Prostate cancer patient with I-125 seed implants Cremated at a funeral home Resulted in...
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Transcript of Prostate cancer patient with I-125 seed implants Cremated at a funeral home Resulted in...
Prostate cancer patient with I-125 seed implants Cremated at a funeral home Resulted in contamination of retort, processing
equipment and surrounding rooms Agreement State required decontamination to
very restrictive limits
Part 1 – implants 63 sources (seeds) 0.250 mCi /seed Total: 15.8 mCi Written discharge instructions ▪ “The Radiation Safety Officer should be notified if the
patient is hospitalized, or if death should occur.” Part 2 – external beam treatments
Temperature: 1400-2100 F Duration: 2-3 hours Combustion Air Flow: 2000 – 2500 cfm Cooling Period: 1 hour at 500 - 1000 cfm Remains: 3-9 lbs (bone fragments)
Soft tissue vaporized Bone fragments normally pulverized after cremation.
Source: Cremation Association of North America
Activity 35 mCi I-125
Dose Rates 0.14 mR/hr @ 1 meter from patient 1.6 mR/hr on contact patient’s abdomen
Source - Journal of Applied Clinical Medical Physics
Two instances in NRC jurisdiction 9.8 mCi – cremated with NRC permission▪ 2 mR/hr on contact w/ plastic bag of remains
▪ Bkg after placing bag in metal urn
12 mCi – cremated with NRC permission▪ No data regarding dose rates
Day (-14): Seeds implanted Day (-3): Patient died Day 0: Clinic notified of death, patient cremated, initial
characterization, clinic RSO helps funeral home complete cremation procedures
Day 1: State regulator notified, remains transferred, facility characterized
Day 2: State inspection and survey Day 6: Follow up surveys – State inspector and clinic RSO Day 7: Chase notified and provides decommissioning
proposal and prepares to mobilize
Day 6 – Day 73: Funeral Home and State negotiate course of action. Options: Shutdown and decay Decommission – refractory was scheduled for relining regardless of
incident Day 73: Funeral Home decides to proceed with
decommissioning Day 73 – Day 103: State decides release criteria Day 103 – Day 107: On-site work Day 110: Final Status Report submitted to State Day 131: State confirmatory surveys complete Day 133: Facility released for unrestricted use
Therapy Clinic RSO responds Conditions
Implant patient ashes in pulverizer 2nd cremated body (ashes) inside retort 3rd body in refrigerator ready to cremate
Dose Rates w/GM detector 100 mr/hr inside retort 10 mr/hr external to pulverizer 1 mr/hr at retort door
Patient remains in plastic bag and plastic transport box – 10 mr/hr contact Remains buried
Remains of 2nd person in plastic bag and plastic transport box – 0.1 mr/hr contact Remains returned to family
Activity homogenously dispersed in ashes
Some items taken to Clinic for DIS Broom head, brushes, whisk broom, dust pan,
leather gloves Clinic makes a commitment to accept all
waste from remediation for DIS State approves DIS at clinic
Clinic RSO performed dose assessment External dose to operator estimated by dose
rate measurements and time-motion study Measurements corrected for energy differences
between Cs-137 (cal source) and I-125 Thyroid scan conducted at local hospital – don’t
know results Total dose was 12 mrem to hand and 0.6 mrem
TEDE
Retort and Exhaust Retort (3’ x 8’) No filters or pollution control equipment
Crematory Room (8’ x 29’) Processing Room (9’ x 10’) (a walled-off
section of the Crematory Room) Office (15’ x 15’)
State regulations are 25 mrem/yr w/ALARA State would not consider dose modeling or application of
NRC default screening values▪ NRC DSV for I-125 is 690,000 dpm/100cm2
Site-Specific Criteria▪ 20 dpm/100cm2 removable based on RG 1.86▪ State not really concerned with total contamination or dose rates▪ Chase implemented criteria of detectability (~1000 dpm/100cm2) as a goal
for identifying areas for remediation to mitigate risk of exceeding removable contamination limits
Direct Measurements Field Instrument for Detection of Low Energy Radiation (FIDLER) Bicron G5 and LMI 2221 Thin Nal(TI) Scintillation Crystal (5” Dia x 0.063” thick) Thin Window: Beryllium, (0.010” thick) Energy window set at 20-40 kev to capture I-125 emission for survey –
AND - to capture I-129 emissions for calibration and efficiency determination (~22% efficiency, ~ 700 cpm bkg)
Removable Measurements Packard Tri-carb 2800 liquid scintillation counter Single channel 0-80 kev, 78% efficiency
Location
Total Activity
(dpm/100cm2)
Removable Activity
(dpm/100cm2) Remediation Method
Office Floor 5K 0.8K Wet Wipe
Prep Table 13K 1.4K Wet Wipe
Process Room Floor312K 5.6K Scabble, Vacuum
Process Room
Pulverizer265K 10K Vacuum,
Scrubbed, scoured and wiped
Retort Room Floor 1.4M 60K Vacuum,
Scrubbed, scoured and wiped
Inside RetortOff Scale
1 mR/hr
24K Vacuumed, dose rate reduced dramatically
Hammered
Removed 2.5” to 5” of floor liner
Process Room
Exhaust Duct3.5K 112 Wet Wipe
All smears (except one) < 20 dpm/100cm2, Direct Measurements up to 1400 dpm/100cm2
NORM in refractory materials 112 dpm/100cm2 inside exhaust duct – performed
dose assessment to leave in place Not accessible for occupancy <<<<<< DSV Short half-life Ridiculous to even think about remediating State accepted
State regulator - conservative release criteria No signs of the SS seed capsules Radioactivity attached to ashes – where there was no
ash, there was no radioactivity Significant mixing of ashes between cremations
If you get cremated, you will have company for eternity Two cases in NRC jurisdiction – NRC does not view
as a concern
Questions?