|
| |
|
| | | CoR Recommended Practice Is Whole Body Screening CT Scan Justified? |
|
The National Radiological Protection Board Effective Typical Doses in Medical Radiation and the Lifetime Fatal Cancer Risks |
The above chart is a reminder that CT scans do involve significant doses of radiation. Although the CT scans quoted above were not done on modern multislice CT scanners, the current whole body CT scans radiation dose averages 10mSv or thereabouts depending on the size of the patient.
Justification, Optimisation and Dose Limitation – do these ring a bell? As radiologists, clinical oncologists and medical physicists, we would have been firmly grounded in the principles of medical imaging and therapeutics, especially those utilizing ionizing radiation. However are commercial gains beginning to override commonsense and safety? Does benefit outweigh risk?
Sectional imaging (CT or MRI) have revolutionized the capabilities for imaging and improved targeted radiation therapy. Unlimited by gas and body habitus as in ultrasound and taking the guessing game out of areas previously not well visualized unless by open surgery – the CT scan which is more widely available than the MRI have definitely benefited many patients and clinched the diagnosis or staged the disease so much more accurately. There is no doubt of its immense value in symptomatic patients and in trauma. Where justified, the radiation risk issue is negligible if it arises at all!
It is therefore natural for researchers to look into using the CT scan, especially the new multislice CT scanners to screen for disease. The whole body screening CT scan package has indeed arrived. Current areas being investigated are CT colonoscopy (virtual colonoscopy), CT lungs and CT heart for risk high individuals.
Unfortunately to date, there is no evidence that screening CT scans in the normal population is beneficial and will reduce mortality from a specific disease. In particular, the interest has been in cancers. Even in screening CT scan studies conducted on smokers – the evidence has not been convincing. The lung nodules detected early in smokers are mostly benign. In one study (Radiology 2005 235: 259-265), some of these lung cancers even though detected early were so aggressive it did not make a difference to the life span of the patient.
As in any modality/investigation, early detection must be accompanied by effective treatment that can reduce the mortality rate and prolong life. Clinical efficacy needs to be established and tests must be scientifically justifiable. Thus far, the cervical pap smear and mammography has withstood countless studies and satisfies criteria for acceptance as screening procedures. Does screening CT satisfy the same criteria, taking into account its higher radiation dose?
The Ministry of Health of Malaysia has approached the CoR to collaborate on establishing guidelines for the use of whole body screening CT scans. Concern has been expressed by various parties as to abuse of the imaging modality in the guise of a full medical supercheckup in normal-risk individuals. The problem does not stop there. There are clinicians out there who do not know CT scans use ionizing radiation!! So prescribing physicians/clinicians also need to be educated.
The CoR’s stand on whole body screening CT scan in healthy normal-risk individuals is clear – there is no justification for this type of investigation currently. In addition, the CoR is interested to work with the MOH to ensure only qualified personnel conduct and interpret CT scans.
College of Radiology, Academy of Medicine of Malaysia Statement on Whole Body Screening CT scans – 12 April 2005 |
The College of Radiology, Academy of Medicine of Malaysia, after reviewing all available current data, does not recommend whole body screening CT scan including routine CT lung, CT colonoscopy and CT coronary arteries in healthy asymptomatic individuals in the absence of risk factors as the risks outweigh the potential benefits. |
All CT & PET-CT scans must be conducted by a trained medical practitioner who is a qualified radiologist with a valid practising licence from the Malaysian Medical Council (MMC) and is listed in the National Specialist Register (The NSR is targeted to come into force later in 2005).
The equipment must be operated by a trained and qualified radiographer. The facility providing the CT or PET-CT service must have in place radiation protection and quality assurance programmes.
In view of the increasing and overuse of radiological examinations, the College of Radiology will work with the Universities and Ministry of Health, Government of Malaysia to ensure that radiation risk appreciation in the judicious prescription of biomedical imaging and intervention (radiological examinations) will be included in the curriculum.
Please check out the presentation on “Dose in MDCT. What is the fuss about?” by Prof Dr KH Ng and A/Prof BJJ Abdullah in the Lectures/Talks Medical Physics section. Click here
The following organizations do not recommend whole body screening CT:
 | © 2001-2008 College of Radiology, Academy of Medicine of Malaysia. All rights reserved. Click here for Terms of Use | last updated Saturday, 07 May 2005 | |
