Bill,
The dose factors in RG 1.109 assume that the intake occurs at a constant rate over the course of a year and the dose is the 50-y committed dose.
More appropriate dose factors in this case are like those provided at
http://www.orau.gov/ehsd/pedose.doc
This document lists dose factors for pediatric nuclear medicine procedures.
For I-131 in the form of NaI, the dose factors for a 10 y-old child are 880 mSv/MBq for the thyroid and 27 mSv/MBq Effective Dose Equivalent.
For 400 uCi, I get 13 Sv for the thyroid and 0.4 Sv EDE.
Looking at some other web sites, the I-131 to destroy the thyroid is at least 30 mCi, so I guess this is not a problem.
Table 15.9 of the revised edition of the Health Physics and Radiological Health Handbook lists excess lifetime risk of thyroid cancer from exposure delivered by I-131 at ages below 18 y as 5 [male] and 10 [female] per 10^6 person rad. Footnotes to this table give the dose range as 6 to 1500 rad; with a 5y minimum latency and the median ages as 9.2 [male], 9.3 [female]. So the thyroid cancer risk is 6.5E-3 to 1.3E-2, and the cancer risk 2E-2 [using a population risk of 5E-2 per Sv from Table 15.16.1 of the Handbook]
Significant?
Regards,
Ben
ben.morgan@pgnmail.com
-----Original Message-----
From: William V Lipton [mailto:liptonw@DTEENERGY.COM]
Sent: Friday, April 04, 2003 10:08 AM
To: radsafe@list.vanderbilt.edu
Subject: medical misadministration to child
Please see the NRC event report that I pasted, below. A 9 year old patient who was in for a thyroid diagnostic scan was supposed to receive 4 uCi. Instead, he (she) received 400 uCi. The cause is stated as, "The wrong dosage was ordered from the radiopharmacy." It seems as if the dose rate should have warned them that something was wrong.
I'm curious about the statement, "The hospital indicated they did not expect any significant adverse health effect." Table E-13, of NRC Regulatory Guide 1.109, "Calculation of Annual Doses to Man From Routine Releases of Reactor Effluents ..." lists a dose factor, for a child thyroid for I-131 ingestion, of 5.72 E-3 mrem/pCi ingested.
Thus, the dose estimate would be:
(5.72 E-3 mrem/pCi)*(400 uCi)*(1 E6 pCi/uCi) = 2.3 E6 mrems = 2300 rems
The nonstochastic occupational limit for a minor would be 5 rems. It seems like the patient could expect a "significant adverse" health effect.
The opinions expressed are strictly mine.
It's not about dose, it's about trust.
Curies forever.
Bill Lipton
liptonw@dteenergy.com
Hospital |Event Number:
39725 |
+------------------------------------------------------------------------------+
+------------------------------------------------------------------------------+
| REP ORG: DEACONESS HOSPITAL |NOTIFICATION DATE:
04/03/2003|
|LICENSEE: DEACONESS HOSPITAL |NOTIFICATION TIME:
16:35[EST]|
| CITY: EVANSVILLE REGION: 3 |EVENT DATE:
03/28/2003|
| COUNTY: STATE: IN |EVENT TIME:
11:00[CST]|
|LICENSE#: 13-00142-02 AGREEMENT: N |LAST UPDATE DATE:
04/03/2003|
| DOCKET:
|+----------------------------+
| |PERSON
ORGANIZATION |
| |BRENT CLAYTON
R3 |
| |TRISH HOLAHAN
NMSS |
+------------------------------------------------+
|
| NRC NOTIFIED BY: DENISE BEAN
| |
| HQ OPS OFFICER: RICH LAURA
| |
+------------------------------------------------+
|
|EMERGENCY CLASS: NON EMERGENCY
| |
|10 CFR SECTION:
| |
|LDIF 35.3045(a)(1) DOSE <> PRESCRIBED
DOSA| |
|
| |
|
| |
|
| |
|
| |
+------------------------------------------------------------------------------+
EVENT TEXT
+------------------------------------------------------------------------------+
| MEDICAL EVENT AT DEACONESS HOSPITAL IN
INDIANA |
|
|
| A medical event occurred on 3/28/03 at 11:00 CST when a 9 year old
patient |
| received an actual dose of 400 microcuries of I-131, for a thyroid
scan and |
| uptake, instead of a planned dose of 4 microcuries of I-131. The
error |
| occurred when the patient couldn't swallow the capsule and the
hospital |
| ordered a liquid form of the radioisotope. The wrong dosage was
ordered |
| from the radiopharmacy. The error was not discovered until after the
dosage |
| had been administered. The hospital indicated they did not expect
any |
| significant adverse health effect. The hospital was performing some
more |
| detailed calculations involving this event. A review was initiated
to |
| clearly identify the cause and initiate corrective actions to
prevent |
|
recurrence.
|
************************************************************************
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