(1) Three cervical radiographs (lateral, antero-posterior and open-mouth peg views) and CT of the brain and cranio-cervical junction.
(2) CT of the brain, cranio-cervical and the cervico-dorsal junctions with two radiographs (lateral and antero-posterior).
(3) A lateral radiograph and CT of the brain and whole cervical spine. The dose of the initial body CT was recorded.
The exposure factors and field of view used were put into the Monte Carlo software, to estimate the CT and radiographic X-ray doses to the body as a whole and the dose to the thyroid associated with each region imaged. The associated nominal additional lifetime cancer risk was assessed.
Excluding inter hospital transfers, where data was incomplete, 87 patients survived to be admitted and fulfilled the criteria. In 30 cases, the CT films were missing, the exposure factors were not recorded or no imaging was performed. In a further 21 cases, the X-ray packets were missing. Three patients had brain and cervico-dorsal CT imaging only, leaving 33 cases for evaluation.
The effective radiation dose for a spiral CT of the brain using the Toshiba Xpress GX CT scanner was 3.8 mSv. The total effective doses for imaging the brain and cervical spine using the three protocols with the same CT scanner were (S.D. as%of mean): (1) 4.4 mSv (5%), (2) 7.1 mSv (10%) and (3) 8.2 mSv (15%). The corresponding mean thyroid doses were: (1) 8.5 mGy (25%), (2) 48.9 mGy (20%) and (3) 66.5 mSv (20%). The resultant nominal lifetime cancer risks were: (1) 1:4500, (2) 1:2800 and (3) 1:2400.
For the Siemens Sensation 16 multislice CT scanner, the total effective doses (S.D. as%of mean) were: (1) 2.3 mSv (10%), (2) 4.3 mSv (25%) and (3) 5.4 mSv (35%). The mean doses to the thyroid were: (1) 5.9 mGy (30%), (2) 36.1 mGy (50%) and (3) 52.4 mGy (40%). The lifetime cancer risks were: (1) 1:8700, (2) 1:4600 and (3) 1:3700.
Using the Toshiba spiral CT scanner, the total dose and additional lifetime nominal cancer risk associated with CT of the chest, abdomen and pelvis (CAP) as 16 mSv and 1:1250, respectively. Using the Siemens multislice CT scanner, these were 11.8 mSv and 1:1700. The cancer risk for protocol 1 when combined with a CT scan of the chest, abdomen and pelvis was 1:1000 for the spiral CT scanner and 1:1500 for the multislice CT (MCT) scanner. The cancer risk for protocol 2 with CAP CT using the MCT was 1:1200. The cancer risk for protocol 3 when combined with a CT scan of the chest, abdomen and pelvis was 1:1100 for the multislice CT scanner. Prior to the introduction of the BTS guidelines for cervical clearance, 12%of cases had CT of the body, which increased to 16%post-guidelines.
CT of the trunk (chest, abdomen and pelvis) is associated with the greatest risk of inducing a fatal cancer in the severely injured patient with a GCS less than 9. In our institution the multislice CT protocols expose the patient to less radiation than single slice CT, which is contrary to much of the published work to date. CT scanning the thyroid (or whole cervical spine) still has a marked effect on the cancer risk in cervical clearance.
Many centres will relax cervical spinal precautions in unconscious trauma patients if the cervical spine CT with reconstructions is normal. CT of the whole cervical spine may be justified in the unconscious, severely injured patient. In conscious trauma patients, the additional lifetime risk may not justify CT of the whole cervical spine as a routine practice.
Purchase PDF (454 K) | A comparison of the costs and benefits of radon remedia... Journal of Environmental Management |
  A comparison of the costs and benefits of radon remediation programmes in new and existing houses in NorthamptonshireJournal of Environmental Management, Volume 59, Issue 1, May 2000, Pages 21-30 A. R. Denman, P. S. Phillips, R. Tornberg Abstract The paper presents the first major analysis of the costs and benefits of radon remediation programmes in both existing and new domestic properties in areas affected by radon in the UK. The study was conducted in Northamptonshire, where over 6%of houses are above the UK domestic Action Level of 200 Bq.m−3, and where new houses in parts of the county, where over 10%of houses are above the Action Level, have been fitted with a radon-proof membrane and provision of a sump, but without a fan. The county also contains areas where 3–10%of houses are over the Action Level, where, until January 2000, only the provision of a sump without a fan was required. Remediation programmes in existing domestic properties, and in new houses in areas with over 10%of houses above the Action Level, can be justified in terms of costs per cancers averted when compared with other health interventions. A modest reduction in lung cancer induction can be predicted, particularly in areas where significant numbers of new houses are being built. However, where UK programmes rely on householder actions, such as remediation of existing houses, they have had limited success—with a large majority of householders taking no action at all. As many countries have regions where domestic properties have raised radon levels, this analysis is generally applicable to many developed European countries. Policy-makers in such areas need to design more inventive public health campaigns, or develop legal or financial incentives, so that the uptake of remediation is stimulated. Purchase PDF (140 K) |
| Mass Screening With CT Colonography: Should the Radiati... Gastroenterology |
| Mass Screening With CT Colonography: Should the Radiation Exposure Be of Concern? Gastroenterology, Volume 129, Issue 1, July 2005, Pages 328-337 David J. Brenner, Maria A. Georgsson Abstract Background & Aims: Computed tomography colonography (CTC), particularly using noncathartic techniques, has the clear potential to increase compliance for colorectal cancer screening. Because the geometry for CTC is highly advantageous, it can be performed with lower radiation doses than almost any other CT examination. If CTC were to become a standard screening tool for the population age 50 years and older, the potential market in the United States would soon be over 100 million people. Therefore, it is pertinent to consider the radiation exposure and any potential radiation risk to the population from such a mass CTC screening program. Methods: Organ doses from CTC examinations can be estimated with standard techniques. These doses can be applied to organ- and dose-specific radiation cancer risk estimates to estimate the excess cancer risk resulting from the radiation from a paired (supine and prone) CTC examination. Results: The cancer risks associated with the radiation exposure from CTC are unlikely to be zero, but they are small. A best estimate for the absolute lifetime cancer risk associated with the radiation exposure using typical current scanner techniques is about 0.14%for paired CTC scans for a 50-year-old, and about half that for a 70-year-old. These values probably could be reduced by factors of 5 or 10 with optimized CTC protocols. Conclusions: In terms of the radiation exposure, the benefit-risk ratio potentially is large for CTC. Purchase PDF (498 K) |
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