Effects do different doses of radiation have on people

One sievert is a large dose. The recommended TLV is average annual dose of 0.05 Sv (50 mSv).

The effects of being exposed to large doses of radiation at one time (acute exposure) vary with the dose. Here are some examples:

10 Sv - Risk of death within days or weeks

1 Sv - Risk of cancer later in life (5 in 100)

100 mSv - Risk of cancer later in life (5 in 1000)

50 mSv - TLV for annual dose for radiation workers in any one year

20 mSv - TLV for annual average dose, averaged over five years

Units used for measuring radiation dose

When ionizing radiation interacts with the human body, it gives its energy to the body tissues. The amount of energy absorbed per unit weight of the organ or tissue is called absorbed dose and is expressed in units of gray (Gy). One gray dose is equivalent to one joule radiation energy absorbed per kilogram of organ or tissue weight. Rad is the old and still used unit of absorbed dose. One gray is equivalent to 100 rads.

1 Gy = 100 rads

Equal doses of all types of ionizing radiation are not equally harmful. Alpha particles produce greater harm than do beta particles, gamma rays and x rays for a given absorbed dose. To account for this difference, radiation dose is expressed as equivalent dose in units of sievert (Sv). The dose in Sv is equal to "absorbed dose" multiplied by a "radiation weighting factor" (W_R - see Table 2 below). Prior to 1990, this weighting factor was referred to as Quality Factor (QF).

Table 2 Recommended Radiation Weighting Factors
Type and energy range	Radiation weighting factor, WR
Gamma rays and x rays	1
Beta particles	1
Neutrons, energy < 10 keV > 10 keV to 100 keV > 100 keV to 2 MeV > 2 MeV to 20 MeV > 20 MeV	5 10 20 10 5
Alpha particles	20

Equivalent dose is often referred to simply as "dose" in every day use of radiation terminology. The old unit of "dose equivalent" or "dose" was rem.

Dose in Sv = Absorbed Dose in Gy x radiation weighting factor (WR)

Dose in rem = Dose in rad x QF

1 Sv = 100 rem

1 rem = 10 mSv (millisievert = one thousandth of a sievert)

1 Gy air dose equivalent to 0.7 Sv tissue dose (UNSEAR 1988 Report p.57)

1 R (roentgen) exposure is approximately equivalent to 10 mSv tissue dose

Units used for measuring radiation energy

The energy of ionizing radiation is measured in electronvolts (eV). One electronvolt is an extremely small amount of energy. Commonly used multiple units are kiloelectron (keV) and megaelectronvolt (MeV).

6,200 billion MeV = 1 joule

1 joule per second = 1 watt

1 keV = 1000 eV, 1 MeV = 1000 keV

Watt is a unit of power, which is the equivalent of energy (or work) per unit time (e.g., minute, hour).

Units used for measuring radiation exposure

X-ray and gamma-ray exposure is often expressed in units of roentgen (R). The roentgen (R) unit refers to the amount of ionization present in the air. One roentgen of gamma- or x-ray exposure produces approximately 1 rad (0.01 gray) tissue dose (see next section for definitions of gray (Gy) and rad units of dose).

Another unit of measuring gamma ray intensity in the air is "air dose or absorbed dose rate in the air" in grays per hour (Gy/h) units. This unit is used to express gamma ray intensity in the air from radioactive materials in the earth and in the atmosphere.

Genetic Radiation Risks to the Live born child in an AIRCRAFT

A live born child conceived after radiation exposure of one or both parents is considered to be at risk of inheriting one or more radiation-induced genetic defects.
Worse case scenario: where both parents have been exposed (Risk is additive) is 171 in 1 million (or 2 in 10,000) which is 0.002% , 1 /100th of the general population risk
Note: These are additional risk factors to the general population rate of serious anatomic abnormalities in offspring which, in the West, is 200 - 300 in 10,000 or 2% to 3%

Tests for Cosmic Radiation in AIRCREW

A British Airway study of 411 pilot deaths did reveal that incidence of malignant melamona, colon and brain cancers were above average.

Women, seem to be at greatest risk. An investigation by Finnair between 1940 and 1992 showed that air hostesses were at twice the risk of breast cancer compared to the average flier.

Source: http://www.flighthealth.org/

Genetic Radiation Risk to the Unborn Child while travelling in AIRCRAFT

For the unborn child the risk of harm depends on several factors

• The stage of fetal development
• The duration of exposure
• The exposure dose
• Dates of exposure during pregnancy

The estimated risk to a child of a serious health defect from prenatal exposure to Cosmic Radiation (flying for 7 months at 100 hours per month, with an exposure of 0.58mSv/100 block hours - say continual work on the Athens - New York route) is 1 in 1,100.

Probable Health Effects resulting from Exposure to Ionizing Radiation

Probable Health Effects resulting from Exposure to Ionizing Radiation
Dose, rem (whole body)	Immediate Health Effects	Delayed Effects
1,000 or more	Immediate death. "Frying of the brain"	None
600 - 1,000	Weakness, nausea, vomiting and diarrhoea followed by apparent improvement. After several days: fever, diarrhoea, blood discharge from the bowels, haemorrhage of the larynx, trachea, bronchi or lungs, vomiting of blood and blood in the urine.	Death in about 10 days. Autopsy shows destruction of hematopoietic tissues, including bone marrow, lymph nodes and spleen; swelling and degeneration of epithelial cells of the intestines, genital organs and endocrine glands.
250 - 600	Nausea, vomiting, diarrhoea, epilation (loss of hair), weakness, malaise, vomiting of blood, bloody discharge from the bowels or kidneys, nose bleeding, bleeding from gums and genitals, subcutaneous bleeding, fever, inflammation of the pharynx and stomach, and menstrual abnormalities. Marked destruction of bone marrow, lymph nodes and spleen causes decrease in blood cells especially granulocytes and thrombocytes.	Radiation-induced atrophy of the endocrine glands including the pituitary, thyroid and adrenal glands. From the third to fifth week after exposure, death is closely correlated with degree of leukocytopenia. More than 50% die in this time period. Survivors experience keloids, ophthalmological disorders, blood dyscrasis, malignant tumours, and psychoneurological disturbances.
150 - 250	Nausea and vomiting on the first day. Diarrhoea and probable skin burns. Apparent improvement for about two weeks thereafter. Foetal or embryonic death if pregnant.	Symptoms of malaise as indicated above. Persons in poor health prior to exposure, or those who develop a serious infection, may not survive. The healthy adult recovers to somewhat normal health in about three months. He or she may have permanent health damage, may develop cancer or benign tumours, and will probably have a shortened lifespan. Genetic and teratogenic effects.
50 - 150	Acute radiation sickness and burns are less severe than at the higher exposure dose. Spontaneous abortion or stillbirth.	Tissue damage effects are less severe. Reduction in lymphocytes and neutrophils leaves the individual temporarily very vulnerable to infection. There may be genetic damage to offspring, benign or malignant tumours, premature ageing and shortened lifespan. Genetic and teratogenic effects.
10 - 50	Most persons experience little or no immediate reaction. Sensitive individuals may experience radiation sickness.	Transient effects in lymphocytes and neutrophils. Premature ageing, genetic effects and some risk of tumours.
0 - 10	None	Premature ageing, mild mutations in offspring, some risk of excess tumours. Genetic and teratogenic effects.

Effects of Cosmic Radiation on Aircrew

Hours Exposure for Effective Dose of 1 millisievert
Altitude (ft)	Altitude (m)	Hours at latitude 30° S(1)	Hours at equator(2)
27,000	8,230	510	1,330
30,000	9,140	380	980
33,000	10,060	300	750
36,000	10,970	240	600
39,000	11,890	200	490
42,000	12,800	170	420
45,000	13,720	150	380
48,000	14,630	140	350
Effects of Cosmic Radiation on Aircrew

Route Estimates	Dose/Flight (µSv)	Flights for 1 mSv
Darwin-Perth	16	62
Perth-Broome-Darwin	8	131
Darwin-Singapore	9	107
Frankfurt-Singapore	39	25
Melbourne-Johannesburg	71	14
Melbourne-Singapore-London	65	15
London-Singapore-Melbourne	42	23
Sydney-Buenos Aires	68	15
Buenos Aires-Sydney	80	13
Data provided by Capt Ian Getley and adapted for presentation 1 mSv = 1000 µSv

Average Natural Background Radiation doses in USA

Average Natural Background: 300 Millirems
The average exposure in the United States, from natural sources of radiation (mostly cosmic radiation and radon), is 300 millirems per year at sea level. Radiation exposure is slightly higher at higher elevations-thus the exposure in Denver averages 400 millirems per year.

(A milliRem is 1/1000th of a Rem. According to McGraw-Hill's Dictionary of Scientific and Technical Terms, a Rem is a unit of ionizing radiation equal to the amount that produces the same damage to humans as one roentgen of high-voltage x-rays. The name is derived from "Roentgen equivalent man." Wilhelm Roentgen discovered ionizing radiation in 1895 at about the same time that Pierre and Marie Curie discovered radium.)

All of these limits are for the amount of radiation exposure in addition to background radiation and medical radiation.

Urinary and Bladder Changes due to Radiation Therapy

Radiation therapy can cause urinary and bladder problems, which can include:

• Burning or pain when urinating or after emptying the bladder
• Trouble starting to urinate
• Trouble emptying the bladder
• Frequent, urgent need to urinate
• Cystitis, a swelling (inflammation) in the urinary tract
• Incontinence, when the patient cannot control the flow of urine from the bladder, especially when coughing or sneezing
• Frequent need to get up during sleep to urinate
• Blood in the urine
• Bladder spasms, which are like painful muscle cramps

Urinary and bladder problems may occur when people get radiation therapy to the prostate or bladder. Radiation therapy can harm the healthy cells of the bladder wall and urinary tract, which can cause inflammation, ulcers, and infection.

Urinary and bladder problems often start 3 to 5 weeks after radiation therapy begins. Most problems go away 2 to 8 weeks after treatment is over.

Fertility-preserving options for women in Cancer treatment

Fertility-preserving options for women 

Protection of the ovaries from radiation therapy. For women receiving radiation therapy to the pelvic region, it can be difficult to shield one or both ovaries. If both ovaries receive radiation treatment, infertility may be permanent. However, in many cases, both ovaries do not receive radiation treatment, so any resulting infertility may not be permanent. Another option is oophoropexy, which involves surgically moving one or both ovaries out of the radiation field.

Embryo cryopreservation. This is the process of harvesting eggs for in vitro fertilization and freezing the embryos for later use in women of reproductive age. Some ethical issues—such as what to do with unused fertilized embryos—arise with this technique and require careful discussion.

Oocyte (unfertilized egg) cryopreservation. Freezing unfertilized eggs is currently investigational.

Ovarian-tissue preservation. This method is currently investigational; it requires the surgical removal, preservation, and reimplantation of ovarian tissue both before and after puberty. This may not be a practical option for girls younger than age 18 because of informed consent issues.

Gonadotropin-releasing hormones (GnRH) analog treatment. In this investigational approach, GnRHs are given along with chemotherapy to potentially reduce the possible harmful effects of chemotherapy on the reproductive organs and to lower the risk of infertility after treatment.

Abdominal radical trachelectomy. Recent research shows that women with cervical cancer who have surgery to remove the cervix while keeping the uterus intact may become pregnant. In such cases, the baby would be delivered by cesarean section.

Oral contraception. Some research shows that women who take oral contraceptives (birth control pills) during chemotherapy may conserve eggs following treatment. This approach is still investigational and may not be recommended for a woman with a tumor that is sensitive to hormones (such as some types of breast cancer).

Fertility-preserving options for men in Cancer treatment

Fertility-preserving options for men 

Protection of the testes from radiation therapy. In men, it is possible to shield the testes from radiation if the cancer is present in other parts of the pelvis.

Sperm cryopreservation (sperm banking). This procedure involves freezing and storing of semen for men who wish to father children later in life. It is an option for most men who have reached sexual maturity.

Testicular-tissue cryopreservation and reimplantation. This investigational option involves the removal, freezing, and storage of testicular tissue that is surgically reimplanted after cancer treatment.

Hormonal gonadoprotection. This approach uses hormone therapy to protect testicular tissue during chemotherapy or radiation therapy, and it is still investigational.

Sexual and Fertility Problems for women due to Radiation Therapy

Problems for women include:

• Pain or discomfort when having sex
• Radiation to the shaded area may cause sexual and fertility changes.
• Vaginal itching, burning, dryness, or atrophy (when the muscles in the vagina become weak and the walls of the vagina become thin)
• Vaginal stenosis, when the vagina becomes less elastic, narrows, and gets shorter
• Symptoms of menopause for women not yet in menopause. These include hot flashes, vaginal dryness, and not having your period.
• Not being able to get pregnant after radiation therapy is over

Occupational Ionising Radiation Dose Limits for Adults

An annual limit of 5 rem (0.05 Sv) total effective dose equivalent (TEDE).

An annual limit of 50 rem (0.50 Sv) to an individual organ or tissue other than the lens of the eye, as determined by the deep-dose equivalent and the committed dose equivalent.

An annual limit of 15 rem (0.15 Sv) to the lens of the eye.

An annual limit of 50 rem (0.50) Sv) to the skin.

An annual limit of 50 rem (0.50 Sv) to each of the extremities.

The above limits must be reduced by the amount of occupational dose received while employed by someone other than Oregon State University during the current year.

Automatic Exposure Control in CT to reduce the Rdiation Dose

Automatic Exposure Control in CT

AEC is analogous to acquisition timing in general radiography. The user determines the image quality requirements (as regards noise or the contrast-to-noise ratio), and the CT system determines the right tube current–time product. In practice, Automatic Exposure Control in CT is relatively straightforward for the system to deliver the desired image quality, once that has been defined. However,  Automatic Exposure Control in CT  can be quite difficult to achieve agreement on the image quality requirement for the various CT examination types and patient age groups.

In defining the required image quality, the user needs to remember that pretty pictures are not needed for all diagnostic tasks, but, rather, a choice can be made between low noise and a low dose, depending on the diagnostic task. The CT system will then adjust the tube current during the gantry rotation, during movement along the z-axis, or during movement in all three dimensions, according to the patient’s body habitus and the user’s image quality requirements. Thus, we differentiate between the modulation of the tube current to achieve a defined image quality, and the prescription of the desired image quality by the user. Together these tasks are referred to as  Automatic Exposure Control in CT .

Mechanisms for Dose Reduction at CT

 Mechanisms for Dose Reduction at CT

Protecting the Embryo-Fetus from Ionising Radiation

Although heritable effects from radiation exposure have not been observed in humans, the embryo-fetus is known to be more sensitive to radiation than are adults. Therefore, individuals who are pregnant, think they are pregnant, or are planning a pregnancy may want to notify the Health Services Department as early as possible. Workplace or task modification is typically not necessary because 96 percent of all National Lab personnel who are monitored receive only background levels of radiation. The Laboratories cannot give this special consideration until the pregnancy is declared.

Radiation dose limits for a pregnant Radiation worker

The "declared" pregnant worker and her employer are encouraged to arrange for a mutually agreeable reassignment of work tasks, with no loss of pay or promotional opportunity, such that occupational radiation exposure is unlikely. 

For a declared pregnant worker who continues working in radiological areas, the following radiation dose limits will apply. The dose limit for the embryo/fetus (during entire gestation period) is 0.500 rem. Efforts should be made to avoid exceeding 50 millirem/month to the pregnant worker. If the dose to the embryo/fetus is determined to have already exceeded 500 mrem when a worker notifies her employer of her pregnancy, the worker should not be assigned to tasks where additional occupational radiation exposure is likely during the remainder of the pregnancy. 

It is important to note that the declaration of pregnancy is a voluntary measure taken by the expectant parent. No special dose limitations may be applied to pregnant workers without their written consent in the form of the declaration of pregnancy. If you have any questions regarding this policy, you should contact the Radiation Control Group. 
Radiation dose limits for a pregnant Radiation worker

Units used for measuring Radioactivity

Radioactivity or the strength of radioactive source is measured in units of becquerel (Bq).

1 Bq = 1 event of radiation emission per second.

One becquerel is an extremely small amount of radioactivity. Commonly used multiples of the Bq unit are kBq (kilobecquerel), MBq (megabecquerel), and GBq (gigabecquerel).

1 kBq = 1000 Bq, 1 MBq = 1000 kBq, 1 GBq = 1000 MBq.

An old and still popular unit of measuring radioactivity is the curie (Ci).

1 Ci = 37 GBq = 37000 MBq.

One curie is a large amount of radioactivity. Commonly used subunits are mCi (millicurie), µCi (microcurie), nCi (nanocurie), and pCi (picocurie).

1 Ci = 1000 mCi; 1 mCi = 1000 µCi; 1 µCi = 1000 nCi; 1 nCi = 1000 pCi.

Another useful conversion formula is:

1 Bq = 27 pCi.

Becquerel (Bq) or Curie (Ci) is a measure of the rate (not energy) of radiation emission from a source.

The NRC limits for I-131

Occupational limits for radionuclide exposure address ingestion, inhalation, and external exposure and are set by the Nuclear Regulatory Commission (NRC) for NRC licensees and by the Department of Energy for DOE facilities. "The NRC limits for I-131" are as follows:

• 2 ×10^-8 µCi/mL (for occupational air exposure)
• 2 ×10^-10 µCi/mL (for effluent air to which the public could be exposed)
• 1 ×10^-6 µCi/mL (in effluent water), and
• 1 ×10^-5 µCi/mL (for monthly average releases to sewers from medical facilities).

These NRC limits are intended to ensure that no worker exceeds 50 mSv (5 rem) of I-131 to the whole body or 500 mSv (50 rem) to the thyroid, and that no member of the public exceeds 1 mSv (0.1 rem) to the whole body.

Annual Radiation Dose Limits

Annual Radiation Dose Limits	Agency
Radiation Worker - 5,000 mrem	(NRC, "occupationally" exposed)
General Public - 100 mrem	(NRC, member of the public)
General Public - 25 mrem	(NRC, D&D all pathways)
General Public - 10 mrem	(EPA, air pathway)
General Public - 4 mrem	(EPA, drinking water pathway)

Average Annual Occupational Radiation.

Average Annual Occupational Radiation.
Occupation	Dose (mrem/yr)
Airline flight crew member	~500
Nuclear power plant worker	310
Medical personnel	70

Organ Radiation dose limits and TJNAF control levels

Organ Radiation dose limits and TJNAF control levels

ORGAN	DOE DOSE LIMIT	TJNAF ADMIN LIMIT
Extremities	50 rem/year	10 rem/year
Skin and other organs	50 rem/year	10 rem/year
Lens of the eye	15 rem/year	3 rem/year

Regulatory Limits for Occupational Radiation Exposure

Many of the recommendations from the ICRP and other groups have been incorporated into the regulatory requirements of countries around the world. In the United States, annual radiation exposure limits are found in Title 10, part 20 of the Code of Federal Regulations, and in equivalent state regulations. For industrial radiographers who generally are not concerned with an intake of radioactive material, the Code sets the annual limit of exposure at the following:

1) the more limiting of:

• A total effective dose equivalent of 5 rems (0.05 Sv)
  or
• The sum of the deep-dose equivalent to any individual organ or tissue other than the lens of the eye being equal to 50 rems (0.5 Sv).

2) The annual limits to the lens of the eye, to the skin, and to the extremities, which are:

• A lens dose equivalent of 15 rems (0.15 Sv)
• A shallow-dose equivalent of 50 rems (0.50 Sv) to the skin or to any extremity.

The shallow-dose equivalent is the external dose to the skin of the whole-body or extremities from an external source of ionizing radiation. This value is the dose equivalent at a tissue depth of 0.007 cm averaged over and area of 10 cm².
The lens dose equivalent is the dose equivalent to the lens of the eye from an external source of ionizing radiation. This value is the dose equivalent at a tissue depth of 0.3 cm.
The deep-dose equivalent is the whole-body dose from an external source of ionizing radiation. This value is the dose equivalent at a tissue depth of 1 cm.
The total effective dose equivalent is the dose equivalent to the whole-body.

Source: http://www.ndt-ed.org/