Gravity: Turbidity Sensor - How to change voltage to NTU?

Hi so I'm wondering if there is any way to convert the input signal (or voltage) from the Gravity: Turbidity Sensor to an actual NTU value rather than a voltage that gives a very rough gauge on the turbidity levels.

The code below was taken from the product wiki page; make_clickable_callback(MAGIC_URL_FULL, '(', 'https://www.dfrobot.com/wiki/index.php?title=Turbidity_sensor_SKU:_SEN0189', '', ' class="postlink"'))

void setup() {
Serial.begin(9600); //Baud rate: 9600
}
void loop() {
int sensorValue = analogRead(A0);// read the input on analog pin 0:
float voltage = sensorValue * (5.0 / 1024.0); // Convert the analog reading (which goes from 0 - 1023) to a voltage (0 - 5V):
Serial.println(voltage); // print out the value you read:
Delay(500);
}

Any help on how to convert from the voltage value gained to an actual NTU value would be much appreciated.