Physics and Quality and Safety Review

0.5 mm

50 mSv

5 mSv (1/10 of annual dose of non-pregnant radiation worker)

2 Gy

150 mSv

2 mrem (0.02 mSv)

100 mCi of Tc or Thallium (lower energy)

10 mCi of Gallium or Indium (medium energy)

1 mCi of I-131 (high energy)

0.5 mSv every month

5 mSv for the duration of the pregnancy

500 mSv

5 mSv - Effective dose limit

15 mSv - Lens of eye

50 mSv - Skin/hands/feet/organs

Side lobes are multiple beams of low-amplitude ultrasound energy that project radially from radial expansion of piezoelectric crystals

- Seen primarily in linear-array transducers

- Strong reflectors present in the path of these low-energy, off-axis beams may create echoes detectable by the transducer.

- Most likely to be recognized as extraneous echoes present within an expected anechoic structure such as the bladder.

Cathode side - x rays have less material to go through

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Absorbed dose is the concentration of energy deposited in tissue as a result of an exposure to ionizing radiation (measured in mGy)

Equivalent dose is an amount that takes the damaging properties of different types of radiation into account (unit Sv (Joules/kilogram))

Absorbed dose tells us the energy deposit in a small volume of tissue. Equivalent dose addresses the impact that the type of radiation has on that tissue. Also known as the " biological dose," the dose equivalent is calculated as the product of absorbed dose in tissue multiplied by a quality factor and then sometimes multiplied by other necessary modifying factors at the location of interest.

Effective dose is a calculated value (measured in mSv) that takes three factors into account:the absorbed dose to all organs of the body,the relative harm level of the radiation, andthe sensitivities of each organ to radiation. The sum of the products of the dose equivalent to the organ or tissue (HT) and the weighting factors (WT) applicable to each of the body organs or tissues that are irradiated (HE = ΣWTHT).

SI unit - Sievert (Sv)

Non SI unit - rem

1 Sv = 100 rem

Approximately 10% per gray (0.1% per rad)

0.5 Gy

M phase - mitotic phase

2 Gy

0.1 Gy

Quantity of charge in air due to ionization from x-rays or gamma rays (C/kg, historical unit was the Roentgen)

Binding energy of the k-shell electron

3 mGy

• It occurs due to the interaction of the X-ray or gamma photon with the outermost (and hence loosely bound) valence electron at the atomic level. The resultant incident photon gets scattered (changes direction) as well as ejects the electron (recoil electron), which further ionizes other atoms.
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Average energy deposited in mass per unit path length

1 Gy - may start seeing nausea/anorexia

7 Gy

500 mrem (5 mSv)

15 Gy

6 Gy

(3 Gy for females)

Notices, instructions and reports to workers

As the dose increases, the probability of occurence increases (not severity)

Greater than 10% annual dose limit expected 

> 500 mrem (5 mSv)/year

Can cause peripheral nerve stimulation - tingling/twitching sensation

TR x number of phase encoding steps x average number of excitations

Above the knee - surgical

Below the knee - thrombolytics

Can cause augmentation of T waves