Safety Code 35 Flashcards
does safety code 35 apply to denstistry, chiro, podiatry, mammo?
no
they have other safety codes for those
somatic effects vs genetic effects
somatic= changes in exposed individual genetic= gives rise to genetic effects
how are estimates of incidence of cancer at low dose determined?
- cannot b measured
- based on linear extrapolation from relatively high doses
linear no treshold hypothesis
health risk from exposure is proportional to dose
4 main aspects of radiation protection for diagnostics
- jutification for medical exam
- patient is protected from excess radiation
- staff are protected
- general public is protected
who is ultimately responsible for safety of facility?
owner
when does responsible personel investigate exposures received by personnel?
- if exposure is higher that usual dose received by that person
- > 1/20 of dose limit for radiation workers
when must staff wear personal dosimeter
-if they are likely to receive a dose in excess of 1/20 of dose limit for radiation worker (i.e. 1 mSv) (i.e. occupationally exposed person)
o CNSC Radiation Protection Regulations says that personnel dosimetry is required for NEWs who have a reasonable probability of receiving an effective dose greater than 5 mSv in a one-year dosimetry period
HL7
health level 7
standard for exchanging information between medical information systems.
DICOM
digital imaging and communications in medicine
general requirements for diagnostics
- x-ray room cannot be used for more than one radiological investigation simultaneously
- unless essential, everyone leaves room when irradiation comes on
- personnel should keep away from x-ray beam
- irradiating someone for traning or evaluation is not allowed
- all personnel must use available protective devices
- workers who are likely to receive > 1/20 of dose limit must be declare radiation workers and wear personal dosimeter
- personal dosimeters must be worn and stored according to recommendations of dosimetry service provider. When a protective apron is worn, personal dosimeter must be worn under the apron. If extremeties likely to be exposed, additional dosimeters should be worn at those locations
- personal dosimetry records must be maintained for lifetime of facility
- female operator must notify employer of pregnancy
- if weak persons need support, holding devices should be used (not staff)
- all entrance doors to xray room should be closed while patient in the room and during exposure
- energized xray machines must not be left unattended
rules regarding mobile x-rays
- only use if needed
- direct xray away from occuppied areas
- operator must not stand in front of direct beam and must be > 3 m away from x-ray tube unless wearing PPE or behind leaded shield
- residual charge must be fully discharged before unit is unattended
requirements of radioscopy
-all persons with possible exception of patient must wear leded apron (shields and curtains are not enough)
one of greatest sources of exposure to personnel in radiology
angiography
requires the presence of a considerable number of personnel close to the patient, radioscopy for extended periods of time and multiple radiographic exposures
recommendations for angiography
- use [protective devices such as shielded drapes etc
- The patient is the largest source of scatter radiation. To avoid this scatter, operate the equipment with the tube under the patient and, if the tube is horizontal, stand on the side of the image receptor.
- PPE (including glasses) and dosimeters must be worn
- personnel not required right by patient should stand behind shields
largest source of scatter radiation in angiography
patient
medical and dental x-rays account for what % of man-made dose to public?
90%
when is risk of pregnancy small? (for pelvic tests)
10 days following menstruation
recommendations for pregnant or potentially pregnant women
Only essential investigations should be taken in the case of pregnant or suspected pregnant women.
When radiological examinations of the pelvic area or abdomen are required, the exposure must be kept to the absolute minimum necessary and full use must be made of gonadal shielding and other protective shielding if the clinical objectives of the examination will not be compromised.
If a radiological examination of the foetus is required, the prone position should be used. This has the effect of shielding the foetus from the softer X-rays and hence reducing the foetal dose.
Radiography of the chest, extremities, etc., of a pregnant woman, for valid clinical reasons, should only be carried out using a well-collimated X-ray beam and with proper regard for shielding of the abdominal area.
xray beam size limit
size of image receptor or smaller
considerations to ensure patient exposure is kept to minimum
- use of an anti-scatter grid or air gap between the patient and the image receptor;
- use of the optimum focal spot-to-image receptor distance appropriate to the examination;
- use of the highest X-ray tube voltage which produces images of good quality;
- use of automatic exposure control devices designed to keep all irradiations and repeat irradiations to a minimum.
what should you do before taking long series of images?
check the first one to ensure correct setup
difference between radioscopy and radiography
radiography is an off-line, static examination technique, while radioscopy is a dynamic examination technique with the potential for on-line examination and process control.
radioscopy is more dose- only use when necessary
why does operator monitor tube current and voltage when using AEC?
both can rise to high values without the knowledge of the operator, particularly if the gain of the intensifier is decreased