Fluke Biomedical 76-419-4150 User Manual

Page 10

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Nuclear Associates 76-419-4150
Operators Manual

2-4

2) Dose

information

. The following dose information obtained by using the CT dosimetry phantom. For any CT

x-ray system designed to image both the head and body, separate dose information shall be provided for each
application. All dose measurements shall be performed with the CT dosimetry phantom placed on the patient
couch or support device without additional attenuating materials present.

(i) The CTDI at the following locations in the dosimetry phantom:

(a) Along the axis of rotation of the phantom.

(b) Along a line parallel to the axis of rotation and 1.0 centimeter interior to the surface of the phantom

with the phantom positioned so that CTDI is the maximum obtainable at this depth.

(c) Along lines parallel to the axis of rotation and 1.0 centimeter interior to the surface of the phantom at

positions 90, 180, and 270 degrees from the position in paragraph (c)(2)(i)(b) of this section. The CT
conditions of operation shall be the typical values suggested by the manufacturer for CT of the head or
body. The location of the position where the CTDI is maximum as specified in paragraph (c)(2)(i)(b) of
this section shall be given by the manufacturer with respect to the housing of the scanning mechanism
or other readily identifiable feature of the CT x-ray system in such a manner as to permit placement of
the dosimetry phantom in this orientation.

(ii) The CTDI in the center location of the dosimetry phantom for each selectable CT condition of operation that

varies either the rate or duration of x-ray exposure. This CTDI shall be presented as a value that is normalized
to the CTDI in the center location of the dosimetry phantom from paragraph (c)(2)(i) of this section, with the
CTDI of paragraph (c)(2)(i) of this section having a value of one. As each individual CT condition of operation
is changed, all other independent CT conditions of operation shall be maintained at the typical
values described in paragraph (c)(2)(i) of this section. These data shall encompass the range of each CT
condition of operation stated by the manufacturer as appropriate for CT of the head or body. When more
than three selections of a CT condition of operation are available, the normalized CTDI shall be provided, at
least, for the minimum, maximum, and mid-range value of the CT condition of operation.

(iii) The CTDI at the location coincident with the maximum CTDI at 1 centimeter interior to the surface of the

dosimetry phantom for each selectable peak tube potential. When more than three selections of peak tube
potential are available, the normalized CTDI shall be provided, at least, for the minimum, maximum, and a
typical value of peak tube potential. The CTDI shall be presented as a value that is normalized to the
maximum CTDI located at 1 centimeter interior to the surface of the dosimetry phantom from paragraph
(c)(2)(i) of this section, with the CTDI of paragraph (c)(2)(i) of this section having a value of one.

(iv) The dose profile in the center location of the dosimetry phantom for each selectable nominal tomographic

section thickness. When more than three selections of nominal tomographic section thicknesses are
available, the information shall be provided, at least, for the minimum, maximum, and midrange value of
nominal tomographic section thickness. The dose profile shall be presented on the same graph and to the
same scale as the corresponding sensitivity profile required by paragraph (c)(3)(iv) of this section.

(v) A statement of the maximum deviation from the values given in the information provided according to

paragraph (c)(2) (i), (ii), (iii), and (iv) of this section. Deviation of actual values may not exceed these limits.

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