate a group culture in which team members would freely share ideas, without fear of being shut down.

Dollar worked closely with Chris McGuffey, now a staff scientist at General Atomics, their projects complementing one another as they learned how to improve their experiments. Their cohort was among the first to run experiments on HERCULES. He also stayed connected with AISES, joining the U-M booth at the college fair to offer his insights on life and studies at Michigan.

Krushelnick remembers Dollar as exceptional for both his productivity and independence. Because Dollar had a fellowship with the National Science Foundation, rather than relying entirely on Krushelnick’s research budget, he had more latitude to pursue his own questions. Dollar’s thesis explored how to get cleaner interactions between the high intensity laser pulses—each about a femtosecond (10 -15 seconds) long—and solid targets. In addition to publishing in high caliber journals, Dollar’s report won the John Dawson Thesis Prize in 2013.

After his PhD, Dollar continued exploring X-ray generation with pulsed lasers as a research associate at JILA, a joint physics institute between University of Colorado, Boulder, and the National Institute of Standards and Technology. Since 2015, he has been a professor at UC Irvine, continuing to explore the questions that captivated him from his time working on HERCULES. This was also the year AISES named him Most Promising Scientist .

Reinventing grad student mentorship

Dollar is taking all that he’s learned about how to survive and thrive in research and using it to reshape the graduate programs at UC Irvine’s School of Physical Sciences. Before he became an associate dean in 2021, he was already working on building and maintaining a strong graduate student community within physics and astronomy by rethinking peer mentoring.

The Physics and Astronomy Community Excellence program is integrated with the curriculum through the faculty lecture series, taking one slot each month. As well as recruiting student mentors, who are then trained in mentorship, these lectures cover key skills and strategies like choosing an advisor, time management, project management, wellness and personal growth. They also provide a direct line for the department to discover the problems graduate students experience, which has been instrumental in turning around a department culture that women found hostile, says Dollar.

In 2021, the program won a four-year grant from the National Osterbrock Leadership Program, totalling $128,000 with matching funds from UCI. That support enables mentors to be compensated for their time and also provides funds for career development opportunities like traveling to conferences. The program materials are available on GitHub for any graduate program to implement, and Dollar is working with other departments to develop their own versions.

“We’re also starting to see, as the climate gets better, our representation for women and other demographics increases,” said Dollar. “And really, the students took the first steps forward that enabled a lot of this. It just took the faculty partnering with them.”

Clarke, founder of U-M’s Applied Physics Program, is delighted to see graduates like Dollar using the program as a model for creating inclusive programs elsewhere.

“This is how real change is made and propagated,” said Clarke. “It’s wonderful to see Franklin applying and expanding best inclusive practices in graduate education at UC Irvine.”

Increasing access for those with limited opportunities

The improvements in support and climate may also be contributing to higher enrollment for Indigenous, Black and Latin American students in recent years, along with what are known as bridge programs. Bridge programs at UC Irvine help students gain conditional acceptance to PhD programs in the physical sciences if they didn’t have the opportunity to participate in research or take upper-level physics classes as an undergraduate.

These students may be drawn from smaller, minority-serving colleges that don’t have a physics department or a nearby national lab to facilitate these opportunities—which are easy to come by in major research institutions for students who know how to find them. UC Irvine participates in multiple programs. 

Dollar is on the executive steering committee for the University of California Leadership and Excellence through Advanced Degrees program. This bridge program serves promising students in the University of California system who are interested in PhDs in science, technology, engineering and math but face financial or educational disadvantages. He also works with the Cal-Bridge program, which provides a pathway for California residents who attended schools in the more accessible California State University system.

“These students look more like California as a whole,” said Dollar.

In addition, the NSF-funded Inclusive Graduate Education Network (IGEN) partners on bridge programs with the American Physical Society (APS), American Chemical Society (ACS) and American Geophysical Union (AGU). Dollar is co-lead of the APS program at UC Irvine and manages the fellowships for all three programs, which provide funding for participating students.

As the University of California system has an abundance of applicants, it is easy to discount bridge students because they don’t have all of the components of a strong PhD application, Dollar explained. But some of the conventional metrics, like the very highest GPAs or exceptional standardized test scores, are poor predictors of success in graduate school. A student who looks great on paper may struggle with the project management and problem-solving of a PhD, and a student who struggles to learn independently with lectures and books may thrive in a team environment, as Dollar did. 

“We look at higher education as a whole, and particularly graduate education, and it really has not changed in 100 years or longer. It’s the same model that we had pre-electricity. It’s worth it to sit down and have a serious conversation about what is the goal of this program? What is it we’re trying to accomplish? And what are the best ways of doing that?” said Dollar.

That extends to admissions. Dollar is part of a movement in higher education to look beyond what boxes a student checks to other indicators of their potential and their motivation, such as how they spend their time outside of academics, to help close opportunity gaps.

U-M faces some of the same struggles, needing to identify students who could thrive here but who haven’t had the opportunities of their better resourced competitors. It is also part of IGEN, running programs with all three partners as well as establishing the Imes-Moore Bridge Program in applied physics, started in 2010. Likewise, U-M also uses a holistic application review process to look beyond boxes checked.

Bringing his perspective

While the graduate program is within his sphere of influence, Dollar remains troubled by the unequal access to undergraduate education. In rural places like his home in Sonoma county, the University of California doesn’t fund visits by recruiters. He knows there are students every year that could do well but never have the opportunity, barred by obstacles akin to the way he had to hitch a ride to take the SAT.

“Those aspects of systemic inequities don’t even get discussed—because people in the system never experience them. Those are the things that really upset me,” said Dollar.

The pandemic normalized virtual events, but they still can’t reach homes in places where companies that provide high speed internet choose not to invest. And we all miss out when those voices never make it into science. 

Dollar, as one of those who might easily have been excluded, considers what he brings to physics and academia.

“There really is a different experience when it’s your homelands, in the way that you look at everything around you. The impact that you’re making might leave a legacy that lasts a very long time,” he said. 

He noted the tendency in US culture to look at history as the last few hundred years. Even in Western Europe, which largely spawned that culture, history goes back to the ancient Greeks but often centers on specific individuals, which is very different from the way Dollar learned to conceptualize the last few thousand years in his own upbringing. The narratives he was raised on include stories of collective responsibility, of collaborating with the natural world rather than conquering it.

“That’s kind of the voice that I try to bring to the table, incorporating those values of looking beyond what our initial frameworks might be,” said Dollar.  “How do we incorporate many voices at the table, especially those that we maybe haven’t heard from before? How do we change the definition of what a physicist or engineer or scientist is, when it already doesn’t apply to many of the people in the room?”

Part of the answer is to keep diversifying the room, and to build a culture that will listen to those voices when they speak. 

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Dental X-ray Equipment

Sep 06, 2014

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Dental X-ray Equipment. DHYG 116 Oral Radiology I. Objectives. Define key terms Discuss regulation of x-ray equipment Recognize x-ray machines used for intra- and extraoral radiography Describe purpose and use of dental x-ray film holders and devices. Dental X-ray Equipment.

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Dental X-ray Equipment DHYG 116 Oral Radiology I

Objectives • Define key terms • Discuss regulation of x-ray equipment • Recognize x-ray machines used for intra- and extraoral radiography • Describe purpose and use of dental x-ray film holders and devices

Dental X-ray Equipment • Chapter 6 reading: Haring (pgs. 66-73) • Questions • What are the component parts of a dental x-ray machine? • What types of x-ray film holders are available and how are they used? • What are beam alignment devices and how are they used?

Dental X-ray Equipment • Dental X-ray Machines • Dental X-ray Film Holders and Beam Alignment Devices

Dental X-ray Machines • Haring (pp. 67-69) • Performance standards • Types of machines • Component parts http://arcweb.sos.state.or.us/rules/OARs_300/OAR_333/333_100.html

Performance Standards • Before 1974, there were no federal standards for the manufacture of dental x-ray machines • After 1974, the federal government regulates the manufacture and installation of dental x-ray equipment • State and local governments dictate how it is used OR-OSHA is responsible for worker safety Radiation Protection Services Office of Environmental Public Health 900 NE Oregon Street, Suite 640 Portland, OR 97232

Types of Machines • Haring (pp. 67-69) (Figs. 6-1, 6-2) • Some units are used for intraoral films • Some units are used for extraoral films

Component Parts • Haring (pp. 15-16, 67-70) (Figs. 2-11, 2-12, 6-3, 6-4) • Tubehead • Extension arm • Suspends and allows for positioning of the tubehead • Control panel • On-off switch and indicator light, exposure button and indicator light, control devices (time, kilovolt peak, milliamperage)

Identify the components: A. B. C. B C A

Component Parts Tubehead Beam Indicating Device Control panel On-off switch Control devices, timer

Dental X-ray Film Holders and Beam Alignment Devices • Haring (pp. 69-71) • Film holder • A device used to hold and align intraoral dental x-ray films in the mouth • Beam alignment device • An instrument used to help the dental radiographer position the PID relative to the tooth and film

Types of Film Holders • Haring (pp. 69-71) (Figs. 6-5, 6-6, 6-7) • Disposable styrofoam bite block • EEZEE-Grip (Snap-A-Ray) • EndoRay • Uni-bite

Types of Beam Alignment Devices • Haring (pp. 69, 71-72) (Figs. 6-8, 6-9, 6-10) • Precision film holders (Masel Orthodontics) • Rinn XCP and BAI Instruments

Collimating Devices • Used with a beam alignment device to restrict size of the x-ray beam to the size of the film • Rectangular collimation significantly reduces exposure

Next… • Chapter 9 – Film Processing • Read pgs. 101 – 108 • We will not spend time on manual processing, but you will be responsible for reading about it. • Continue reading pg. 113 – 127. • Be sure to review the quiz at the end of the chapter.

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A new report published by Future Market Insights (FMI) provides an 8-year long prediction on Global Dental X-ray systems Market. The primary focus of this report is to lend a holistic view of the dental X-ray systems market by providing key insights and updates. This descriptive report provides valuable insights by analysing the historical data for the period 2013 u2013 2017 and the forecast has been provided for the period 2020-2026. The market has been evaluated in terms of volume (units) and revenue (US$ Mn). The report begins with a detailed executive summary on the dental X-ray systems market, which sheds light on the demand drivers, restraints, opportunities, and threats influencing the sales of the dental X-ray systems. In the bid to understand the sales opportunities of the dental X-ray systems, key segmentations of this market are analysed. A section consisting of opportunity analysis has been incorporated in the report, which provides the stakeholders an idea about the lucrativeness of this dental X-ray systems market. Request a Sample of this Report @ https://www.futuremarketinsights.com/reports/sample/rep-gb-8960 Another salient feature of this report is that it provides a detailed analysis of this market in terms of absolute $ opportunity. This helps the stakeholders of this global dental X-ray systems market understand the level of opportunities available in the market. Dental X-ray Systems: Segmentation of the Market In the bid to offer a comprehensive analysis of this dental X-ray systems market to the stakeholders, the market has been divided on the basis of regions, end user, and product type. Depending on the basis of end user, dental X-ray systems market has been classified into dental clinics, dental laboratories, dental hospitals, and others. The section highlights the key findings of this market in this report. Based on the product type, the dental X-ray systems market has been fragmented into Cephalometric Projections Systems, Portable Intraoral X-ray Systems, Panoramic X-ray Systems, and Intraoral X-ray Systems Mounted on the Floor. Depending on the basis of the geographies, the dental X-ray systems market has been divided into the regions such as North America, Europe, Latin America, Middle East & Africa (MEA), and China. On the basis of this detailed segmentation of this market, the report aims to equip the stakeholders of this market with market attractiveness. This will help them devise sustainable business strategies. Dental X-ray Systems: Research Methodology A comprehensive analysis of Dental X-ray systems market has been carried out by assessing various growth drivers and restraints. The crucial segments of this market have been analysed and discussed in this descriptive report with the help of the data extracted from the primary and secondary sources. Currency rates have been taken into consideration while assessing this global dental X-ray systems market. Dental X-ray Systems: Competitive Landscape of the Global Market An incisive view on the key companies innovating the existing landscape of dental X-ray systems market is included in the report. Global study on the dental X-ray systems market incorporates an in-depth analysis of leading players devising new strategies in the market. The leading players analysed in the report comprise of FONA, PLANMECA OY, Prexion Corporation, Owandy Radiology, Vatech Co. Ltd., The Yoshida Dental Mfg. Co. Ltd., Dentsply Sirona, LED Medical Diagnostics Inc., Cefla S.C., Air Techniques, Inc., and Danaher Corporation, among others. Ask an Analyst @ https://www.futuremarketinsights.com/ask-question/rep-gb-8960 A descriptive analysis of each of these companies has been included in the market study, apart from their novel business strategies, overview, size, and value for this global dental X-ray systems market. This insightful report will aid the stakeholders in gaining valuable market insights, which will ultimately help them sustain their position in the dental X-ray systems market. ABOUT US: Future Market Insights is the premier provider of market intelligence and consulting services, serving clients in over 150 countries. FMI is headquartered in London, the global financial capital, and has delivery centers in the U.S. and India. FMIu2019s research and consulting services help businesses around the globe navigate the challenges in a rapidly evolving marketplace with confidence and clarity. Our customized and syndicated market research reports deliver actionable insights that drive sustainable growth. We continuously track emerging trends and events in a broad range of end industries to ensure our clients prepare for the evolving needs of their consumers. CONTACT US: Mr. Abhishek Budholiya Unit No: AU-01-H Gold Tower (AU), Plot No: JLT-PH1-I3A, Jumeirah Lakes Towers, Dubai, United Arab Emirates MARKET ACCESS DMCC Initiative For Sales Enquiries: [email protected] For Media Enquiries: [email protected]

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