Masep Medical
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Professor and neurosurgeon, Lars Leskell of the Karolinska Institute in Stockholm, Sweden, first recognized the need for an instrument to target deep-seated intracranial structures without the risks of invasive open skull surgery in the late 1940s, and introduced the concept of stereotactic radiosurgery. After 20 years of further research, he developed the first functional Gamma Knife along with Professor Borge Larsson, and the Elekta Company in 1968.
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Product description
System Structure
Technical Parameters
Treatment Planing System
Treatment Process
Treatment Center

Intracranial(SRRS)Professor and neurosurgeon, Lars Leskell of the Karolinska Institute in Stockholm, Sweden, first recognized the need for an instrument to target deep-seated intracranial structures without the risks of invasive open skull surgery in the late 1940s, and introduced the concept of stereotactic radiosurgery. After 20 years of further research, he developed the first functional Gamma Knife along with Professor Borge Larsson, and the Elekta Company in 1968.

Through advanced imaging, and three-dimensional planning techniques, gamma knife radiosurgery delivers multiple, very narrow beams of gamma radiation to small targets inside the brain. It sends radiation beams through holes in a device called the collimator helmet. Only at the point where all the gamma beams converge at a single, finely focused point is enough radiation delivered to treat the diseased tissue while the surrounding healthy tissue is left unharmed.

In August 1999, MASEP developed the rotary gamma system in China. The rotary gamma system uses 25 Cobalt sources distributed in a spiral mode, and rotates with collimator to precisely target a selected lesion. The rotary gamma system features the precision focusing of the Leskell gamma knife, yet allows for dynamic gamma beams, instead of the static beams provided by the non-rotational Leskell design. The advantage is obvious.

It delivers the same dose rate at the focal point while reducing the number of radioactive sources. This technique provides less harm to healthy tissues. The focal point is sharp and crystal clear.

A variety of indications including AVM, benign and malignant tumors, and functional diseases can be treated

with Gamma radiosurgery. Many previously untreatable conditions are now treatable. There is minimal risk of of post-treatment complications, plus a high cure rate. In addition, the procedure is painless, and patients can return to their regular daily schedules within a couple of days. The gamma system uses 25 Cobalt-60 sources distributed on the surface of a hemispherical shell in spiral mode. Passing through collimators, gamma rays are precisely converged in the center of the sphere forming the focus. During treatment, the stereotactic system aligns the selected lesion with the focus. The rotary gamma system retains the precision focusing design in similar device while greatly enhancing the focal quality as a result of rotary concept.

In similar Gamma Knife, each gamma beam is static. MASEP focusing is dynamic and rotating in 360 degrees. However, both static and dynamic focusing deliver the same amount of radiation to destroy intracranial lesions. At the same time, the radiation of gamma rays to surrounding healthy tissues is small so that the damage to surrounding healthy tissues is minimized.


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MASEP Gamma System is composed of four parts:


Masep Rotary Gamma Ray Stereotactic Extracranial System is equipped with 25 Co-60 sources. Each source contains f1x1 cobalt granules welded into 2 layer stainless steel casing using argon fluorine welding technique to ensure a tight seal. The total combined initial loading activity is 241 TBq ±10%/ 6500Ci±10%. Source specific activity is 300 Ci/g. Source active zone is f3.1x30. At initial loading, the water absorption dose rate at the focusing point is greater than 3Gy/min. 25 cobalt sources are placed in the collimator passages.

Main System


Shielding structure: includes sources, switching device, shields, shielding door, front and rear door frames.

Sources: Cobalt sources and primary collimators.

Switching device: rotates with source adding extra protection.

Exterior shielding: shields gamma rays to reach regulated requirement on air emission inside the treatment room.

Shielding door: shields gamma ray to prevent leakage.

Collimator passage: consists of 2 parts; source collimator passage and switching device collimator passage. The collimator passage is used to change the radiation field during treatment to form radiation distribution adapting to tumor nature and shape.

Treatment bed: supports patient and adjusts position to achieve patient comfort during treatment.


Consists of electrical cabinet, operator console, motor driving mechanism, sensors, power supply and connecting cables.

Electrical cabinet: incorporates motor driving controller, motor driving mechanism, PLC, transformer, AC/DC converter, wiring terminals. Main switch is installed on the cabinet to control power supply to the whole system.

Operator console: incorporates color monitor, touch screen, pushbuttons, intercom system. By using touch screen and pushbuttons to display system status and input treatment parameters. Color monitor is used to monitor patient and intercom is used to talk to patient.

Motor driving mechanism: includes source motor, switching device motor, shielding door motor and treatment bed motor.

Sensors: monitors mechanical positioning.

UPS power system: includes UPS and battery box. 30 minutes backup is provided in case of power failure to automatically turn off switching device, recover treatment bed and close shielding door.

Treatment planning system

Includes hardware and software.

Hardware system:

High speed laser printer.

Image import computer.


On-line UPS

Flatbed reflecting/transmission scanner

Software system:

Image import system V2.0

Treatment planning software SuperPlan V2.5

Image transfer software Dicom Gateway V1.0


Technical Parameters

Focusing method

Rotary Focusing



Helmet structure

Cylinder shape

Types of Collimators


Collimator diameter (mm)


Max. treatable space inside helmet

F340 mm

Collimator change

Fast, visual and manual

Radiactive protection inside treatment chamber

Switchable shielding +helmet



Mechanical precision (mm)


Focus to lesion accuracy (mm)


Total activity of Co 60 at initial loading (Bq)


Focus dose rate at initial loading

>3 Gy/min

Maximum machine surface doserate


Dimensions (mm)


Weight (kg)


Power supply

220V/50Hz or 110V/60Hz


Treatment Planning System

Case Information and Image Data includes add, delete and retrieve case information

Dicom 3.0 standard direct connection to CT/MRI or other imaging devices for image transfer

Interactive detection of image fiducial marks and automatic setup of coordinate system

Detection of automatic and manually traced contours on multiple structures

Copy and paste contours from slice to slice

Extend or shrink slice to slice profile

Edit the name,color, attributes and density of structure profile

Changeable windows mode for image and profile display

Three-dimensional surface contour display with the ability change color and transparency

Flexable and efficient point,length,area, and volume measurements



Six window display modes

Three-dimensional REV display

(BEV) display

Recontruction and display axial, coronary and sagittal images

Image zoom, move, turn, rotate and movie play creation

Image width and window level adjustments


Bed angle design

Automatic collision verification between bed and frame

Multiple targets design

Advanced physical modeling and 3D algorithms

Support to multiple planning

Support to both approximate and precise algorithms


Isodose display for axial, coronary and sagittal image

Three-dimensional isodose volume and transparency display

Real time dosage display at any point

Linear dosage distribution display

Multi-structural dosage volume histogram (DVH)

DVH comparison for different plans

Printout of treatment plan

Printout of evaluation graph and image

System configuration parameter

Treatment Process

Diagnose the type of lesion and attach the stereotactic frame

Perform CT, MRI,or DSA positioning scan

Collect and transfer image data to plan treatment

According to the treatment plan, adjust X, Y and Z coordinates, select gamma angle and collimator type and place the patient on the treatment bed

Confirm relevant treatment parameters on the control panel

Start the equipment, open the shielding door and move the treatment bed into the treatment chamber

Source body aligns with the intermediate shielding and the helmet. Gamma rays pass through the collimator to form the focus. Treatment begins

End of treament: Treatment bed retreats. Helmet disengages from the intermediate shielding body

Remove the patient from the treatment bed, remove the stereotactic frame

Patient is released to the care of the hospital

If more than one shot location is required, re-adjust the X, Y, and Z coordinates and gamma angle.

Move the patient into treatment chamber and complete plan


Gamma Ray System Center: Includes patient reception area, patient rooms, restrooms, control rooms, treatment planning rooms, treatment rooms, and consultation rooms.

Patient reception area: Patients must be accompanied by a responsible adult family member or caregiver. A reception area provides a comfortable area to wait during patient treatment.

Positioning room:: The patient is placed on the treament bed in preparation for therapy.

Control Room: Gamma Ray Sytem is is a shielded room. It is equipped with a computer, console, surveillance equipment, communications equipment and electrical equipment, and should be close to the treatment room.

Treatment Planning Room: CT/M/ or Angiographic images are sent to a specialized treatment-planning computer. The physician along with other specialist will design the treatment plan. The physician designs the treatment in the planning room.

Intracranial(SRRS) Intracranial(SRRS)


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