Radiation pneumonitis following large single dose irradiation: A re-evaluation based on absolute dose to lung

In, J H~d,‘,,,,,nOn,,,,,,41 Pnntcd tn Ihc I b ,

H,,,, 411 r,ehl.

Ph,c Lul rcwrvcd

‘,pp

461

4h-

??Original Contribution RADIATION PNEUMONITIS FOLLOWING LARGE SINGLE DOSE IRRADIATION: A RE-EVALUATION BASED ON ABSOLUTE DOSE TO LUNG .I. VAN DYK, M.Sc., F.C.C.P.M.,* T.J. KEANE, M.B.. M.R.C.P.I., F.R.C.P.(C),t S. KAY, M.D..$ W.D. RIDER, M.B., F.R.C.P.(C), F.R.C.R.$ AND C.J.H. FRYER. L.R.C.P.. M.R.C.S.. F.R.C.P.(C)** The Ontario Cancer Institute. The Princess Margaret Hospital, 500 Sherbourne Street Toronto. Ontario M4X I K9 The acute radiption pnmunonitis syndrome is 8 major complic8tion for patients receiving tot81 tborrcie irrrdirtion in a brge single dose. Previous studies have evnlwted tk onset of rrdi8tion pkumonitis on tk ksis of r8dirtion doses c8krloted 8ssuming nnit density tissues. In tbis report, tk incidence of radintion pneumoniti is determined as a function of absolute dose to lung. A sintfde algorithm relating dose correction factor to 8nteriorposteriar patient di8meter ks been derived using a CT-aided trntment pl8tming system. This 8Igorithm ~8s used to determine, retrospectively, tk dose to lnng for a group of 303 patients who kd been trnted with hrge kid irrndiation tecbnques. Of tbis groop, 150 patients kd no previous lung disense and kd virtually no 8ddkonall~ irrndiation prior or sobsequent to their large kid treatment. Tk rctnnri8l i&dence of rndiation pMnmonitisver!utsdoseto lung was evnhmted using 8 simplified probit 8nrlysis. Tk rennR8nt host fit sigmoidal complkation curve demomstrrtlcsthe onset of ndbtiea pmeulnodtis to occur 8t about 750 md witb tk 5 46 8ctonrinl ioci&mx occuring 8t rpproritnntely 820 nd. Tk errors usocirted with tk dose determkntion procedure as well 8s tk ncttmri8l incidence akubtions 8re considered. Tbe time of onset of rndiition pneumonitis occnrs between 1 to 7 motWbs after irrndi8tion for 90% of the p8ticnts who developed pneutnonitis witb tk pook incii occnrring at 2 to 3 tnontk. No correlation ~8s found between time of onset and tk dose to hmg over a dose r8nge of 650 to 1250 r8d. R8diation

pneumonitis.

Large field radiotkmpy.

Tissue inhomogeneity,

INTRODUCTION Half

body

irradiation

Because treatment lung irradiation,

disseminated

this organ’s

from

this

Fryer er al.’ describing doses of radiation radiation dyspnea oped

pneumonitis

method

malignant

syndrome

available.

conjunction

was published

by

dures to determine

lung.

of increasing

radiographic patients

patient

In

to the entire

and characteristic

in 44 of the 245

become

a

with

the toxic effects of large single

given

The

studied.

The

with

a precision

recent study”

acute

actuarial

patients

and 1000 rad. respectively.

These doses were calculated

dosage correction

patients

consisted

of

unit

This

this

series of

tomography

density

information

inhomogeneity than

(CT)

information can

be

has

used

dose calculation

doses at any point greater

were studied

try

the

for

within

previously

in

proce-

the patient possible.

A

how CT was used to determine with a

precision of better than 23% for radiation qualities ranging from cobalt-60 to 25 MV X rays. Twenty-three

devel-

was found to increase from single doses to lung of 800

that

specific

illustrated

incidence of this syndrome 29% to 84% for uncorrected assuming

rates

the dose to lung for upper half body radiotherapy

cough with

changes

Dose

the advent of computerized

detailed

to radiation.

tolerance

institution

With more

total

has provided

tissues only.

pknning.

patients ranged from SO to 400 rad per minute.

for

disease.‘.’

of the upper half body involves

the half body technique

means of analyzing

1978. a report

waterlike

provides an excellent

the palliation of widely

Dose corrections, Tre8tment

and lung

normal

density.

healthy

density

to determine data

factors.

average

lung geome-

and corresponding For cobalt-60

lungs, corrected

radiation

mid-lung and for

doses were found

to be

**Radiation Oncologist, Assistant Professor of Paediatrics. Cancer Control Agency of British Columbia, 2656 Heather Street, Vancouver, B.C. Canada VSZ 353. Reprint requests to: J. Van Dyk, M.Sc. Acknowledgements-We appreciate the discussions with Dr. P.M.K. Leung and the statistical help of Theresa Chua. Accepted for publication I8 December 1980.

Supported by grants from the NCI (Canada) and The Ontario Cancer Treatment and Research Foundation. *Medical Physicist. *Radiation Oncologist. $Clinical Fellow, Radiation Oncology. $Head, Radiation Oncology Department and Professor of Radiology. 461

362

Radiation

greater

by

??Physics

Oncology 0 Biology

IO to 24% compared

to their

April

198

I,

Volume 7. Number

4

uncorrected

values. In this paper. absolute

we describe

a method

lung doses retrospectively.

be obtained

addition, with

analyzed

and a toxicity

group of 58 patients

half

body

to provide

Lung

or total

treated

body

2 0.6391

thltkncss

+QlC52

In

since 1977

irradiation

more comprehensive

111

thscknes

1 Oatlant

curve

on the basis of real dose to lung.

another

upper

Least slluares

such that the patients

of the Fryer study4 could be reviewed could

of determining

were

toxicity

data.

METHODS AND MATERIALS To determine

the dose to lung in a retrospective

sis. a dose calculation uses patient patient

procedure

specific data that has been recorded

at the time

posterior recorded

of their

analy-

must be developed treatment.

which

for every

Since

anterior-

patient diameters in the thorax region were for all patients in the Fryer study.’ an attempt

was made to relate these to the dose at the middle lung. Van Dyk ef al.” reported made on a group ment

planning

tions were calculated then making a ratio

first assuming

tissue inhomogeneity

of the corrected

dose correction

mid-lung

thickness In

By taking

Using

between

thickness

is plotted

patient

indicates

on the average,

is 0.64 of the total

lung thicknesses from this linear correction

deviate

thickness:

by as much

squares

factor

fields

using

the lung

however,

as 3 cm (or 23%)

between

thickness

the correlation

patient

thickness

between is much

pleural

Hermluation

illustrate

for 50 x 60 cm tissue-air

dose correction

factor

14

I6

182Q22242629~

thckncss (cm)

oj’Fryrr’s original

radiation

ratio

and

the correlation

discrepancies.

Even the data points for a 7 year-old child fall very close to the linear best fit curve. In summary, this data provides a very simple procedure to estimate, retrospectively. the dose correction factor for cobalt-60 radiation for patients wirh normal lungs who received large field radiotherapy. By knowing the patient thickness. the dose correction factor can be determined.

description

pneumonitis findings.

the

much greater

12

r.

thickness versus patient thickness. (b) Dose for large tield cobalt-60 radiation versus

For a detailed

This

deviation is 3.5%. The points for abnormal containing high density tumor masses or

effusions)

0

R ESU LTS

is illustrated.

than

6

patient thickness.

paper by Fryer

between lung thickness and patient thickness. In fact, for the data of Figure I b. more than 80% of the points for normal lungs lie within I.57 of the best fit straight line; the maximum lungs (mostly

Fig. I. (a) Lung correction factor

dose

equivalent

better

6

mid-lung

was calculated the

4

Pohent

some

(TAR) method as developed by Sontag and Cunningham.‘” A comparison of Figure I a and Figure I b reveals that

2

clinical

factor and patient

dose correction

0

fit

best tit.

I b, the relationship

In Figure

cobalt-60

that.

least

was

these points is shown by the solid line. The slope curve

linear

between

thickness

through thickness

A

I.04 1

the same

against of this

thickness.

lung

I

I

,“/’

lC6

lung thickness

factor and patient la.

treattissues,

as well as the relationship

Figure

fucmf = thKkw%

mtmt

+QB075

dose, a mid-lung

was determined.

dose correction

determined.

corrections.

the relationship

Dose carfuctlan

dose distribu-

unit density

to uncorrected

factor

group of patients. and patient

using a CT-aided

For each patient,

IIt m nc+mat

O.Ol27l.

on specific measurements

of 23 patients

system.

of the

Least squares lunq data

syndrome

the reader

data

of the appearance is referred

et ui.” For comparison

sake of clarity

reviewed

in Table

incidence

of radiation

the original

of the

and the corresponding to the original purposes

incidence

and for

tigures

arc

I of this paper. This table gives the pneumonitis

rected dose 10 lung. No patients

as a function were excluded

of uncorbecause of

additional radiation treatments or because of known lung disease. The actuarial risk increased from 18’7 to 847 for uncorrected

doses of 600 to 1000 rad respectively.

By applying the appropriate dose correction factors using the procedure outlined above. corrected lung doses were determined for the same group of patients. Table 2 summarizes the results. Because of greater variability in lung

dose. the patients

now had to be subdivided

into

smaller groups according w ~1specitied dose interval. The 50 rad increment was a compromise between a large interval which includes many patients in one group and a smaller patients tainties.

interval which produces small numbers of in each group with resultant statistical unccr-

In Fryer’s mediastinum

study.’ btgnificant .’ radiation to lungs in addition to the half body treatment

and was

Radiation

pncumonitis

(rad)

Actuarial risk

Crude incidence

Number of patients

VAh

(o/o

(%)

Number of patients

Dose l/49 3124 281149 I2123 245

~600 600 800 1000 Total

found

order

to increase

to evaluate

risk of radiation

incidence

of pneumonitis, irradiation

for abnormal

2 were re-analyzed significant

data

are

the actuarial

(b)

pneumonitis

Using

Finney’

the data

number

of patients

location

on the sigmoidal

incidence

were

number

of

centered

at 850.

incidence

points

probit

per group

given

patients

zero

900 and

in

950

as their

Points

weight.

occurred

rad.

for these dose intervals

regression

as outlined according

as well

curve.

it

complication

analysis

were weighted

until

dose to lung. probit analysis

by a mathematical

the full

total

at about 800

rapidly

the best fit sigmoidal

can be determined

procedure.

lung

3. The

occurred

increased

reached 100% at about I 100 rad absolute This data was also evaluated using curve

by

to the relative

of 0% or 100%

Since the

the

dose

and since

occurred

largest intervals percent

on the rising

Table 2. The incidence of radiation pneumonitis for corrected dose to lung for all the patients in Fryer’s original study“

Dose -

(rad) o-574

Number of patients 47

575-624

3

Crude incidence (%,I

Actuarial risk (%)

0 1 4 5 I 120

2

3

3

0

0

0

I!

9

17

I5

675-724

I4

14

17

0 100 22 I6 28 0 50 57 77 67

0 100 33 28 49 0 100 100 74 100

II 0 0 17 7 I2 0 0 0 I5 0

I I I8 93 32 0 2 7 I3 3 245

Actuarial risk

(S)

(R)

0 0 0 0 0 100 I3 I6 20

0 0 0 0 0 100 I3 24 27

0 0 0 0 0 0 I2 8 I4

0 0 75 80 0

0 0 100 IO0 0

0 0 0 0 0

Standard deviation

part

of

the

weighted

dures while To

sigmoidal

very

avoid

procedure

curve,

heavily problem

0% and 100% incidence 99.9% the

incidence

analyses.

number

illustrates

they would

the percent

Those points with

were assumed each

ignored. regression

at 700 rad and including

to a probit.

Weighting

were proce-

to have 0. I o/r,and

also be included

point

according

a least squares fit was performed

back

in Figure

to a percent 2 was obtained.

an incidence

incidence,

in

to the

versus the log of the dose. By converting

best fit probits illustrated

so that

of patients,

the probits

probit

more than 3 patients,

was transformed

points

analysis

were virtually

a simplified

was used. Beginning with

data

probit

the other data points this

only those points incidence

these

in the full

of the

the curve

This best fit curve

of 1% at 800 rad and 7% at 850

rad.

Probit Regression Line

Standard deviation

625-674

725-?74 775-824 825-874 875-924 925-914 915- 1.024 I ,025-l .074 1.075-1.124 l,l25-1.174 1,175-1.224 Total

975-1.024 I ,025-l .074 I .075- I, I24 1.125-1.174 1.175-1.224 Total

I

Crude incidence

the lung. The

in the analysis was 120.

incidence

in which

is

who had (a)

previous

in Table

remaining

above

the data of Table

masses within

summarized

of patients

procedures

8 44 I5

significant

outlined

those patients

irradiation.

The onset of radiation rad;

method

33 I 3 4 0

O-514 575-624 625-674 675-724 725-774 775-824 825-874 875-924 925-974

In

from the analy-

lungs. Hence.

disease and (c) known tumor number

with

be removed

excluding

additional

adjusted

pneumonitis.

the patients

should

the dose correction

inaccurate

(rad)

the effect of a large single dose on the

additional sis. Also

3 18 36 84

2 13 19 52

the

463

DYk ef al.

Table 3. The incidence of radiation pncumonitis for corrected dose to lung for Fryer’s study’ excluding those patients with (a) significant previous and subsequent lung irradiation (b) previous lung disease and (c) tumours in lung

Table I. The incidence of radiation pncumonitis for uncorrected dose to lung. (Data taken from Fryer ef a/.‘)

Dose

??J.

rcKvaluated

Bawd on patients in

/

Dose to lung (rod)

arlqinol study (l960Encludino :

YI,

Fig. 2. Best fit sigmoidal complication curve using simplified probit regression analysis for the patients in Fryer’s study.’ The solid dots represent the points from Table 3 that were used to produce this curve. (Standard deviations do not apply for 0 or 100% incidence).

464

Radiation Oncology 0 Biology 0 Physrcs

Additional

analysis of patients treated since / 977

Fryer’s

original

study4 considered

patients

treated

up

to the end of 1976. During

1977 and 1978. another

of 58 patients

using large held radiotherapy.

were treated

Because of the toxicity

data provided

study.’ most of these patients rected

doses of

patients

who

marrow have

less than

received

tumor

dose region.

nally

by

in the

Fryer

held

et al.’ Also,

results of Table

incidence

irradiation

previous

with previous

with

the actuarial

incidence

the larger

rapidly.

simplified

probit

Figure

incidence

with

and large

patients

lung irradiation. in the lung have

which

Tables

the incidence

the results

of the

above. This best fit

of 3% at 800 rad and

3 and 5 as well as Figures

3, it will be noticed that only the dose interval 800

rad

shows

incidence patients

of

ial incidence. ered,

2 out

pneumonitis

difference

pneumonitis.

there

that patient

a marked

For

was only one patient

developed When of

original in that

pneumonitis-hence the additional

5 patients

resulting

in

this

in an actuarial

2 and

centered

in the

the

at

group interval

of and

are consid-

interval incidence

developed

Crude incidence

Actuarial

Number of

(rad)

patients

(S)

(S)

O-574 575-624 625-674 675-724 725-774 715-824 825-874 875-924 925-974 975-1.024 I ,025-I ,074 1,075-1,124 l,125-1,174 l,l75-1,225 Total

65 4 15 26 8 IO 23 93 32 0 2 7 I3 5 303

2 0 7 12 13 30 22 15 28 0 50 57 77 80

risk

2 0 II I3 I3 37 41 28 49 0 100 I00 74 100

(‘7)

(‘k)

Standard deviatron

0 0 0 0 0 10 20 I6 25 0

0 0 0 0 0 53

0 0 0 0 0 27

II

II

23 35 0

8 I4 0

I 4 5 3

0 75 80 67

0 100 100 100

0 0 0 0

I 50

Total

The

high

incidence

for this dose interval

concern

when it is considered

context

of the rest of the data,

statistically

the dose intervals

centered

much

show a lower incidence. that the high incidence of 2 out of 5 patients

in the

incidence

is

for example.

at 650. 700 and 750 rad. The for a total

5 demonstrates

Also. the dose intervals

950 tad contain

high

Consider.

3 shows 0 incidence

the data of Table

patients.

this

not very significant.

data of Table

is of serious

on its own. However.

larger

0 incidence

centered numbers

Therefore,

for I9

at 850.900

and

of patients

and

when it is considered

in this particular

developing

of 7 patients

point

pneumonitis

is a result

and when it

of 53F.

Table 4. The incidence of radiation pneumonitis for corrected dose to lung for Fryer’s study’ plus additional group of patients treated since 1977. all inclusive.

Dose

.4ctuarial risk

39 3 6 IO 3 5 IO 45 16 0

1.075-1.124 1.125-1.174 1.175-1.224

while

actuarial

100% actuar-

patients

Crude incidence

zero up to

12% at 850 rad. In comparing

o-574 575-624 625-674 675-724 725-774 775-824 825-874 875-924 925-974 975-I .024 1.025.- 1,074

of patients

remains

as described

curve gives an actuarial

the crude

number

3 illustrates

analysis

above.

data. The

5. those

of pneumonitis

a dose level of about 750 rad beyond increases

dose correction

treated

In Table

and subsequent

Even with

of 58 patients

described

lung disease, or with tumor

been excluded.

uncorrected

Number of patients

Dose (rad)

bone

to those origi-

4 illustrate

Table 5. The incidence of radiation pneumonitis for corrected dose to lung for Fryer‘s study’ plus additional group of patients treated since 1977. Excluded are those patients with ~a) significant previous and subsequent lung irradiation (b) previous lung disease (c) tumour in lung.

two

for

the original

of 303 patients

techniques.

with signiticant

group

identical

4

uncor-

addition.

1000 rad

using the method

This new data was combined accumulated

In

irradiation

This additional

were obtained

actuarial

body

using procedures

outlined

factors

rad.

7. Numhr

original

with

(at a dose rate near 5 radjmin)

also been included

was reviewed

750

total

transplantation

by Fryer’s

were treated

group

April 198 I. Volume

Probit

Regression

Line

Standard deviation

2 0

II 7 12 17 I6 7 12 0 0 0 I5 0

so0

700

Boo 900 1000 1100 1200 Dose to lung (rod1

1011,

Fig. 3. Best tit sigmoidal complication curve using simplified probit regression analysis for the patients in Fryer’s study as well as the additional patients treated since 1977. The solid dots represent the points from Table 5 that were used to produce this curve. (Standard deviations do not apply for 0 or 100% incidence).

is placed

in the context

significance Figure

pneumomtts

data.

its statistical

of the other

is not very high.

3 demonstrates

Radiation

In fact. the smooth

re-evaluared

??.I.

VA\

D\ h ef al

465

curve of

the best tit to ail the data. StOtldOrd

Time

of msel

pneunwniris

qf

after

The ttme of onset of radiation reported six

previously

months

~y.‘.‘.‘.‘~

after

s

l40-

to be in the neighborhood

of two to

$ E t

I20

-

100

-

of onset for the group The

the

peak

months.

of

course

the frequency

of 52 patients

acute the

radiation

of radiotheraversus the time

in this study

pneumonitis

distribution

occurs

while 90% of these patients

who

syndrome.

between

developed

2 to 3

pneumoni-

8 ‘0 2 g ‘a u f c

1 and 7 months.

tis between

meon

has been

a fractionated

the

about

pneumonitis

Figure 4 illustrates

developed

dewotlon

irradiation

Me0n

so-

60.

40 t

There

are only

a few

evaluate

the relationship

to lung.

Michaelson

clinical

pulmonary

proportional

toxicity with

treatment

insufficiency with

the 52 patients

though

in dogs to be inversely

increase

in time

of onset of

in dose has also been

fractionation in human

used

subjects.’

in

who developed

between

pneumonitis

in Figure

in our study.

5 and shows no obvious

time of onset and dose to lung even

cobalt-60

radiation

radiotherapy

using

XXI

800

Fig. 5. Time

to

lOO0

I I200

Imp

1 1300

)

(rod

*Is,

of onset of radiation

pneumonitis

lung for all 52 patients who developed radiation

versus dose 10 pneumonitis.

Error bars represent standard deviations.

patient

is about

tissues although to 24% depending 16% increase rad assuming an absolute

anterior-posterior

fields. the dose to lung for the average

on lung geometry

for 928 rad to lung

of the dose administered in the lung

method

fields.”

of a dose correction

factor

patient

2 I .5%

differences

for

the midpiane within

factor

lung,

are

using

especially

the

patients

is defined

corrections than

23%

for

the determination earlier

is accurate

studied,

for a point

Although

mid-lung

although

near

this

dose. there the anterior

the determination study is related actual treatment

of lung

the

in lung near point

may

are regions and posterior

that receive a 2 to 4% higher and probably

in the

on the basis of the anterioras described

the dose distributions

I?). Fourthiy,

difficult

Secondly.

of the patient.

an average

lung surfaces, example,

procedure to better

a few

error

as large as 3.5% have been noted. Thirdly.

dose correction represent

diameter 80%, of

curve, of

for inhomogeneity

to be accurate

is nearly

to lung. Because

sources

the dose computation TAR

of

curve requires

complication

possible

these large radiation

to

the incidence

such a steep complication

has been shown

dose of 800

for 800 rad to lung is only 38, the

regarding

posterior

A

tissues. the lungs would receive

incidence

First.

IO

unit density

control

comments

density

and lung density.”

dose of 928 rad. Although

50%. Obviously,

equivalent

it is to unit

for an uncorrected

pneumonitis

careful

than

in dose can vary between

means that

corresponding

order.

16% higher this increase

of this steepness

0123456709 Time

900

Oose

radiation

DlSCUSSlON heid

600

the

We have

the dose to lung varies from 650 to 1250 rad.

For large

L 1100

20

of onset of

the time of onset versus dose to lung for all

This data is illustrated correlation

the time

decrease

conventional

that

time of onset and dose

cl al.” found

of lung cancer

also evaluated

in the literature

between

to dose. This

pulmonary observed

reports

dose (see, for

of Figure

I. reference

the largest source of error dose for the patients

in

of this

to the inaccuracies associated with the of the patient. Although this error is

to determine

precisely.

an estimate

of ~54,

in

the delivery of tumor dose is probably reasonable. Combining these possible sources of error, the determinaof onset of pneumonitis

(months)

Fig. 4. The frequency distribution of the time of onset for ail 52 patients who developed radiation pneumonitis.

tion of lung dose for the patients

in this study is accurate

to 25%’ at best and -t 10% at worst. Errors in the determination of the actuarial

incidence

Radiation Oncology ??Biology 0 Physics

466

$

‘1

I

I

P .

1

I

1

zar’s study

1

would

Regression Line with Error Estimates

Probit

April 1981, Volume 7. Number 4

is 880 rad.

ment with Salazar’s

!!

From

yield an incidence

the data

of Figure

of 23% which

estimates

6. this

is in good agree-

of IO to 20%.

SUMMARY The

use of

standard

half

is also being therapy

evaluated

body irradiation

more frequently leukemic

600*900 1000 1100 1200 Iu)o Dose to lung (rod )

111s.I

Fig. 6. Error estimates superimposed on the sigmoidal curve of Fig. 3. Both the minimum and maximum error estimates are demonstrated.

pneumonitis

ial statistical

method

for small

less than 6 patients illustrate

are mainly

related

groups

of patients

per dose interval).

an incidence

of

Tables

nitis

these points contain

patients

though

without

even

a diagnosis

the actuarial last remaining having

patients

Tables

between

actuarial

risk values. is mainly

the

patients

the

were diagnosed

actuarial

figures

the crude

The mag’nitude

figures

minimum

and maximum

on the sigmoidal Salazar

the

estimated

complication

of patients

tion pneumonitis

to be between

using

IO MV data

X

rays.

as derived

Using from

IO and

magnitude

errors

On

in the 1.5%. of the

superimposed

Our experience

is a serious

of radia-

IO and 20%# for 800 rad half body irradiation

average

geometric

and

estimated

average

dose to lung for the patients

in Sala-

these

This is a unique toxicity

data.

toxicity

treatment

planning

the AP patient accounting

treated

with partial

rad.

at relating

and. because of the resultant Using

a CT-aided between factor

has been obtained. retrospec-

dose to lung of a series of patients or total body irradiation These patients

giving

fraction

pneumonitis

occurring

demonstrating

the onset of

750 rad with

at approximately

this dose the sigmoidal

rises dramatically.

pneumonitis

treatments,

occurs at about

incidence

large

were evaluated,

with respect to the radiation

For single

Above

the incidence dose to lung.

and the dose correction

doses in a single fraction.

5% actuarial

tech-

levels.

was then used lo determine.

the absolute

retrospectively.

pneumo-

data such that the dose to

for lung inhomogeneities

syndrome.

lungs of the

system. a simple relationship

tively,

for

involves

that radiation

be repeated.

diameter

This relationship

radiation

transplantation techniques

to the absolute

experience cannot

sarco-

are also being used

use of total lung irradia-

to non-toxic

pneumonitis

of radical

of these treatment

is a first attempt

of radiation

this technique form

to the total

indicates

the increased

detailed

This report

complication

the 820

curve

a 50 and 95
at 930 and 1060 rad. respectively.

In addition.

the time of

onset

pneumonitis

syndrome

of

the

months.

clinical

between

treatment

with

radiation

I to 7 months

the peak

No distinct

incidence

correlation

after

the

occurring

was found

radiation at 2 lo 3

between

the

time of onset and the dose to lung even over the large dose range of 650 to I250 rad. Certainly.

CT scan measurements”

(i.e. 22 cm A-P diameter, 14 cm of lung with relative electron density of 0.24). and previously published central ray data for IO MV X rays,” a mid-lung dose correction factor of I. IO has been calculated. Thus the

of

complication

lung can be limited

occurred

3.

the incidence

dose to lung for upper

density

279.

error

curve of Figure

PI ~1.~ have estimated

uncorrected

between

graphically

in the

of these standard

on the number

lies somewhere

6 illustrates

figures.

deviations

a group and is. at best, 8% and at worst.

Figure

as are

figures

and actuarial

standard

the basis of all the data points, the estimated incidence

died

because the

and the real incidence

dependent

of

(see crude incidence).

of the group

3 and 5 also illustrate

deviations

of

than

small groups

100%’ incidence

Hence.

an overestimate

are somewhere

within

yields

pneumonitis.

probably

some

of pneumonitis

method

3 and 5

Each

niques. Certainly,

(e.g.

100% for doses greater

1100 rad. However, and

to the actuar-

procedures

a

metas-

as well as Ewing’s

large single doses administered patient.

tion requires of radiation

Hospital,

prior to bone marrow

patients.

has become

of widespread

as an adjuvant

for oat cell carcinoma

ma. Total 700

radiotherapy

for palliation

tases. At the Princess Margaret

c--( Mmtmum error estlmote b-4 Mowmum error estimate

600

body

procedure

the data

of this study

indicate

that

lung

complications can only be avoided by precise individualized dosage calculations which include corrections for lung inhomogeneities. The corresponding absolute dose to lung should then single fraction.

be limited

to less than

800 rad in a

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D.J.:

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