Challenge to an occupational dose reductionin the medical field based on the dose mapping
obtained by a small type OSL dosimeter
Tohru Okazaki1, Tokiko Nakamura2, Ikuo Kobayashi1, 3, Shoichi Suzuki2,Takuya Hashizume1, 4, Vergil L E Cruz1, Cheng Wei Hsin1
1Nagase-Landauer, Ltd., Japan, 2Daido Hospital, Japan,3Fukui University, Japan, 4SOKENDAI, Japan

Introduction of our company
microSTARii
nanoDot

microStar

Provider of OSL dosimetry system
Personal dosimetry service

Tsukuba

IbarakiNagase-Landauer, Tsukuba

CraftMAP; http://www.craftmap.box-i.net/

Occupational dose of our customers
Mission of our company is …
• Report occupational doseof radiation workers.
• Reduce radiation
exposure according toALARA principle.
Collective effective dose of our customers in 2012 - 2016

We start the challenge to reduce
the occupational dose in hospital.

We focus on the staff ofinterventional Radiology (IR).

Exposure during IR procedures
Take measures
150 cm100 cm

50 cm
Image of Interventional radiology (IR).

Protective aprons

To reduce the radiation exposure, we focus on how to evaluate• The position of radiation source and the dose distribution.
• The effect of the procedure improvement when we takesome measures.

Jungle gym method (JG Method)
Assemble jungle gym by paper pipes andplastic joints that don’t disturb the dosedistribution.
To evaluate the dose distribution, put
dosimeters on the jungle gym at equalintervals.
We used a small type OSL dosimeter;
nanoDot for dose mapping.

nanoDot
Detection region

nanoDot; 10×10×2 mm

Doses of 50, 100, 150 cm height are mapped.

Invisible dosimeters in medical image don’t
disturb dose distribution in the field.

Measurement of nanoDot
Measuring nanoDot takes lessthan 10 s by portable OSL
reader (microStar).
microStar can work only withcommercial AC power supply.
nanoDot has good linearity inless than 10 μGy.

T. Okazaki et al., Applicability of Practical Calibration of a Small-type
OSL dosimeter for Measuring the Exposure Doses Effected byScattered and Penetrating X-rays, Progress in Nuclear Science andTechnology (In press)

Experiment of X-ray exposure
Exposure conditions
Tube voltage: 115 kV
Tube current: 2.5 mA
Exposure time: 10 min.
X-rays were exposed toacrylic phantom fromabove the couch.
Dose distribution of the position of medical staff during
IR procedures was evaluated in different 2 conditions.
The irradiated field size is Exp._1: 40 × 40 cm2Exp._2: 20 × 20 cm2

Dose map around the irradiated field

The X-rays exposed from overthe patient are mainly
scattered to above the patient.
Collimating the irradiation
field ¼, the dose reduced to ¼
in all area.
→ The collimator didn’t
make scattered X-rays.
Typical position of doctor

How to reduce the occupational dose?
Dose distribution in 150 cm Height
40×40 cmCouch

The dose map clearly shows
The high / low dose position.
The impact of work procedurechange on dose distribution.
Medical staff
20×20 cm

Medical staff

Couch

The dose map is a useful tool to have a
discussion toward the dose reduction.
Where is better position?
Whether or not the measures areuseful?

Conclusions
The Jungle Gym (JG) method can evaluate thedose distribution around the irradiation field.
The JG method using nanoDot makes it easy toevaluate the dose distribution on site.
JG method is useful tool to evaluate the dose
distribution toward the reduction ofoccupational dose.