Question

Provide complete answers to the following items in your own words.

Radiation Safety concerns in CT. In your response, please acknowledge the public’s perception of radiation exposure and the Cedars Sinai brain scan case.

List ways to minimize patient dose.

Research and define Image Gently and Image Wisely initiatives at the ASRT.

What role does “Smart mA” play is patient dose reduction?

What is the relationship between image quality and dose reduction when scanning extremities?

Answer 1

The main concern for any patient undergoing a diagnostic CT examination is the risk of developing a radiation- induced cancer,which may be fatal or nonfatal.The total patient risk is related to the effective dose,which depends on the dose to each organ,organ radio sensitivity as well as patient age.

Ways to minimize patient dose: Six Critical tips

1. Eliminate unnecessary examination .First step in dose reduction is not to use any dose by eliminating unnecessary examinations or using alternative modalities that don’t use radiation like ultrasound or MRI.
2. Avoid using multiphase CT examinations whenever possible.Often doctors take CT of the body,they may scan the patient two or three times.This May involve an arterial phase and portal venous phase examination
3. Adjust dose to patient patient size.Modify the technique according to the patients size especially in the pediatric population.The main driver of dose in CT is the tube current,which is the mAs.Optimize the tube current by keeping the mAs as low as possible.Many systems provide automatic exposure control,which can reduce dose by as much as 50 percent.
4. Calibrate exposure for key areas: Change exposure to focus on key areas that answer the clinical question.For instance,when looking for lung or skeletal pathology,the user can lower the dose even more
5. Shield dose sensitive organs:Certain organs that are more dose sensitive,the eyes,the thyroid and the breasts.For a facial scan cover the eyes,neck shield the thyroid.This technique reduce dose to that organs,but doesn’t diminish image quality.
6. Pulse fluoroscopy and capture screen save images:Instead of continuous fluoroscopy,use pulse fluoroscopy.The pulse can vary from 30 to three-and- half frames per second.The lower the pulse,lower the dose.That can decrease the effective dose by five- to 10- fold.Instead of taking spot image,use a screen saver.The screen saver captures the last object imaged and stays on the screen.By capturing an image of the screen saver,the patient is not exposed to any additional radiation.

Image Gently / Image Wisely initiative by the the American Society of Raddiologic Technologists(ASRT).Image gently campaign was launched in January 2008 to raise awareness about methods to reduce radiation dose during pediatric medical imaging examination.

Image wisely campaign,the joint task force collaborated with the American Association of Physicists in Medicine and the American Society of Radiologic Technologists to create the Imag Wisely campaign with the objective of lowering the amount of radiation used in medically necessary imaging studies and eliminating unnecessary procedures.

Role of Smat mA in dose reduction: Automatic exposure control systems have a number of potential advantages,including better control of patient radiation dose,avoidance of photon starvation artifacts,reduced load on the X-ray tube and the maintenance of image quality,in spite of different attenuation values on CT scan.

Relationships between image quality and dose reduction when scanning extremities: Lower extremity CTA using 70 kVp,high pitch acquisition and signogram- affirmed iterative reconstruction (SAFIRE), except increasing imaging noise,allows for lower radiation dose and contrast matervolume without compromising image quality.