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Keywords:
Radioprotection / Radiation dose, Professional issues, Conventional radiography, Digital radiography, Technical aspects, Radiation safety, Health policy and practice, Occupational / Environmental hazards, Dosimetric comparison, Quality assurance
Authors:
R. P. P. Almeida, J. R. Santos, S. Rodrigues, P. Sousa, L. P. V. Ribeiro, K. B. Azevedo, J. P. Pinheiro, A. F. Abrantes; Faro/PT
DOI:
10.1594/ecr2016/B-1246
Methods and materials
This is a quantitative experimental study.
The sampling method consisted of measuring the dose within the crystalline,
thyroid gland and body,
subject to Orthopantomography tests in a standard and pediatric protocol,
in order to compare the results with the reference dose levels and other previous studies.
The measurement was initially held without protection and subsequently with the respective safeguards with a total of 20 exposures.
Instruments:
- GE Orthopantomography OP 100
- Dosimeter AT1123 Atomtex
- Thermoluminescent dosimeters
- Anthropomorphic phantom
- Barium protection for the lens (equivalent to 0,125mm lead)
- Lead cervical collar
- Lead apron.
The study was performed in a phantom,
using manual exposure parameters.
In order to use the most similar to reality,
a survey of exposure parameters was conducted over two months.
It was later performed an analysis of various exposure parameters predefined by the equipment,
in order to integrate the measurements with the termoluminescent dosimeters (TLD) on the phantom.
The phantom was positioned in the panoramic radiography equipment (figure 1) and subsequently the various TLD dosimeters were placed on left eye to study ESD (Entrance Surface Dose) on crystalline,
the neck to study the thyroid and on the upper abdomen (figure 2 and 3).
Then we carried out the image acquisition to ensure correct positioning and proceed with the measurements.
For quantification of the ESD,
12 TLD dosimeters were used in four different configurations:
- 1st Measurement: Examination Standard unprotected
- 2nd Measurement: Pediatric Exam unprotected
- 3rd Measurement: Standard Test with protection
- 4th Measurement: Pediatric Exam with protection
For each configuration 3 dosimeters were always placed at the same anatomical sites (crystalline,
thyroid and body) and 5 exposures were performed for each configuration. Table 1 shows the respective exposure parameters.
Table1: Standard for dosimeter placement on specific anatomical sites and exposure parameters used.
|
Standard Exam
|
Paediatric Exam
|
Without radiological protection
|
Crystalline
|
Dosimeter 1
|
Dosimeter 4
|
Thyroid
|
Dosimeter 2
|
Dosimeter 5
|
Body
|
Dosimeter 3
|
Dosimeter 6
|
With radiological protection
|
Crystalline
|
Dosimeter 7
|
Dosimeter 10
|
Thyroid
|
Dosimeter 8
|
Dosimeter 11
|
Body
|
Dosimeter 9
|
Dosimeter 12
|
Exposure parameters
|
70kV,
6,3mA e 17,6s
|
60kV e 13mA e 16,8s
|