13 quality assurance and quality control definitiva pedroortiz

7/29/2019 13 Quality Assurance and Quality Control Definitiva Pedroortiz

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Quality AssurancedndQuality Controluality Control

.

IAEAInternational Atomic Energy Agency


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What can happen in the absence of a

Ambi uities in the urchase order and

Incomplete delivery of equipment, softwareve , e e , u , u

Limitations in the use of the e ui ment due

to deficiencies in installation

,

which should have been included

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What can happen in the absence of a

Work without knowin the radiation dosesresulting in radiation injuries

e u y

Waste of existin features because of

leaving them disabled at installation

at acceptancer, maintenance and repairs

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A programme of quality is, therefore,



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Some definitions ISO 9000

ua y managemen nc u es a e ac v es a

organizations use to direct, control, andcoor na e qua y.

Quality assurance is a set ofactivities intended to

establish confidence that quality requirements willbe met (part of quality management)

Quality control is a set of activities intended to

ensure that ualit re uirements are actuall beinmet (part of quality management)

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International Basic Safety Standards

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International Basic Safety Standards

Licensees shall ensure that

For image guided interventional procedures,

medical imaging, calibration, dosimetry and qualityassurance, including the acceptance and

commissioning of medical radiological equipment,

are fulfilled by or under the oversight of or with thedocumented advice of a medical physicist,

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The principal parties responsible for

rotection and safet are:

a censees, or e person or organ za on

responsible for facilities and activities; (b) Employers, in relation to occupational

exposure;

(c) Radiological medical practitioners, in relation tomedical exposure;

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Requirements on quality assurance

eg s ran s an censees s a es a s a

comprehensive programme of qualityassurance for medical exposures with the

active artici ation ofmedical h sicists

radiological medical practitioners, medical

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Licensees shall ensure that programmes of quality

assurance for medical exposure include:

(a) Measurements of the physical parameters of medicalradiological equipment made by, or under the

supervision of, a medical physicist

mp emen a on o correc ve ac ons measurevalues are outside established tolerance

factors used in radiological procedures;

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d Maintainin records of relevantprocedures and results;

e e e econditions of operation ofdosimetry and

monitoring equipment

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When are the test to be performed?

(i) At the time ofacceptance and commissioning ofe equ pmen pr or o s c n ca use on pa en s;

(ii) Periodically thereafter; (iii) Afterany major maintenance procedure that

could affect rotection and safet of atients

(iv) After any installation of new software or

protection and safety of patients;

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,

purchasing the equipment



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First steps before purchase

Identif in the clinical needs in detail and Preparing a set ofspecifications to meet

ese nee s, nc u ng equ pmen antraining

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Equipment specifications are crutial for

e ec on o r g equ pmen , accessor es

Purchase order and contract with su lier Installation, acceptance tests and warranty

ompliance with industry standards andregulations

Efficient and safe work during the life time of

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After purchase order, during installation: collaborate

with hos ital architect and en ineer in verif in

a a componen s are e ng ns a e

Connections amon the different com onents Physical location of equipment components,

installation

Environmental conditions are adequate

Documents for tests and use

IAEA


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Acce tance tests



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What is the purpose ofacceptance tests

To assure that the specifications contained in thepurc ase or er con rac are u e

To assure compliance with standards andregulations

To avoid unnecessar mechanical electrical and

radiation risks to staff and patients.

performed at installation and in presence of a

To have a propertransfer of ownership and

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Acceptance tests

Upon satisfactory completion of the acceptancees s, e user p ys c s s gns a ocumen

certifying that these conditions are met The final payment can be then made and

ownership of the equipment transferred to the

institution The warrant time be ins.

These conditions place an important responsibility

these tests.

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IEC Standard

replaced by patient entrance referencedose)

so ose maps or sca ere ra a on

Dose indicatorsAdditional indicators: cummulative

IAEAme, num er o c ne rames, a r erma

at interventional reference ointParte 4. Produccin de rayos X y equipos

de angiografa

20


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omm ss on ng



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Commissioning:

now e ge o mage qua y an ra a on

exposure in all conditions ofuse and modesof operation

tests

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Electrical, mechanical, geometrical

ccuracy an prec ss on o movemen s an

positions of C-arm, height, rotations

, Movements and positions of monitors

Safety interlocks

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Calibration of indicators of exposure

r erma a n erven ona re erence po n

(patient reference entrance dose) Product air kerma x area meter

Calibration against independent dosimetryequipment

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Generator, tube, collimators, fi lters

arame ers, , average m , pu se

frequencies, pulse width,pulse mA amplitude Last image hold, LIH, sequence loops

Collimator, rectangular, iris, eliptical,combinations

Virtual collimation on LIH

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R f th AEC t i


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Response of the AEC system: air

Influence of modes: low, normal, highfluoroscopy, and cine mode

Influence of pulse frequency

Choice of curves-algorithms from the menu

Remark: the choice of curves and algorithmshas to be made with the collaboration of

service en ineer

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Image quality

Low-contrast discrimination Image noise, signal to noise ratio, SNR

Distortion

Focal spot size

g a process ng ea ures

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Integrity and characteristics of


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Integrity and characteristics of

e ng-suspen e screen

Table to -sus ended courtains Aprons

oggles

Hangers and racks

Labelling of the devices

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Some examples of characterization



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Influence of the operation mode (Eq 1)

1400

1600

asa e e ra e versus opera on mo e or cm

1200

800

400

600

0

200

Baja Media Alta

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Variation of the entrance kerma


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Variation of the entrance kerma

800

900

e

600

700

400

500

200

300

0

100

18 cm 22 cm 26 cm

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Effect of separating the image system


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Effect of separating the image system

Variation of Ke with the distance of image intensi fier to patient

2,5

1,5

2

KeenmGy/min

0,5

1

0

106 (5) 117 (15)Distancia

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Variation of the entrance surface kerma and


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a at o o t e e t a ce su ace e a a d

ambient dose when image system is separated

from the patient

0,3

,

0,2

,Entrada mGy/s

0,1

, m en a m y

0

,

FID 90cm FID 120cm

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C l i


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Conclusion

n t s equ pment,

when the image0,35

system is separated0,15

0,2

0,25

,

Entrada mGy/s

skin dose increases,0

0,05

0,1

imparted is reducedFID 90cm FID 120cm

IAEA

Also in this case the irradiated volume decreases because


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Also in this case the irradiated volume decreases because

the collimator automatically closes to a smaller solid angle

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f


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Alejamiento con campo fijo

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Conclusion

,

the se aration of the ima edetector causes an increase

as the entrance surface airerma

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Periodic tests,tests after maintenance and repairs


What is the purpose ofperiodic controls


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p p p

o ensure t at c aracter st s rema n sta e,

i.e. there are no significant deviations fromthe initial values verified at commissioning

IAEA

For the purpose of detecting deviations


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For the purpose of detecting deviations

It is not necessar to erform each timecomplex tests with heavy phantoms

u e e e e eperiodic tests and establish initial values at

commissioning to be verified afterwards

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Qualit assurance includes more thanequiment, but it includes procedures and

,


Evaluation image quality


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Evaluation image quality

Evaluation of Evaluation of clinicalequipment

performance by means

images from real

atientsof phantoms

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Identification of accidental exposure:


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investigate:

Any exposure arising from an image guidedinterventional procedure that is substantially

greater than was intended;

Calculate or estimate the doses received andthe dose distribution within the patient;

IAEA

Prevention of accidental exposures


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Prevention of accidental exposures

e me o s o preven ons w e

discussed in the next lecture The correct application of these methods

assurance programme

These methods include the use dose

indicators for each individual, from wichunusual exposures may be detected

IAEA

Doses should be assessed


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Doses should be assessed

Identificate patients with higher exposure.xamp e:

P hi her than 300 cG cm2 One hour fluroscopy, several thousend of cine

Calculate relevant patient dose (for examplemax mum s n ose

Antici ate ossible radiation effects transientor permanent) and

IAEA

All this steps tasks


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All this steps tasks

ou orm par o e proce ures

And be art of the ualit assuranceprogramme

IAEA

With such a programme in place


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With such a programme in place

It is very unlikely that

Patients will get severeradiation injuries

Staff gets lesions, suchas lense opacities

IAEA


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Thank you for your atention

Perguntas?
