MAUDE Adverse Event Report: RAYSEARCH LABORATORIES AB (PUBL) RAYSTATION; RADIATION THERAPY TREATMENT PLANNING SYSTEM

Model Number 5

Device Problems Application Program Problem: Dose Calculation Error (1189); Nonstandard Device (1420)

Patient Problem No Known Impact Or Consequence To Patient (2692)

Event Type  No Answer Provided  

Event Description

For two patients, radiation therapy plans using proton pencil beam scanning were setup with a combination of parameters that caused the analytical proton pbs dose engine to yield significant errors in dose.The parameters were.Targets close to the patient surface, in combination with: beams/spots entering the patient surface at an oblique angle, and/or large lateral inhomogeneities within the patient.Using a range shifter, large air gap.As described in the raystation reference manual, the proton pbs dose engine treats any range shifter device as an extension of the patient and the pencil beam tracing will start at the entrance of the range shifter.This means the patient outline becomes a large lateral inhomogeneity when it is angled to the ray traces.When a range shifter is used in combination with a large air gap, the broadening of each pencil beam ray trace becomes significant when reaching the patient surface and the infinite slab approximation may be inaccurate.The effect is mainly hot spots and cold spots within the intended target, but hot spots outside the target could potentially occur.The error is more pronounced for shallow targets and increases with increasing air gap.The error also increases the more the beam to patient surface angle deviates from 90°.When comparing the planning dose to the dose obtained using an alternative dose engine based on the monte-carlo (mc) principle in a patient case, significant cold spots were found within the target.The plan had a shallow target at the chin/throat area and two beams partially at a pronounced angle to the patient surface with ~35 cm air gap.The dose error manifested itself as a general shift of the mc dvhs by -7%, with severe cold spots, and some hot spots in the ctv.For this case, the d95% dose level for the high dose ctv region decreased by 18%, the d98% by 25%, and the d2% increased by 4%, when comparing the mc dose to the plan dose.The -7% shift is expected due to the nuclear halo effect, as described in the raystation reference manual, and should be revealed and compensated for in the patient specific qa procedure.The effect of such dose scaling would be to increase the quoted d95% and d98% levels (i.E., for the better) and to increase the d2% dose (for the worse).The cold and hot spots are on the other hand not expected to be revealed in the qa procedure.For the moment, no consequences to the patients are known.The clinic may have organized a patient follow-up to detect any post-irradiation consequences.

• Brand Name: RAYSTATION
• Type of Device: RADIATION THERAPY TREATMENT PLANNING SYSTEM
• Manufacturer (Section D): RAYSEARCH LABORATORIES AB (PUBL); sveavägen 44; stockholm, 11134 ; SW 11134
• Manufacturer (Section G): RAYSEARCH LABORATORIES AB (PUBL); sveavägen 44; stockholm, 11134 ; SW 11134
• Manufacturer Contact: david hedfors ; box 3297; stockholm, 10365 ; SW 10365 ; 8 5105300
• MDR Report Key: 6141088
• MDR Text Key: 61318072
• Report Number: 3007774465-2016-00005
• Device Sequence Number: 1
• Product Code: MUJ
• Combination Product (y/n): N
• Reporter Country Code: IT
• PMA/PMN Number: K160093
• Number of Events Reported: 1
• Summary Report (Y/N): N
• Report Source: Manufacturer
• Source Type: health professional
• Reporter Occupation: Health Professional
• Remedial Action: Recall
• Type of Report: Initial
• Report Date: 12/02/2016

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Date FDA Received: 12/02/2016
• Is this an Adverse Event Report?: Yes
• Is this a Product Problem Report?: No
• Device Operator: Health Professional
• Device Model Number: 5
• Is the Reporter a Health Professional?: Yes
• Date Manufacturer Received: 10/28/2016
• Was Device Evaluated by Manufacturer?: Yes
• Date Device Manufactured: 04/20/2016
• Is the Device Single Use?: No
• Type of Device Usage: Reuse
• Patient Sequence Number: 1
• Patient Outcome(s): Other