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LUNG MODELLING CONTRIBUTION : DEPOSITION AND CLEARENCE STUDIES IN MAN

Objective

DEPOSITION AND CLEARANCE MODELS FOR RADIOACTIVE PARTICLES IN THE HUMAN RESPIRATORY TRACT ARE PRESENTLY THE SUBJECT OF A REVISION BY ICRP TO BE IN LINE WITH RECENT SCIENTIFIC ADVANCES IN THE FIELD. ADDITIONAL STUDIES ARE HOWEVER STILL NEEDED TO DETERMINE QUANTITATIVELY CERTAIN MODEL PARAMETERS AND TO ASSESS THEIR BIOLOGICAL VARIABILITY. THE WORK PROPOSED ARISES FROM THE COOPERATION OF 3 RESEARCH TEAMS INVOLVING SPECIALISTS OF AEROSOL PHYSICS AND PHYSICIANS FROM HOSPITAL DEPARTMENTS FOR PULMONARY DISEASES WHO CAN FOLLOW MANY PATIENTS. THE WORK INTENDS TO STUDY:
- DEPOSITION AND ITS VARIATION WITH AGE, ANATOMY AND FUNCTIONAL STATE OF THE AIRWAYS, SMOKING, VENTILATION RATE...
- REGIONAL DEPOSITION IN DEFINED AREAS ACCORDING TO THE ICRP MODEL,
- CLEARANCE IN NORMAL PERSONS AND IN PATIENTS SUFFERING FROM DEFINED DISEASES SUCH AS THOSE INVOLVING THE MUCUS, THE CILIAE, CERTAIN CELLS, THE INTERSTITIUM.
The study has dealt, under normal conditions of ventilation, with deposition of particles from 1 um to 3 um inhaled by healthy adults, patients with impaired lung function and children from 5 to 15 years of age.
Compared with healthy adults, patients deposited more.
In children deposition did not differ much from that in the adults (children's airways are structurally mature and therefore just miniaturised adult ones).The lower ventilation, on the one hand, prevents more particles from entering the airways, but on the other hand, the smaller lung dimensions increase deposition probability. In order to be precise in the important role of lung dimensions, studies have shown that ventilation should be constant for all ages and body size, and include morphometric measurements at least of the nasal passages that are the easiest to reach.
THE FOLLOWING METHODS WILL BE UTILIZED:
NON-RADIOACTIVE OR INERT AEROSOLS.
- HETERODISPERSED: NATURAL DUSTS OF THE ATMOSPHERE (LESS THAN 0.5 MICROMETERS) FROM WORK PLACES (OF ALL SIZES DEPENDENT ON SITE) WILL BE STUDIED WITH RESPECT TO THE RESPIRABLE MASS.
- MONODISPERSED AEROSOLS FOR TESTS ARE PRODUCED BY DIFFERENT GENERATORS (SPINNING TOP OR EVAPORATION-RECONDENSATION OF LAMER/SINCLAIR) WILL BE USED TO OBTAIN REFERENCE PARAMETERS FOR DEPOSITION FOR DIFFERENT AEROSOL DIAMETERS.
RESPIRATORY MANOEUVRE WILL BE USED TO STUDY REGIONAL DEPOSITION AND CLEARANCE:
INHALATION CONDITIONS
VARIOUS INHALATION CONDITIONS CAN BE APPLIED, NASAL AS WELL AS BY MOUTH, SPONTANEOUS AND CONTROLLED, DEPENDENT ON THE PARAMETER TO BE STUDIED; CONTROLLED VENTILATION APPEARS MOST SUITABLE TO OBTAIN REPRODUCIBLE DEPOSITION MEASUREMENTS.
MEASUREMENT OF THE RETENTION OF INERT AEROSOLS:
AEROSOLS OF A SIZE LOWER THAN 0,5 MICROMETERS WILL BE MEASURED WITH COUNTER MEASURING CONDENSATION NUCLEI AND DIFFUSION BATTERIES. AEROSOLS OF MMAD FROM 0.5 TO 15 MICROMETERS ARE MEASURED WITH A GRANULOMETRIC COUNTER WHICH DIRECTLY DETERMINES THE SPECIAL AERODYNAMIC CONDITIONS. CLEARANCE MEASUREMENTS:
THREE EUROPEAN TEAMS WILL COOPERATE: IPSN/DPS/SEAPS FONTENAY-AUX-ROSES, HOPITAL DE LA SALPETRIERE PARIS AND THE GSF FRANKFURT. THE LATTER WILL CONTRIBUTE TO THE RESULTS ON THORACIC DEPOSITION WHICH ARE USED BY ICRP FOR SIZE OF 0.5 TO 7 MICROMETERS MMAD. NASO-PHARYNGEAL CLEARANCE IS STUDIED BY NRPB, CHILTON.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Commissariat à l'Energie Atomique (CEA)
Address
Centre D'études De Fontenay-aux-roses
92265 Fontenay-aux-roses
France