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Daavlin Dosimetry

Common Myth: It’s all the same lamps, so the only difference between different manufacturer’s clinical phototherapy machines is cosmetic appearance. Reality: There are significant differences between machines equipped with integrated dosimetry, and those without it. If your goal is accurate dose control for optimum treatment outcome, Daavlin integrated dosimetry offers significant advantages over timer controllers. Integrated dosimetry systems like the Daavlin Flex and the SmartTouch dosimetry controllers measure the actual energy output of the phototherapy device in real time and adjust the treatment length to give exactly the programmed dose. Integrated dosimetry has been the preferred controller on large cabinet type phototherapy devices for many years due to the ability to eliminate dose uncertainty caused by environmental factors and lamp conditions. Daavlin offers integrated dosimetry systems on virtually every type of phototherapy device manufactured including hand/foot units and home phototherapy devices. A brief discussion of why optimal dose is important helps show why integrated dosimetry offers significant advantages: Phototherapy Dose Curves Compared to Skin Photoadaptation
The ideal treatment plan (green line) is one that is close to the erythemal threshold (dashed line) at all times, neither overdosing (red line), which can cause severe patient discomfort, nor underdosing (blue line), which can be ineffective, and can needlessly increase lifetime UV exposure. This chart was extrapolated from the most current clinical literature1,2 comparing phototherapy dosing regimes. Some benefits of integrated dosimetry can include:
  • Faster clearing
  • Less risk of burning
  • A better chance of successful treatment
  • Lower long term side effect risks
The easiest way to explain the advantage of integrated dosimetry is to show exactly what happens to the power output of a phototherapy device as it warms up:
In this chart, the actual measured output of a phototherapy device with a calibrated output of 22mW at 5 minutes of operation is shown. For the first minute the lamps are emitting approximately half of the calibrated output and the power of the lamps is changing rapidly. In this example, an initial 15 second treatment using a timer controller would deliver 60milliJoules, but a subsequent treatment of the same duration would deliver about 120milliJoules. With a dosimetry controller, exactly the same dosage would have been given for both treatments. If the temperature in the room changes, even by a few degrees, this warm-up time will be prolonged or shortened significantly. And, there are other environmental factors besides temperature that can significantly influence the output of the lamps. Besides the more obvious disadvantages of overdosing, there are significant disadvantages to under dosing as well. By giving repeated, small, ineffective doses of UV radiation, the skin will adapt causing the erythemal threshold to increase and the cumulative dose required to clear will be needlessly increased with a consequent risk of greater long term side effects. It is particularly worth noting that current research3 shows that pigmentation causes a surprisingly small amount of the skin’s adaptation response to phototherapy, so even patients that do not visibly tan are undergoing adaptation responses. 1 Kim HS, Lee CW, Kim KH, Preference of Near-erythemogenic Narrow-band UVB Phototherapy in Psoriasis and Change of Dendritic Cells and Chemokines. Korean J Dermatol. 2005 Jul;43(7):876-886 2 Palmer, et al. Photoadaptation during Narrowband Ultraviolet-B Therapy Is Independent of Skin Type: A Study of 352 Patients Journal of Investigative Dermatology (2006) 126, 1256–1263 3 (Hennessy A, Oh C, Rees J, Diffey B (2005) The photoadaptive response to ultraviolet exposure in human skin using ultraviolet spectrophotometry. Photodermatol Photoimmunol Photomed 21:229–33)