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Correspondence |

Estimation of the Radiation Dose From CT in Cystic Fibrosis Response FREE TO VIEW

Pim A. de Jong, MD, PhD; Harm A. Tiddens, MD, PhD; Maarten H. Lequin, MD, PhD; Terry E. Robinson, MD; Alan S. Brody, MD
Author and Funding Information

Affiliations: University Medical Center Utrecht, Utrecht, the Netherlands,  Erasmus MC-Sophia, Rotterdam, the Netherlands,  Stanford University Medical Center, Stanford, CA,  Cincinnati Children's Hospital Medical Center, Cincinnati, OH,  Institute de Veille Sanitaire, Saint Maurice, France,  Centre Hospitalier Universitaire de Montpellier, Montpellier, France,  Centre d'Assurance de Qualité des Applications Technologiques dans le Domaine de la Santé, Bourg la Reine, France

Correspondence to: Pim A. de Jong, MD, PhD, University Medical Center Utrecht, Radiology, Utrecht, the Netherlands; e-mail: pimdejong@gmail.com



Chest. 2008;133(5):1289-1291. doi:10.1378/chest.07-2840
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Donadieu and colleagues1 (October 2007) reported the effective dose (ED) of radiation over the past 21 years from chest CT scans in their cystic fibrosis (CF) patients in France. Their findings stress the importance of implementing low-dose protocols in CF. Donadieu and colleagues1found a relatively high mean ED of 6.5 millisieverts (mSv) [range, 1.5 to 29.3 mSv]. Previously, another center reported 1 mSv (range, 0.5 to 1.9 mSv) for routine biennial inspiratory sequential CT scans in CF children.2Huda3estimated ED for a “conventional” and a “future” protocol of a 5-year-old CF patient as 2.1 mSv and 0.5 mSv, respectively. Long4reported an ED of 0.22 mSv for CF infants, and Robinson reported an ED of 1.5 mSv (combined inspiratory and expiratory) for children.5

Several CT dose-reduction strategies are available. First, a reduction in the kilovoltage peak (kVp),4 and second a reduction in the milliamperes per second exposure (mA/s) provide important dose-reduction opportunities. Third, for a volumetric CT protocol, the pitch is an important parameter. Fourth, scanned body volume differs between an interval technique and a full-lung volumetric technique.

In the proposal of Huda,3a volumetric inspiratory CT is performed with 20 mA/s, 100 kVp, and a pitch of 1.5. In the CF infants studied by Long,4 volumetric inspiratory 64-slice scans are obtained at 80 kVp, 40 mA, 0.5-s gantry rotation time, and a pitch of 1.35. In a current therapeutic development network study evaluating the natural history of progressive lung disease in CF children, 100 kVp, 40 to 80 mA, 0.5-s gantry rotation time, and a pitch of 1.0 (inspiratory) and 1.2 (expiratory) are used on a 64-slice scanner.

In conclusion, the data reported by Donadieu et al1 should not be regarded as representative of current chest CT radiation exposure in CF patients, but as the experience of one institution. Fortunately, with current CT technology, chest CT radiation dose in CF patients can be reduced approximately sixfold.

The authors have no conflicts of interest to disclose.

The authors have reported to the ACCP that no significant conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Donadieu, J, Roudier, C, Saguintaah, M, et al (2007) Estimation of the radiation dose from thoracic CT scans in a cystic fibrosis population.Chest132,1233-1238. [PubMed] [CrossRef]
 
de Jong, PA, Mayo, JR, Golmohammadi, K, et al Estimation of cancer mortality associated with repetitive computed tomography scanning.Am J Respir Crit Care Med2006;173,199-203. [PubMed]
 
Huda, W Radiation doses and risks in chest computed tomography examinations.Proc Am Thorac Soc2007;4,316-320. [PubMed]
 
Long, FR High-resolution computed tomography of the lung in children with cystic fibrosis: technical factors.Proc Am Thorac Soc2007;4,306-309. [PubMed]
 
Robinson, TE Computed tomography scanning techniques for the evaluation of cystic fibrosis lung disease.Proc Am Thorac Soc2007;4,310-315. [PubMed]
 
To the Editor:

The aim of our study in CHEST (October 2007)1was to assess the actual CT scan dosimetry studies that are “routinely” performed in cystic fibrosis (CF) patients in a university hospital. Although not representative, because the assessment was based on data gathered in a single diagnostic radiology center, the study reported on both current medical practice and associated dosimetry, a subject that, to date, has rarely been discussed in the literature. The study is therefore not contradicted by the references24 quoted by de Jong et al5 in their letter, since none of the studies cited provided similar information. Indeed, these three studies24 can be considered as a technical discussion but not as an evaluation the effective dose (ED) received by a cohort of CF patients undergoing a routine CT scan. These studies24 suggested the parameters for a protocol for performing lung CT scans in CF patients, leading to a clear decrease in the ED provided by CT scan, but the investigators did not assess how such protocols are routinely applicable and, overall, how such protocols could provide the same diagnosis information comparatively in common practice. On this basis, we know from a pilot study by de Jong et al5that an attempt to decrease the ED of CT scans was unsuccessful because the information on diagnosis derived from the CT scan had decreased. If, on one hand, one wants to open the debate about the risk-benefit relationship of performing repeated CT scans in CF patients, the assessment of the exposure to x-rays should take into account routine examinations and not just specific experimental protocols; otherwise, the ED received by the patients will be systematically underestimated. On the other hand, the quality of the information on diagnosis provided by the CT scan has to be kept at the highest possible level to clearly contribute to the care of the patient, which has been questioned by some authors.6

References
Donadieu, J, Roudier, C, Saguintaah, M, et al Estimation of the radiation dose from thoracic CT scans in a cystic fibrosis population.Chest2007;132,1233-1238. [PubMed] [CrossRef]
 
Huda, W Radiation doses and risks in chest computed tomography examinations.Proc Am Thorac Soc2007;4,316-320. [PubMed]
 
Long, FR High-resolution computed tomography of the lung in children with cystic fibrosis: technical factors.Proc Am Thorac Soc2007;4,306-309. [PubMed]
 
Robinson, TE Computed tomography scanning techniques for the evaluation of cystic fibrosis lung disease.Proc Am Thorac Soc2007;4,310-315. [PubMed]
 
de Jong, PA, Nakano, Y, Lequin, MH, et al Dose reduction for CT in children with cystic fibrosis: is it feasible to reduce the number of images per scan?Pediatr Radiol2006;36,50-53. [PubMed]
 
Langton Hewer, SC Is limited computed tomography the future for imaging the lungs of children with cystic fibrosis?Arch Dis Child2006;91,377-378. [PubMed]
 

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References

Donadieu, J, Roudier, C, Saguintaah, M, et al (2007) Estimation of the radiation dose from thoracic CT scans in a cystic fibrosis population.Chest132,1233-1238. [PubMed] [CrossRef]
 
de Jong, PA, Mayo, JR, Golmohammadi, K, et al Estimation of cancer mortality associated with repetitive computed tomography scanning.Am J Respir Crit Care Med2006;173,199-203. [PubMed]
 
Huda, W Radiation doses and risks in chest computed tomography examinations.Proc Am Thorac Soc2007;4,316-320. [PubMed]
 
Long, FR High-resolution computed tomography of the lung in children with cystic fibrosis: technical factors.Proc Am Thorac Soc2007;4,306-309. [PubMed]
 
Robinson, TE Computed tomography scanning techniques for the evaluation of cystic fibrosis lung disease.Proc Am Thorac Soc2007;4,310-315. [PubMed]
 
Donadieu, J, Roudier, C, Saguintaah, M, et al Estimation of the radiation dose from thoracic CT scans in a cystic fibrosis population.Chest2007;132,1233-1238. [PubMed] [CrossRef]
 
Huda, W Radiation doses and risks in chest computed tomography examinations.Proc Am Thorac Soc2007;4,316-320. [PubMed]
 
Long, FR High-resolution computed tomography of the lung in children with cystic fibrosis: technical factors.Proc Am Thorac Soc2007;4,306-309. [PubMed]
 
Robinson, TE Computed tomography scanning techniques for the evaluation of cystic fibrosis lung disease.Proc Am Thorac Soc2007;4,310-315. [PubMed]
 
de Jong, PA, Nakano, Y, Lequin, MH, et al Dose reduction for CT in children with cystic fibrosis: is it feasible to reduce the number of images per scan?Pediatr Radiol2006;36,50-53. [PubMed]
 
Langton Hewer, SC Is limited computed tomography the future for imaging the lungs of children with cystic fibrosis?Arch Dis Child2006;91,377-378. [PubMed]
 
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