CHAPTER 37 - RADIOGRAPHY / FLUOROSCOPY PATIENT RADIATION DOSE

three decades

Medical imaging has experienced considerable change, especially during the past _________.

• Radiography

• fluoroscopy

• computed tomography

_______, ________ and _________ are examples of projection imaging.

digital radiography

Radiography is still the most widely used but it too has changed significantly from screen-film radiography to ____________.

Digital Radiography

________ now dominates medical imaging, having replaced screen-film radiography in all but a few private offices

• Entrance skin exposure

• mean marrow dose

• genetically significant dose

• tissue dose

__________, ____________, __________, and __________ are each important ways to express patient radiation dose.

age groups

the frequency of x-ray examination is increasing among all __________.

late effects of diagnostic x-ray exposure

The possible ___________ are of concern; therefore, attention must be given to good radiation control practices.

ALARA (as low as reasonably achievable).

When a diagnosis can be obtained with a low radiation dose, or with an alternate imaging modality such as MRI or diagnostic ultrasound, it should be used because of reduced risk. This is in keeping with ____________.

entrance skin exposure (ESE)

Patient dose from diagnostic x-rays usually is reported in one of the following ways. Exposure to the entrance surface, or _____________, is reported most often because it is easy to measure.

bone marrow

The dose to the __________ is important because bone marrow is the target organ believed responsible for radiation-induced leukemia. It is expressed as mean marrow dose (MMD).

mean marrow dose (MMD).

The dose to the bone marrow is important because bone marrow is the target organ believed responsible for radiation-induced leukemia. It is expressed as _________________.

entrance skin exposure (ESE)

Bone marrow dose cannot be measured directly; it is estimated from __________.

gonadal dose

The ___________ is important because of possible genetic responses to medical x-ray exposure. It is expressed as genetically significant dose (GSD).

genetically significant dose (GSD)

The gonadal dose is important because of possible genetic responses to medical x-ray exposure. It is expressed as _______________.

• technique

• equipment

• beam-on time to be estimated easily.

Patient radiation dose during fluoroscopy is too dependent on (3):

patient dose

Entrance skin exposure most often is referred to as the ___________.

patient dose

It is used widely because it is easy to measure, and reasonably accurate estimates can be made in the absence of measurements.

• Thermoluminescence dosimeters (TLDs)

• optically stimulated luminescence dosimeters (OSLDs)

__________ and __________ are used most often. The size, sensitivity, and accuracy of these dosimeters make them very satisfactory patient radiation monitors.

three methods

________ for estimating ESE are available in the absence of patient measurements.

70 kVp

At _______, radiographic output intensity varies from approximately 20 to 100 μGya/mAs at 80 cm SSD.

entrance skin exposure (ESE)

The _______ is the easiest of the four measures of patient dose to estimate or measure.

30% to 50%

When projection radiography is performed, one can measure the intensity of radiation to the entrance skin directly. Whatever that value is, it should be__________ less than that associated with screen-film radiography.

4 cm

The half value layer of projection x-rays in soft tissue is approximately _________.

shape of the image receptor response function

There are many reasons for patient radiation dose reduction using digital techniques but the main reason is the ______________.

30 shades of gray

Viewing a screen-film image is limited to approximately ___________.

• leukemia

• lymphoma

• myeloma

One of the risks of projection radiography is the induction of blood disorders such as _____, ______ and ________.

bone marrow

One of the risks of projection radiography is the induction of blood disorders such as leukemia, lymphoma, and myeloma. These stochastic responses are linked to the radiation dose to the stem cells of the ___________.

rarely

The hematologic effects of radiation are _______ experienced in diagnostic radiology.

Mean Marrow Dose

The _________ is the average radiation dose to the entire active bone marrow

Measurements and estimates of gonad dose are important because of the suspected genetic effects of radiation.

significant dose (GSD)

Similar to mean marrow dose, the genetically _____________ is an attempt to place a radiation dose value to our gene pool.

0.2 mSv/yr.

In the United States the GSD is estimated at ___________.

GSD

The population gonad dose of importance is the ______, the radiation dose to the population gene pool.

gonad dose

The genetically significant dose is the _______ that, if received by every member of the population, would produce the total genetic effect on the population as the sum of the individual doses actually received. Thus it is a weighted-average gonad dose.

weighted-average gonad dose

The genetically significant dose is the gonad dose that, if received by every member of the population, would produce the total genetic effect on the population as the sum of the individual doses actually received. Thus it is a ____________.

large-scale epidemiologic studies

The GSD can be estimated only through ______________.

skin

The various tissues and organs of the body have different sensitivity to radiation dose. One of the least radiation sensitive tissues is the ______ and yet it is of primary concern.

Radiation-induced skin burns

_____________ have appeared since the earliest days but are not normally associated with radiography.

technique employed

Radiographic tissue dose is very dependent upon the _______________ for the study and therefore a range of values is possible for each type of study.

digital radiographic tomosynthesis (DRT)

The newest radiographic imaging modality is _________. Many think that this will replace a number of routine CT examinations.

digital radiographic tomosynthesis (DRT)

is already approved for mammography and additional uses are sure to be approved.

skin

The _____ is the principal tissue of importance in fluoroscopy.

serious skin injuries

The increasing use of high-level fluoroscopy in the cardiology practice and in interventional radiology has resulted in many __________.

fluoroscopy

Entrance skin exposure in ________ is much more difficult to estimate than that for radiography because the x-ray field moves and sometimes varies in size.

40 mGya/min.

For the average fluoroscopic examination, one can assume an ESE of _________

15 Gyt

The CDRH considers that any skin dose exceeding _______ is a sentinel event and must be reported.

sentinel event

A __________ is always followed by severe skin damage.

Entrance skin exposure

________ is usually identified as the patient dose because it is easy to express, compute, and measure

TLDs and OSLDs

__________ are the radiation monitors of choice for patient radiation dose.