1. Characterisation of calcium compounds by linear attenuation- A MARS CT project of potential significance in the diagnosis of breast disease Rachel Cullens Medical Imaging Lecturer, CPIT Dr Anthony Butler, Dr Nanette Schleich and Syen Nik DCIS (Sickles, E., Radiology, 2000)

2. Breast Screening and Biopsy 1 in 8 women in NZ will develop breast cancer Screening has reduced mortality rate but 16-35% Mammography is 90 % sensitive technique by not highly specific Only 1 in 7 needle biopsies performed has a positive result for cancer Anxiety, discomfort Needle Biopsy (Andersson, L. Janzon, BMJ, 1988) (Linver, S. et al, Radiology, 1992) (Pisano, C. et al, NEJM, 2005) (Giotto, online, 2009)

3. Breast Microcalcifications Microcalcifications occur in 60 % of breast lesions Maybe be benign or malignant: Calcium hydroxyapatite in both malignant and benign Calcium oxalate benign only  (Youk, J. et al, Radiographics, 2007)

4. Dual Energy- Renal Stones Dual energy CT- high and low kV exposures Attenuation changes across the energies Separation of uric, calcium hydroxyapatite and calcium oxalate renal calculi Dual-energy CT identifies composition of urinary stones. Red dots: uric acid in stones. Blue dots: no uric acid. (Gould, P., online, 2009)

5. Dual Energy- Renal Stones Dual energy CT- high and low kV exposures Attenuation changes across the energies Separation of uric, calcium hydroxyapatite and calcium oxalate renal calculi 8 (NIST, online, 2010)

6. Experiment: MARS CT of calcium compounds Capillary tubes of air, calcium oxalate and hydroxyapatite MARS CT at 8 energy levels Measured linear attenuation across the energies Air. Ca hydrox. Ca oxalate

7. Image Processing Errors Pixel Grey scale value Cupping Artifact

8. Conclusions This experiment has established the feasibility of imaging calcium compounds on MARS-CT Distinguishing compounds requires improving the quality of data reconstructions If proved clinically beneficial this application could assist in distinguishing benign from malignant calcifications and reduce the number of unnecessary breast biopsies

9. Any questions?