| 1. |
- Nyström, Josefina, et al.
(författare)
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Objective measurement of Radiation Induced Erythema by nonparametric hypothesis testing on indices from multivariate data
- 2008
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Ingår i: Chemometrics and Intelligent Laboratory Systems. - : Elsevier BV. - 0169-7439 .- 1873-3239. ; 90:1, s. 43-8
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Tidskriftsartikel (refereegranskat)abstract
- Three instrumental measurement techniques: Laser-Doppler Imaging (LDI), Digital Colour Photography (DCP) and Near InfraRed (NIR) spectroscopy were tested for their potential to objectively measure radiation-based erythema in breast cancer patients. The irradiation dose intervals were 0, 8-16, 18-26, 28-34, 36-44 and 46-50 Gy. In addition, two types of skin lotion for reducing erythema were tested on the patients and these were compared to using no lotion. The measured results had very skew distributions for all three techniques making nonparametric testing necessary. The Wilcoxon Signed Rank Sum Test (WSRST) was used for this purpose. LDI was performed to produce univariate average perfusion values leading to a perfusion increment ratio. These ratios showed a good sensitivity to erythema, with a median detection limit of 18 Gy. DCP was used to extract average red-green-blue (RGB) values that were used in multivariate models. Results for a combination of principal component score values showed a marked increase in median erythema from 8 Gy on. The Multivariate data from NIR spectroscopy were data-reduced to principal component scores and combinations of these were tested. The score combinations were used to show median detection limits down to 8 Gy. The difference between the lotions and using no lotion gave no significant result for the WSRST paired comparison for any used measurement technique.
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| 2. |
- Nyström, Josefina, et al.
(författare)
-
Objective measurements of radiotherapy-induced erythema
- 2004
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Ingår i: Skin research and technology. - Copenhagen : Munksgaard. - 0909-752X .- 1600-0846. ; 10:4, s. 242-250
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Tidskriftsartikel (refereegranskat)abstract
- Background/aims: The development of acute radiation erythema is a common phenomenon among patients undergoing radiotherapy treatment. Because of the absence of reliable objective classification methods, the degree of skin reaction can at present mainly be judged subjectively in the clinic. This has motivated the present preliminary study, concerning the first steps in the development of an objective method for skin reaction classification. Methods: Three non-invasive techniques were used: near-infrared (NIR) spectroscopy, laser Doppler perfusion imaging and digital photography. The NIR spectra were analysed with principal component analysis (PCA), and the results from the other two with traditional univariate methods. Measurements were made on breast cancer patients who had been exposed to different irradiation doses. A total of 28 breast cancer patients participated one to three times each; 12 were treated with photons at 4 or 6 MeV and 16 were treated with high-energy electrons between 10 and 20 MeV to a maximum dose of 50 Gy. Results: PCA of NIR spectra shows that information on radiation dose lies mainly in the first principal component. It is observed that the higher the dose the higher the score value. The results from the laser Doppler measurements show that in 79% of the cases the perfusion increases significantly with radiation dose. Analysis of the digital photography shows that a proposed skin redness index (SRI), increases with a higher radiation dose. However, the increase in most cases is not significant. By combining all data, correlation to radiation doses was seen for 74% of the patients who participated more than once. Conclusion: All three non-invasive methods correlate with the radiation dose but to various degrees. NIR spectroscopy, laser Doppler and a combination of the three techniques are the most promising methods for characterising erythema
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