The Function of X-Ray Tubes

The Function of X-Ray Tubes



An X-ray tube is basically a vacuum tube that produces X-rays, which are used in X-ray machines. X-rays are part of the electromagnetic spectrum, an ionizing radiation with wavelengths shorter than ultraviolet light. X-ray tubes evolved from experimental Crookes tubes with which X-rays were first discovered in the late 19th century. The discovery of this controllable source of X-rays created the field of radiography: the imaging of opaque objects with radiation that penetrates. X-ray tubes are also used in airport luggage scanners, CAT scanners, X-ray crystallography and for industrial inspection.

As with any other type of vacuum tube, there is a cathode, which emits electrons into the vacuum and an anode to collect the electrons ─ creating a flow of electrical current, known as the beam, through the x-ray tube. A high voltage power source is connected across the cathode and the anode to accelerate the electrons. The X-ray spectrum depends on the anode material and the accelerating voltage.

In many applications, the current flow is able to be pulsed on for between approximately 1ms to 1s. This allows for consistent doses of x-rays, and taking snapshots of motion. Until the late 1980s, X-ray generators were merely high-voltage, AC to DC variable power supplies. In the late 1980s a different method of control emerged, which became known as high-speed switching. This followed the electronics technology of switching power supplies (also known as switch mode power supply), and allowed for: more accurate control of the X-ray unit, higher-quality results, and reduced exposure to X-ray.

Electrons from the cathode collide with the anode material, usually tungsten, molybdenum or copper, and accelerate other electrons, ions and nuclei within the anode material. About 1% of the energy generated is emitted/radiated, usually perpendicular to the path of the electron beam, as X-rays. The rest of the energy is released as heat. Over time, tungsten is deposited from the target onto the interior surface of the x-ray tube, including the glass surface. This slowly darkens the tube and was thought to degrade the quality of the X-ray beam, but research has suggested there is no effect on the quality. Eventually, the tungsten deposit becomes sufficiently conductive that at high enough voltages, arcing occurs. The arc jumps from the cathode to the tungsten deposit, and then to the anode. The arcing causes an effect called "crazing" on the interior glass of the X-ray window. As time goes on, the tube becomes unstable even at lower voltages, and must be replaced. At this point, the x-ray tube assembly (also called the "tube head") is removed from the X-ray system, and replaced with a new tube assembly. The old tube assembly is shipped to a company that reloads it with a new, replacement X-ray tube.

The range of photonic energies emitted by the system can be adjusted by changing the applied voltage, and installing aluminum filters of varying thicknesses. Aluminum filters are installed in the path of the X-ray beam to remove "soft" (non-penetrating) radiation. The numbers of emitted X-ray photons or doses are adjusted by controlling the current flow and exposure time.

In simple terms, the high voltage controls X-ray penetration, and thus the contrast of the image. The tube current and exposure time affect the dose and consequently, the darkness of the image.

Some x-ray examinations (such as: non-destructive testing and 3-D microtomography) need very high-resolution images and therefore require x-ray tubes that can generate very small focal spot sizes, typically below 50 µm in diameter. These tubes are called microfocus x-ray tubes.

There are two basic types of microfocus x-ray tubes: solid-anode x-ray tubes and metal-jet-anode x-ray tubes.

Solid-anode microfocus x-ray tubes are in principle very similar to the Coolidge tube, but with the important distinction that care has been taken to focus the electron beam into a very small spot on the anode. Many microfocus x-ray sources operate with focus spots in the range 5-20 µm, but in rare cases spots smaller than 1 µm may be produced.

The major drawback of solid-anode microfocus x-ray tubes is the very low power in which they operate. To avoid melting of the anode, the electron-beam power density must be below a maximum value. This value is somewhere in the range 0.4-0.8 W/µm depending on the anode material. This means that a solid-anode microfocus source with a 10 µm electron-beam focus can operate in the range 4-8 W.

In metal-jet-anode microfocus x-ray tubes, the solid metal anode is replaced with a jet of liquid metal, which acts as the electron-beam target. The advantage of the metal-jet anode is that the maximum electron-beam power density is significantly increased. Values in the range 3-6 W/µm have been reported for different anode materials (gallium and tin).[4][5] In the case with a 10 µm electron-beam focus a metal-jet-anode microfocus x-ray source may operate at 30-60 W.

The major benefit of the increased power density level for the metal-jet x-ray tube is the possibility to operate with a smaller focal spot to increase image resolution, and at the same time acquire the image faster, since the power is higher (15-30 W) than for solid-anode tubes with 10 µm focal spots.

Shockwave Lithotripsy for Blasting Kidney Stones

Shockwave Lithotripsy for Blasting Kidney Stones



Exactly what causes kidney stones is not known. There can be many different reasons. The most common type in about 80% of cases is composed of calcium oxalate crystals. Other types of kidney stones are composed of magnesium, ammonium, phosphate, calcium phosphate and cystine. Uric acid stones are another different type of stone in about 5–10% of cases.

Even though calcium is one of the major minerals in kidney stones, research now shows that having a low calcium diet actually increases the incidence of kidney stones. When calcium levels are low your body produces more oxalate which does increase your risk of kidney stones.

Usually kidney stones can pass without assistance or are removed from the body without causing permanent damage. However, if a kidney stone blocks urine flow for a period of time, complications can arise. Prevention of kidney stones is important because repeated occurrences of kidney stones increase the risk of developing chronic kidney disease.

A complication of kidney stones is the need for invasive treatments. If the stone cannot pass on its own, the first treatment tried is often shockwave lithotripsy. The shockwave lithotripsy procedure uses high-energy sound waves directed at the stone to break it up into smaller pieces so that it may be more easily passed.

According to the American National Kidney and Urologic Diseases Information Clearinghouse, more than 5 percent of the US population will have kidney stones, which is probably generalizeable to other countries. Men are more likely than women to acquire kidney stones, particularly between the ages of 40 and 70. For women, the prevalence actually decreases after age 50. Extracorporeal shockwave lithotripsy, or "blasting" of the stones, is a popular treatment for kidney stones.

In extracorporeal shockwave lithotripsy, shockwaves that are created outside the body travel through the skin and body tissues until they hit the denser kidney stones. After the stones have been hit, they will break down into sand-like particles that are easily passed through the urinary tract in the urine.

Extracorporeal shockwave lithotripsy uses shockwaves to break up stones, so that they can easily pass through the urinary tract. Most people can resume normal activities within a few days. Complications of extracorporeal shockwave lithotripsy include blood in the urine, bruising, and minor discomfort in the back or abdomen

PACS ------------- Picture Archiving and Communications Systems

Why PACS Workstations are Essential Tools













What exactly is PACS?
Picture Archiving and Communications Systems, or as they are more commonly known, PACS, are being used in most hospitals and radiology clinics. This digital imaging technology has replaced the old way of capturing x-rays and scans on film and paper, enabling clinical images to be stored electronically and viewed on screen.
PACS work with x-ray and scanning technology such as Computerized Tomography (CT), Magnetic Resonance Imaging (MRI) and ultrasound to make x-rays and scanned images available to view on screens within radiology, and to share with other hospital departments like accident and emergency, neurology and orthopedics.

With PACS, clinical images are instantly and simultaneously available for study at multiple locations within a trust. PACS supports more effective team working between clinicians and therefore aids swifter and more accurate diagnoses and treatment for patients.

In radiology, PACS is combined with a radiology information system, or RIS. Radiologists report on the x-rays and scanned images they can view on PACS, and the subsequent reports they produce are then accessible from the images with which they are associated.
Why do we need PACS?
For the past 100 years, film was the main means for capturing, storing and displaying radiographic images. However, film is a fixed medium with usually only one set of images available.

PACS allows for a near filmless process, with all of the flexibility of digital systems. It also removes the costs associated with hard film processing and releases valuable space previously used for film storage. Most importantly, PACS is helping to transform patients’ experience of the care they receive across the NHS. It does this by enabling a speedier diagnosis and by removing the risk of images being lost or misplaced.

How does PACS improve patient care?
With PACS clinicians can access the right image in the right place at the right time. The technology enables:
Faster accessibility to medical images for the clinicians who evaluate and report on them. This can lead to the speedier availability of results.
No lost or misplaced images, which means fewer patients having their consultations or operations postponed or cancelled.
Fewer unnecessary re-investigations, which in turn reduces the amount of radiation to which patients are exposed.
Flexible viewing, with the ability to manipulate images on screen, ensuring that patients can be diagnosed more effectively.
Instant access to historic images, so that new and old images can be compared and the progress of patients’ treatment and condition(s) monitored.
Better teamwork and collaboration because, with PACS, images can be viewed from multiple terminals and locations within a trust by a range of clinicians. And the vast majority of trusts now have the ability to share images electronically with other trusts.
As a result of all of these improvements, PACS is enabling patients to move on quickly to the next stage in their treatment

TRUTH ABOUT VERSED

Why Flag Versed (Midazolam) ?

Here is a list of the complaints about Versed we commonly encounter:

* Too often, the drug is used in a sneaky or furtive manner. Every manner of lying, cheating and BS-ing has been reported by people who unwittingly received this drug. Knowledgeable people, including medical people, have been given Versed after clearly refusing it.

* Versed is NOT a pain medication. The main effects are AMNESIA and patient compliance. Many patients feel they were mishandled, given inadequate pain management, or both. The impression is that the medical staff tries to hide behind the amnesia the patient is expected to have.

* Paradoxical reactions including anxiety, delirium and aggression. This includes patients attacking or trying to leave. They lose touch with reality, not knowing where they are or what is really occurring.

* Some patients experienced a distorted, nightmarish version of their procedure accompanied by feelings of abandonment and panic. This is often accompanied by the next item:

* A kind of sleep paralysis - patient is aware but cannot move and cannot communicate.

* Amnesia did NOT take place for some patients. Patients recall a bad experience!

* Some patients report a "creepy obedience" overcoming them.

* PTSD. Many patients report symptoms of Post Traumatic Stress Disorder after having this drug.

* Weird panic or anxiety episodes ("flashbacks") for some time (weeks, months, years) post-op.

* Long term memory disruption. Memories formed prior to the use of Versed are lost. Some people are unable to retain new information or complete tasks.


What is Versed?

Versed (Midazolam) is an amnestic. It is commonly administered in combination with anesthesia before and during surgery. It is also commonly used for minor procedures like colonoscopies so that patients won't remember pain and discomfort. However, that does not mean that those sensations will not be experienced.

Why be concerned about Versed?

If you are a person who wishes to be involved in your medical care, want to interact with your treatment providers, and want to be as aware and alert as possible during procedures, then you will want to be aware of this commonly-used drug.

How would you feel if you were given a drug, without your knowledge, that wiped out any memory of events that occurred over a period of hours?

That is what happened to us, Tim, Mary and Kirt - three people who were administered the drug Versed for surgery without our consent. We each spent several hellish months trying to come to grips with what happened to us (for our personal accounts, see below). Many people feel that they were ambushed and remained shaken by the experience for a long time.

A person who is under the influence of Versed can function, and can even carry on a conversation, but will remember nothing once the drug wears off. The use of Versed can open the door to abuse. If there is mishandling of the patient during procedures the patient will have no memory.

We are not saying that people should never be anesthetized, or that sedation should never be an option, but rather that:

* One should be given a complete description of what is going to be done to them. If Versed (conscious sedation) is to be used, the patient should be aware of the amnesia that will result.
* When possible, you should have a choice about being awake for any procedure or part thereof. We take exception to being denied a choice in those cases where one exists. One reason we have this site is because so many people report being deceived.
* Attention should be paid to the fact that some people find anesthesia very upsetting and may prefer a few minutes of moderate physical discomfort to a longer period of mental discomfort. Versed appears to cause PTSD in some people.
* Having a bad experience blocked from long term memory is not the same as never having had the experience in the first place. We think that if they have to make you forget, then they are not taking adequate steps to manage pain and discomfort.
* Versed is not a requirement for surgery. Medical professionals should be completely honest about the effects, and not try to trick or coerce a patient into having it. It should not be used solely for the profit or convenience of the medical staff.


What can you do?

Watch out for these commonly used phrases:

* "I am giving you something to relax you." This is too often an understatement, given the frequent side effects. This statement also completely avoids mentioning the amnesia Versed causes.
* "You will be given Conscious Sedation." or "You will be awake, but won't remember anything." This means they probably want to use Versed.
* "You will be in La-La Land." How you can be anywhere you don't remember beats us! "La-La Land" would be more like having a large dose of pain killers - you would be awake but not care. With Versed you will be functional but won't remember a thing.
* Beware of "Most People..." When you have a choice with your anesthesia, you should not feel pressured to make a decision based on what "most people" receive.
* "You are not a Doctor " So what? That does not make you uninformed. For all they know other doctors (your primary care physician for starters) may have already told you enough to make an informed decision. Besides, this is no excuse for pushing you to have an amnesia drug!

Insist on answers!

* Remember that anesthesiologists are not employees of the hospital, but they have no problem hiding behind hospital rules when there is a problem.
* Keep in mind that they are working for you, so ultimately YOU are the boss. Most of them will not volunteer anything, so you must be prepared to ask them very specific questions, and be very assertive. A patient advocate, who can be a caring friend or relative, should accompany you to all appointments and procedures and take notes.
* Be sure to find out what your financial liability will be if you are not satisfied.

If you aren't happy, complain!

There are concerned people out there who will accept your feedback. At least we like to think there are a few. They can't read our minds. Complain first to the hospital. They may ask you to put it in writing. Do so. That way there is a record of your complaint. Then, talk to your anesthesiologist. Chances are, he/she works through a group. If the anesthesiologist does not respond, try going to the associates group.

If someone botches a repair job on your car people don't fault you for complaining. But many people feel bad about complaining to a doctor or a hospital, even though they are working on something far more precious - YOU. Don't be intimidated!


Personal Accounts

Kirt's Account:

I had bilateral hernia surgery with laparoscopy. I knew I was facing general anesthesia, but I fell hook line and sinker for the 'I am giving you something to relax you' line before the surgery.

I had what seemed like a good conversation with the anesthesiologist and was feeling like I could trust him, so I thought 'OK I will be a little groggy, but conscious until he puts me to sleep for the main event'. No mention of conscious sedation or Versed was made. Just after I reached the operating table I realized something was happening, and then my memory disappeared in a roar of static.

I awoke to discover that not only had I been put to sleep for the main event, I had even been excluded from the prep.

When I later complained, I was told "Most People are very happy to wake up and have the procedure over with". Well I wasn't, I was livid, and when I was told the above I should have said "that's fine for them, but what does it have to do with me?"

It has been eight months since the surgery and I still feel taken advantage of, treated as if I was a five year-old, and yes, raped of my memory. I cannot see how a trained MD or anyone can justify the withholding of fundamental information like this. Even when I confronted him several weeks after the surgery he still tried to avoid saying I had been given Versed, until I finally said 'you gave me Versed didn't you?' I can only think that there must be a problem with this drug if they don't want to tell you they are using it.

Worse yet, the anesthesiologist's response to my questioning him was to lecture me about how I had to 'trust those who know what they are doing', and told me that I was one of those people who wanted to know everything. Personally I will never trust another anesthesiologist in my life. I wish I had said that, but I was still so shaken from my original experience that I just listened, dumbfounded.

While the surgery was technically successful I will always regard it as a failure because of the above.

Mary's account:

I went in for out-patient abdominal surgery. I had had several surgeries in the past and am not squeamish about surgery.

Prior to being wheeled down to surgery, I was told that they were giving me "something to relax me." I recall getting in the chair and going part way to the OR, but that is where my memory stopped. I have no recall of meeting the surgical team, getting onto the table, etc.

When I awoke, I was very agitated and upset. I remember wondering what had happened to me, with the sense that something very bad had happened but I couldn't remember what. I had finger-mark bruises on my upper arms and several other, larger bruises elsewhere. My neck hurt so bad that I was unable to turn my head for 24 hours.

I was extremely distressed that the hospital had not told me about the effects of versed and experienced severe anxiety for months about the memory gap. I had to go to counseling and was put on an anti-anxiety medication.

When I complained to the hospital, I was patronized and treated like a little kid. I did not feel as if they took me seriously.

Weeks later, I went to use my instant cash card, put it into the machine, and went to enter the PIN number, when I realized, much to my shock, that I had absolutely no idea of what the number was. I had used the same PIN for years. It never did come back. No doubt there are other 'lost' things, but I haven't recognized what they are.

Tim's Account:

I had bilateral hernia repair in September of 2004. The original plan was to use MAC ("Monitored Anesthetic Care"). The anesthesiologist did not explain the effects of Versed and did not explain that the MAC would be initiated in the holding area before I was wheeled to the OR.

The drug was not named. I was only told that from my perspective, the experience would seem like general anesthesia. This did not make sense - it seemed contradictory. The "A" word (amnesia) was not mentioned. I have had numerous operations in the past and my experience led me to assume that the main event would occur in the OR. The anesthesiologist introduced the Versed into the IV while I was still in the holding area. I asked what it was and the reply was simply "benzodiazepines." I know what benzos are and thought I was getting something like Valium. I was shocked when, from my perspective, I found myself in recovery what seemed like a few minutes later.

After surgery I was told that I had a bad reaction to the Versed so they ended up putting me under. The nurse in the PACU said that my legs were shaking and this is why they used general anesthesia. The surgeon's report stated that I was moving my extremities and would not be still. I was also told that I was unable to follow instructions. This is disturbing since I am not squeamish about surgery nor have I ever been out of control like this.

When I later spoke with my anesthesiologist, she used a lot of euphemistic baby talk, describing the amnesia as "making you forgetful" and describing the general anesthesia as "we had to make you more sleepy". My surgeon dodged the bullet saying "We're always ready to do general when we do MAC". This is all BS. Looking back on the experience, my wife and I agree that the anesthesiologist was very deceptive.

I am an electrical engineer. In the weeks after my return to work, I found that I had no recall of certain details of my job. We are very procedure and detail oriented. I found that certain blocks of information seemed to have simply disappeared from my long term memory. What else have I forgotten?

For three years post-op I experienced flashbacks of anxiety that occurred randomly - while at work, while driving, while teaching. These were accompanied by an odd sensation of trying to recall a memory but it refused to come into focus. Very strange, very unsettling - and I never experienced anything like this before exposure to Versed.

I was in my 40's when this happened. I have had several surgeries, numerous emergency room visits and my share of dental work. I never had a bad outcome or cause to complain until my Versed episode.

Top 10 Signs You Joined A Cheap HMO

10. Annual breast exam conducted at Hooters.
9. Directions to your doctor’s office include, “take a left when you enter the trailer park.”
8. Tongue depressors taste faintly of Fudgesicle.
7. Only proctologist in the plan is “Gus” from Roto-Rooter.
6. Only item listed under Preventive Care feature of coverage is “an apple a day”.
5. Your “primary care physician” is wearing the pants you gave to Goodwill last month.
4. “Patient responsible for 200% of out-of-network charges” is not a typo.
3. The only expense covered 100% is embalming.
2. With your last HMO, your heart pills didn’t come in different colors with little “M”’s on them.
1. You ask for Viagra. You get a popsicle stick and duct tape.

Conjunctivitis Spreadinf in New Delhi

Its the monsoon season again and the water seems to be pouring down in Delhi.

The water gives rise to a lot of diseases and the current epidemic to hit Delhi is viral and allergic conjunctivitis.

Without getting into the details,

the best course of preventive as well as treatment course is to use good antibiotic eye drops which are available OTC (Over the counter) such as Festive or Ciplox.

Put them in 2 times a day and be SAFE.

Dr Harkeerat

Gastric Bypass

Gastric bypass

Gastric bypass surgery makes the stomach smaller and allows food to bypass part of the small intestine. You will feel full more quickly than when your stomach was its original size, which reduces the amount of food you eat and thus the calories consumed. Bypassing part of the intestine also results in fewer calories being absorbed. This leads to weight loss.

The most common gastric bypass surgery is a Roux-en-Y gastric bypass.

In normal digestion, food passes through the stomach and enters the small intestine , where most of the nutrients and calories are absorbed. It then passes into the large intestine (colon), and the remaining waste is eventually excreted.

In a Roux-en-Y gastric bypass, the stomach is made smaller by creating a small pouch at the top of the stomach using surgical staples or a plastic band. The smaller stomach is connected directly to the middle portion of the small intestine (jejunum), bypassing the rest of the stomach and the upper portion of the small intestine (duodenum).

This procedure can be done by making a large incision in the abdomen (an open procedure) or by making a small incision and using small instruments and a camera to guide the surgery (laparoscopic approach).

See a picture of a Roux-en-Y gastric bypass .
What To Expect After Surgery

Most people can return to their normal activities in 3 to 5 weeks.

After surgery, you'll need to make big, permanent changes in how you eat:

* You can eat only a few ounces of food at a time. Your new stomach will only hold a tiny amount of food.
* You must eat very slowly and chew your food to mush. Otherwise, you may vomit often and have pain.
* You won't be able to drink for 30 minutes before you eat, during your meal, and for 30 minutes after you eat. There won't be room in your stomach for both drinks and solid food.
* You probably will need to take vitamins and supplements.
* You may have to avoid foods that contain simple sugars-like candy, juices, ice cream, condiments, and soft drinks. Simple sugars may cause a problem called dumping syndrome. This happens because food moves too quickly through the stomach and intestines. It can cause shaking, sweating, dizziness, rapid heart rate, and often severe diarrhea.

Why It Is Done

Although guidelines vary, surgery is generally considered when your body mass index is 40 or higher or you have a life-threatening or disabling condition related to your weight.

Your doctor may only consider doing gastric bypass surgery if you have not been able to lose weight with other treatments.

The following conditions may also be required or are at least considered:

* You have been obese for at least 5 years.
* You do not have an ongoing problem with alcohol.
* You do not have untreated depression or another major psychiatric disorder.
* You are between 18 and 65 years of age.

All surgeries have risk. And it is important for you and your doctor to discuss your treatment options to decide what is best for you.
How Well It Works

Most people who have gastric bypass surgery quickly begin to lose weight and continue to lose weight for up to 12 months. One study noted that people lost about one-third of their excess weight (the weight above what is considered healthy) in 1 to 4 years. Some of the lost weight may be regained.

The laparoscopic approach showed similar results, with 69% to 82% of excess weight lost over 12 to 54 months.
Risks

Risks common to all surgeries for weight loss include an infection in the incision, a leak from the stomach into the abdominal cavity or where the intestine is connected (resulting in an infection called peritonitis), and a blood clot in the lung (pulmonary embolism). About one-third of all people having surgery for obesity develop gallstones or a nutritional deficiency condition such as anemia or osteoporosis.

Fewer than 10 out of 1000 people die after weight-loss surgery.

After a Roux-en-Y gastric bypass:
* An iron and vitamin B12 deficiency occurs more than 30% of the time. About 50% of those with an iron deficiency develop anemia.
* The connection between the stomach and the intestines narrows (stomal stenosis) 5% to 15% of the time, leading to nausea and vomiting after eating.
* Ulcers develop 5% to 15% of the time.
* The staples may pull loose.
* Hernia may develop.
* The bypassed stomach may enlarge, resulting in hiccups and bloating.

What To Think About

Gastric bypass surgery may increase your chances of living longer. Some studies show that people who have weight-loss surgery have a smaller chance of dying of heart problems, diabetes, or cancer.

In a gastric bypass, the part of the intestine where many minerals and vitamins are most easily absorbed is bypassed. Because of this, you may have a deficiency in iron, calcium, magnesium, or vitamins. This can lead to long-term problems, such as osteoporosis. To prevent vitamin and mineral deficiencies, you may need to work with a dietitian to plan meals, and you may need to take extra vitamin B12 as pills, shots, or nasal spray.

There is also a possibility that you may develop gallstones after gastric bypass. Sometimes the gallbladder is removed as part of the surgery. But if your gallbladder is not removed, then you may need to take medicine to prevent gallstones.

Early studies of the laparoscopic approach to surgery for obesity suggest that it reduces recovery time and postsurgery complications.