some radiology for pediatricians
Добавлено: Пт сен 28, 2007 7:52 pm
September 10, 2007 — The American Academy of Pediatrics has issued a report to help healthcare providers in their decision making about the use of computed tomographic (CT) scans used for diagnostic tests for children and to help them lead discussions about these risks. The report, which is intended to aid in decision making and discussions with the healthcare team, patients, and families, is published in the September issue of Pediatrics.
"Imaging studies that use ionizing radiation are an essential tool for the evaluation of many disorders of childhood. Ionizing radiation is used in radiography, fluoroscopy, angiography, and computed tomography scanning," write Alan S. Brody, MD, and colleagues from the American Academy of Pediatrics Section on Radiology. "Computed tomography is of particular interest because of its relatively high radiation dose and wide use. Consensus statements on radiation risk suggest that it is reasonable to act on the assumption that low-level radiation may have a small risk of causing cancer."
By minimizing radiation doses to the extent possible and by performing CT scanning only when necessary, the medical community should attempt to decrease radiation exposure associated with CT scans. Consensus opinion suggests that the benefits of CT scanning, when performed for a valid indication, far outweigh the risks.
Healthcare providers in pediatrics play important roles in deciding when CT scanning is indicated and in discussing the associated risks with patients (when age-appropriate) and their families. Radiologists should be consulted to develop imaging strategies, and they should design specific protocols with scanning techniques optimized for pediatric patients. Families and patients should be encouraged to ask questions about the risks and benefits of CT scanning.
Exposure to high doses of ionizing radiation has been shown to increase the risk for cancer, and recent reports have highlighted the potential risk for cancer associated with the lower radiation exposure inherent in CT examinations. Although these reports have aroused concerns in pediatricians, patients, and families, literature review suggests widely differing opinions regarding the cancer risk associated with diagnostic imaging studies. Despite the variety of statements on ionizing-radiation risk in the literature, all seem to agree that the estimated risk from a CT scan is far less than the likely benefit to the patient for indicated examinations.
In terms of radiation dose, a head CT is equivalent to 200 chest x-rays, a chest CT to 150 chest x-rays, and an abdominal CT to 250 chest x-rays.
The following specific information is offered as a basis to underlie discussions of CT examinations and risks:
Radiation is a necessary component of a CT examination.
CT scanning is associated with low-level radiation exposure.
The cause-and-effect relationship between low-level radiation, such as that associated with CT scanning and cancer is still unclear. Expert consensus panels that have reviewed this issue have suggested that there is a small risk for cancer that increases with increasing radiation exposure.
Because no direct connection between CT scanning and subsequent development of cancer has yet been shown, the risks from CT scans must be estimated. These estimates vary according to the information underlying them.
The amount of radiation exposure associated with a CT examination depends on the protocols and equipment settings used, as well as on other factors.
As an overall rule, CT examinations performed properly in children should expose a child to a much lower radiation dose than that for the same procedure performed on an adult.
There is clinically recognized and documented potential benefit from an indicated CT examination, which greatly exceeds the potential cancer risk.
The as low as reasonably achievable (ALARA) principle states that radiologists are CT specialists trained to use the least amount of radiation necessary.
"There is wide agreement that the benefits of an indicated CT scan far outweigh the risks," the authors conclude. "It is the responsibility of those health care professionals who use CT scanning to ensure that each CT scan is indicated. It is the responsibility of radiology personnel to ensure that radiation risk is minimized by using the ALARA principle to determine the correct technique."
The American Academy of Pediatrics offers the following caveats: the recommendations in this report do not indicate an exclusive course of treatment or serve as a standard of medical care, variations based on specific circumstances may be appropriate, and all recommendations automatically expire 5 years after publication unless reaffirmed, revised, or retired at or before that time.
Pediatrics. 2007;120:677-682.
_____________________________________________________
Clinical Context
Ionizing radiation, high-energy radiation that produces ionization in exposed tissues, has natural and manmade sources. One manmade source is medical radiation, including CT scans.
As reviewed by the Biological Effects of Ionizing Radiation Committee of the National Academy of Sciences, increasing doses of ionizing radiation are linked to increased risk for cancer. But the effect of lower level radiation exposure from CT scans on the risk for cancer is not known.
This clinical report summarizes opinions regarding the risk for cancer from CT radiation exposure and recommendations about the roles of pediatric healthcare providers and radiologists in ordering and performing CT studies in children.
Study Highlights
Ionizing radiation:
1 Gy, the absorption of 1 J of radiation energy by 1 kg of matter, equals 100 rad.
A sievert (Sv) is based on the dose and radiosensitivity of each exposed organ.
Average background radiation from natural and manmade sources is 3 mSv/year per person in the United States.
Possible radiation-related risk for cancer is different in children vs adults because of increased sensitivity of growing tissues and organs, possible long latency period, and smaller cross-sectional area.
Diagnostic imaging:
X-ray doses depend on patient's age and size, equipment settings and model, and duration of procedure.
CT scans provide radiation exposure disproportionate to its use.
CT scan indications and frequency of use are increasing.
CT scan techniques that vary in radiation exposure result in similar images; 5% to –90% reduction in adult dose was adequate for CT study in children.
CT scans use less than a 100-mSv dose of radiation.
Radiation doses from CT scans of chest (3 mSv), head (4 mSv), and abdomen (5 mSv) correlate to 150, 200, and 250 chest x-rays, respectively.
No studies have been done to directly link CT scans to cancer.
Expert panel reviews suggest a possible small risk for cancer from low-level radiation from imaging studies that increases with increasing radiation dose:
The Biological Effects of Ionizing Radiation Committee of the National Academy of Sciences in 2005.
The United Nations Subcommittee on Atomic Radiation in 2000.
The International Commission on Radiation Protection in 2005.
Only up to 12.5% of healthcare providers recognize a possible link between CT scanning and cancer.
75% of clinicians underestimated the amount of radiation dose of CT scans vs chest radiographs.
Radiation exposure can be decreased by using ALARA radiation doses and only when needed.
Recommended role of pediatric healthcare provider:
Discuss risks and benefits of CT scanning with patients and families.
Make decision after appropriate consultation with other providers and family.
Realize that 11% of CT scanning is in children.
Be aware of increased CT use for conditions including trauma, appendicitis, and renal calculi.
Provide radiology practice information to families on training and certification of radiology practice and clinicians as well as size- or age-based protocols for CT scanner settings.
Communicate with radiologist about appropriateness of CT scanning and alternative imaging studies.
Limit times or phases (number of passes) of CT scanning.
Recommended role of radiologist:
Perform only appropriate imaging studies.
Communicate with pediatric healthcare provider if questionable indication for CT imaging.
Create protocols for age-appropriate scanning techniques to use ALARA radiation doses.
Be able to provide information on CT protocols and risks to healthcare providers and families.
Keep up with current CT technology.
If CT scanning is indicated, the benefit is greater than the risk for cancer.
Pearls for Practice
Low-level radiation from CT studies might carry a small risk for cancer, but the risk is outweighed by the benefits of indicated CT studies in children.
In performing CT studies in children, pediatric healthcare providers and radiologists should be responsible for considering indications, discussing the risk with patients and families, and optimizing age-appropriate techniques.
"Imaging studies that use ionizing radiation are an essential tool for the evaluation of many disorders of childhood. Ionizing radiation is used in radiography, fluoroscopy, angiography, and computed tomography scanning," write Alan S. Brody, MD, and colleagues from the American Academy of Pediatrics Section on Radiology. "Computed tomography is of particular interest because of its relatively high radiation dose and wide use. Consensus statements on radiation risk suggest that it is reasonable to act on the assumption that low-level radiation may have a small risk of causing cancer."
By minimizing radiation doses to the extent possible and by performing CT scanning only when necessary, the medical community should attempt to decrease radiation exposure associated with CT scans. Consensus opinion suggests that the benefits of CT scanning, when performed for a valid indication, far outweigh the risks.
Healthcare providers in pediatrics play important roles in deciding when CT scanning is indicated and in discussing the associated risks with patients (when age-appropriate) and their families. Radiologists should be consulted to develop imaging strategies, and they should design specific protocols with scanning techniques optimized for pediatric patients. Families and patients should be encouraged to ask questions about the risks and benefits of CT scanning.
Exposure to high doses of ionizing radiation has been shown to increase the risk for cancer, and recent reports have highlighted the potential risk for cancer associated with the lower radiation exposure inherent in CT examinations. Although these reports have aroused concerns in pediatricians, patients, and families, literature review suggests widely differing opinions regarding the cancer risk associated with diagnostic imaging studies. Despite the variety of statements on ionizing-radiation risk in the literature, all seem to agree that the estimated risk from a CT scan is far less than the likely benefit to the patient for indicated examinations.
In terms of radiation dose, a head CT is equivalent to 200 chest x-rays, a chest CT to 150 chest x-rays, and an abdominal CT to 250 chest x-rays.
The following specific information is offered as a basis to underlie discussions of CT examinations and risks:
Radiation is a necessary component of a CT examination.
CT scanning is associated with low-level radiation exposure.
The cause-and-effect relationship between low-level radiation, such as that associated with CT scanning and cancer is still unclear. Expert consensus panels that have reviewed this issue have suggested that there is a small risk for cancer that increases with increasing radiation exposure.
Because no direct connection between CT scanning and subsequent development of cancer has yet been shown, the risks from CT scans must be estimated. These estimates vary according to the information underlying them.
The amount of radiation exposure associated with a CT examination depends on the protocols and equipment settings used, as well as on other factors.
As an overall rule, CT examinations performed properly in children should expose a child to a much lower radiation dose than that for the same procedure performed on an adult.
There is clinically recognized and documented potential benefit from an indicated CT examination, which greatly exceeds the potential cancer risk.
The as low as reasonably achievable (ALARA) principle states that radiologists are CT specialists trained to use the least amount of radiation necessary.
"There is wide agreement that the benefits of an indicated CT scan far outweigh the risks," the authors conclude. "It is the responsibility of those health care professionals who use CT scanning to ensure that each CT scan is indicated. It is the responsibility of radiology personnel to ensure that radiation risk is minimized by using the ALARA principle to determine the correct technique."
The American Academy of Pediatrics offers the following caveats: the recommendations in this report do not indicate an exclusive course of treatment or serve as a standard of medical care, variations based on specific circumstances may be appropriate, and all recommendations automatically expire 5 years after publication unless reaffirmed, revised, or retired at or before that time.
Pediatrics. 2007;120:677-682.
_____________________________________________________
Clinical Context
Ionizing radiation, high-energy radiation that produces ionization in exposed tissues, has natural and manmade sources. One manmade source is medical radiation, including CT scans.
As reviewed by the Biological Effects of Ionizing Radiation Committee of the National Academy of Sciences, increasing doses of ionizing radiation are linked to increased risk for cancer. But the effect of lower level radiation exposure from CT scans on the risk for cancer is not known.
This clinical report summarizes opinions regarding the risk for cancer from CT radiation exposure and recommendations about the roles of pediatric healthcare providers and radiologists in ordering and performing CT studies in children.
Study Highlights
Ionizing radiation:
1 Gy, the absorption of 1 J of radiation energy by 1 kg of matter, equals 100 rad.
A sievert (Sv) is based on the dose and radiosensitivity of each exposed organ.
Average background radiation from natural and manmade sources is 3 mSv/year per person in the United States.
Possible radiation-related risk for cancer is different in children vs adults because of increased sensitivity of growing tissues and organs, possible long latency period, and smaller cross-sectional area.
Diagnostic imaging:
X-ray doses depend on patient's age and size, equipment settings and model, and duration of procedure.
CT scans provide radiation exposure disproportionate to its use.
CT scan indications and frequency of use are increasing.
CT scan techniques that vary in radiation exposure result in similar images; 5% to –90% reduction in adult dose was adequate for CT study in children.
CT scans use less than a 100-mSv dose of radiation.
Radiation doses from CT scans of chest (3 mSv), head (4 mSv), and abdomen (5 mSv) correlate to 150, 200, and 250 chest x-rays, respectively.
No studies have been done to directly link CT scans to cancer.
Expert panel reviews suggest a possible small risk for cancer from low-level radiation from imaging studies that increases with increasing radiation dose:
The Biological Effects of Ionizing Radiation Committee of the National Academy of Sciences in 2005.
The United Nations Subcommittee on Atomic Radiation in 2000.
The International Commission on Radiation Protection in 2005.
Only up to 12.5% of healthcare providers recognize a possible link between CT scanning and cancer.
75% of clinicians underestimated the amount of radiation dose of CT scans vs chest radiographs.
Radiation exposure can be decreased by using ALARA radiation doses and only when needed.
Recommended role of pediatric healthcare provider:
Discuss risks and benefits of CT scanning with patients and families.
Make decision after appropriate consultation with other providers and family.
Realize that 11% of CT scanning is in children.
Be aware of increased CT use for conditions including trauma, appendicitis, and renal calculi.
Provide radiology practice information to families on training and certification of radiology practice and clinicians as well as size- or age-based protocols for CT scanner settings.
Communicate with radiologist about appropriateness of CT scanning and alternative imaging studies.
Limit times or phases (number of passes) of CT scanning.
Recommended role of radiologist:
Perform only appropriate imaging studies.
Communicate with pediatric healthcare provider if questionable indication for CT imaging.
Create protocols for age-appropriate scanning techniques to use ALARA radiation doses.
Be able to provide information on CT protocols and risks to healthcare providers and families.
Keep up with current CT technology.
If CT scanning is indicated, the benefit is greater than the risk for cancer.
Pearls for Practice
Low-level radiation from CT studies might carry a small risk for cancer, but the risk is outweighed by the benefits of indicated CT studies in children.
In performing CT studies in children, pediatric healthcare providers and radiologists should be responsible for considering indications, discussing the risk with patients and families, and optimizing age-appropriate techniques.