Physica Medica: European Journal of Medical Physics - Volume 32 - Supplement 1

D.418

EXTREMITY DOSES ASSESSMENT OF NUCLEAR MEDICINE PERSONNEL

INVOLVED IN 99MTC-RADIOPHARMACEUTICALS PREPARATION: A

MULTICENTER STUDY – PRELIMINARY RESULTS

O. Zoccarato

* , a ,

R. Matheoud

b ,

D. Zanni

c ,

D. Fantinato

a ,

M. Brambilla

b ,

S. De Crescenzo

c .

Servizio di Fisica Sanitaria IRCCS FSM (IS Veruno e Pavia),

Veruno, Italy;

Servizio di Fisica Sanitaria AO Novara, Novara, Italy;

Servizio

di Fisica Sanitaria AO Niguarda, Milano, Italy

Rationale:

Manipulating unsealed radiopharmaceuticals the skin of the

hands of the nuclear medicine’s staff is the organ at highest risk for irra-

diation. The dose limit, to be applied to the average of 1 cm

of skin

regardless the surface of the exposed area, is of difficult assessment. The

WP4 of the ORAMED project identified the tip of the index of the non-

dominant hand as the point of maximum exposure. Moreover, the proportion

of workers liable to exceed the extremities annual dose limit is estimated

between 15 and 20%. Finger dose monitoring is highly recommended es-

pecially in busy labs.

Aims:

To evaluate under routine operating conditions, in 3 nuclear med-

icine departments, the irradiation dose to the extremities of workers involved

in the preparation of 99mTc-radiopharmaceuticals.

Materials and Methods:

According to ORAMED indications, two opera-

tors for each center were monitored by using 4 TLD (LiF: Mg, Cu, P) for 2

weeks. In order to determine the dose equivalent and dose equivalent rates

per unit of manipulated activity, for each single task the operational time

and the manipulated activities were recorded.

Results:

The following table summarizes the obtained results.

Dose equivalent (μSv/GBq).

Legend: TLD n°) hand position

Mean Min Max

1) Index tip of non-dominant

38.5

10.8

58.0

2) Base of the index of non-dominant

18.9

6.0

29.0

3) Wrist of non-dominant (towards the palm)

5.4

2.8

6.9

4) Index tip of dominant

63.7

13.7 141.6

The mean daily 99mTc activity manipulated was 56 GBq. The highest dose

equivalent measured is at the lower limit of the range reported by ORAMED

(33-2062, mean 432 μSv/GBq).

Conclusions:

In the enrolled labs, conversely to the ORAMED findings, the

index fingertip of the dominant hand receives the highest dose. In spite

of the low value of the mean dose equivalent measured, based on the daily

handled activities, the dose limit could be exceeded in 138 working days,

thus confirming the concerns raised by many authors.

http://dx.doi.org/10.1016/j.ejmp.2016.01.425

D.419

PATIENT DOSIMETRIC EVALUATION IN ANGIOGRAPHY PRACTICE:

APPLICATION IN INTERVENTIONAL NEURORADIOLOGY

I. Zucca

* , a ,

E. Cicer

i b ,

A. Vassena

c ,

E. Barbaglia

a ,

V. Caldier

a b ,

G. Farag

o b ,

A. Torresin

a ,

L. Fumagall

i a ,

A. Ostinell

i c ,

L. Garlat

i d ,

F. Ghielmetti

a .

Medical

Physics, Fondazione Neurological Institution C.Besta, Milano, Italy;

Interventional Neuroradiology, Fondazione Neurological Institution C.Besta,

Milano, Italy;

Medical Physics, Sant’Anna Hospital, Como, Italy;

Energy

Department, Politecnico di Milano, Milano, Italy

Purpose:

To evaluate the risk of a deterministic skin injury from

Interventional Radiology (IR) procedures, the Peak Skin Dose (PSD) and the

skin dose mapping should be estimate. Dose metrics commonly available

such as cumulative air kerma at the interventional reference point (Ka,irp)

are usually employed. However, as the PSD may be substantially different

from Ka,irp, it is necessary to estimate the PSD and skin dose mapping more

accurately.

Materials and Methods:

A custom made MatLab code has been devel-

oped; its output is the PSD and a visual display of the surface dose mapped

onto a spherical or cylindrical phantom modeling the head or the trunk

of the patient respectively. The code works by translating the Ka,irp (cor-

rected by back-scatter factor) to the location of the patient’s skin, represented

by a surface of the geometrical model and using dosimetric and geomet-

ric parameters (primary and secondary angles of the two tubes, longitudinal

displacement of the bed) for each radiation event stored in the radiation

dose structured report (RDSR). The setting of the dimension of the geo-

metrical phantom depends on the anatomical size of the patient measured

from images stored during IR procedures.

To validate the code, arrays of thermoluminescent dosimeters (TLD) were

placed on the phantom surface and on the skin of 9 patients undergoing

neuroendovascular treatments, both cerebral and spinal (Artis zee biplane,

Siemens).

Results:

The Ka,irp provided by the Angiography System overestimates the

measured PSD by more than 50% for head treatments. The percent differ-

ence between the PSD calculated and measured by TLD is within 35%. The

skin dose mapped on the surface of the geometrical model is in agree-

ment with the dose distribution measured by TLD.

Conclusion:

In Neuro-IR, the use of more detailed information from RDSR

can improve the accuracy of the calculated PSD. The implemented algo-

rithm can be applied to evaluate the PSD and skin dose mapping without

direct dosimetry.

http://dx.doi.org/10.1016/j.ejmp.2016.01.426

e123

Abstracts/Physica Medica 32 (2016) e116–e123