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- Albert, F, et al.
(author)
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Laser produced X-ray source in the 10-60 keV range at 1 kHz. Modified irradiation schemes in order to reach medical imaging quality
- 2001
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In: Journal de Physique IV. - : EDP Sciences. - 1155-4339. ; 11:PR2, s. 429-432
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Journal article (peer-reviewed)abstract
- By tightly focusing ultra-short pulses from a Ti:sapphire terawatt laser onto a high-Z metallic target, hard x-ray pulses of short duration are produced. In most of our previous work concerning x-rays, a 150 mJ laser pulse with a 110 A duration has been used. Using mostly tin and tantalum targets, hard x-rays in the 10-60 keV range have been produced and used in differential absorption imaging around the K-alpha absorption edge of a contrast agent and also in imaging employing gated viewing for suppression of scattered radiation. In order to increase the x-ray yield (shortening the acquisition time) an increase in the laser repetition rate is desirable while still staying in the K-alpha energy regime. We have used a I kHz repetition-rate laser delivering 35 fs pulses in order to work towards these goals. We have clear evidence of hard x-ray generation above 30 keV, even for low laser pulse energies. We also studied the effect of a fs prepulse. The medical imaging capability of the source was explored. The use of a prepulse has been optimized in order to improve the image quality as well as the overall x-ray generation yield.
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- Sjogren, H., et al.
(author)
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Cytogenetic and spectral karyotype analyses of benign and malignant cartilage tumours
- 2004
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In: International Journal of Oncology. - 1019-6439. ; 24:6, s. 1385-91
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Journal article (peer-reviewed)abstract
- To date, there have been few studies published on benign and malignant cartilage tumours using high resolution molecular cytogenetic techniques such as spectral karyotyping (SKY). In this study we have used a combination of chromosome banding, SKY and FISH to characterize the chromosomal pattern in 18 benign and malignant cartilage tumours and one small cell osteosarcoma with mesenchymal chondrosarcoma-like features. Clonal structural and/or numerical aberrations were detected in 14 of these tumours. All chondroblastomas and the chondromyxoid fibroma had diploid or near-diploid karyotypes with often relatively simple karyotypes. Although no consistent abnormalities were detected in the chondroblastomas, recurrent breakpoints were found at 2q35, 3q21-23, and 18q21. The chondromyxoid fibroma had an inv(6)(p25q13) as the sole anomaly, suggesting that this is a primary abnormality characteristic of this entity. The karyotypic findings in the chondrosarcomas were, as a rule, more complex than those in the benign tumours. A typical feature was the frequent occurrence of unbalanced rearrangements leading to genomic imbalances with losses and gains of certain chromosomes or chromosome regions. The following breakpoints were recurrent: Xq21, 6p10, 9p13, 20p11 and 22q11-12. Despite the use of high-resolution molecular cytogenetic techniques, we were not able to identify any consistent abnormalities in chondrosarcomas, suggesting that tumour-specific chromosome changes are not likely to be found in this group of tumours.
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