Two phases with four lines power supply !?

I have a Technical Specification of a medical x-ray equipment which states that it requires : Two phases with four lines 380v power supply

I need to know what does that mean ?

Specifications: Power Output : 40KW
X-ray Tube : Rotary anode
Focus : 1.0mm
Thermal Capacity : 150 KHU
Commute Method : Full Wave Commutation
Tube Voltage : 50～125KV,interval 1KV
Tube Current : 100mA(min) ～500 mA (max) Adjustable
with different grades
Exposure Time : 0.020s～5.000s(23 grades)
Bucky grid : Grid Density : 40L/cM
Grid Ratio : 10:1
Focus Distance : 120cm
Stationary Dimension : 17″17″
Power Supply : Two Phases with Four Lines(380V±10％,
50Hz Inner-resistance≤.3Ω Capacity
≥0KVA)
Structure
Bed Size : 2000×760mm
Bed Height : ≤00mm
Bed Transverse Movement Distance : ±110mm
Bed Longitudinal Movement Distance : ±325mm
Cassette Movement Distance : ≥60mm
X-ray Generator Revolution around Pillar Center: ±90°
Pillar Turning : 40°×9°
Pillar Movement Range along Bed : ≥350mm
Distance Between Focus and Film(SID) : 480～1230mm
Time Limit of Collimator Lamp : 45sec
Vertical Movement of Sternum Plank : 470～1468mm
Film Size : 5"×7"～14"×17"

Features:
1. Anti-electroshock, radiation-proof, and full wave commutation.
2. With electromagnetism controlling system, fluctuation bed board
and manual operation pillar to ensure a fast and reliable
location.
3. Structure designed based on anthropotomy, with beautiful
appearance, and easy to operate.
4. Convenient to take stretcher photograph.
5. A sternum plank is optional (grid density: 40L/cm; grid ratio:
10:1; focus distance: 120cm;stationary, dimension: 17″×17″,
and distance adjustable)