Radiation Exposure and Safety

X-rays ionize human tissue and deposit energy that can cause harmful changes within the body (break the DNA chain). Additionally, there is a cancer risk from exposure to x-rays. The dose of radiation is cumulative. X-rays are considered carcinogenic. The government is attempting to minimize the use of unnecessary CT scans and x-rays to prevent unnecessary exposure to radiation. It is important for doctors to pay close attention to the risks involved with the use of x-rays. The cancer risk associated with radiation exposure is documented in cases of atomic bomb survivors.

radiationThe risk for medical uses is controversial and usually played down by physicians. Radiation at a high level is carcinogenic but, the level of radiation from x-ray exposure is low. The effects of low level radiation is not known.

What is the safe radiation level?

The safe level of radiation is not known.

ctscanIt is known that CT scans, fluoroscopy, mammography, and x-rays expose the public to high levels of radiation, especially in young females. The risk of exposure should balance the medical benefits.

Optimize radiation doses by only exposing the patient to enough radiation to get a clear image. There is a growing concern about the risk associated with giving a patient large doses of radiation. The use of CT scans has increased recently in adults and children, possibly exposing the patient to an unnecessarily high dose of radiation. A CT scan is often the method used to diagnose cancer, diseases, and fractures, exposing the patient to a much larger dose of radiation than x-rays. Radiation from a CT scan of the pelvis equals the same amount as 100 chest x-rays. Children are ten times more sensitive to radiation than adults. 3-4 million children receive CT scans and about 1,500 of them will develop cancer two decades later. Additionally, children should not be given an adult dose of radiation.

Radiation Dose Limits

dose limitsA CT scan of the pelvis has the highest level of exposure to the skin, marrow, and gonads. A mini fluoroscopy C-arm should be used whenever possible. Fluoroscopy emits a lot of radiation. The closer the extremity is to the radiation source, the higher the dose of radiation the patient receives. When the distance from the beam increases, the dose of radiation is less. Attempt to decrease exposure time. Radiation intensity follows the inverse square law. It is all about distance!

If the intensity of radiation at 1 meter from the source is 100mR/hr, then the intensity of radiation at 2 meters from the source is ¼ or 25mR/hr in the same unit area. At 3 meters from the source, the intensity of radiation is 1/9 the original or 11.1mR/hr.

inversion square lawUnits of Radiation

  • Roentgen
    • Unit of radiation exposure in the air
  • Rad
    • Energy absorbed per gram of tissue
  • Rem
    • Biological effect of a rad

There is less exposure to the physician when imaging a smaller body part. Larger body parts create an increased exposure to the physician when imaging a patient with the C-arm. It is important to not be in the direct path of the radiation beam.

less expoMethods of protection include: monitoring, shielding, and position. A dosimeter badge records how much radiation you have received; however, it does NOT protect you from exposure to radiation. Lead gowns and aprons work to stop exposure to fluoroscopic radiation. Lead aprons attenuate scattered radiation by about 95%. Rapidly dividing cells are most sensitive to radiation exposure and include: sperm, lymphocytes, and cells inside the small intestine and stomach.

Radiation damage seldom appears at the time or irradiation. The first effects of radiation damage is usually seen as a drop in the white blood cell count. The first external sign of damage is usually a skin burn. Studies suggest that people who use fluoroscopy extensively have a higher rate of cataracts.

Early effects of radiation exposure include:

  • Death
  • Hematologic depression
  • Chromosome aberration
  • Skin erythema
  • Epilation

My recommendations:

A CT scan examination is usually done without justification by most insurances. In my opinion, 1/3 of CT scan studies that are given could be avoided; they are an added cancer risk with no benefit. The CT scan study should be justified. There is no close oversight or uniform standard in place to eliminate radiation exposure, and this is something that should be taken seriously.

shieldPatient education is important. The patient should ask if the study is necessary and what is the lowest dose possible that can be given without compromising the study. Additionally, there should be a universal x-ray bank where patient’s x-rays can be accessed by any medical facility. This would eliminate the unnecessary repeating of x-rays.

In summary, the bone marrow, breast tissue, gonads, and lymphatic tissue are susceptible to radiation induced tumors. It is important to shield the gonads from exposure. Always wear protective equipment such as lead aprons and monitor your radiation exposure with the dosimeter badge.

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Pudendal Nerve Palsy

Damage to the pudendal nerve can occur suddenly as a result of trauma to the pelvic region, prolonged bicycling, fractures, or from falls. The pudendal nerve re-enters the pelvis under the sacrotuberous ligament and gives three branches.

usepudendalThe first branch, the inferior rectal nerve, provides rectal tone and perianal sensation. The second branch, the Perineal Nerve, gives scrotal sensation. The third branch, the dorsal nerve of the penis, give branches to the corpus callosum.

The pudendal nerve arises from S2, S3, and S4. The pudendal nerve carries sensations to the external genitals, the lower rectum, and the perineum.

The symptoms of pudendal nerve palsy can start suddenly or develop over time. Symptoms include the loss of sensation or numbness, burning or stabbing pain, difficulty with bladder and bowel functions, and sexual dysfunction.

morenerves

Causes of pudendal nerve palsy include prolonged sitting exercises such as bicycling or following fracture table traction—the nerve is compressed between the ischium and the hard object.

Treatment options are typically conservative, as the condition is usually transient and will improve over time. Treatment includes:

  • Restbike
  • Physical therapy
  • Stretches and exercises
  • Anti-inflammatory medications
  • Injections/nerve blocks
  • Surgery (as a last resort)

 

Prevention options for bicyclists consists of changing the sitting position while riding the bicycle and changing the seat from a narrow seat to a wider seat.

Tarsal Coalition

Tarsal coalition is a congenital anomaly in which the tarsal bones fuse together, leading to a rigid flat foot, foot pain, and multiple ankle sprains. There are two types of tarsal coalition. The first is known as a Talocalcaneal Coalition, which is a coalition between the talus and the calcaneus. The second is referred to as a calcaneonavicular coalition which is a coalition between the calcaneus and the navicular. When talocalcaneal coalition occurs, it usually happens around 12-15 years of age. The calcaneonavicular coalition presents at an earlier age. About 50% of coalitions are bilateral, and around 20% have multiple coalitions in the same foot. Coalition may be fibrous, cartilaginous, or bony and occurs due to failure of segmentation. It could be associated with fibular hemimelia or Apert’s syndrome.

tarsal anatomy

Symptoms typically consist of patient’s complaining of a painful foot, a history of repeated ankle sprains, and a flat foot deformity. Tarsal coalition may result in a peroneal spastic flat foot. During the physical examination, the physician may find hindfoot valgus. On toe standing, the arch does not reconstitute and heel cord contracture may also be evident during the exam. Furthermore, there may be restriction in the subtalar joint’s range of motion. It is important to check both feet as the condition may be bilateral.

hindfoot

The best imaging study is a CT scan. It can determine the size and location of the coalition. And MRI is also useful in detecting a fibrous or cartilaginous coalition. AP, Lateral, and Oblique view x-rays should be ordered. On a lateral view x-ray, the Calcaneonavicular Coalition can be identified by the “anteater nose sign” and the elongation of the anterior calcaneal process.

ant

A lateral view of a Talocalcaneal Coalition may show talar beaking which is a traction spur that occurs due to the limited motion of the subtalar joint. Additionally, the C sign may be seen which is a radiological sign outlining the talar dome and the sustentaculum. A 45° oblique view is the best for showing calcaneonavicular coalitions.

45oblique

Nonoperative treatment usually consists of anti-inflammatory drugs, modified activities, or the use of a brace or cast. Surgical treatment for the calcaneonavicular coalition usually consists of resection with an interposition of the extensor digitorum brevis muscle or a fat graft no matter the size of the coalition. Similarly, Talocalcaneal coalitions that involve less than 50% of the subtalar joint are also resected. A triple arthrodesis procedure is performed for large coalitions, failed resections, or advanced conditions.

Unbelievable Bacteria

One of the ways bacteria enters the body is through an open wound. When an open wound goes straight down to a fractured bone it is called and open fracture. When bacteria gains access to the deeper tissue beneath the open wound, the tissues become contaminated. Preoperative and prophylactic antibiotics are given to the patient to help decrease the infection rate with the hope of killing the bacteria in the contaminated field.

open fx bacteria

Additionally, a special treatment is done during an open fracture to further help prevent infection. This treatment consists of irrigating and washing the wound, as well as debridement of the dead tissue. Once the tissue has been adequately cleaned, the fracture needs to be reduced and stabilized. Three different ways to stabilize the fracture is with a plate, a rod, or an external fixator. The open wound is either left open for a variable amount of time and it is closed later on. At the time of wound closure, a skin graft will be needed. To promote healing of the fracture a bone graft will be needed usually four to six weeks after the injury.

skin graft

A bone graft is obtained from the pelvis as the pelvis has a large reserve of bone that can be utilized. The bone that is harvested is cut into pieces and then added to the fracture where needed. Despite the best care, a certain percentage of open fracture injuries will become infected. When the tissues become infected by bacteria, white blood cells are attracted to the infected site where the bacteria are multiplying and causing inflammation.

multiple bacteria

Bacteria multiply by replicating their DNA and then dividing into two identical bacterial cells. Due to the doubling of bacterial cells, the population of the bacteria grows rapidly. Once at the site of infection, the white blood cells begin to ingest the bacteria. These bacteria however, may survive and multiply within the white blood cells, causing the cells the burst. When this occurs, the bacteria is then released back into the tissues.

Other types of bacteria can also produce a thick capsule that prevents them from being engulfed. Engulfed bacteria may also produce toxins used to destroy cells that try to attack them. Bacteria can also hide in dead bone or bone cells. When this happens, antibiotics and white blood cells are unable to reach the bacteria, since the dead bone has no blood supply. In addition to the bacteria hiding in the bone, the bacteria grow rapidly.

engulf

During this growth period, the bacteria communicate with one another through a process known as quorum sensing. Quorum sensing is the use of a chemical signals from one bacteria to another. As the bacterial population grows, the concentration of the chemical signal. Once the concentration of the chemical signal reaches a certain threshold, the bacteria then begin their attack. The bacteria will attack the tissues causing it to break down and die which can lead to an abscess formation. The abscess must be drained and evacuated, followed by antibiotic treatment.

bacteria communuity

Antibiotics can kill bacteria in several different ways. One way is by disrupting the cell wall which ruptures the bacteria. Another way, is by preventing DNA replication by blocking the unwinding of the DNA. A third way is by inhibiting the ribosomes from making proteins needed for the cellular structure and function. The last way is by blocking the enzymes that produce folate. Folate is needed for DNA synthesis, and without it the cell will die.

When hardware is used to stabilize the fracture, the story can become much more complex.