public static PixelDataManager GetInstance(StudyStorageLocation storage)
        {
            string key = storage.Key.ToString();

            lock (_cache)
            {
                PixelDataManager instance = _cache[key] as PixelDataManager;
                if (instance == null)
                {
                    instance = new PixelDataManager(storage);
                    _cache.Add(key, instance, null, Cache.NoAbsoluteExpiration, ImageStreamingServerSettings.Default.CacheRetentionWindow, CacheItemPriority.Default, UnloadPixelDataManager);
                }
                return(instance);
            }
        }
        private static void UnloadPixelDataManager(string key, object value, CacheItemRemovedReason reason)
        {
            PixelDataManager instance = value as PixelDataManager;

            instance.Dispose();
        }