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Dose Information
43
Note: Previously the dose display on the user interface
was labeled “CTDI
W
“. This displayed CTDI
W
was also cor-
rected for the pitch and was therefore identical to the
current CTDI
Vol
.
The CTDI
w
value does not provide the entire informa-
tion of the radiation risk associated with CT examina-
tion. For this purpose, the concept of the “Effective
Dose“ was introduced by ICRP (International Commis-
sion on Radiation Protection). The effective dose is
expressed as a weighted sum of the dose applied not
only to the organs in the scanned range, but also to the
rest of the body. It could be measured in whole body
phantoms (Alderson phantom) or simulated with
Monte Carlo techniques.
The calculation of the effective dose is rather compli-
cated and has to be performed by sophisticated pro-
grams. These have to take into account the scan
parameters, the system design of the individual scan-
ner, such as X-ray filtration and gantry geometry, the
scan range, the organs involved in the scanned range
and the organs affected by scattered radiation. For
each organ, the respective dose delivered during the
CT scanning has to be calculated and then multiplied
by its radiation risk factor. Finally, the weighted organ
dose numbers are added up to get the effective dose.
The concept of effective dose allows the comparison of
radiation risk associated with different CT or X-ray
exams, i.e. different exams associated with the same
effective dose would have the same radiation risk for
the patient. It also allows a comparison of the applied
X-ray exposure to the natural background radiation,
for example, 2 – 3 mSv per year in Germany.
Summary of Contents for SOMATOM
Page 4: ...4 Overview Respiratory Gating 484 Children 508 ...
Page 5: ...Overview 5 ...
Page 121: ...Workflow Information 121 ...
Page 135: ...Contrast Medium 135 ...
Page 157: ...Application Information 157 Program to define capture options ...
Page 161: ...Application Information 161 ...
Page 167: ...Head 167 ...
Page 183: ...Head 183 ...
Page 187: ...Head 187 ...
Page 191: ...Head 191 ...
Page 195: ...Head 195 ...
Page 211: ...Neck 211 ...
Page 217: ...Neck 217 ...
Page 223: ...Shoulder 223 ...
Page 239: ...Thorax 239 ...
Page 249: ...Thorax 249 ...
Page 269: ...Abdomen 269 ...
Page 273: ...Abdomen 273 ...
Page 277: ...Abdomen 277 ...
Page 287: ...Abdomen 287 ...
Page 293: ...Abdomen 293 ...
Page 307: ...Spine 307 ...
Page 311: ...Spine 311 ...
Page 321: ...Pelvis 321 ...
Page 327: ...Pelvis 327 ...
Page 338: ...338 Upper Extremities Hints For image reconstruction of soft tissue use kernel B30s B31s ...
Page 339: ...Upper Extremities 339 ...
Page 342: ...342 Upper Extremities Hint For image reconstruction of soft tissue use kernel B30s B31s ...
Page 343: ...Upper Extremities 343 ...
Page 357: ...Lower Extremities 357 ...
Page 369: ...Vascular 369 ...
Page 375: ...Vascular 375 ...
Page 379: ...Vascular 379 ...
Page 383: ...Vascular 383 ...
Page 387: ...Vascular 387 ...
Page 393: ...Vascular 393 ...
Page 397: ...Vascular 397 ...
Page 401: ...Vascular 401 ...
Page 405: ...Vascular 405 ...
Page 409: ...Vascular 409 ...
Page 413: ...Vascular 413 ...
Page 421: ...Specials 421 ...
Page 423: ...Specials 423 ...
Page 435: ...Specials 435 ...
Page 455: ...Specials 455 CARE Vision and Biopsy layout for CAREView equal size display Biopsy two segment ...
Page 461: ...Specials 461 ...
Page 469: ...Radiation Therapy 469 ...
Page 483: ...Radiation Therapy 483 ...
Page 517: ...Children 517 ...
Page 521: ...Children 521 ...
Page 525: ...Children 525 ...
Page 529: ...Children 529 ...
Page 533: ...Children 533 ...
Page 537: ...Children 537 ...
Page 545: ...Children 545 ...
Page 553: ...Children 553 ...
Page 557: ...Children 557 ...
Page 561: ...Children 561 ...
Page 565: ...Children 565 ...
Page 573: ...Children 573 ...
Page 577: ...Children 577 ...
Page 581: ...Children 581 ...
Page 585: ...Children 585 ...