Durro

WITNLITS What Is The Next Letter In This Series ?

My working hypothesis was that you were so relaxed before the test that it enhanced your ability to answer the questions. Either that, or you have an IQ in the stratosphere that even under your self imposed handicapping system outshines most of the rest of us. Obviously, as shown by your rigorous scientific experiment, the results show that alcohol and drug intake is beneficial. This might explain why so many university students are perpetually stoned - they're enhancing their studying abilities. Further to this, it just might be time to lobby governments to remove those needless drink-driving laws, so that we are all safer on the roads. Durro

Ha ! I didn't realise the date of the original post. I only joined yesterday and browsed through some of the topics of interest, finding this one. Oh well. For what it's worth, here's my take on medical radiation exposure from a professional's point of view... (I originally posted this over at the Richard Dawkins Foundation website) When considering dosages received from x-rays, CT scans, Nuclear Medicine scans and Mammograms, etc, it's like what Einstein said about Tasmania - everything's relative. Yes, patients receive a radiation dose and yes, radiation is one of the causative agents of cancers and genetic mutations, but you have to put things into perspective and not get too alarmist about it. X-rays are a form of ionising radiation - electromagnetic energy that breaks molecular bonds and allows the creation of free radicals like H+ and OH- when water molecules split. These free radicals can go on to adversely affect other molecules within the body. X-rays can also directly interact with the DNA strands in cells and may cause mutations which may either A/ have no discernable effect, B/cause cell death, C/cause the cell to start dividing in a disorderly and even uncontrollable fashion (which = cancer) and D/ if the cell is a sexual cell such as an ovarian follicle or sperm cell, may pass on altered genetics to offspring. But what people have to realise is a few things. Firstly, our body's cells are continually undergoing reproduction and growth with mutations from various causes and in general, the body's immune system recognises and eliminates harmfully altered cells. Every day in your body there are events which may lead to cancer formation - spontaneous mutations in DNA, exposure to other sources of radiation, sunlight exposure, cigarette smoking, etc - but the body generally takes care of itself and repairs the damage or kills the offending cells before they take hold and get out of control. So too when a person is exposed to radiation, the body's own immune system usually takes care of the damage. Secondly, we are continuously exposed to radiation through various means. Cosmic radiation bombards us despite our protective atmosphere. Radioactive isotopes are all around us and inside us already - that's how Carbon 14 dating and other radiometric dating processes can be used. There are radioactive gases in the air and radioactive minerals in the ground. A brief comparative chart of radiation exposes can be found here at :- http://www.nyc.gov/html/doh/downloads/p ... _sheet.pdf As you can see, people that live at higher altitudes receive more radiation (cosmic radiation) as the atmosphere is thinner than at sea level and doesn't filter the radiation as much. But what would you think if I told you that people that live at high altitudes and get more cosmic radiation actually have less cancer formation than their sea level cousins ? The answer is that there are multiple causative agents for cancers and people at altitude are generally exposed to less air pollution, toxic gases, nuclear power plant emissions etc, etc. There's not too many fast food restaurants in the Himalayas so there isn't as much bowel cancer in Kathmandu compared to say New York City. Anyhow, you get the idea. The exposures received in diagnostic radiology also have to be considered comparatively. A chest x-ray dose is about equivalent to a transcontinental plane flight - high altitude flight exposes you to more cosmic radiation. Pilots obviously fly daily and aren't all dropping dead from cancer thanks to receiving one or two chest x-ray doses every working day. When x-raying various body parts, consideration has to be given to how thick and dense the body part is. A hand dose is tiny compared to a lateral lumbar spine dose. Statistically, there's about a 1 in 10,000 chance of getting a cancer from medical x-ray exposure. I do thousands of x-rays and CT scans per year and so I probably cause cancer to at least one or two people a year. However, without seeming to sound flippant about it, one must realise that the other 9,998 or so people had their conditions diagnosed or excluded, their lives improved and in some case, their lives literally saved. Medical exposure to x-rays is a case of risk Vs reward, with the perceived benefits of exposure meant to outweigh the risks associated with it. The people more at risk are the ones having multiple repetitive x-rays of the same body areas using higher dosages - multiple angiograms, multiple CT scans, serial lumbar spine x-rays, etc. As a radiographer, one of my duties is to evaluate the requested x-ray and determine if the risk is outweighed by the reward. I am ethically and legally obliged to refuse to do x-rays or scans that are for inappropriate reasons, are not supported by adequate clinical history, or may create more harm than good in the patient. I regularly refuse to do x-rays or scans, sometime to the anger/frustration/confusion/education of the referring doctor. People might be interested to learn that x-ray doses in radiology dropped by 2/3rds in the mid 1980's. X-Rays were recorded by an intensifying screen which fluoresced in response to x-ray exposure, thus fogging the film inside the x-ray cassette proportionally to the intensity of the x-ray shadow emerging from the patient. The film was developed and the latent image appears on the film. In the mid-80's, the calcium tungstate screens were replaced by rare earth screens, and overnight, all x-ray exposures in medicine were reduced to 1/3rd of what they had been. In the 90's with advanced in digital technology, films are being replaced with electrostatic cassettes which are digitally recorded and read. This has reduced dosages even further. So 4 or 5 x-rays of one body part today is only the equivalent dose to only 1 x-ray of the same body part taken 20 years ago when I started in Radiography. And that's just in my lifetime. There have been many other advances over the last 100 years that have dramatically reduced doses from the bad old days at the turn of the 19th century. But back to the present. Radiographers work on the ALARA Principle - as low as reasonably achievable. There are many tricks of the trade we use to minimise radiation dose, such as using longer focal film distances where possible, using extra filtration of the x-ray beam to reduce lower energy and less penetrative x-ray photons, using compression of body parts, using lead protection and shielding, collimating the x-ray beam to a minimum, using higher kV x-rays where possible, minimising the number of exposures, positioning radiosensitive body parts away from the entrance side of the x-ray beam, etc, etc. We make a conscious effort to reduce radiation doses wherever possible. There are non-ionising radiation alternatives available in some instances, but these aren't always appropriate for anatomical reasons, technological limitations, time efficiency and/or cost. Ultrasounds don't use x-rays, but cannot image inside bone and cannot penetrate through bone or air. Some U/S scans can see small avulsion fractures or disruptions of the bony cortex, but generally can't be used to reliably demonstrate most fractures and other bony conditions. U/S is restricted to largely soft tissue and blood vessel imaging in areas not obscured by gas, air or bone. MRI scans also don't use radiation, but do use very strong magnetic fields and are therefore a contraindication for people with metallic implants, pacemakers, aneurysm clips, some joint prostheses and the like. They are also very expensive and generally have a long waiting list for imaging anyhow. MRI scans do not image air and as most scans take several minutes or more, they have trouble imaging areas that move from patient respiration such as the abdomen. In short, x-rays are quite useful and play a large role in diagnosing and managing patients. They are cost effective, quick to produce and analyse, and come with only a small risk of adverse effects if used properly. Durro

Well, as a Radiographer, this one is right up my alley. However, it's 11pm here and I really should be going to bed. I promise to come back to this and provide an explanation of the medical use of radiation and the associated risk factors. I'd be happy to answer questions as well. Talk to all you soon. Durro

Blazarwolf is very close to the reason, and yes, we call 4th and 5th metacarpal fractures in Radiography "Boxer's Fractures", as well as some less polite names to do with masturbation. The reason for the fracture is that boxers often punch with a hook, as opposed to karate and other martial arts where straight punches are taught. When a hook punch is thrown, the leading edge and point of contact with the punch is the metacarpo-phalangeal joints of the 4th and/or 5th knuckle. If you draw a line along the axis of your 4th/5th metacarpals, the oblique force line terminates at or just past the wrist. Punching straight with the 2nd and 3rd knuckles shares the force of the punch straight up the entire forearm. Hitting with a hook and connecting with the 4th and 5th metacarpal heads is simply too much force for these smallish hand bones and they typically snap just below the knuckle. I x-ray at least 4 or 5 people a week who typically get drunk or angry (or both!) and then hit a wall/door/car/lamp post or other hard object with a wild swing and connect with their 4th and 5th metacarpals and break their bones. If they had hit straight, there would have been a lesser chance of fracturing the 2nd and 3rd metacarpal heads. I almost never see 2nd or 3rd MC head fractures. It's the curved swing and connecting with the outside of the hand that causes the problem 9 times out of 10 in my experience. So even with gloves on, the sheer force of the punches thrown in an arc and the connection with solid body parts exerts enough force on the 4th and 5th metacarpal heads to cause fractures. Straight punches would virtually eliminate this injury, but boxing is in love with hooks. Durro

Dunno about the cerebral cortex, but I've got a good one for the 12 cranial nerves... Durro

Brain death means that the person cannot function without ventilation and other supportive mechanisms. Withdrawal of support will mean certain death and even with aggressive therapy, the profound brain damage and loss of function may mean that multisystem organ failure will lead to death anyhow. There are a number of tests for brain death that can be performed to ensure that not even the most basic reflex functions are viable. Apart from an EEG that shows no brain function, some of the tests include taking the patient off mechanical ventilation to see if they breath spontaneously at all, sticking a tongue depressor down the throat of the patient to stimulate the gag reflex (or note that it's absent) and squirting ice cold water in the ear canal to stimulate the shiver reflex there. If these most basic functions are inoperative, there is no hope for recovery of the patient at all and they are for all purposes, brain dead. These are the types of patients that are candidates for organ donation, before their uncontrollable blood pressure, temperature maintenance, and other autonomic nervous system functions go completely haywire leading to organ failure. Incidentally, in case people don't realise, the reason that the heart beats on despite tremendous brain damage sometimes is that the cardiac pacemaker - the SA node - works largely independent of the nervous system. By way of comparison, people who are in a "coma" are merely largely unresponsive and unconscious, but may have markedly varying degrees of brain function. Some will have reflexes, involuntary movements and of course, control of their blood pressure, digestion and temperature regulation. Some people in comas care able to hear and feel, but are unable to give responses to the effect that they are receiving input from the world around them. Comas may be reversible and the patient may emerge with some or all of their normal brain function, depending on what was the causative agent for their coma in the first place. The layperson often confuses a coma with brain death, but in medical terms, they are markedly different entities. Cheers, Durro

Hi, I'm new here and just saw this topic. I am a Radiographer who takes X-rays and CT scans for a living, so I might be able to add to this discussion. Cervical spines can and do become unstable from various flexion and extension and/or rotational forces. I've seen this literally thousands of times from car accidents, sporting injuries, diving accidents and othe mechanisms of force. I presume that given enough force, the cervical spine would be susceptible to injury from someone twisting the neck forcefully. The neck is stabilised by a number of ligaments that run between the vertebral bodies and between various other parts such as the facet joints. The joints themselves also place limitations on normal range of movement - the facets allow a small amount of rotation and flexion/extension, but there are limits. However, if these limits ar exceeded by force, the ligaments can tear and the bones forming the joints can break as well. The superior and/or inferior articular facets, which form either side of the facet joint, can actually break and allow unstable movement of the vertebral column. The cervical spine can then move and damage the cervical spinal cord. Sudden force can also create intervertebral disc herniation, particularly from forced neck flexion. Disc herniations can also cause nerve damage. The nerves that supply the diaphragm exit the cervical spine at the C4 level. Severe spinal damage above this level is fatal, as the body loses the ability to breathe. Below this level, various degrees of quadriplegia (now called tetraplegia) or paraplegia can occur, depending on the level of damage and which spinal nerves exit at an undamaged level. So, can a neck be "broken" with human hands. I really think so, but it would have to be very forceful to overcome the stability of the cervical joinst and ligaments. I've seen necks broken and/or dislocated from diving onto the head, where 70 kilograms of body weight landing on the neck creates enough force to cause severe injury. Same with car accidents, where sudden deceleration of the body but continued forward movement of the head caused hyperflexion and bilateral facet dislocation. Hangman's fractures are caused by the suuden sideways movement of the C1/2 articulation when a head is forced laterally by the hangman's boose or other causes that mimic this. If strong human hands can reproduce these types of forces, then yes, a cervical spine can be severely damaged and paralysis or even death could be caused. Cheers, Durro.

Ahhhh, denial - it isn't just a river in Egypt. Excessive alcohol intake comes with a number of negative health effects, brain impairment and permanent damage being just one part of the spectrum. Cirrhosis, oesophageal varices, pancreatitis, several types of cancer, obesity, diabetes and the like can be added to the plethora of neurological impairments and psychiatric conditions that are closely associated with alcoholism. To try to justify a large intake of alcohol as anything other than risky behaviour is a dangerous thing, particularly if it's a regular occurence. I hope that you are joking about justifying a large alcohol intake with a fallacy. As always, "all good things in moderation" and it probably goes without saying, all bad things in minimal amounts. Stay healthy. Durro

WITNLIT_ "S" ? Durro

The letters OTTFFSSE stand for the numerals one to eight. One Two Three Four Five Six Seven Eight So the next in the series would be N and T (Nine and Ten), etc. Durro Oops, just saw the post above mine and realised the fact that it's been solved. Sorry.

I've got the answer to the "impossible" brain teaser. The solution involved putting a line through one of the circles, and not just touching it. Now, if I can only work out how to attach the image from my computer... Hey, this is only my 2nd post, so be kind. Durro P.S. Hey, you can just attach images here ! Woo-hoo. That makes life easier. Here it is.

Hello, I'm Durro, a 42 year old Radiographer from Brisbane, Australia. I was alerted to this site over at the Richard Dawkins Forum when a fellow RDF member mentioned that one of our more notorious and recently banned members was now trolling over here. I thought that I would take a look and liked what I saw - your forum that is, not the trolling. I thought that I might visit now and then, and perhaps contribute to discussions, particularly in the areas of medicine and general science. Your brain teasers section looks inviting too. A bit about me ? I'm married with two lovely children. I'm a black belt in karate and a keen tennis player. I spent 5 years in Saudi Arabia with my wife and am currently writing a book about our many weird experiences there. I like to read and am keen to learn more from sites such as this one. Have a great day from Down Under. Durro