Master in Medical Physics 2015 to 2016

Practical Report Radiation Survey of a clinicalinstallation

Francisco J. Hernandez Flores

International Centre for Theoretical Physics

franciscohernandez_f2010@hotmail.com

December 24, 2015

Abstract

This task is relationship whit the Radiation Survey of a clinical installation,The objective is to establish basic requirements for protection against the risksassociated with exposure to ionizing radiation and for the safety of radiation sourcesthat may deliver such exposure. The Standards have been developed from widelyaccepted radiation protection and safety principles, such as those published in theAnnals of the ICRP and the IAEA Safety Series. One usually thinks of radiationsafety as keeping patient and personnel exposure as low as reasonably achievable;however, radiation protection activities play an important role in quality assurancefor both the clinical and physical aspects. Radiation protection has several aspects:The first step is the design of the irradiation device and its shielding.

I. Introduction

The radiation protection include clinical application because in different areaslike radiology (diagnostic with x-ray of low dose and nuclear medicine) andradiation therapy use ionizing radiation. In radiology and radiotherapy theradiation administered is external to the patient; in nuclear medicine, it isinternal. The discussion of each of these two classes of applications addressestypes of procedures, utilization, radiation doses, and radiation regulation andcontrol.This report talk about radiation protection in clinical application and the im-portance of radiation protection in the safety of the patient and the worker thiswas based in layout of the bunker for different type of machine and differentenergies.

II. Theory

I. Radiation protection areas

Radiation protection areas are established in the case of activities requiring apermit under national radiation protection legislation. Depending on the levelof radiation exposure. [1]

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Master in Medical Physics 2015 to 2016

I.1 Monitoring areas

Monitoring areas are in-plant areas which do not belong to the controlled areasand in which persons may receive an effective dose of more than 1 mSv ororgan doses higher than 15 mSV for the eye lens or 50 mSv for the skin, hands,forearms, feet and ankles in a calendar year.

I.2 Controlled areas

In controlled areas persons may receive an effective dose of more than 6 mSV ororgan doses higher than 45 mSv for the eye lens or 150 mSv for the skin, hands,forearms, feet and ankles in a calendar year.

I.3 Exclusion areas

Exclusion areas are part of the controlled areas where the local dose rate maybe higher than 3 millisievert per hour.

II. Biological Effects due to ionization radiation

The biological effects of ionizing radiation are broadly divided into two classes:deterministic and stochastic

II.1 Deterministic effects

(which can include blood changes, burns, nausea, diarrhoea, death) arise early(and/or late) in the exposed individual as a result of high radiation dosesreceived over a short time. Severity increases with radiation dose.

II.2 Stochastic effects

(primarily cancer and hereditary effects) may affect the exposed individual orfuture generations. The probability of their occurrence increases with radiationdose. (âAIJStochasticâAI means âAIJpertaining to chanceâAI)

III. Materials and Methods

CT, Ionization chamber and phantom.This practical was used the power point presentation for to explain us how

were structured the layout of the different equipment of clinical applicationand talked about shielding block of some area as: Linac radiation therapy,brachytherapy room and CT room. they talked us about different areas (con-trolled and uncontrolled), personal dosimetry and the responsibility of theofficer of radiation protection. The parameter used in the CT during all thismeasure are show in table 1.

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Master in Medical Physics 2015 to 2016

kV mA Thickness FOV120 200 8 cm 32 cm 400 L

Table 1: parameter of the CT during measure

After explaining to the class session we went to the layout of the equipmentand we check the diffuse radiation, inverse square law verification and shieldingverification of the CT room. The parameter used in CT for to make all of this

• For the check diffuse radiation we put the camera at 1.2 meter of theisocenter and we took three reading using and without using the phantom.

• For verify the square law we put the the camera at three difference distancefrom isocenter of CT and obtain the average of three lecture in eachposition of the camera.

• The last test was the shielding CT verification we took the measure indifferent parts of the bunker CT the table 4 show the place and result ofmeasure.

IV. Results and discussion

The table 2 show the outcome of the measure with the ionization camera withand without phantom we can see that the dispersion of the dose increase in thesame position when we use phantom.

without phantom 1.12 µSvwith phantom 7.20 µSv

Table 2: outcome of diffuse radiation at 1.2 meter from isocenter

The data show in the table 3 are the data measure changing the distancebetween source and camera. whit the result we can probe that the dose reducewith the distance.

Distance from source [m] reading [µSv]1 11

1.4 4.61.6 3

Table 3: Inverse square law verification

The last outcome are the measure about the verification of the shielding inCT scanner in different point the fig. 1 and the table 4 describe the differentplace that were positioning the ionization camera for to obtain the data. with

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Master in Medical Physics 2015 to 2016

this result we prove that the place of console behind of the glass is sure thenthe technique and radiology or oncology can work without problem becausethe dose is zero µ Sv.

Glass Shielding Door Wall ApronIn front Behind In front Behind In front Behind In front Behindo.65 µSv 0 µSv 0.65 µSv 0µSv 0.65 µSv 0 µSv 0.77 µSv 13.3 µSv

Table 4: reading about shielding verification in each point as its mention in the table but thelecture of apron were measure in the couch at 1 meter.

Figure 1: Plan of CT bunker [2]

V. Conclusion

• The good clinical practice and good shielding decrease the dose andprevent deterministic effects and reduction of the probability of stochasticeffects both patient and workers.

• The shielding must be sure that the dose in controlled areas and uncon-trolled areas must be low than dose reported for the International Basic.Safety Standards for bout worker and public.

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Master in Medical Physics 2015 to 2016

References

[1] IAEA, Radiation Protection and Safety of Radiation Sources: International BasicSafety Standards Revision of IAEA Safety Series No. 115, IAEA, Vienna Austria,2011

[2] Dedenaro, Lecture Radiation protection Italian law , Mageore Hospital TriesteItaly, 3rd trimester 2015.

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