Skip to main content
Journal ArticleOPEN ACCESS

Comparison of the CTDI and AAPM report No. 111 methodology in adult, adolescent, and child head phantoms for MSCT and dental CBCT scanners

  • Li C
  • Thakur Y
  • Ford N
Journal of Medical Imaging (2017) 4(03) 1
DOI: 10.1117/1.jmi.4.3.031212
7Citations
Citations of this article
36Readers
Mendeley users who have this article in their library.

Abstract

© The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. This study investigates the dosimetry methodology proposed by the American Association of Physicists in Medicine (AAPM) task group 111 and compares with the computed tomography dose index (CTDI) method and the SEDENTEXCT DI method on one clinical multislice CT and two dental cone beam CT (CBCT) scanners using adult, adolescent, and child head phantoms. Following the AAPM method, the normalized (100 mAs) equilibrium doses (Deq) for Toshiba Aquilion One MSCT computed using dose measurements from the central hole of the phantom (Deq;c), the peripheral hole of the phantom, (Deq;p), and by the CTDIw equation (Deq;w) are in the range from 20 to 25 mGy. For i-CAT Next Generation dental CBCT, the normalized Deq;c, Deq;p, Deq;w, and D0 eqs by the two SEDENTEXCT DI methods are in the range from 12 to 15 mGy. Fitting the AAPM equation is not possible for the limited scan lengths available on the CS 9300 dental CBCT. This study offers a simple CTDI-like measurement that can approximate the AAPM Deq in clinical CBCT scanners capable of providing four or more scan lengths.

Figures

  • Fig. 1 Phantom schematics from the transverse plane. Center positions are labeled with number 1, midhole positions are labeled with number 2, and peripheral positions are labeled with number 3. (a) The Food and Drug Administration (FDA) CTDI adult head PMMA phantom, (b) the SEDENTEXCTDI dose index phantom, (c) the custom-built adolescent head PMMA phantom, and (d) the custom-built child head PMMA phantom.
  • Fig. 2 Experimental setups for all three CT imaging scanners. (a) The adolescent head phantom positioned within the head holder of the Toshiba Aquilion One scanner with the thimble chamber inserted into its posterior hole; the towel is used to immobilize the phantom. (b) The experimental setup of the SEDENTEXCT DI dose index phantom positioned on the tripod in the i-CAT Next Generation CBCT scanner with the thimble chamber inserted into its anterior hole and aligned to z ¼ −80 mm. (c) The experimental setup of the SEDENTEXCT DI dose index phantom positioned on the tripod in the CS 9300 CBCT scanner with the thimble chamber inserted into its anterior hole and aligned to z ¼ þ40 mm.
  • Fig. 3 Experimental setup of the phantom (schematic). In the example, the ionization chamber is centered inside the phantom, and the center of L is aligned to z ¼ −20 mm with a scan length of 60 mm.
  • Fig. 4 Summary of all the results obtained using the AAPM method on the Toshiba MSCT. Deq;c, Deq;p, and Deq;w (actual values are summarized in Table 2) are calculated from the AAPM fit [Eq. (2)] with error bars. CTDIw values are calculated by the CTDIw equation using thimble chamber measurements (19.61 mGy for adult, 20.93 mGy for adolescent, and 24.99 mGy for child) and pencil chamber measurements (17.70 mGy for adult, 19.86 mGy for adolescent, and 22.43 mGy for child) at L ¼ 100 mm, respectively. The error bars of all three Deq values are overlapping for adolescent and child, respectively; and the CTDIw values calculated using the thimble chamber measurements are within the error ranges. For adult, the Deq;c and the CTDIw by thimble chamber are different from each other and the Deq;p and Deq;w values. The standard CTDIw method using the pencil chamber results in lower dose indices as compared to the AAPM method for all phantoms.
  • Table 1 Scatter dose percentages for Toshiba MSCT scanner (left) and i-CAT Next Generation dental CBCT scanner (right) in adult, adolescent, and child head phantoms at different scan lengths. The scatter dose percentages are calculated using the three parameters (Deq, α, and Leq) from the AAPM fit [Eqs. (2)–(4)] in the central hole.
  • Fig. 5 Toshiba MSCT scanner: comparison of AAPM curves fitted using the central and peripheral dose measurements by the thimble chamber with the AAPM curve fitted using the CTDIw values calculated from dose measurements by the thimble chamber for the (a) adult, (b) adolescent, and (c) child head phantoms. The AAPM fits using the standard CTDIw values measured by the pencil chamber are also shown. All dose measurements are normalized to 100 mAs. The values of the three parameters Deq, Leq, and α are summarized in Table 2(a).
  • Table 2 Summary of the three parameters Deq, Leq, and α from the AAPM fit in (a) Toshiba MSCT scanner and (b) i-CAT Next Generation dental CBCT scanner. (a) For each patient group, theDeq values from thimble chamber measurements are very close to each other, with the highest being present in the child head phantom and the lowest in the adult head phantom. The pencil chamber measurements generate larger Deq, α, and Leq values. (b) The AAPM method and the two Sedentex methods result in similar Deq, α, and Leq values for each patient group.
  • Fig. 6 Toshiba MSCT center dose profiles with (a) L ¼ 4 mm and (b) L ¼ 100 mm and Toshiba MSCT anterior dose profiles with (c) L ¼ 4 mm and (d) L ¼ 100 mm for adult, adolescent, and child head phantoms. Dose estimation within z ¼ L∕2 is fairly consistent. Greater difference between theoretical and experimental dose values is seen beyond z ¼ L∕2. Dose profiles for 32-, 40-, 60-, and 80-mm scan lengths are not shown.

References Powered by Scopus

Comparative dosimetry of dental CBCT devices and 64-slice CT for oral and maxillofacial radiology

Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and Endodontology
698Citations
N/AReaders
Get full text

Dosimetry of 3 CBCT devices for oral and maxillofacial radiology: CB Mercuray, NewTom 3G and i-CAT

Dentomaxillofacial Radiology
638Citations
N/AReaders
Get full text

Effective dose range for dental cone beam computed tomography scanners

European Journal of Radiology
470Citations
N/AReaders
Get full text
View more at Scopus

Cited by Powered by Scopus

Estimation of Computed Tomography Dose Index (CTDI) Using Monte Carlo Simulation

Moscow University Physics Bulletin
7Citations
N/AReaders
Get full text

Accuracy of weighted CTDI in estimating average dose delivered to CTDI phantoms: An experimental study

Medical Physics
7Citations
N/AReaders
Get full text

Optimization of cone beam computed tomography image quality in implant dentistry

Clinical and Experimental Dental Research
6Citations
N/AReaders
Get full text
View more at Scopus

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Cite

CITATION STYLE

APA

Li, C. L., Thakur, Y., & Ford, N. L. (2017). Comparison of the CTDI and AAPM report No. 111 methodology in adult, adolescent, and child head phantoms for MSCT and dental CBCT scanners. Journal of Medical Imaging, 4(03), 1. https://doi.org/10.1117/1.jmi.4.3.031212

Readers over time

‘17‘18‘19‘20‘21‘22‘23‘24036912

Readers' Seniority

Tooltip

PhD / Post grad / Masters / Doc 7

44%

Researcher 6

38%

Lecturer / Post doc 2

13%

Professor / Associate Prof. 1

6%

Readers' Discipline

Tooltip

Medicine and Dentistry 7

44%

Physics and Astronomy 5

31%

Nursing and Health Professions 2

13%

Engineering 2

13%

Save time finding and organizing research with Mendeley

Sign up for free
0