bss: specific requirements for medical exposures

BSS: Specific Requirements for

Medical Exposures

2nd Regional Workshop on the Implementation of the International BSS

28th October- 1st November 2013; Manila, Philippines

Maria del Rosario Pérez

Department of Public Health and Environment

Justification

BSS WS Manila 28th October to 1st November 2013

The paradigm: science, recommendations, standards

Scientific basis Effects, risks,

sources, levels, trends, …

Recommendations System of RP (philosophy,

principles, dose criteria, …)

Standards (safety requirements,

regulatory language,..)

Medical settings

Implementation of

the standards

Safety guides, technical reports, tools


Justification of medical exposures Evolution of ICRP recommendations

Should be dealt with in the same way as justification of any other practice

But adds that each procedure is subject to a separate decision, so that there is an opportunity to apply a further, case-by-case, justification for each procedure. Notes that this may be important for complex investigations and for therapy.

1990 – ICRP 60

2007 – ICRP 103

– ICRP 105

1996 – ICRP 73

2011/2 – New BSS

A more complex approach - 3 levels

•Justification of a practice

•Generic justification of a defined procedure

•Justification for an individual patient

ICRP 73 approach is maintained – medical exposure

different and more detailed of patients calls for a

approach to the process of justification

1996 – BSS 115


Justification in the BSS: the "what" and the "who"

In its chapter 1, the new BSS note that the

general safety requirement on justification

needs a special approach when it applies for

medical exposures. In chapter 3, the

requirement 37 focuses on justification of

medical exposures.

Three levels:

– General/overarching justification of the use of

ionizing radiation in medicine (level 1);

– Justification for a generic clinical condition (level 2);

– Justification of a radiological procedure for an

individual patient (level 3).


What is the level 1 of justification?

The first level refers to the general

justification of the use of ionizing

radiation in medicine.

As a general approach, the use of

radiation in medicine is accepted as

doing more good than harm, economic

and social issues being considered.

Therefore, this first level of general

justification can be taken for granted.


What is the level 2 of justification?

Second level -generic justification- refers to a

particular radiological medical procedure for

patients with a given clinical condition, or for a

group of individuals at risk to a given condition

that can be detected and treated.

This generic justification is assigned to the

health authority in conjunction with appropriate

professional bodies. It shall be reviewed from

time to time, with account taken of advances in

knowledge and technology developments.

Referral guidelines/ appropriateness criteria

reflect this level of justification.


The level 3 : individual justification

Third level- individual justification of a

procedure judged to do more good than harm to

a particular patient.

It is assigned to health professionals involved in

the patient's care ("consultation between the

radiological medical practitioner and the

referring medical practitioner, as appropriate").

They have to integrate the best available

scientific evidence with their individual clinical

expertise to decide what is appropriate for that

individual patient,

RISKS

BENEFITS


The BSS say that account has to be taken of:

– The appropriateness of the request;

– The urgency of the procedure;

– The characteristic of the medical exposure;

– The characteristic of the individual patient;

– Relevant information from the patient's previous radiological

procedures

– Particular attention: children, pregnancy and beast-feeding.

Relevant national or international referral guidelines shall be

taken into account (evidence-based decision-support tools).This

relies on professional judgment considering, inter alia, patient

values, local expertise, and availability of resources.

The level 3 : individual justification (cont.)


Roles and responsibilities in

justifying at level 3? Two roles identified in the new BSS

– Radiological medical practitioner

– Referring medical practitioner

The BSS say that justification of

medical exposure for an individual

patient "shall be carried out through

consultation between the radiological

medical practitioner and the referring

medical practitioner, as appropriate"


Justification- Respective Roles

Respective roles of the referring and the radiological

medical practitioner

– Who is responsible?

• Clinical context, medical history

• Knowledge about procedure – benefits, risks

• Responsibilities under a RP framework

• Potential financial conflict of interest

• Defensive medicine

• “Request for consultation” versus “instruction to perform”

• Referral criteria / criteria of appropriateness

– Practicalities

• Feasibility in busy imaging facilities?

• Modalities of consultation ?


JUSTIFICACION

BENEFITS

RISKS

RISKS

BENEFITS

Asymptomatic

individuals


Population screening vs. Individual Health

Assessment (IHA)

IHA is neither diagnosis nor screening. Presumptive

diagnosis of disease is based on signs/symptoms vs.

"possible disease" is based on individual risk factors.

Evidence-based referral guidelines and

appropriateness criteria for medical imaging assist

decision making about the best imaging procedure for

a patient with a given clinical condition.

Consensus about criteria for medical imaging of

asymptomatic people for IHA does not exist.

13


BSS and asymptomatic individuals

Any radiological procedure on an

asymptomatic individual that is intended

to be performed for the early detection of

disease, but not as part of an approved

health screening programme, shall require

specific justification by the radiological

medical practitioner and the referring

medical practitioner.

The individual shall be informed of the

expected benefits, risks and limitations (e.g.

heart CT, lung CT, colon CT, other/s …)


BSS: other specific justification requirements

Volunteers as part of a research

programme;

Female patients of reproductive

capacity

Breastfeeding and nuclear medicine

Radiological audits and critical review

of the implementation of the

justification principle.


Biomedical research

–Justification of medical exposures

in biomedical research

• Helsinki Declaration

• Guidelines of the Council for

International Organizations of

Medical Sciences

• Recommendations of the ICRP

• Approved by ethics committee or

equivalent


Issues on Justification of medical

exposures – (1)

– Awareness of radiation risks and hence the actual

need for justification

• Regulations may require justification

– But little is actually happening

• Regulatory body needs to promote awareness/guidance?


– Appropriateness

• Joint responsibility

– The referring medical practitioner (benefits?)

– The radiological medical practitioner (risks?)

• Development and use of appropriateness criteria

– Professional bodies

• Availability of relevant information from the patient’s

previous radiological procedures

– The regulatory body as a facilitator?

Issues on Justification of medical exposures – (2)


– Inspection/Audit

• What can the regulatory body do in this area?

– Medical domain versus radiation protection

• What should the regulatory body look for during its

inspections?

– Regulatory body needs specialized/trained inspectors in

this area?



– Asymptomatic individuals

• “Worried well”

• Pressures from advertising, media

• Fragmented health systems

• Lack of continued health care



– Biomedical research projects

– Regulatory bodies need to ensure there is a system

in place so that ethics committees (or equivalent) are

able to make a decision on the “justification of the

use of radiation” in the proposed project

• Dose & risk assessment

• Application of dose constraints


Optimization


Old vs. new BSS – optimization in

medical exposures

Old BSS

– Optimization biggest sub-section

– A mixture of requirements and guidance

• Much technical detail

New BSS

– Same headings as in BSS 115 retained

– Only requirements (the "what")

– Guidance and detail (the "how") removed

• To go into the companion Safety Guide (under development,

cosponsored by IAEA, PAHO and WHO)


BSS over-arching requirement on

optimization

Registrants and licensees and radiological medical

practitioners shall ensure that protection and safety is

optimized for each medical exposure

Components to consider: Design considerations

Operational considerations

Calibration

Patient dosimetry

DRLs

QA

Dose constraints

Requirement 38: Optimization of protection & safety


Design considerations

Registrants and licensees, in cooperation with

suppliers, to ensure that:

– Medical radiological equipment, and

– Software that could influence the delivery of

medical exposure,

Is used only if it conforms to applicable standards

– Including: radiation generators,

cassettes/screens, gamma cameras, image

intensifiers, flat panel detectors, etc.


Operational considerations - 1

For diagnostic radiological procedures and image guided interventional procedures:

– The radiological medical practitioner, in cooperation with the medical radiation technologist and the medical physicist (and if appropriate with the radiopharmacist), must ensure that the following are used:

• Appropriate medical radiological equipment and software, and

• Appropriate radiopharmaceuticals (for nuclear medicine)

• Appropriate techniques and parameters to deliver a patient exposure that is the minimum necessary to fulfil the clinical purpose of the procedure taking into account

– relevant norms of acceptable image quality, and

– relevant diagnostic reference levels


– To ensure:

• proper collimation of the primary X Ray beam to

minimize the volume of patient tissue being irradiated

and to improve image quality

• appropriate values of operational parameters (kVp,

mA…)

• appropriate image storage techniques in dynamic

imaging (number of images per second)

• adequate image processing factors (chemicals,

developer temperature, …)




To ensure that the particular aspects of medical exposures

are considered in the optimization process for:

– Paediatric patients

– Individuals exposed as part of a health screening programme

– Volunteers exposed as part of a programme of biomedical

research

– Relatively high doses to the patient

– Exposure of the embryo/foetus, especially if abdomen or pelvis

is exposed to the useful beam or if significant dose

– Exposure of a breast-fed infant following a procedure with

radiopharmaceuticals


Calibration

The medical physicist must ensure:

– All sources giving rise to medical exposures

• Calibrated – appropriate quantities and protocols

– Calibrations carried out

• At commissioning prior to clinical use

• After maintenance that could affect dosimetry

• Intervals approved by the Regulatory Body

– Calibration of all dosimeters used for dosimetry of

patients and for the calibration of sources is traceable to

a standards dosimetry laboratory


Patients Dosimetry

Licensees must ensure that dosimetry of patients is

performed and documented:

– By or under the supervision of a medical physicist

– Using calibrated dosimeters

– Following internationally or nationally accepted protocols

– To determine:

• For diagnostic medical exposures

– Typical doses to patients for common procedures

• For image guided interventional procedures

– Typical doses to patients


Diagnostic reference levels (DRLs)

Licensees must ensure that:

– Local assessments are made at approved intervals for

those radiological procedures for which DRLs have been

established

– A review of the optimization of patient protection is

conducted to determine whether corrective action is

needed for a given procedure if the typical doses

• Exceed the relevant DRL; or

• Fall substantially below the DRL and the exposures

are not providing useful diagnostic information or do

not yield the expected medical benefit to the patient


DRL2

The initial DRLs are chosen as a percentile point on the observed distribution of

doses to patients (e.g. percentile 75). The values are selected by professional

bodies in conjunction with the health authority and the regulatory body, and

reviewed at intervals that represent a compromise between the necessary

stability and the long-term changes in dose distributions.

Diagnostic Reference Levels

DRL1

Number of

procedures

dose

75 %


Trends in DRLs with time

UK has > 20 years of experience with DRLs

– Reviews in 1995, 2000 and 2005

– 2005 review showed for radiography:

• On average about 16% lower than 2000 review

• Typically less than 50% of original DRLs

HPA-RPD-029, Health Protection Agency, UK, 2007


Quality assurance for medical exposures -1

Licensees must ensure a comprehensive

programme of QA for medical exposures

– Active participation of

• Medical physicists

• Radiological medical practitioners

• Medical radiation technologists

– Taking into account principles established by:

• WHO

• PAHO

• Professional bodies


Quality assurance for medical exposures -2

To ensure the QA programme includes, as

appropriate to the facility:

– Measurements by, or under the oversight of, a medical

physicist of the physical parameters of medical

radiological equipment:

• At acceptance & commissioning, prior to clinical use on patients

• Periodically, thereafter, and

• After any major maintenance that could affect patient safety

• After any installation of new software or modification of existing software that

could affect protection and safety of patients

– Corrective actions, regular independent audits.


Dose constraints in the BSS

In medical exposures, dose

constraints only apply for:

– Carers & comforters (persons, other than

workers, who assist in the care, support

or comfort of exposed patients).

– Volunteers in a programme of biomedical

research


Multidisciplinary team working to prevent

unnecessary/unintended exposures: the example of medical imaging

Gate keeper

Bo

ok

ing

Re

gis

tra

tio

n

Pre

para

tio

n

Ex

am

inati

on

Rep

ort

Tra

nsc

rip

tio

n

Va

lid

ati

on

Deli

ve

ry

QA / Error reduction

Justification Optimization

Patient journey

(adapted from Dr. L. Lau IRQN/ISR)


Optimization of protection – issues

This is an area where much can be achieved

– Many tools available

– But “coordination” is needed

• Calibration, dosimetry, DRLs, QA

• Operational aspects

• So that protection is optimized for each exposure


•Implementation of the “consultation requirement”? Roles

of the health authorities and health professional bodies

•Good strategy to start with justification for “sensitive”

groups?

•Regulatory Body roles: promoting of awareness,

facilitating for the development of referral criteria,

encouraging hospitals to implement electronic

solutions?

•Involvement of a medical physicist depending on

complexity/risks. RB approach?

•How to ensure measurement/records of typical doses?

Discussion Topics


Acknowledgements

Presentation delivered by Maria del Rosario Pérez,

Radiation Programme, Department of Public Health and

Environment (PHE), World Health Organization (WHO).

It includes material developed in collaboration with, or

adapted from John Le Heron, Division of Radiation,

Transport and Waste Safety (NSRW), International Atomic

Energy Agency (IAEA) and Pablo Jimenez, Regional

Advisor in Radiological Health, Health Systems based on

Primary Health Care (HSS), Pan American Health

Organization (PAHO).

Collaboration to support BSS implementation in the medical

sector and enhance radiation safety and quality in healthcare

bss: specific requirements for medical exposures

Documents