In 1996 we set out to use the phototherapy principles referred to earlier to try to overcome the limitations and disadvantages of night phototherapy. In particular the objective was to improve effectiveness to the point where the required phototherapy time was sufficiently short to make treatment while awake a valid and acceptable alternative. This has been achieved. Further improvements are achievable.
The design of a sit-up, light box system providing multi-sided phototherapy has been progressively improved from the first 1996 design to the latest 2005 version. The latest (2005) design incorporates the following improvements over night phototherapy systems. Please refer to photographs and sketches.
1. The light box incorporates 42 TL52 tubes of 2 ft length (600 mm). This involves use of 756 watts of power input, more than twice that used in typical night-lights. There are 16 tubes at the back, 9 tubes on the seat and 3 tubes behind the legs, The front box is pulled into the back box/seat by the user and uses 7 tubes on the vertical surface close against the torso and 7 tubes on the horizontal surface above the thighs. All tubes are fan cooled.
2. Behind the tubes and on all internal surfaces the light box is lined with highly reflecting acrylic mirror. Any light not directly falling on skin is reflected around the inside of the box until it does reach skin. Very little light escapes from the box. Wastage of light is very small compared with night phototherapy systems. The irradiance at all points inside the box is a relatively even 7 to 9 milliwatts per sq.cm. (As measured with an International Light IL 1440A light meter).
3. The users back, seat, back of thighs, back of calves and torso are in contact with the safety screen and about 1 inch (2-3 cm) from the light tubes. This compares with 25 35 cm for overhead lights.
4. The most important improvement is that all skin surfaces (except the head) (80-85% of skin) receive phototherapy concurrently, compared with about 35% of skin area for single sided night-lights. This factor alone reduces phototherapy time by 50 to 60%.
5. The combination of the various improvements means that the sit-up box is between 4 and 6 times more effective than overhead lights especially for adolescents and adults. After 120 days the tubes have been used for only 120 to 360 hours depending on the seriousness of the users CNS condition. This means that the tubes do not deteriorate as quickly and function at an average level of output substantially greater than tubes used in night phototherapy.
In summary, the light box is many times more effective than night lights because...
The result is that phototherapy time is short enough for daytime phototherapy to be a valid and relatively attractive option. The improved effectiveness provides substantial lifestyle advantages.
In 1996, Lauren, then aged nearly 5 years, required 6 hours overhead phototherapy each night to maintain blood bilirubin concentration at an acceptable and stable level. With the sit-up lights she was able to maintain blood bilirubin at acceptable levels with one hour of phototherapy per day (often in two half-hour sessions) while eating, reading or watching television. Lauren now nearly 15 (mid 2006) has slept normally without phototherapy at night for ten years. Blood bilirubin levels have been maintained at acceptable levels.
Several other children now use sit-up lights successfully. Using an earlier design that has since been significantly improved, a child with the most serious form of CNS required about 2 hours per day in summer and 3 hours per day in winter. This compared with 10 to 12 hours of overhead phototherapy at night. For this active child night phototherapy was becoming unacceptable and 3 hours per day in sit-up lights was also too long.
A CNS lady who normally takes Phenobarbital to control blood bilirubin concentration has, as an alternative, used an innovative light box design during her pregnancy.
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