LDR Prostate Medical Event Definition John Wochos, MS Gundersen Lutheran La Crosse, Wisconsin April 22, 2011
Conflicts of Interest NONE Three LDR Medical Events at GLMC
Outline Definition of Medical Event Recent Prostate Medical Events Significance / Purpose of Medical Event Radiation Oncology Safety Issues Wisconsin LDR Prostate Medical Events NRC, ASTRO position Proposed NCCAAPM Recommendation
Philosophy I am NOT a Tea Party Member I do believe there is a strong role for regulators in the use of radiation and radioactive material I do think Radiation Oncology needs significant work in reporting and compiling incidents I do think each institution needs to periodically review procedures from a patient endpoint perspective.
Oct 24, 2010
Definition of Medical Event
Definition cont.
Definition Details & Prostate LDR Improper Administrations implies the sources were not administered according to the prescription What is the Prescribed Dosage? Many have taken this to be D90; the dose received by 90% of the target (PTV or prostate)
RTOG Protocol 0232 Study designed to compare External Beam with LDR prostate brachytherapy (no where are regulatory implications mentioned). CTV = Prostate PTV = CTV + (2-5mm) all directions except Posterior CT 3-5 weeks post procedure per protocol D90 = 90%-130% Acceptable D90 = 80%-90% OR D90>130% Unacceptable D90 < 80%
Philadelphia VA 2008 LDR Prosate Medical Events Analysis by Hagan, et.al., (Brachytherapy, in press) of 62 of the reported Medical Events at the VA Post implant Day 1 CT images were used to evaluate the implants. Edema resulted in a 56% increase in volume (SD 56% also) over the intraoperative ultrasound. Correcting for this edema reduces the number of MEs to 20 using dose criteria.
Cont. Philadelphia VA MEs Re-evaluation based on total activity (strength) 11 cases had >20% of the seeds beyond the treatment site (included designed margin). 3 of these had >40% outside treatment site. 10 of these 11 cases also fail the D90 >80% criteria and the one that did not had questionable volume
NRC Reported Prostate LDR Med Events (Jan 2010 March 2011) State Level Comments Colorado 32% underdose mistake Air Kerma and Activity Kentucky D90 5.2Gy vs 133 planned Not acknowledge by Institution 27% mistake Air Kerma and Activity Illinois Missed gland by 4-5 cm Indiana D90 72% D90 64% "Dose Received" 44% "Dose Received" 44% North Carolina Peripheral implant; seeds outside gland 59% discovered day of implant Ohio 67% of Presc Dose 75% of Presc Dose Dose <20% of prescribed Cold Cold Cold 72% 68% 71% D90 63% aborted implant 13 seeds in bladder Bones too narrow
Cont. MEs 2010-2011 State Level Comments Louisianna D90 = 9% Missed by 3 cm Nevada 79% of Prescribed Connecticut D90 58% Gave external beam boost D90 = 59% felt to be adequate coverage Mississippi VA 10 cold events D90 < 80% 1 cold event D90 < 50% Missouri 11% of prescribed
Cont. MEs 2010-2011 State Level Comments Wisconsin D90 differ 20% D90 = 75% D90 = 75% D90 = 77% D90 = 78% D90 = 121% D90 = 121% D90 = 55% D90 = 78% D90 = 74% D90 = 64% D90 = 75% Overdose Overdose Overdose Overdose Overdose Overdose Underdose Underdose Underdose Underdose D90 = 118% D90 = 69% D90 = 77% D90 = 79% D90 = 70%
NRC Reported MEs 2010-2011 for LDR Prostate Brachytherapy Nine state with two or fewer events One state (Indiana) with 4 events One state (Mississippi) with 11 events, all VA One state (Ohio) with 11 events One state (Wisconsin) with 28 events
Possible Conclusions From Report Medical Events Three states do most of the LDR prostate seed implants? Three states perform significantly worse prostate seed implants? Three states (really two), in particular Wisconsin, have radiation regulators that are investigating differently?
Report Non-Dosimetry MEs *W Butler ABS 2011 20 Gross target misses or wrong target treated 9 wrong strength used 11 leaking sources (mostly MICK jams) 8 reports of lost seeds 1 prescription error (monotherapy vs. boost) 1 wrong patient (and I-125 vs Pd-103) 3 shipping errors
Nov 21, 2010
August 10, 2010 NRC Proposed Amendment voted down Unanimous vote by 5 commissioners NRC staff was recommended to work with their Advisory Committee and the Medical Community to develop a new approach.
What happened at Gundersen 3 on-site visits 2 conference calls July 2010 initial on-site inspection indicated we had established criteria, we were thanked and told there would like be no recommendations Follow-up phone call indicated they did not like our criteria. We needed to establish our own criteria and implement them. Subsequent follow up visit September 2010
September 2010 visit Long discussions on criteria. We did suggest they follow the NRC recommendation and back off on the grey zone cases, zeroing in on clear events. Again, we were told we could establish our criteria and then we were required to stand by it (sounds like phone call recommendation)
Gundersen Initial Criteria and Rationale (Pd-103 exclusively) Since D90 of 80% is acceptable by RTOG standards, a level 20% below that should be an event. Alternatively, if D90 of 90% is a good implant, a D90 of 70% could be an event Upper limit for Pd-103 less well defined, from Brachytherapy 8, D90>140% as upper event. Urethra, no clear limit in literature Bladder, no clear limit in literature Rectum: ESTRO 2cc < 100%
Subsequent Conference Call We could pick our own criteria and live by it as long as it was the State s criteria. We were told our interest was clinical results, their interest was a regulation. They felt the +/-20% dose in the regulations was all that was needed. The range of dose recommended in the regulation was intended for I-131 thyroid treatment and dose not apply here. Thus, a D90 of 100% is the implied prescription.
What we agreed on D90 < 80% is event D90 > 160% is event (gave us higher value for Pd-103) Subsequent review over 2+ years indicated 3 events out of 187 implants. D90 = 78% (PSA 11.83 to 0.54) D90 = 71% (Follow-up April 22, 2011) D90 = 77% (PSA 16.16 to 0.06)
Example of Med Event Contouring uncertainty
D90 of 80% within uncertainty
Definition of Medical Event Improper Administration of radioactive material should we be looking at the RESULT of the procedure to determine if the Administration was Improper? Probably, but.. Total Dosage differs by more than 20% from intended. -->should we be looking at dose? Or, administration of the radioactive material?
ASTRO Working Group Problems in Using Dose Dose based definition has many problems Timing of post implant imaging Imaging modality differences Observer variability Planning margins used vary Planning system uncertainties Seed migration (administration of material vs. result)
ASTRO Working Group Conclusion If a dose based definition for permanent implants is applied strictly many medically acceptable implants would be inappropriately classified as a Medical Event and rather than achieving the intended goal of patient safety, there will be a detrimental effect on brachytherapy.
ASTRO Recommendation Source strength based criterion (>20% of source strength implanted outside PTV) is more appropriate for defining ME in permanent brachytherapy.
Thomadsen Proposal Proposed definition For permanent prostate implants, a medical event should be defined when either: A. For the target, D 90 <70% of the clinical target volume (CTV) AND Less than 5% of sources occupy any octant of the PTV, except by design (e.g. for preservation of normal tissue or escalated treatment to a particular region), as specified in the written directive. B. For the normal tissues, 1. For the bladder and rectum, the D 5cc on post-implant dosimetry exceeds 150% of the prescription dose OR 2. For the urethra, the D 5cc on post-implant dosimetry exceeds 150% of its value on the planned, approved dose distribution.
Wochos Request NCCAAPM submit a letter to Wisconsin Radiation Safety Section requesting they hold off on the enforcement of a Medical Event using D90 criteria of <80% or >140%. Wait for NRC guidance. There is no radiation safety benefit being seen by the patients (of the 28 MEs found there are NO adverse reactions). Why enforce an ambiguous regulation when there is no benefit to anyone? This is a waste of resources for both the Medical Institutions and the Radiation Section Staff
Until Further Guidance Received Current regulation is Dose based There is still a need to call a bad implant a Medical Event D90 was not invented as a regulatory tool, but it is being used as a quantitative measure of implant quality Higher D90 s have better outcomes. But D90 s of 80% still have satisfactory outcomes compared to other modalities Suggest a D90 < 60% for the time being
Radiation Oncology & Safety Need to reduce number of incidents (not limited to Medical Events). Even though percent of incidents is low, the results can be horrific (Cure, palliation, side effects, death). Need a national data base on incidents and near misses. Both at institution and national level we need to determine methods to reduce errors. Outside professional review (peer review, e.g. ACR survey (ASTRO)
Acknowledgements Bruce Thomadsen Mary Ellen Jafari Kimberly Schmidt Kari Adank (Compliance)
Feb 6, 2011