Targeted ultraviolet B phototherapy in vitiligo: A comparison between once-weekly and twice-weekly treatment regimens.

BACKGROUND: Targeted ultraviolet B (T-UVB) phototherapy in vitiligo is usually administered twice or thrice a week on non-consecutive days. It is difficult for many patients to adhere to this regimen, forcing them to discontinue treatment. AIM: The study aimed to compare the efficacy of twice-weekly and once-weekly targeted ultraviolet B phototherapy regimens in vitiligo. METHODS: Sixty patients with non-segmental vitiligo on the face, neck or trunk were divided into two groups of 30 patients each. The patients in group A received targeted ultraviolet B twice weekly, while those in group B received targeted ultraviolet B once weekly. Repigmentation was monitored and graded as excellent (≥75% repigmentation), good (50-74% repigmentation) and poor (<50% repigmentation). The extent of repigmentation at each body site (primary outcome measure), the number of doses required for initiation of pigmentation, and the cumulative dose of targeted ultraviolet B administered was calculated and compared between both groups. RESULTS: A total of 90 lesions (48 in the twice weeklygroup and 42 in the once weekly group) were treated on the face, neck and trunk. Excellent results were obtained in 62.5% (30/48) of lesions treated twice weekly, and 64.3% (27/42) in lesions treated once weekly. The mean number of doses required for initiation of pigmentation was 4.69 in the twice weekly group, and 4.35 in the once weekly group. The patients in the twice weekly group received a mean cumulative dose of 8.26 J/cm 2, while the once weekly group received 7.69 J/cm2. No statistically significant differences were observed between the two groups with respect to the outcome, with respect to the total repigmentation, the number of doses till onset of pigmentation, as well as the cumulative dose of targeted UVB. CONCLUSION: Once-weekly targeted ultraviolet B phototherapy appears to be as efficacious as the twice-weekly regimen in vitiligo.

Dose calculation in biological samples in a mixed neutron-gamma field at the TRIGA reactor of the University of Mainz.

To establish Boron Neutron Capture Therapy (BNCT) for non-resectable liver metastases and for in vitro experiments at the TRIGA Mark II reactor at the University of Mainz, Germany, it is necessary to have a reliable dose monitoring system. The in vitro experiments are used to determine the relative biological effectiveness (RBE) of liver and cancer cells in our mixed neutron and gamma field. We work with alanine detectors in combination with Monte Carlo simulations, where we can measure and characterize the dose. To verify our calculations we perform neutron flux measurements using gold foil activation and pin-diodes. Material and methods. When L-α-alanine is irradiated with ionizing radiation, it forms a stable radical which can be detected by electron spin resonance (ESR) spectroscopy. The value of the ESR signal correlates to the amount of absorbed dose. The dose for each pellet is calculated using FLUKA, a multipurpose Monte Carlo transport code. The pin-diode is augmented by a lithium fluoride foil. This foil converts the neutrons into alpha and tritium particles which are products of the (7)Li(n,α)(3)H-reaction. These particles are detected by the diode and their amount correlates to the neutron fluence directly. Results and discussion. Gold foil activation and the pin-diode are reliable fluence measurement systems for the TRIGA reactor, Mainz. Alanine dosimetry of the photon field and charged particle field from secondary reactions can in principle be carried out in combination with MC-calculations for mixed radiation fields and the Hansen & Olsen alanine detector response model. With the acquired data about the background dose and charged particle spectrum, and with the acquired information of the neutron flux, we are capable of calculating the dose to the tissue. Conclusion. Monte Carlo simulation of the mixed neutron and gamma field of the TRIGA Mainz is possible in order to characterize the neutron behavior in the thermal column. Currently we also speculate on sensitizing alanine to thermal neutrons by adding boron compounds.

Determination of minimal erythemal dose for narrow band-ultraviolet B radiation in north Indian patients: comparison of visual and Dermaspectrometer readings.

BACKGROUND: Minimal erythemal dose (MED) for narrow band-ultraviolet B radiation (NB-UVB) varies with race and skin type. The aim was to estimate the MED for NB-UVB and compare visual readings with those from a Dermaspectrometer in a north Indian patients as the available data is sparse. METHODS: Forty one patients who visited the dermatology outpatient department were recruited for this study. Skin type was grouped as per Fitzpatrick skin type scale. Patients' upper backs were irradiated after applying a novel template with 8 windows of 2 x 2 cm each, with a test dose ladder of 250-1500 mJ/cm2 in a Waldmann (700K) TL-01 chamber. MED and erythema index were read after 24 hours, the latter by using Dermaspectrometer. RESULTS: Forty one patients (10 males, 31 females) with mean age of 30.5 (14-65) years were recruited. 23 patients were of skin type 5, 17 of type 4 and one of skin type 3. The estimated MEDs were 1000 mJ/cm2 in 17, 750 mJ/cm2 in 19, 1100 mJ/cm2 in four and 500 mJ/cm2 in one patient. The median and mode MED was 1000 mJ/cm2. There was an exponential rise in the erythema index with increase in irradiation (17.18-26.25/250-1500 mJ/cm2). Student's t-test applied to detect differences between the visual and Dermaspectrometer readings was found to be statistically not significant. CONCLUSION: The estimated MED for NB-UVB varied from 500 to 1100 mJ/cm2, the median MED being 1000 mJ/cm2. The darker skin types did not have low MED while some patients with lighter skin type displayed lower MED. There was no significant difference in MED determined by visual and Dermaspectrometer readings.