MOD 8 - Minimizing Patient Dose, Dose Limits, DRLs

International Commission on Radiation Protection (ICRP) Principles

1. Justification

   • role of the ordering physician and ALARA principle

2. Optimization

   • customizing exposure factors for diagnostic images at the lowest dose

3. Dose Limit

   • DRL values which are calculated as the 75% percentile of overall exam exposures

Diagnostic reference level (DRL)

= used as a reference value, instead of dose limits

• NOT dose limits

The MUSTS for Prescription of X-ray Examinations

• prescriptions must be based on clinical evaluation

• the # of imaging exams must be minimized

• pregnancy must be ruled out prior to imaging

Guidelines for Radiological Examinations during Pregnancy

• delay exams if they aren’t emergent or consider other modalities (u/s)

• keep the exposure to the absolute minimum

• utilize prone position

• collimate

pregnancy once declared should not exceed

4mSv during the period of pregnancy

Guidelines for Radiological Procedures

• AEC

• all exams are justified

• max SSD

• optimization

• document (rejects, repeats)

the MUSTS of Mobile Radiation Safety

• operator must not stand in the path of the CR

• equipment must be disabled when left unattended

• operator must stand 3m away from source if not wearing lead ppe

• operator must wear protective apparel

• forewarning of radiation around surrounding personnel

• must announce "X-ray in room ___"

Lower Mainland Clinical Site Pregnancy Screening Protocol

techs are only required to ask about pregnancy to females between age 11-55 when performing imaging on patients between the diaphragm and the pubic symphysis

Negative Effects of Lead Shielding

• increasing internal scatter (scatter travelling out of the body might bounce back into the body due to lead)

• causing equipment malfunction if placed too near to the imaging field

• exposure to infectious microbes