Tags

Type your tag names separated by a space and hit enter

How to Appropriately Calculate Effective Dose for CT Using Either Size-Specific Dose Estimates or Dose-Length Product.
AJR Am J Roentgenol. 2015 May; 204(5):953-8.AA

Abstract

OBJECTIVE

The purpose of this study is to show how to calculate effective dose in CT using size-specific dose estimates and to correct the current method using dose-length product (DLP).

MATERIALS AND METHODS

Data were analyzed from 352 chest and 241 abdominopelvic CT images. Size-specific dose estimate was used as a surrogate for organ dose in the chest and abdominopelvic regions. Organ doses were averaged by patient weight-based populations and were used to calculate effective dose by the International Commission on Radiological Protection (ICRP) report 103 method using tissue-weighting factors (EICRP). In addition, effective dose was calculated using population-averaged CT examination DLP for the chest and abdominopelvic region using published k-coefficients (EDLP = k × DLP).

RESULTS

EDLP differed from EICRP by an average of 21% (1.4 vs 1.1) in the chest and 42% (2.4 vs 3.4) in the abdominopelvic region. The differences occurred because the published kcoefficients did not account for pitch factor other than unity, were derived using a 32-cm diameter CT dose index (CTDI) phantom for CT examinations of the pediatric body, and used ICRP 60 tissue-weighting factors. Once it was corrected for pitch factor, the appropriate size of CTDI phantom, and ICRP 103 tissue-weighting factors, EDLP improved in agreement with EICRP to better than 7% (1.4 vs 1.3) and 4% (2.4 vs 2.5) for chest and abdominopelvic regions, respectively.

CONCLUSION

Current use of DLP to calculate effective dose was shown to be deficient because of the outdated means by which the k-coefficients were derived. This study shows a means to calculate EICRP using patient size-specific dose estimate and how to appropriately correct EDLP.

Authors+Show Affiliations

1 Department of Radiological Sciences, St Jude Children's Research Hospital, 262 Danny Thomas Pl, Memphis TN, 38105.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

25729893

Citation

Brady, Samuel L., et al. "How to Appropriately Calculate Effective Dose for CT Using Either Size-Specific Dose Estimates or Dose-Length Product." AJR. American Journal of Roentgenology, vol. 204, no. 5, 2015, pp. 953-8.
Brady SL, Mirro AE, Moore BM, et al. How to Appropriately Calculate Effective Dose for CT Using Either Size-Specific Dose Estimates or Dose-Length Product. AJR Am J Roentgenol. 2015;204(5):953-8.
Brady, S. L., Mirro, A. E., Moore, B. M., & Kaufman, R. A. (2015). How to Appropriately Calculate Effective Dose for CT Using Either Size-Specific Dose Estimates or Dose-Length Product. AJR. American Journal of Roentgenology, 204(5), 953-8. https://doi.org/10.2214/AJR.14.13317
Brady SL, et al. How to Appropriately Calculate Effective Dose for CT Using Either Size-Specific Dose Estimates or Dose-Length Product. AJR Am J Roentgenol. 2015;204(5):953-8. PubMed PMID: 25729893.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - How to Appropriately Calculate Effective Dose for CT Using Either Size-Specific Dose Estimates or Dose-Length Product. AU - Brady,Samuel L, AU - Mirro,Amy E, AU - Moore,Bria M, AU - Kaufman,Robert A, Y1 - 2015/03/02/ PY - 2015/3/3/entrez PY - 2015/3/3/pubmed PY - 2015/7/1/medline KW - CT KW - dose-length product KW - effective dose KW - pediatrics KW - size-specific dose estimate SP - 953 EP - 8 JF - AJR. American journal of roentgenology JO - AJR Am J Roentgenol VL - 204 IS - 5 N2 - OBJECTIVE: The purpose of this study is to show how to calculate effective dose in CT using size-specific dose estimates and to correct the current method using dose-length product (DLP). MATERIALS AND METHODS: Data were analyzed from 352 chest and 241 abdominopelvic CT images. Size-specific dose estimate was used as a surrogate for organ dose in the chest and abdominopelvic regions. Organ doses were averaged by patient weight-based populations and were used to calculate effective dose by the International Commission on Radiological Protection (ICRP) report 103 method using tissue-weighting factors (EICRP). In addition, effective dose was calculated using population-averaged CT examination DLP for the chest and abdominopelvic region using published k-coefficients (EDLP = k × DLP). RESULTS: EDLP differed from EICRP by an average of 21% (1.4 vs 1.1) in the chest and 42% (2.4 vs 3.4) in the abdominopelvic region. The differences occurred because the published kcoefficients did not account for pitch factor other than unity, were derived using a 32-cm diameter CT dose index (CTDI) phantom for CT examinations of the pediatric body, and used ICRP 60 tissue-weighting factors. Once it was corrected for pitch factor, the appropriate size of CTDI phantom, and ICRP 103 tissue-weighting factors, EDLP improved in agreement with EICRP to better than 7% (1.4 vs 1.3) and 4% (2.4 vs 2.5) for chest and abdominopelvic regions, respectively. CONCLUSION: Current use of DLP to calculate effective dose was shown to be deficient because of the outdated means by which the k-coefficients were derived. This study shows a means to calculate EICRP using patient size-specific dose estimate and how to appropriately correct EDLP. SN - 1546-3141 UR - https://www.unboundmedicine.com/medline/citation/25729893/How_to_Appropriately_Calculate_Effective_Dose_for_CT_Using_Either_Size_Specific_Dose_Estimates_or_Dose_Length_Product_ L2 - https://www.ajronline.org/doi/10.2214/AJR.14.13317 DB - PRIME DP - Unbound Medicine ER -