Though the rationale behind scalp cooling is known among researchers, a key issue has been the difficulty of providing controlled uniform cooling throughout the treatment period (Janssen, 2007). Inconsistent cooling and loosely fitted caps can also lead to patchy hair loss. Over the years, several methods to induce scalp hypothermia have been used and studied in a wide variety of chemotherapy regimens (Tollenaar, 1994; Breed, 2004; Grevelman & Breed, 2005).

The methods applied to induce scalp cooling include chilled air for cooling, simple bags with crushed ice, frozen cryogel packs, packs with endothermic cooling reaction and special helmets with cryogel and an insulation layer. Usually frozen pre-cooled caps are chilled at very low temperature of about –24°C (-75°C) and can be heavy to wear. Moreover, frequent cap changes make the process labor-intensive for the nursing staff. More recently thermocirculators and caps connected to a cooling machines using air or fluid as a cooling medium were used- However, the conventional refrigerated cooling machines do not have adjustable temperature settings nor automatic compensation of temperature deviations to induce truly uniform cooling.

The DigniCap™ system
Aware of the shortcomings in existing methods, Yvonne Olofsson, an oncology nurse with years of experience in the use of scalp cooling, collaborated with an engineer to build the digitized DigniCap™ scalp cooling system. The DigniCap™ system presents a combination of features believed to be superior to presently marketed scalp cooling systems. In addition to the provision of continual scalp cooling, the DigniCap™ system utilizes computerized and sensor techniques to ensure that the cooling is temperature-controlled to maintain treatment consistency. Nurses can also monitor treatment progress and adjust the temperature on a touch-screen panel. Disconnections (i.e. for restroom visits) are quick and easy and the action does not compromise the cooling temperature, as a valve will automatically compensate for any deviations in temperature by pumping the right amount of liquid coolant to the cap. To ensure proper and tight cap fitting for best results, the silicon caps are soft and available in several sizes. The inner surface of the silicon cap is smooth to ensure maximal thermal contact. Much consideration was given to patient compliance and comfort, which is why the cap is applied at room temperature and the temperature is lowered gradually and stepwise to minimize patient discomfort. Moreover, the cap is light and does not cover the ears and forehead, to ensure patient comfort.

Since its introduction in 2001, the DigniCap™ system has been installed in Scandinavia, Germany, Russia, Japan, and more recently in Malaysia and France. Thousands of patients have been successfully treated with the DigniCap™ system, and the data of 2249 patients in Scandinavia were recently collected in a post-market surveillance report (2007).