ENS 48465
ENS Event | |
|---|---|
22:37 Oct 17, 2012 | |
| Title | Agreement State Report - Possible Medical Event Involving Misadministration |
| Event Description | On 10/17/12, the licensee notified RHB (Radiation Health Branch) of an issue related to prostate brachytherapy and questioned if this falls into the category of Medical Event (ME). RHB is currently investigating this matter to evaluate if a ME had occurred.
The RSO called RHB for guidance about three permanent prostate seed implants for which post-implant dosimetry showed less than ideal dose coverage of the gland. The RSO reiterated that none of these deviations were a surprise all were expected based on intra-operative experience. In one Iodine-125 case, poor coverage of the lateral base resulted from significant pubic arch interference. In the other two cases, both Palladium-103, poor coverage of the base occurred from vendor failure to disclose an additional unplanned spacer at the end of each seed strand. As stated, the D90 value (minimum dose to 90% of the CT-defined prostate one month following the implant) for the I-125 case was 77% and for the two Pd-103 cases was 68% and 53% of the dose prescribed as a minimum peripheral dose to the ultrasound-defined prostate +margin prior to the implant. The RSO requested RHB read this statement carefully, as it compares apples to oranges 'The RSO will make the case that the post-plan D90 is relevant as an assessment of plan and programmatic quality but is irrelevant for definition of a medical event'. The RSO indicated that the hospital's physicians do not prescribe by D90. What is prescribed is a minimum peripheral dose (MPD) to the ultrasound-defined prostate gland plus planning margin (PTV). A pre-plan is generated to deliver the intended MPD (145 Gy for I-125 monotherapy and 125 Gy for Pd-103 monotherapy) to the PTV. The resulting planned combination of radionuclide, source strength, and number of sources is what is approved, prescribed, ordered, and implanted. Very often, changes are made intra-operatively to account for implantation difficulties and clinical factors (deviation of urethra from predicted path, pubic arch interference, presence of more aggressive disease in a specific part of the gland, etc). In addition, extra seeds are ordered for each case, to be implanted at the discretion of the Authorized User (AU). Extra seeds may be implanted to boost areas of sparse coverage following implantation of planned seeds. Extra seeds may also be implanted to boost areas of known aggressive disease to a dose higher than the initial MPD. It is impossible to mentally arrive at a new dose that might correlate to a D90 on post-implant dosimetry under these conditions. The AU recognizes that this will result in an increase to the D90 on the post-plan but does not alter the dose on the written directive but only the number of sources (in part to of the written directive following implant but prior to release of the patient) to reflect the intra-operative changes. This is because the prescribed dose refers to a MPD for the pre-implant ultrasound prostate volume with margin (as our policy states). It was never meant to correlate with a D90 on a CT-defined prostate volume (which volume may be double the ultrasound-defined pre-implant volume) a month after the implant. As a result of the clinically discretional implantation of extra seeds, many of our D90 results in post-implant dosimetry actually exceed 100% of the prescribed dose. Several even exceed 120% of the 'prescribed' dose, and this is intentional. Nevertheless, the radionuclide, source strength, number of seeds, and duration of implant (permanent) indicated on part 2 of each written directive (the part completed following implantation but prior to release of the patient) correctly reflects what was done, as required by 10 CFR 35.41. The RSO called RHB about these three cases because the dose delivered to parts of these prostate glands was less than intended, an anticipated but initially unplanned result due to known but unplanned and uncontrollable outside factors. The Authorized Users for these cases are still reviewing the clinical data to determine what, if any, additional medical actions will be taken. Note that none of these cases meet the criteria for a medical event as recommended by the Nuclear Regulatory Commission's Advisory Committee on the Medical Use of Isotopes on October 18, 2011 (see attached). These criteria analyze the spatial distribution of seeds within octants of the gland as well as the overall D90 (threshold for which is lowered to 60% of prescription dose, and only in conjunction with failure of the spatial analysis). In each of these cases (and in contrast to what happened in the VA cases), very few seeds (only a few percent) were implanted outside the planning margin of the prostate CTV. Even by the older document the state reference, the May 18, 2011 Prostate Permanent Implant Brachytherapy and Associated Medical Event Questions and Answers from Clarification of Current Guidance for Prostate Permanent Implant Brachytherapy, the hospital assert (as in Case 2) that ' in accordance with NRC regulations, a ME has not occurred, since the delivered activity is equal to the prescribed activity for the treatment site (as defined by the AU). Even though the D90 values differ by more than 20 percent; the AU does not use D90 to prescribe dose, and is therefore, not required to use D90 to perform the regulatory evaluation of the prescribed dose'. CA 5010 Number: 101712 |
| Where | |
|---|---|
| Saint Joseph Hospital Eureka, California (NRC Region 4) | |
| License number: | 1703-12 |
| Organization: | California Radiation Control Prgm |
| Reporting | |
| Agreement State | |
| Time - Person (Reporting Time:+332.22 h13.843 days <br />1.977 weeks <br />0.455 months <br />) | |
| Opened: | Kent Prendergast 18:50 Oct 31, 2012 |
| NRC Officer: | Charles Teal |
| Last Updated: | Oct 31, 2012 |
| 48465 - NRC Website | |
Saint Joseph Hospital with Agreement State | |
WEEKMONTHYEARENS 516702015-11-09T07:00:0009 November 2015 07:00:00
[Table view]Agreement State Agreement State Report - Medical Event Involving High Dose Rate Therapy ENS 484652012-10-17T22:37:00017 October 2012 22:37:00 Agreement State Agreement State Report - Possible Medical Event Involving Misadministration ENS 480582012-05-02T07:00:0002 May 2012 07:00:00 Agreement State Agreement State Report - Potential Medical Event Due to Leaking I-125 Seeds ENS 478312012-04-04T07:00:0004 April 2012 07:00:00 Agreement State Agreement State Report - Tc-99M Generator Inadvertantly Sent to Non-Licensed Recipient ENS 474842011-11-25T08:00:00025 November 2011 08:00:00 Agreement State Agreement State Report - Package Containing Radioactive Material Left Unattended 2015-11-09T07:00:00 | |