DMLC IV

Additional Manufacturer Narrative

THE RISK ASSESSMENT CONCLUDES AN UNDESIRABLE EFFECT WITH RESPECT TO DMLC IV. DURING TREATMENT, THE LEAVES OF THE COLLIMATOR ARE SHAPED ACCORDING TO THE CURRENT GANTRY POSITION DETECTED BY THE DMLC GANTRY SENSOR. INCORRECT READOUT OF THE GANTRY POSITION CAN BE CAUSE OF MISTREATMENT (OVER OR UNDERDOSE). IT IS UNK BY HOW MUCH THE GANTRY POSITION MAY BE OUT. THE FAULT MAY OCCUR AND PERSIST OVER THE MAJORITY OF THE BEAM DELIVERY RESULTING IN A COMPLETELY STATIC DMLC SHAPE, OR THE FAULT MAY BE INTERMITTENT, THUS CAUSING ONLY A SMALL GANTRY ERROR FOR THE REST OF THE TREATMENT. THE PRODUCT IS ALREADY END OF SALES AND FURTHER DESIGN ENHANCEMENTS ARE NOT PLANNED. A (B)(4) IS BEING PREPARED FOR EXISTING CUSTOMERS.

Description of Event or Problem

THIS ISSUE IS CONCERNING DMLC IV ONLY. THE ANGLE INFORMATION DETERMINES THE LEAF POSITION. DURING ENGAGEMENT, THE LEAVES OF THE COLLIMATOR ARE SHAPED ACCORDING TO THE CURRENT GANTRY POSITION DETECTED BY THE DMLC GANTRY SENSOR. THE POTENTIAL FOR INCORRECT READOUT OF THE GANTRY POSITION WAS FOUND DURING AN INTERNAL INVESTIGATION.