Radiation Dose Information

 

. Common Terms

. Doses from Radioactive Material Procedures

. Doses from Diagnostic Radiology Procedures

. Fetal Dose Estimates

. Occupational Exposure Limits

 

 

COMMON TERMS

EDE

The concept of effective dose equivalent (EDE) was introduced to provide a mechanism for assessing the radiation detriment from partial body irradiations in terms of data derived from whole body irradiations. EDE is expressed in rem and takes into account the quality factor of the radiation, the dose to all the organs that are irradiated and their sensitivity to radiation. The rem has been replaced by the sievert in the SI system of units (1 sv = 100 rem).

RAD

The original unit developed for expressing absorbed dose, which is the amount of energy from any type of ionizing radiation (e.g., alpha, beta, gamma, neutrons, etc.) deposited in any medium (e.g., water, tissue, air). A dose of one rad is equivalent to the absorption of 100 ergs (a small but measurable amount of energy) per gram of absorbing tissue. The rad has been replaced by the gray in the SI system of units (1 gray = 100 rad). www.hps.org

REM (Roentgen Equivalent Man)

A unit in the traditional system of units that measures the effects of ionizing radiation on humans.
The rem has been replaced by the Sievert in the SI system of units (1 Sievert = 100 rem).
www.hps.org

For diagnostic x-ray exposure, a rem is approximately equivalent to a rad

ALARA
Acronym for "As Low As Reasonably Achievable." It means making every reasonable effort to maintain exposures to ionizing radiation as far below the dose limits as practical. Be consistent with the purpose for which the licensed activity is undertaken, taking into account the state of technology, the economics of improvements in relation to state of technology, the economics of improvements in relation to benefits to the public health and safety, and other societal and socioeconomic considerations. These means are in relation to utilization of nuclear energy and licensed materials in the public interest. www.hps.org

See http://hps.org/publicinformation/radterms/ for additional radiation terms

 

RADIATION DOSE ESTIMATES FROM COMMONLY USED RADIOPHARMACEUTICALS
(Taken from the Radiation Internal Dose Information Center, RIDIC, dose estimate tables)

Radiopharmaceutical	Typical Dose (mCi)	Organ Receiving Highest Dose	Organ Dose (rad)	Effective Dose Equivalent (rem)
F18 FDG	10	Bladder Wall	7.0	1.1
In111 White Blood Cells	0.5	Spleen	11	1.2
I123 Sodium Iodide	0.4	Thyroid	5.2	0.18
I131 Sodium Iodide	25	Thyroid	32,500	975
Xe133 Gas (5min breathing)	15	Lung	0.06	0.04
Tl201 Chloride	3	Heart Thyroid	3 6.9	1.8
Tc99m Pertechnetate	10	Bladder Wall	1.3	0.39
Tc99m Red Blood Cells	20	Bladder Wall	1.6	0.54
Tc99m Pyrophosphate	20	Bone Surface	2.8	0.44
Tc99m MDP	30	Bone Surface	3.9	0.66
Tc99m Mag3	10	Bladder Wall	5.1	0.44
Tc99m DTPA - Renal	20	Bladder Wall	5.6	0.6
Tc99m Sulfur Colloid	8	Liver	2.56	0.4
Tc99m Disofenin (HIDA)	5	G.B. Wall	2	0.47
Tc99m Sestamibi (Cardiolite)	20	Upper Lg Int.	3.7	1.1
Ga67 Citrate	5	Bone Surface	6	2.05
Tc99m MAA	4	Lungs	1.0	0.19
Tc99m DTPA Aerosol	1.1	Bladder	0.13	0.02

 

 

EFFECTIVE DOSE EQUIVALENTS FOR COMMON DIAGNOSTIC PROCEDURES

PROCEDURE	ESTIMATED EDE (mrem)*
Chest X-Ray	8
Skull X-Ray	22
Cervical Spine	20
Lumbar Spine	127
KUB	56
Upper GI	244
Barium Enema	406
Diagnostic Cardiac Catheterization**	2500**
*Adapted from NCRP Report 100 ** W. Huda, "Patient Dose in Radiology,",www.imagingeconomics.com/issues/articles/2001-07_01.asp
PROCEDURE	ESTIMATED EDE (mrem)
*Adult Head CT	100-200
*Adult Body CT (chest or abdomen/Pelvis)	500-1000
**Coronary Artery Calcium CT	100-300
**Coronary CT Angiography	500-1200
W. Huda, E.L. Nickeloff and J.M. Boone. "Overview of Patient Dosimetry in Diagnostic Radiology in the USA for the past 50 years", Medical Physics, Vol. 35, No. 12, pp 5713-5728 *The total dose to the patient increases when scans are performed with and without the administration of iodinated contrast materials. **McCollough, Cynthia H. PhD, et al. Dose Performance of a 64 Channel Dual Source CT Scanner. Radiology, 2007;243:775-784

 

FETAL RADIATION DOSE ESTIMATES FROM COMMONLY USED RADIOPHARMACEUTICALS
(Taken from the Radiation Internal Dose Information Center, RIDIC, dose estimate tables)

Radiopharmaceutical	Typical Dose (mCi)	Early Fetal Dose (rad)	3 month Fetal Dose (rad)	6 month Fetal Dose (rad)	9 month Fetal Dose (rad)
F18 FDG	10	1.0	0.63	0.35	0.3
In111 White Blood Cells	0.5	0.26	0.19	0.19	0.19
I123 Sodium Iodide	0.4	0.030	0.021	0.016	0.014
I131 Sodium Iodide	25	6.6	6.0	21.3	25
Xe133 Gas (5min breathing)	15	0.023	0.003	0.002	0.001
Tl201 Chloride	3	1.1	0.64	0.52	0.3
Tc99m Pertechnetate	10	0.4	0.8	0.5	0.3
Tc99m Red Blood Cells	20	0.5	0.35	0.26	0.21
Tc99m Pyrophosphate	20	0.44	0.48	0.26	0.21
Tc99m MDP	30	0.69	0.6	0.3	0.3
Tc99m Mag3	10	0.7	0.5	0.2	0.2
Tc99m DTPA - Renal	20	0.9	0.8	0.4	0.34
Tc99m Sulfur Colloid	8	0.05	0.06	0.09	0.11
Tc99m Disofenin (HIDA)	5	0.3	0.3	0.22	0.12
Tc99m Sestamibi (Cardiolite)	20	1.1	0.9	0.6	0.4
Ga67 Citrate	5	1.7	3.7	3.3	2.4
Tc99m MAA	4	0.03	0.04	0.054	0.04
Tc99m DTPA Aerosol	1.1	0.023	0.017	0.0092	0.012

 

FETAL DOSE ESTIMATES FOR COMMON X-RAY EXAMS

Assumes Average Size Adult

Exam	Average SkinExposure (mR)*	Conversion FactorDose (mrad/R)**	Estimated Fetal Dose(mrad)
AP L-S Spine	350	272	95
PA Chest - Grid	15	2.0	0.03
PA Chest - No Grid	5	2.0	0.01
Abdomen	300	330	99
Pelvis	300	353	106
Cervical Spine	95	No detectable contribution	---
Lateral Skull	70	No detectable contribution	---
Extremities	--	No detectable contribution	---
CT Exams***	CT scans of pregnant patients results in embryo doses that range between 1000 and 3500 mrad when the embryo/fetus is in the direct x-ray beam, but much lower doses when the conceptus does not undergo direct irradiation such as in a chest CT scan.

* Taken from New York State Department of Health Guide for 400 Speed Film/Screen System.

** Taken from "Handbook of Radiation Doses in Nuclear Medicine and Diagnostic X-Ray", CRC Press, 1980, James G. Kereiakes and Marvin Rosenstein. Assumes Half Value Layer of 3.0 mm. of Al.

*** W. Huda, E.L. Nickeloff and J.M. Boone. "Overview of Patient Dosimetry in Diagnostic Radiology in the USA for the past 50 years", Medical Physics, Vol. 35, No. 12, pp 5713-5728

 

 

OCCUPATIONAL EXPOSURE LIMITS

	Annual Dose Limit	ALARA I Level	ALARA II Level
Whole Body	5 rem	0.125 Rem/quarter	0.375 Rem/quarter
Extremity	50 rem	1.875 Rem/quarter	5.625 Rem/quarter
Skin	50 rem	0.750 Rem/quarter	2.25 Rem/quarter
Lens of Eye	15 rem	0.125 Rem/quarter	0.375 Rem/quarter

ALARA I - Notify employee.
ALARA II - Notify employee and investigate cause. Take corrective action.