No, there is no cutoff value for the number of CT scans that can be performed. The decision to perform each scan is based on the expert medical judgment of the requesting physician, who includes radiation dose and cumulative radiation dose in the risk/benefit consideration.
Is there a maximum number of CT scans that is considered safe?
No, there is no cutoff value for the number of CT scans that can be performed. The decision to perform each scan is based on the expert medical judgment of the requesting physician, who includes radiation dose and cumulative radiation dose in the risk/benefit consideration.
MRI-safe pacemaker-Revo MRI SureScan Limitations
Medtronic first-generation Revo MRI SureScan Pacing System has some significant limitations.
1. The MRI-pacemaker is for new heart patients. Patients who already have a pacemaker can not get this new model unless they undergo the risky procedure of having their old pacemaker completely removed. Usually, when it comes time to replace the battery in a pacemaker (about 5-7 years), the metal case containing battery and circuitry is detached from the leads, and a new model device is hooked up to the leads. But doctors generally consider it too risky to remove the old leads from the heart for fear of tearing the heart or the veins through which the leads are inserted into the heart. Part of the design of the Revo pacemaker is its new leads and so they must be the leads that connect the pacemaker to the patient’s heart.
2. Patients must have the Revo pacemaker implanted for 6 weeks before receiving an MRI.
3. The Revo pacemaker requires a certain position of the patient inside the MRI tube so as to avoid most chest scans. This is to prevent overheating the metal tips of the leads that are attached to the heart. So heart scans are forbidden with this first generation model.
4. And Owen Faris, senior scientific reviewer for the FDA, explains that the new pacemaker won’t work for all types of MRI scans and won’t work in all MRI scanners. In his words:
In addition to the chest scan exclusion, there is a restriction on how much radio-frequency energy can be deposited into the body by the scanner. MRI scanners have two operating modes for most clinical applications. ‘Normal operating mode’ is how the scanner is normally programmed and that mode restricts the scanner to lower-energy scans (less than 2 Watts per kilogram). This is sufficient energy for most clinical MRI scans. However, for some patients and for certain scans, more power is needed. In those cases, the MRI scanner is placed in ‘First level control’ mode, which allows for greater energy deposition (up to 4 Watts per kilogram). For patients implanted with the REVO MRI pacemaker, those patients are not allowed to have these higher energy scans.
MRIs for these patients are also restricted to only allow use of 1.5 tesla MRI systems. "Tesla" is a measure of the strength of the magnetic field.
5. Medicare does not now pay for MRI scans on a patient who has a pacemaker. Medtronic spokesperson Wendy Dougherty says that the company will not speculate on whether Medicare will cover MRIs done on patients wearing the new Revo pacemaker. The federal agency is considering a petition from a physician to cover MRIs done during an investigational study to determine the risk of MRIs involving pacemakers already in use. During the comment period for this request, Medtronic asked Medicare to restrict MRI payment to patients wearing pacemakers approved by the FDA for use with MRIs. Medicare’s decision is due by March 1. Patients on Medicare would be wise to check on whether their plan will pay for an MRI before getting the test, which costs between $1,600 and $3,500 at different medical centers and offices.
Radiation doses from common CT scan and other imaging studies
The typical radiation doses associated with some common imaging tests are shown below. Remember, the annual dose we all receive from background radiation is from 3 to 5 mSv.
| Test | Dose (mSv) | Equivalent period of background radiation | Citation |
| Chest x-ray (standard two views) | 0.06-0.1 | 8-12 days | 1, 2 |
| Mammography | 0.13-0.7 | 16-88 days | 1, 2 |
| Abdomen x-ray | 0.5-0.7 | 62-88 days | 1 |
| Lumbar spine x-rays | 1.8 | 7 months | 1 |
| Head CT scan | 2.0 | 8 months | 2 |
| Chest CT scan | 8.0 | 3 years | 2 |
| Abdomen and pelvis CT scan | 10.0 | 3 years | 2 |
| Virtual colonoscopy | 10.2 | 3 years | 3 |
| Whole body PET/low dose non-contrast CT scan | 8.5-10.3 | 3 years | 4 |
| Whole body PET/full dose contrast-enhanced CT scan | 23.7-26.4 | 8-9 years | 4 |
| Prospective ECG-gated coronary CT angiogram | 4.0 | 1 year | 6 |
| Retrospective ECG-gated coronary CT angiogram | 18.0 | 5 years | 6 |
| Tc-99m sestamibi 1 day cardiac rest-stress test | 12 | 3.5 years | 4 |
| Coronary angiography (diagnostic) | 4.6-15.8 | 2-5 years | 1 |
| Coronary angiography (with intervention) | 7.5-57.0 | 2-19 years | 1 |
CAR Renatal Agencies in RWANDA
Agence de Voyage et Tourism
Avenue des Mille Collines
Phone Contacts: +250 252501388
Email: oida56@ahoo.com
Cite Tours & Travel
Phone Contacts: +250 252571277
Fax: +250 252571278
Email: cite&rwand1.com
Gorilland Safaris Ltd Tours
Phone Contacts: +250 252574565
Fax: +250 252519120
Email: gorillasnd@rwanda1.com
International Tour and Travel Ltd
SORAS Building
Phone Contacts: +250 252574057
Fax: +250 252575582
Email: itt@rwanda1.com
Kiboko Tours & Travel
Avenue de la Paix, Kigali Centre
Phone Contacts: +250 252520118
Fax: +250 252501741
Email: kiboko@rwanda1.com
Kigali Safaris S.a.r.L
Email: kglsafaris@yahoo.fr
Nord Sud International Travel & Tour Agency
Ave. de la Paix
Phone Contacts: +250 252570449
Fax: +250 252575349
Rwanda Eco-Tours Agency
Ave. De La, Gakingiro
Phone Contacts: +250 252500331
Email: info@rwandaecotours.com
Web: www.rwandaecotours.com
Satguru Travel & Tours Services
Ave. du Commerce
Phone Contacts: +250 252572643
Fax: +250 252573853
Email: stt@rwanda1.com
Socor Top Travel & Tour Agency
De la Revoulution
Phone Contacts: +250 252572552
Fax: +250 573853
Email: socor@rwanda1.com
The Travel Company
Phone Contacts: +250 252505151
Fax: +250 252577472 Email: info@thetravelcompany.rw
Traser (Travel Agency Service)
Phone Contacts: +250 252574990
Fax: +250 2525745564
Email: tnserw@yahoo.com
Zebra Country Tours
Cell: +250 788468152
Email: info@zebracountry.rw
Web: www.zebracountry.rw
Avenue des Mille Collines
Phone Contacts: +250 252501388
Email: oida56@ahoo.com
Cite Tours & Travel
Phone Contacts: +250 252571277
Fax: +250 252571278
Email: cite&rwand1.com
Gorilland Safaris Ltd Tours
Phone Contacts: +250 252574565
Fax: +250 252519120
Email: gorillasnd@rwanda1.com
International Tour and Travel Ltd
SORAS Building
Phone Contacts: +250 252574057
Fax: +250 252575582
Email: itt@rwanda1.com
Kiboko Tours & Travel
Avenue de la Paix, Kigali Centre
Phone Contacts: +250 252520118
Fax: +250 252501741
Email: kiboko@rwanda1.com
Kigali Safaris S.a.r.L
Email: kglsafaris@yahoo.fr
Nord Sud International Travel & Tour Agency
Ave. de la Paix
Phone Contacts: +250 252570449
Fax: +250 252575349
Rwanda Eco-Tours Agency
Ave. De La, Gakingiro
Phone Contacts: +250 252500331
Email: info@rwandaecotours.com
Web: www.rwandaecotours.com
Satguru Travel & Tours Services
Ave. du Commerce
Phone Contacts: +250 252572643
Fax: +250 252573853
Email: stt@rwanda1.com
Socor Top Travel & Tour Agency
De la Revoulution
Phone Contacts: +250 252572552
Fax: +250 573853
Email: socor@rwanda1.com
The Travel Company
Phone Contacts: +250 252505151
Fax: +250 252577472 Email: info@thetravelcompany.rw
Traser (Travel Agency Service)
Phone Contacts: +250 252574990
Fax: +250 2525745564
Email: tnserw@yahoo.com
Zebra Country Tours
Cell: +250 788468152
Email: info@zebracountry.rw
Web: www.zebracountry.rw
List of banks in Libya
| Central Bank of Libya مصرف ليبيا المركزي | ||
| Headquarters | Tripoli | |
|---|---|---|
| Established | 1956 | |
| Central bank of |  Libya | |
| Currency | Libyan dinar | |
| ISO 4217 Code | LYD | |
| Website | cbl.gov.ly | |
| Preceded by | Libyan Currency Committee | |
Tips for decreasing the Radiation exposure to the healthcare provider
Time
Decreasing the amount of time you are exposed to medical radiation will automatically decrease your dose, if all other factors are the same. This means thorough pre-procedure planning to increase efficiency and streamline the workflow during the procedure, intimate knowledge of the devices and/or radioactive materials used during the exam, and a healthy respect for the power of radiation beams that you can't see.
Distance
When you increase your distance from the radiation source, your amount of radiation exposure is reduced by a square of the distance. For instance, if you move 2 feet away, your exposure level decreases by a factor of 22, or 4. While there are practical limits to how much distance you can put between yourself and the radiation source, even a small increase can be beneficial. The Inverse Square Principle makes distance one of the best safeguards in reducing dose. Even one step back from the imaging field can have a profound effect on reducing exposure from scatter.
Shielding
The appropriate material for adequate shielding from radiation depends on the type of radiation being used. For many medical imaging procedures, such as X-rays and CT scans, lead shielding is used. This can be lead aprons worn by radiological technologists and radiologists, or lead aprons draped from the procedure table to act as a barrier between the radiation source and the healthcare provider. Some people prefer not to use the recommended shielding protocols because shielding equipment can be inconvenient, bulky, uncomfortable, and time-consuming to put on and take off. For instance, lead aprons and thyroid shields can get heavy and cause strain when worn for long periods of time, and goggles can be difficult to get used to. However, these measures are critical for safe radiation use, and many are mandated by regulatory authorities. In addition, one should always wear a monitor badge and follow institutional guidelines for having it read. Never take shortcuts when it comes to radiation safety.
Lead shielding for Radiation
Lead is used for shielding in x-ray machines, nuclear power plants, labs, military equipment, and other places radiation may be encountered. There is great variety in the types of shielding available both to protect people and to shield equipment and experiments. Personal shielding includes lead aprons (such as the familiar garment used during dental x-rays), thyroid shields, and lead gloves. There are also a variety of shielding devices available for laboratory equipment, including lead castles, structures composed of lead bricks, and lead pigs, thick containers for storing and transporting radioactive samples.
Criteria for the Selection of a Shield Material
Theoretically, almost any material can be used for radiation shielding if employed in a thickness sufficient to attenuate the radiation to safe limits. However, due to certain characteristics discussed below, lead and concrete are among the most commonly used materials. The choice of the shield material is dependent upon many varied factors, such as final desired attenuated radiation levels, ease of heat dissipation, resistance to radiation damage, required thickness and weight, multiple use considerations (e.g., shield and/or structural), uniformity of shielding capability, permanence of shielding, and availability.
Properties of "Lead for Radiation Shielding"
The properties of Lead which make it an excellent shielding material are its density, high atomic number, high level of stability, ease of fabrication, high degree of flexibility in application, and its availability.
For gamma rays and x rays, lead is a particularly effective shield because lead has a high atomic number (Z) of 82. The atomic number is the number of protons in an atom. Since the number of protons per atom of lead is large, the number of electrons is also large, and it is the electrons that stop gamma rays and x rays. So, density, thickness, and atomic number can all be important.
Shielding reduces the intensity of gamma rays and x rays in an exponential manner (more or less). In other words, a shield reduces the intensity of the radiation getting through, but it might never stop all the gamma rays (at least theoretically). What I am saying is that the phrase "complete protection" in the question might be better changed to "almost complete protection" because some gammas have the potential to get through any shield (in theory). I recognize I am splitting hairs here.
Forms of "Lead Used for Radiation Shielding"
LEAD GLASS (X-RAY GLASS, RADIATION SHIELDING GLASS, LEADED GLASS) STANDARD SIZES
8" x 10"
10" x 12"
12" x 12"
12" x 16"
12" x 24"
12" x 36"
16" x 24"
18" x 24"
24" x 24"
24" x 48"
30" x 24"
30" x 30"
32" x 40"
36" x 24"
36" x 30"
36" x 36"
40" x 40"
40" x 42"
42" x 42"
48" x 36"
48" x 40"
48" x 42"
48" x 48"
60" x 36"
60" x 40"
60" x 42"
60" x 48"
72" x 36"
72" x 40"
72" x 42"
72" x 48"
84" x 36"
84" x 40"
84" x 42"
96" x 42"
96" x 48"
108" x 54"
Criteria for the Selection of a Shield Material
Theoretically, almost any material can be used for radiation shielding if employed in a thickness sufficient to attenuate the radiation to safe limits. However, due to certain characteristics discussed below, lead and concrete are among the most commonly used materials. The choice of the shield material is dependent upon many varied factors, such as final desired attenuated radiation levels, ease of heat dissipation, resistance to radiation damage, required thickness and weight, multiple use considerations (e.g., shield and/or structural), uniformity of shielding capability, permanence of shielding, and availability.
Properties of "Lead for Radiation Shielding"
The properties of Lead which make it an excellent shielding material are its density, high atomic number, high level of stability, ease of fabrication, high degree of flexibility in application, and its availability.
For gamma rays and x rays, lead is a particularly effective shield because lead has a high atomic number (Z) of 82. The atomic number is the number of protons in an atom. Since the number of protons per atom of lead is large, the number of electrons is also large, and it is the electrons that stop gamma rays and x rays. So, density, thickness, and atomic number can all be important.
Shielding reduces the intensity of gamma rays and x rays in an exponential manner (more or less). In other words, a shield reduces the intensity of the radiation getting through, but it might never stop all the gamma rays (at least theoretically). What I am saying is that the phrase "complete protection" in the question might be better changed to "almost complete protection" because some gammas have the potential to get through any shield (in theory). I recognize I am splitting hairs here.
Forms of "Lead Used for Radiation Shielding"
- Lead Brick - Convenient, easily handled; may be moved and re-used
- Lead Sheet – Plate and Slab Permanent shield installations
- Lead Shot - Where solid Lead is impractical to fill due to location, shape and accessibility. The Shots offers convenient solutions for shielding
- Lead Wool - Lead Wool is used for filling deep cracks in a Radiation barrier
- Lead Pipe - Shielding of radioactive liquids
- Lead-lined / Lead-clad Pipe - Shielding of radioactive liquids
- Lead Powder - Dispersed in rubber or plastic for flexible shielding; also mixed with concrete and asbestos cement
- Leaded Glass
- Lead Plate
- Lead Pigs
- Custom Lead Fabrication and Lead Casting
LEAD GLASS (X-RAY GLASS, RADIATION SHIELDING GLASS, LEADED GLASS) STANDARD SIZES
8" x 10"
10" x 12"
12" x 12"
12" x 16"
12" x 24"
12" x 36"
16" x 24"
18" x 24"
24" x 24"
24" x 48"
30" x 24"
30" x 30"
32" x 40"
36" x 24"
36" x 30"
36" x 36"
40" x 40"
40" x 42"
42" x 42"
48" x 36"
48" x 40"
48" x 42"
48" x 48"
60" x 36"
60" x 40"
60" x 42"
60" x 48"
72" x 36"
72" x 40"
72" x 42"
72" x 48"
84" x 36"
84" x 40"
84" x 42"
96" x 42"
96" x 48"
108" x 54"
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