DocumentCode :
3328295
Title :
Distribution of absorbed dose in cone-beam breast computed tomography: A phantom study with radiochromic films
Author :
Russo, Paolo ; Coppola, Teresa ; Mettivier, Giovanni ; Montesi, Maria Cristina ; Lauria, Adele
Author_Institution :
Dipt. di Sci. Fisiche, Univ. di Napoli Federico II, Naples, Italy
fYear :
2009
fDate :
Oct. 24 2009-Nov. 1 2009
Firstpage :
3463
Lastpage :
3470
Abstract :
Cone-beam breast computed tomography (CBBCT) of the pendant breast with dedicated scanners is an experimental X-ray 3-D imaging technique for breast cancer diagnosis under evaluation in comparison to conventional two-view 2-D mammography of the compressed breast. In CBBCT it is generally assumed that a more uniform distribution of the radiation dose to the breast volume can be obtained, with respect to mammography, at equal mean glandular dose (MGD) levels. In fact, in CBBCT the X-ray beam rotates for 360 deg around the breast, while in a mammography view the breast is irradiated from one side only. Using a CBBCT laboratory scanner developed by our group, we have measured the distribution of the radiation dose in a hemi-ellipsoidal PMMA breast phantom of 14 cm diameter simulating the average uncompressed breast, using radiochromic films type XR-SP inserted at mid-plane in the phantom. The technique factors were 80 kVp (5.6 mm Al half value layer), tube load 23-100 mAs, for an air kerma at isocenter in the range 4.7-20 mGy, corresponding to a MGD of 3.3-15.8 mGy for a 14 cm diameter breast of 50% glandularity. Results indicate a relative dose variation ¿ = ((edge-center)/center) up to 25% at a distance of 50 mm from the nipple. As for the relative dose variation along the phantom longitudinal axis, the maximum value measured is ¿ = ((nipple-chest wall)/chest wall) = -15%, indicating that the dose decreases from the chest wall toward the nipple. The values of the parameters ¿ and ¿ depend also on the height of the X-ray tube focal spot with respect to the phantom vertex (nipple).
Keywords :
biological organs; cancer; computerised tomography; dosimetry; mammography; medical image processing; optical films; phantoms; 2-D mammography; CBBCT laboratory scanner; X-ray 3-D imaging technique; X-ray beam rotation; X-ray tube focal spot; absorbed dose distribution; aluminium half value layer; breast cancer diagnosis; chest wall; cone-beam breast computed tomography; distance 50 mm; glandularity; hemiellipsoidal PMMA breast phantom; mean glandular dose levels; nipple; phantom vertex; radiation absorbed dose 3.3 mGy to 20 mGy; radiochromic films; relative dose variation; size 14 cm; size 5.6 mm; voltage 80 kV; Biomedical imaging; Breast cancer; Breast tumors; Computed tomography; Imaging phantoms; Lesions; Mammography; Medical diagnostic imaging; Optical imaging; X-ray imaging;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Nuclear Science Symposium Conference Record (NSS/MIC), 2009 IEEE
Conference_Location :
Orlando, FL
ISSN :
1095-7863
Print_ISBN :
978-1-4244-3961-4
Electronic_ISBN :
1095-7863
Type :
conf
DOI :
10.1109/NSSMIC.2009.5401788
Filename :
5401788
Link To Document :
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