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Errors in radiation oncology: A study in pathways and dosimetric

impact

Eric Klein, Robert E. Drzymala, James A. Purdy and Jeff Michalski

Journal of applied Med. Phys. 2005

Error type:

Typical # of

fraction in which

it was detected

Method of detection

# of

events

#of record and

verify

Incorrect treatment

coordinate(s)

first

Port film

19

7

Wrong gantry angle

first

Port film

15

8

Wrong or omitted

cerrobend block

first

Port film

15

N/A

Incorrect

calculation

2 to 5 fractions

In vivo dosimetry;

physicist chart review

11

N/A

Wrong field size

first

Port film.

9

8

Incorrect collimator

angle

first

Port film

8

3

Missing

compensation filter

2 to 5 fractions

In vivo dosimetry;

physicist chart review

6

N/A

Incorrect MU

2 to 5 fractions

In vivo dosimetry

5

4

Wrong photon

energy

2 to 5 fractions

In vivo dosimetry

3

3

Missing or incorrect

MLC shape

first

Port film

3

Incorrect wedge

direction

1,5,16 fractions

Later diode check;

physics check

3

Incorrect number of

fractions for given

set of fields

1 to 3 fractions

Physicist review

3

2

Incorrect or rotated

compensating filter

2 or 11 fractions

Therapist discovery; in

vivo dosimetry

2

N/A

Patient treated

head to gantry but

scanned foot to

gantry

First fraction

Port film

1

N/A

With entrance in vivo

dose measurements

30/3900

Detected errors

49/3900

Errors over a 30

months on 7 linacs

equiped with R&V

system

.

No complete

electronic transfer of

treatment set-up

data.