Bruce ThomadsenBruce ThomadsenUniversity of WisconsinUniversity of Wisconsin

MadisonMadison

Some Current Regulatory issuesSome Current Regulatory issuesfrom the ACMUIfrom the ACMUI

The ACMUIThe ACMUI

The Advisory Committee on Medical The Advisory Committee on Medical Uses of Isotopes Uses of Isotopes

for the for the

U.S. Nuclear Regulatory CommissionU.S. Nuclear Regulatory Commission

ACMUIACMUI

Patient AdvocacyPatient Advocacy State Government State Government

Radiation ProgramsRadiation Programs Radiation Safety OfficersRadiation Safety Officers Healthcare AdministrationHealthcare Administration Nuclear PharmacistsNuclear Pharmacists Nuclear Medicine Nuclear Medicine

PhysiciansPhysicians Nuclear CardiologistNuclear Cardiologist

Radiation Oncologist – Radiation Oncologist – BrachytherapyBrachytherapy

Radiation Oncologist – Radiation Oncologist – GammaKnifeGammaKnife

FDAFDA Medical Physicist – Medical Physicist –

RadiotherapyRadiotherapy Medical Physicist – Medical Physicist –

Nuclear MedicineNuclear Medicine

Members representative of (not representing):Members representative of (not representing):

ACMUI Agenda April 2011ACMUI Agenda April 2011

1.1. Medical Events Subcommittee ReportMedical Events Subcommittee Report

2.2. RulemakingRulemaking

3.3. Part 35 Expanded RulemakingPart 35 Expanded Rulemaking

4.4. Permanent Implant Brachytherapy RulemakingPermanent Implant Brachytherapy Rulemaking

5.5. Permanent Implant Brachytherapy RulemakingPermanent Implant Brachytherapy Rulemaking

6.6. Permanent Implant Brachytherapy RulemakingPermanent Implant Brachytherapy Rulemaking

7.7. GrandfatheringGrandfathering

8.8. Preceptor AttestationPreceptor Attestation

9.9. Patient ReleasePatient Release

10.10. Patient ReleasePatient Release

Patient Release CriteriaPatient Release Criteria Between 1986 and 1997 Between 1986 and 1997 131131I thyroid patients I thyroid patients

receiving more than 30 mCi had to be receiving more than 30 mCi had to be hospitalized.hospitalized.

This limit was based on:This limit was based on: The assumption that the source material acted The assumption that the source material acted

like a point source,like a point source, There was no attenuation in the patient,There was no attenuation in the patient, Use of the physical half-life instead of the Use of the physical half-life instead of the

effective half-life.effective half-life. Keeping the exposure < 5 mR/h @ 1 m. Keeping the exposure < 5 mR/h @ 1 m.

Revised Patient Release CriterionRevised Patient Release Criterion

In 1997 the criterion changed from a fixed In 1997 the criterion changed from a fixed activity to a dose.activity to a dose.

The new criterion: Family at home <5 mSv The new criterion: Family at home <5 mSv for complete decay.for complete decay.

Other persons still <1 mSv*.Other persons still <1 mSv*. Includes external and internal exposures.Includes external and internal exposures. Requires User to know living conditions and Requires User to know living conditions and

calculate projected doses.calculate projected doses.

Projected DosesProjected Doses

Where:Where:D(∞)= 500 mremD(∞)= 500 mremG= Exposure-rate constant=2.2 R cmG= Exposure-rate constant=2.2 R cm22/(mCi h) for /(mCi h) for 131131IIQQoo= Activity administered in mCi,= Activity administered in mCi,

O= Occupancy = 0.25 if not known better,O= Occupancy = 0.25 if not known better,F= fraction of the administered activity taken up by the thyroid F= fraction of the administered activity taken up by the thyroid or rest of body,or rest of body,T= Effective half-life for either the thyroidal or extrathyriodal T= Effective half-life for either the thyroidal or extrathyriodal activityactivity

Or Based on Or Based on Measured Exposure RatesMeasured Exposure Rates

WhereWhere D(∞)= 500 mremD(∞)= 500 mrem 103h= Effective life in h for 103h= Effective life in h for 131131II O= Occupancy = 0.25 if not known better,O= Occupancy = 0.25 if not known better, RRoo= Initial exposure rate at 1 m,= Initial exposure rate at 1 m,

The ControversiesThe Controversies

1. Moves to go back to the 30 mCi release criteria.1. Moves to go back to the 30 mCi release criteria.Initiated by a petition from Peter Crain.Initiated by a petition from Peter Crain.

Demanded by Congressman MarkeyDemanded by Congressman Markey

2. Questions about having patients go directly to 2. Questions about having patients go directly to

a hotel.a hotel.

3. Questions about patients going to nursing 3. Questions about patients going to nursing

homes.homes.

The Arguments for 30 mCiThe Arguments for 30 mCi

Releasing patients with over 30 mCi exposes family Releasing patients with over 30 mCi exposes family members to unsafe levels of radiation and radioactive members to unsafe levels of radiation and radioactive contamination.contamination.

Patients may take public transportation and expose Patients may take public transportation and expose unwitting bystanders to excessive doses.unwitting bystanders to excessive doses.

Patients may vomit soon after taking the NaI and Patients may vomit soon after taking the NaI and spread contamination.spread contamination.

Some users may not give adequate instructionsSome users may not give adequate instructions..

The Arguments for the Current The Arguments for the Current RuleRule

Studies with family members badged have Studies with family members badged have show that they receive considerably less than show that they receive considerably less than calculated doses.calculated doses.

Other passengers at 50 cm would get 1 mSv Other passengers at 50 cm would get 1 mSv in about 2.2 h from a patient containing 200 in about 2.2 h from a patient containing 200 mCi (no attenuation) – So no long plane trips.mCi (no attenuation) – So no long plane trips.

Most practitioners keep patients for an hour Most practitioners keep patients for an hour for the radionuclide to get absorbed, and give for the radionuclide to get absorbed, and give antiemetics.antiemetics.

The Arguments for the Current The Arguments for the Current RuleRule

Surveys show that users do give instructions. Surveys show that users do give instructions. Anyway, that should only lead to regulators checking Anyway, that should only lead to regulators checking that instructions are given.that instructions are given.

Insurance companies will not pay for hospitalization.Insurance companies will not pay for hospitalization. Increase the dose to hospital staff who would care Increase the dose to hospital staff who would care

for such patients repeatedly.for such patients repeatedly. National and International bodies have National and International bodies have

recommended a dose-base release criterion if recommended a dose-base release criterion if feasible.feasible.

HotelsHotels

Hotel stays for radioactive patients are more Hotel stays for radioactive patients are more controversial.controversial.

Calculation of dose to workers indicate they would Calculation of dose to workers indicate they would be unlikely to receive >1 mSv for a patientbe unlikely to receive >1 mSv for a patient’’s stay.s stay.

But, they may from multiple patients, such as may But, they may from multiple patients, such as may happen for major referral centers.happen for major referral centers.

Vomiting seems not to be an issue.Vomiting seems not to be an issue. Not as dangerous as hepatitis patientsNot as dangerous as hepatitis patients..

Release Criterion NoteRelease Criterion Note

The 30 mCi rule is just a special case of the The 30 mCi rule is just a special case of the current rule with:current rule with:

No attenuation in the patientNo attenuation in the patient No information on the biological half-life (the No information on the biological half-life (the

physical is used)physical is used) The default occupancy (0.25)The default occupancy (0.25)

Why not use the best information available?Why not use the best information available?

9999Mo ProductionMo Production

The ACMUI has discussed this but is not in a The ACMUI has discussed this but is not in a position to do anything about it other than position to do anything about it other than recommend that the NRC facilitate US recommend that the NRC facilitate US production. We can talk about this later if production. We can talk about this later if there is interest.there is interest.

Medical Event DefinitionMedical Event Definitionfor Prostate Implantsfor Prostate Implants

Current ME definitionCurrent ME definition (1) A dose that differs from the prescribed (1) A dose that differs from the prescribed

dose or dose… by more than 0.05 Sv (5 rem) dose or dose… by more than 0.05 Sv (5 rem) effective dose equivalent, 0.5 Sv (50 rem) to effective dose equivalent, 0.5 Sv (50 rem) to an organ or tissue, or 0.5 Sv (50 rem) shallow an organ or tissue, or 0.5 Sv (50 rem) shallow dose equivalent to the skin; anddose equivalent to the skin; and (i) The total dose delivered differs from the (i) The total dose delivered differs from the

prescribed dose by 20 percent or more;prescribed dose by 20 percent or more;

Medical Event DefinitionMedical Event Definitionfor Prostate Implantsfor Prostate Implants

Current ME definitionCurrent ME definition (3) A dose to the skin or an organ or tissue (3) A dose to the skin or an organ or tissue

other than the treatment site that exceedsother than the treatment site that exceeds by 0.5 Sv (50 rem) to an organ or tissue and by 0.5 Sv (50 rem) to an organ or tissue and 50 percent or more of the dose expected from 50 percent or more of the dose expected from

the administration defined in the written directive the administration defined in the written directive (excluding, for permanent implants, seeds that (excluding, for permanent implants, seeds that

were implanted in the correct site but migrated were implanted in the correct site but migrated outside the treatment site).outside the treatment site).

ME Definition ProblemME Definition Problem

Many acceptable implants have doses to Many acceptable implants have doses to some parts of the target <80% of the some parts of the target <80% of the prescribed dose.prescribed dose.

ALLALL implants have doses >120% of the implants have doses >120% of the prescribed. (Near the sources D=>∞.)prescribed. (Near the sources D=>∞.)

Dose to nearby organs can easily change by Dose to nearby organs can easily change by >50% through movement. (The prostate >50% through movement. (The prostate moves cm over short periods of time.)moves cm over short periods of time.)

Utility and PriceUtility and Price The current definition works well for temporary The current definition works well for temporary

implants where there is good control over source implants where there is good control over source placement and treatment duration.placement and treatment duration.

Not so well for permanent implants.Not so well for permanent implants. Classifying adequate implants has its prices:Classifying adequate implants has its prices:

Time and expense of dealing with an METime and expense of dealing with an ME Law suitsLaw suits PublicityPublicity Practitioners forgoing the practice. (This has Practitioners forgoing the practice. (This has

happened!)happened!)

Commissions’ CommentsCommissions’ Comments

They have rejected these definition, saying They have rejected these definition, saying that they do not know what is right, but the that they do not know what is right, but the current definition isn’t.current definition isn’t.

BackgroundBackground

Some of this is fueled by the situation at the Some of this is fueled by the situation at the Philadelphia VA.Philadelphia VA.

There there were 107 implants identified as There there were 107 implants identified as ME. Some were very bad.ME. Some were very bad.

Target Volumes: ICRU 62Target Volumes: ICRU 62

GTVGTV

CTVCTV

IMIM

SMSM

PTVPTV

OAROAR

PRVPRV

The IM and the SM do not The IM and the SM do not just add – that gives too just add – that gives too much margin.much margin.

May combine as May combine as uncertainties, which is uncertainties, which is why the PTV is smaller why the PTV is smaller than the SM added to the than the SM added to the IMIM

The OAR may limit the The OAR may limit the expansion to the PTV.expansion to the PTV.

Target VolumeTarget Volume

So what is the target volume?So what is the target volume? If the CTV (i.e., prostate), then seeds placed in the If the CTV (i.e., prostate), then seeds placed in the

margin are out of the target and so is the dose.margin are out of the target and so is the dose. If the PTV (where seeds may be placed to cover the If the PTV (where seeds may be placed to cover the

prostate) then the dose to the PTV will be low.prostate) then the dose to the PTV will be low. RTOG uses DRTOG uses D9090, the dose that covers 90% of the , the dose that covers 90% of the

target, and a protocol violation is Dtarget, and a protocol violation is D9090<80%D<80%Dscriptscript. . That is That is

not a real event, just less than the protocol accepts.not a real event, just less than the protocol accepts. This is different from DThis is different from D100100<80%D<80%Dscriptscript..

Target Volume DoseTarget Volume Dose

Many implants fail the D<80% based on CT the day of Many implants fail the D<80% based on CT the day of or day following the implant.or day following the implant.

This is due to edema (swelling) from the trauma, This is due to edema (swelling) from the trauma, separating the sources and lowering the dose.separating the sources and lowering the dose.

This clears up a little on scans done after four weeks.This clears up a little on scans done after four weeks. It is often very hard to get patients back in four weeks.It is often very hard to get patients back in four weeks. Also, identifying a gap in sources at four weeks is too Also, identifying a gap in sources at four weeks is too

late.late. Even with edema, gaps can be identified and fixed.Even with edema, gaps can be identified and fixed.

Effects on the VA EventsEffects on the VA Events

Correcting for edema, reduced the number Correcting for edema, reduced the number of events from 107 to just over a handful. of events from 107 to just over a handful. More in the next presentation.More in the next presentation.

Current Definition for Other Current Definition for Other OrgansOrgans

The 50% increase in dose is a problem also.The 50% increase in dose is a problem also. Take the skin at maybe 6 cm deep. The dose is Take the skin at maybe 6 cm deep. The dose is

roughly 45U x (1cGy/h)/U x 0.272 x (1cm/6cm)roughly 45U x (1cGy/h)/U x 0.272 x (1cm/6cm)22 = = 0.34 cGy/h0.34 cGy/h

If, due to gas at the time of the CT the distance is If, due to gas at the time of the CT the distance is 5 cm (a common change) the dose becomes 5 cm (a common change) the dose becomes 45U x (1cGy/h)/U x 0.367 x (1cm/5cm)45U x (1cGy/h)/U x 0.367 x (1cm/5cm)22 = 0.66 = 0.66 cGy/hcGy/h

That is an increase of 94%That is an increase of 94%

Another Option discussedAnother Option discussed

ME when >20% sources outside the target.ME when >20% sources outside the target. Of course, this would have to be the PTV.Of course, this would have to be the PTV. This correlates well with bad implants, but This correlates well with bad implants, but

would not identify problems where all would not identify problems where all sources are in the prostate but bunched.sources are in the prostate but bunched.

The ACMUI endorsed the ASTRO definition, The ACMUI endorsed the ASTRO definition, discussed in the next presentation.discussed in the next presentation.

Other OrgansOther Organs

The rectum contacts the prostate, and lies at The rectum contacts the prostate, and lies at the edge of the high dose gradient. the edge of the high dose gradient.

Millimeters of motion can make more than Millimeters of motion can make more than 50% changes in dose.50% changes in dose.

The currents regulations have no volume The currents regulations have no volume component, so even one pixel with a dose component, so even one pixel with a dose change >50% is an ME.change >50% is an ME.

SummarySummary

These issues are not easy. These issues are not easy. Patient release itself is pretty straight forward Patient release itself is pretty straight forward

until hotel stays or nursing homes come into until hotel stays or nursing homes come into the picture.the picture.

Medical event definition has many Medical event definition has many unintended consequences.unintended consequences.

Sculpting a ME definition that covers Sculpting a ME definition that covers everything is challenging.everything is challenging.