Bush__The_Essential_Physics_for_Medical_Imaging - Biomedical ...

FIGURE 1-4. A computed tomography (

angles around the patient. These pr

FIGURE '-8. Sagittal (upper left),

ducer, which records the returning

TABLE 1-1. THE LIMITING SPATIAL RES

WAVELENGTH(nanometers)FREQUENCY(her

The physical properties of the most

The energy required to remove an el

An electron cascade does not always

160150140130120110100N

The binding energy can be calculate

INTERACTION OF RADIATIONWITH MATTER

x10 3 7becomes electrically neutral

Electrons can undergo inelastic int

The nuclide produced by neutron abs

Compton scattering results in the i

CharacteristicX-rays:A: 0.6 keV (N~

10030 \~ r.." Photoelectric Effect

Attenuation is the removal of photo

The relationship between material d

HVL). Most practical applications o

MFP = 1- = __ 1__ = 1.44 HVLI.l 0.6

For x- and gamma rays, kerma can be

1 R = 2.58 X 10- 4 C/kg (exactly)Ra

TABLE 3-4. RADIATION WEIGHTING FACT

TABLE 3-6. RADIOLOGICAL QUANTITIES,

Computers were originally designed

TABLE 4-2. CONVERSION OF 42 (DECIMA

Binary Representationof Signed Inte

Chapter 4: Computers in Medical Ima

TABLE 4-5. MAXIMAL ERRORS WHEN DIFF

Main memory is used for these funct

A CPU fetches and executes the inst

FIGURE 4-6. Hard-disk drive. Aread/

Table 4-6 compares the characterist

erwise identical, the computer with

function, such as a disk head crash

Scintillation camera planarSPECTPET

(1.4 MB/disk)(l,024 2 bytes/MB)/[(6

DAC converts each digital number to

UnpolarizedlightHorizontallypolariz

FIGURE 4-15. Graphs of four transla

For example, it is often useful to

X-RAY PRODUCTION, X-RAYTUBES, AND G

1 _2 -3-1Impact with nucleus:Maximu

FIGURE 5-4. Generation of a charact

Cable sockets ~FIGURE 5-6. The majo

~C1.61.41.2 _~ 1.0::l0 0.8Q).00.62-

Rotor~~ ~+-statorFIGURE 5-11. The a

There are three major tradeoffs to

FIGURE 5-16. Various tools allow me

5.3 X-RAY TUBE INSERT, TUBE HOUSING

TABLE 5-3. MINIMUM HALF VALUE LAYER

Induced electronflow in conductorRe

Power is the rate of energy product

used to modulate voltage, autotrans

mAand mAscontrolPhototimercircuitsF

(a)Electron flow through single rec

asic components of a single-phase t

In three-phase generator designs, h

greater overall input power). Next,

nected to the contactors that dose

600500~5 4001:~•..=:l()300Q).0=:l

100% Ripple \5% Ripple /\ ••.-

TABLE 5-6. X-RAY TUBE FOCAL SPOTSIZ

Chapter 5: X-Ray Production, X-Ray

of the chart. Like the single-expos

Projection radiography, the first r

IEi\\i~eFIGURE 6-2. The sides andhe

sure on the screens, the cassette m

version efficiency, the approximate

(and vice versa). This phenomenon i

~80o"-'"{)' 70c.~ 60lij 50c.240 .

film OD. If the screen is made thic

Film has excellent spatial resoluti

-(/l~ 2.0-c:8 1.51.0-(/l~ 2.0-c:8 1

educed latitude. The shaded region

TABLE 6-2. TISSUE HALF-VALUELAYERS

PrimaryScatterFIGURE 6-22. A: Scatt

ferent locations from within the pa

lar to the direction of the slits.

FIGURE 6-30. Air gap geometry canre

silver halidecrystalssensitivityspe

•FIGURE 7-3. The fate of an expos

DeveloperActivatorRestrainerPreserv

increased too much because the numb

can be achieved. Film manufacturers

Modern x-ray equipment is computer

wee en0.25Ol0U. 0.20+Q)(f) 0.15COCO

Mammography is a radiographic exami

Other modalities that have been use

plished by magnetic induction. A so

ReferenceAxisCentra0AxisProjectedfo

30 kVp26 kVp30 kVp26 kVp(b)2.01.81.

OJE 25.E(fl.9 20o~ 15"'___ to 45 x

TABLE 8-2. REQUIREMENTS FOR MINIMUM

TerminationCircuitFIGURE 8-15. The

simulations and experimental measur

1.21.11.00.90.80.70.60.50.40.30.20.

2!£.= 1.85 xSODSOD35cmSID65cmOlD30

Film BaseFilm EmulsionPhosphor Scre

equiring a compensatory increase in

0.25 -Base + Fog0.20Density 0.150.1

characteristic curves, the correspo

achieving a pixel size at the image

Chapter 8: Mammography 223TABLE 8-6

ifies that the mammography facility

TABLE 8-9. SUMMARY TABLE OF ANNUAL

preting radiologists, mammography t

with the fluoroscopy imaging chain

FIGURE 9-4. A scanningelectron micr

cm 2 area of the 9-inch-diameter in

_ 100~I 20 em patient ~~•.... _~-

Video CamerasGeneral OperationThe c

FIGURE 9-11. The flat panelimaging

higher. Cine radiography uses very

put, and consequently frame averagi

contrast" selections on the console

specific applications, such as GIIG

3'2'E~wtJ)w 0.3~,======_o~"~~--;~ _

time estimate of the amount of radi

.~! ~i !j t--------------Ij• •s

'E 2O . O 80(,)~ 100_70-~0CIlIIIr::

40003500CIl 3000::s~ 2500CIlB 2000U

can be radically changed. Therefore

FIGURE 10-10. A: An isometric displ

FIGURE 10-13. Some physical mechani

some clinical applications, the blu

would correspond to 1 cycle/mm. If

I;:' 0.6irI-:!: 0.41.0 2.0 3.0 4.0S

or stochastic component into the im

~~2IIIs:::I I>o40 60 80 100 120 140

The term quantum is defined as "som

Stage Description System P System Q

.g tides:eis.Ec(~ co~o o 2 4 6 8 10

detectorelements[-I I detector aper

Since most patient anatomy does not

detail curves are commonly used in

actually calls nor-The specificity

Digital radiographic image receptor

-8 0.8:J:=~0.6«g! 0.4:;:;ellGi0::

to a very bright light source, whic

Lens Coupled Intensifying ScreenFIG

discretedetectorelementsFIGURE 11-7

light sensitive areaFill Factor = a

for digital stereotactic biopsy. Br

Because the slot width (4 mm) is mu

One of the advantages of having an

ness. Windowing and leveling of a d

nel is called a delta function,anyw

pixels are averaged to go from a 51

Geometric tomography, also called b

ground anatomy causes geometric tom

of relatively rapid readout, allowi

system, the amount of vascular sten

dual-energy subtraction is availabl

point on the image. Consequently, w

FIGURE 13-3. Computedtomographic (C

FIGURE 13-5. First-generation (rota

FIGURE 13-7. Third-generation (rota

FIGURE 13-10. The fan beam geometry

helical x-ray tubepath around patie

septa that separate the individual

detector array modules. With a trad

Slice Thickness: MultipleDetector A

This implies that the upper limit o

FIGURE 13-22. An image of a test ob

The constant ~t factors out, result

6 8A+B=77 A+C=6A+D=57 B+C=9B+D=8C+D

simple backprojection, p(x) is back

The units for the x-axis in Fig. 13

msec is preprocessed, mathematicall

FIGURE 13-33. The coronal, sagittal

ware through the volume data set, f

of CT slices. The MSAD could be mea

position along torsoFIGURE 13-37. D

Factors AffectingSpatial Resolution

x-ray beam hardeningFIGURE 13-38. T

FIGURE 13-41. A partialvolume artif

motion of the electrons in either a

Biologically relevant elements that

FIGURE 14-4. A: A single proton pre

FIGURE 14-5. A: The laboratory fram

magnetic field are separated by an

8 1 at Larmor FrequencyzMot:/81....

The "decay" of the FID envelope is

method to determine the T1 time of

50 msec). Molecular motion, size, a

TEI'I180 0 EchoRotatingframe./FID s

--_. unsaturatedpartiallysaturated:

the figure on the left (longitudina

Imageintensit)GrayWhiteFat1000 2000

TRTERFpulses90 0readout~~~~~~--n~18

Transverse decay (T2)Imageintensit~

Rotating frame../FIGURE 14-29. Grad

very shortTR. In these two regimes,

FIGURE 14-32. A spoiled transverse

acquired. Because the BOLD sequence

412 Section II: Diagnostic Radiolog

MAGNETIC RESONANCE IMAGING(MRI)The

Net gradient = ~G 2 + G 2 + G 2x Y

strength, an applied RF pulse with

FIGURE 15-7. The width of the sinc

1•1 cycle/em :1::UAmplitude: 1.0~

positionally dependent phase shift

xImage (grayscalevalue)FIGURE 15-14

8. The final image is a spatial rep

~.......--, ----J+*-.J4~====~_~~.\-

FEG n n n IL.-ct--Echo ,I.16 ms 32

ing time is approximately equal to

sition of the signals (Fig. 15-24),

this is unacceptable for standard c

FIGURE 15-27. Evolution of a narrow

Unsaturated spins: high signalFlow-

volume and places this value in the

In MRI, artifacts manifest as posit

·······i..··I·I~IdealFIGU

FIGURE 15-33. A single bad pixel in

On Tl-weighted images of the head,

A higher frequency encode gradient

c:~...:L~"'FOii·"·"""~·~- ~; t--

purely resistive system is the abil

RF coils create the B 1 field that

86~~ c:~"0~"0m0::214Axial distance

15-2. Qualitative and quantitative

RF exposure causes heating of tissu

Transducer/ ArrayInterrogate bodywi

and its resistance to being com-ulu

are determined by the imaging appli

TABLE 16-2. DECIBEL VALUES. INTENSI

ZI = PICI~~IncidentReflection(echo)

When C2 > Cl, the angle of transmis

Penetrationdepth, cm(Distance trave

Plastic CaseMetal shieldAcoustic ab

~ ----+thicktransducer~ ----+thintr

intermediate to those of soft tissu

Linear ArraysLinear array transduce

sound beam path is thus largely con

phase differences of adjacent beams

III ¢ __ Red;e'vane';ons-~Thicknes

FIGURE 16-22. Axial resolution iseq

One way to accomplish this is to ac

Ultrasound equipment is rapidly evo

TABLE 16-6. TYPICAL PRF, PRp, AND D

(3) Demodulation and"Envelope" dete

systems, and digitally in high-end

drifted easily and were unstable ov

State-of-the-art ultrasound scanner

Image Frame Rate and Spatial Sampli

els of gray scale. Image storage (w

Based on the harmonic imaging work

FIGURE 16-40. Conventional (left) a

exactly phase reversed, and their s

FIGURE 16-43. Three-dimensional ult

occasionally induced by environment

LiverBoundarydisplacementFIGURE 16-

Blood moving towards transducerprod

The continuous-wave Doppler system

DopplerSignalLow frequencyDoppler s

eam is aligned at a particular orie

information is displayed on the vid

Transducerarray &BeamFormerPulse-ec

FIGURE 16-54. A comparison of color

c024VerticalbandE 60..c8-0..(])0 10

TABLE 16-8. RECOMMENDED QC TESTS FO

In the pulsed mode of ultrasound op

ecommends adherence to the ALARA pr

COMPUTER NETWORKS, PACS,AND TELERAD

tions protocols. Failure to conform

The most common LAN medium is Ether

nodes are both on the same segment

physics/text will obtain, from a se

can be programmed to read the traff

CT North EJCT04_MRG1-:::S:::(Toshib

a laser and the other using a colli

(14 x 17 inch) film should be digit

equipped with specialized software

The storage may be centralized (i.e

FIGURE 17-10. Interpretationworksta

Spatial linearity (freedom from spa

the faces of the monitors, and to a

Disadvantagesof PACS1. Initial and

ital portions of the system can deg

RADIOACTIVITY AND NUCLEARTRANSFORMA

TABLE 18-3. PHYSICAL HALF-LIFE (Tp1

A plot on a lineat axis of activity

Although the ~- particles emitted b

The capture of an orbital electron

RADON-220Alpha DecayT 1/2 = 55 seco

TECHNETIUM 99MIsomeric TransitionT1

RADIONUCLIDE PRODUCTION ANDRADIOPHA

continue to acquire kinetic energy,

come the nuclear binding forces. Th

duced), the reactor is said to be s

chemically separated from other fis

FIGURE 19-7. Picture of a "wet" mol

een achieved, the daughter activity

feres with the preparation of some

high abundance (94%), their low ene

Cell SequestrationRBCs are withdraw

ReceptorBindingThis class of radiop

closure of alternative treatments;

RADIATION DETECTION ANDMEASUREMENTT

Q)•..III•..a:c~010,000800060004

This equation can be written as fol

LimitedGeiger-MuellerRegionProporti

Unlike ion chambers, which can func

as well. However, most photodiodes

Chapter 20: Radiation Detection and

tional to the intensity of the ligh

"=@ @=@=II "II II II=@-@=@=II II II

tional to the energies deposited in

changing the voltage produced by th

X-Ray and Gamma-Ray Spectroscopy wi

gamma rays deposit exactly the same

trum on the left shows a large phot

FIGURE 20-23. Thyroid probe system.

FIGURE 20-26. Automatic gamma wellc

FIGURE 20-27. Dose calibrator. Thed

The concentration of Mo-99 is most

Toss of a coinToss of a dieObservat

TABLE 20-3. FRACTIONAL ERRORS(PERCE

Multiplication of a number with ran

NUCLEAR IMAGING-THESCINTILLATION CA

FIGURE 21-1. Modern rectangular hea

PulsesfromindividualPMTsPositioncir

Image in crystal. .LTtTTTlT1llT1TT.

FIGURE 21-7. Ways that x- and gamma

front of the collimated camera. Sol

distant point source if the collima

TABLE 21-2. TYPICAL INTRINSIC PERFO

spatial resolution improves (narrow

LEHRFan-beamPinhole5 10 15 20 25Obj

X and Y correctionlookup tablesDigi

methods for measuring the camera pe

tangle. The MCA-type display presen

lution collimator may improve spati

Pairs of digitalposition signalsX 3

Image Processing in Nuclear Medicin

FIGURE 21-25. End-diastolic (top) a

NUCLEAR IMAGING-EMISSIONTOMOGRAPHYT

FIGURE 22-1 (continued). (B) double

\- -, ffIffIffIffIffI\\\,\\ , \\fIf

FIGURE 22-5. SPEeT images created b

time, attenuation correction in SPE

Radial~-~IIIIIIIIIIIICenterf----at-

FIGURE 22-9. Center-of-rotation (CO

FIGURE 22-11. Head tilt. The camera

These phantoms are very useful for

FIGURE 22-15. True coincidence (lef

TABLE 22-2. PROPERTIES OF SEVERAL I

elatively low conversion efficiency

equire less activity to be administ

Source containingpositron-emitterDD

RodSourceFIGURE 22-24. Rod source f

Some cameras are equipped with filt

Factors Affecting the Availability

RADIATIONDOSIMETRY,PROTECTION,AND B

is exposed to cosmic radiation near

TABLE 23-1. ESTIMATED AVERAGE TOTAL

TABLE 23-2. ESTIMATED AVERAGE ANNUA

TABLE 23-5. SUMMARY OF THE ANNUAL C

Terrestrial28 mremlyrInternal40 mre

Most film badges can record doses f

Gamma or X-Ray(Ionization)Digital p

isfy the majority of the requiremen

TABLE 23-8. TYPICAL EXPOSURE RATE A

TABLE 23-9. EFFECT OF DISTANCE ON E

FIGURE 23-8. The varioussources of

~ 20~E~(§) 15~ii:.s 1025-.:- 20"*

0.75); other walls and ceiling have

and solving for T yields the requir

and the corresponding closest dista

Ị ..2cQ)(.)0.!!!.E 0,gQ)(.)c.l9(/

constant (expressed in units of R-c

FIGURE 23-13. Dose preparation work

(e.g., a 400-speed screen-film rece

Figure 23-14 shows a severe skin in

protocols (mAs values) are adjusted

of each workday) and wipe tests (ty

TABLE 23-17. RECOMMENDATIONS FOR CE

Eo = initial exposure rate (~15 min

ation detector (typically a GM surv

health issues that serve as the ref

Exposure to airborne activity is al

RADIATION DOSIMETRYOF THE PATIENTTh

RadiographyFluoroscopyMammographyNu

isks. The International Commission

FIGURE 24-1. The geometry formeasur

0.309 R x 173 mrad = 53.5 mradRDose

TABLE 24-7. EFFECTIVE DOSE PER ENTR

cumulated activity in each source o

p p p p p -ABLE 24-8. Tc-99m S FACT

Accuracy of Dose CalculationsAlthou

Rarely have beneficial applications

tenets in radiation biology is that

dition at the time of irradiation,

lead to carcinogenesis through acti

anaphasic separation. The extent of

paragraphs, including dose rate, LE

.!!2Qi()OJC.;;.~::JCJ)15Qi.0E ::JZ1

FIGURE 25-10. Phases of the cell'sr

Specific Organ System ResponsesThis

In general, the gonads are very rad

TABLE 25-4. APPROXIMATE DOSE (INAIR

for a measurable depression in the

TABLE 25-5. SUMMARY OF THE STAGES,

the integration of regulatory signa

Atomic-bomb detonation exposures an

Source: Adapted from National Acade

Incidence in exposedpopulationSpont

The National Academy of Sciences/Na

OverviewLeukemiaof Specific Cancer

older than 55 years of age. The ris

irths in the succeeding generation,

a specific organ system (the so-cal

Similar effects have been reported

TABLE 25-12. ABSORBED DOSE mGy/MBq

Doll R, Wakeford F. Risk of childho

FUNDAMENTAL PRINCIPLESOF PHYSICSA.1

Mass. Length. and TimeMass is a mea

amount of charge in the system does

, Current·I·,\. ..:'~ ~.~--------

FIGURE A-5. A: Direct current. B: S

FIGURE A-6. Magnetic field descript

ElectromagneticInductionIn 1831, Mi

ing potential difference across the

as to cancel in pairs; however, in

C: GeometryArea of circleCircumfere

Densityg/cm 3At massg/moleK-edgekeV

888 Section V: AppendicesTABLE C-'(

890 Section V: AppendicesC.3 MASS E

892 Section V' AppendicesTABLE C-4(

894 Section v.. AppendicesTABLE C-5

896 Section V: AppendicesTABLE C-6

898 Section V' AppendicesTABLE C-7(

TABLE D-1. ROUTE OF ADMINISTRATION,

U) TABLE D-1 (continued).0~Method o

Should be administered within 10 mi

Patient should not have fatty foods

TABLE 0-2. TYPICAL ADMINISTERED ADU

Effective dose15 yr 10 yr 5 yr 1 yr

There are a number of professional

...*...!.....,:..":.., , ' ..-'."-.

CCD. See Charged-coupled devicesCel

continuous Doppler operation, 534-5

pincushion distortion, artifact, im

Latitude, 163LCD. See Liquid crysta

Multi-path reflection artifact, ult

for screen film system, 151Quantum

Resistive magnet, magnetic resonanc

Speed artifact, ultrasound, 528f, 5

Srrbjcc~ Index 933Wavelengthelectro