1. Part No...., Module No....Lesson No
Module title
IAEA Regional Training Course on Radiation Protection of patients for Radiographers, Accra, Ghana, July 2011
Optimization of protection in radiography – What radiographers can do?
Part …: (Add part number and title)
Module…: (Add module number and title)
Lesson …: (Add session number and title)
Learning objectives: Upon completion of this lesson, the students will be able to: …
. (Add a list of what the students are expected to learn or be able to do upon completion of the session)
Activity: (Add the method used for presenting or conducting the lesson – lecture, demonstration, exercise, laboratory exercise, case study, simulation, etc.)
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Materials and equipment needed: (List materials and equipment needed to conduct the session, if appropriate)
References: (List the references for the session)
IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

2. What is optimization in radiography?
To obtain diagnostic images
containing required diagnostic information
with the minimum patient exposure
within prevailing resource limitations
15.1: Optimization of protection in radiography: technical aspects

3. Which aspects to consider ?
How to optimize?
Which aspects to consider ?
Equipment
Examination/technique
Interpretation
15.1: Optimization of protection in radiography: technical aspects

4. What radiographers can do in optimization
Outline
Optimization in conventional radiography
- Technical aspects
- Radiation protection aspects
Optimization in digital imaging
What radiographers can do in optimization

5. Optimization in Conventional Radiography
What radiographers can do in optimization

6. Image formation in film-screen imaging
Part No...., Module No....Lesson No
Module title
Image formation in film-screen imaging
Bone
Air
Soft
tissue X
Primary
collimation
Film, fluorescent screen
or image intensifier
Beam intensity
at detector level
« Latent »
radiological
image
Antiscatter Grid
Scattered
radiation
The beam intensity at the detector level is modulated by the density of the irradiated structure (air, bone, soft tissue etc). The latent radiological image has to be revealed through the processing to become visible.
What radiographers do in optimization
IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

7. Identification of screen by type and format
1. Screen film system: A particular intensifying screen used with a particular type of film
Screen-film combination should be selected according to manufacturer’s recommendations
Identification of screen by type and format
type mismatch (use of different types of screens) FOR THE SAME FORMAT is not ADVISABLE
Screen film contact
loss of spatial resolution, blurred image
Cleanliness
What radiographers can do in optimization

8. 2. Film processing: automatic processors
Constant temperature
Constant processing time
Automatic replenishment of chemicals
Drying of films
BUT
Can introduce artifacts
What radiographers can do in optimization

9. What radiographers can do in optimization
Film processor QC
Most important QC features:
proper film storage
cassette and screen care
processor chemical care
Identify artifacts
processor cleanliness
What radiographers can do in optimization

10. Manual Processing
There are many places where X Ray films are processed manually, in open tanks
Manual processing can be very effective, BUT there can be many quality problems
What radiographers can do in optimization

11. Dark room conditions in some hospitals
What radiographers can do in optimization

12. Basic film processing Requirements
Temperature - constant and optimum
Time - measured
Developer activity (chemical condition) - fresh and unoxidised
What radiographers can do in optimization

13. Dark room Darkroom characteristics Safelight External light tightness
number (as low as possible), distance from the table
type and colours of filters
bulb color (red) or adapted to film
External light tightness
Hygrometry ( %)
Room temperature < 20°
Film storage conditions
15.1: Optimization of protection in radiography: technical aspects

14. 3. Viewing box characteristics
Since the viewing conditions are essential for a good interpretation of the diagnostic images, the viewing conditions must be optimal
Cleanliness of external/internal surface
Brightness
homogeneity within the same viewing box
Coloring
color mismatch must be avoided
Environment
ambient light level: 50 lux maximum
15.1: Optimization of protection in radiography: technical aspects

15. Viewing box color and brightness5 7 8 1 6 2 3 4 9
BLUE
COLOR
WHITE
COLOR
WRONG
CONFIGURATIONS
(cd/m2)
What radiographers can do in optimization

16. Example of poor viewing box
What radiographers can do in optimization

17. Radiation protection aspects
Part No...., Module No....Lesson No
Module title
Radiation protection aspects
Optimization of patient radiation protection requires periodic evaluation of doses and image quality.
Operators of the X Ray system should be aware of the interdependence between technical parameters, dose and image quality
Procedures should be established for each examination to ensure a proper use of equipment.
Explanation or/and additional information
Instructions for the lecturer/trainer
What radiographers can do in optimization
IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

18. 1. Skin focus distance
In general radiography (except dental), the skin-focus distance should not be lower than 30 cm
In radiography with fixed equipment, the skin-focus distance should not be lower than 45 cm
Usually chest x-ray examinations ( chest stand; FFD= 180 ( ) cm
Abdominal x-ray examinations: FFD= 115 ( ) cm
What radiographers can do in optimization

19. What radiographers can do in optimization
2. Awareness
e.g. when there are suspicions about a malfunctioning of the X Ray unit or of the imaging chain in a room that might affect the protection of the patient (i.e., because the images become over or underexposed without changing the technique), this should be reported to the responsible person of the room in order to reevaluate the equipment if necessary and to introduce corrective actions.
What radiographers can do in optimization

20. What can radiographers do in optimization
3. Procedures
Image annotation (patient ID, exam date, markers ) on film
Patient instructions and patient positioning
The usual radiological technique for each projection on a given equipment, with details of the associated image device should be written and be readily accessible, close to the control panel. It should be specified for patients of standard as well as uncommon size
What can radiographers do in optimization

21. ………Procedures
It is advisable to use the highest kVp (and the lowest mAs) compatible with the image that one expects to obtain. In this way the patient irradiation will be lower, although it might get lower image contrast. Therefore the optimization is to find the proper balance between contrast and dose
The shortest exposure time as possible should be selected, above all when examining non- collaborating patients (shorter time means reduction in kinetic blurring)
What can radiographers do in optimization

22. …. Procedures: x-ray beam limitation
The smallest film and cassette size compatible with the expected image must be used together with automatic collimation. Otherwise the patient would be over-irradiated, by receiving radiation over a larger volume and transversal surface, and the raise in scattered radiation would reduce the image quality and increase the operating personnel doses.
When using equipment without automatic X Ray beam collimation, it should be verified that the radiation field is reduced up to the smallest size compatible with the required image.
What can radiographers do in optimization

23. Periodic evaluation of the image quality
A periodic evaluation (at least once a year) of the image quality obtained in each room allows the detection of malfunctioning in the imaging chain or in the generator (almost always associated to high patient doses and poor image quality)
A periodic evaluation of the number of rejected and repeated radiographs and the analysis of the causes of rejects and retakes allow the detection of failures in the X Ray equipment, associated image devices, as well as in the examination procedures and in the skill and training of the staff
What can radiographers do in optimization

24. Corrective actions
When some corrective measures are proposed after the detection of a malfunctioning, recording the follow up of their implementation is advisable (in a logbook)
What can radiographers do in optimization

25. Optimization in Digital imaging
What can radiographers do in optimization

26. Radiation dose in digital radiology
Conventional films allow to detect mistakes if a wrong radiographic technique is used: images are too white or too black
Digital technology provides user always with a “good image” since its dynamic range compensates for wrong settings even if the dose is higher than necessary
What radiographers can do in optimization

27. What radiographers can do in optimization
Underexposure results in a “too noisy” image
Overexposure yields good images with unnecessary high dose to the patient
Exposure level 2,98
Exposure level 2,36
What radiographers can do in optimization

28. An underexposed image is “too noisy”
Exposure level 1,15
Exposure level 1,87
20: Digital Radiology

29. Three approaches to digital radiography
Translate developed film into digital form
(Digitizing conventional films).
II Capture the radiographic projection by non-
photographic method and digitize during development
(Computed radiography, CR)
Capture the radiographic projection or its fluorescence
directly in digital form (Direct radiography, DR).
15.1: Optimization of protection in radiography: technical aspects

30. Typical CR system
15.1: Optimization of protection in radiography: technical aspects

31. Typical DR system
15.1: Optimization of protection in radiography: technical aspects

32. How to move from film-screen to digital?
Typically the initial setting for the automatic exposure control using CR, should be the same or similar to the existing with film-screen. Optimisation (including possible kV changes) and potential dose reduction should be initiated later once radiologists become familiar with digital.
Audit DICOM header. It contains a lot of useful information.
Radiation Protection in Digital Radiology L01 Fundamentals of Digital Radiography

33. What can a radiographer do?
Generally as for film screen imaging
Image annotation
Patient positioning and collimation
Radiographic exposure per examination
Image viewing conditions
Patient dose and image quality evaluation
15.1: Optimization of protection in radiography: technical aspects

34. Specific for digital imaging
Exposure parameters and image processing (follow
manufacturer guidance
Lower mAs than in film–screen
High or low kVp? (generally lower than in film-screen
protective shielding (assure that area being examined is not covered)
Post processing (adequate, avoid too much processing since artifacts can result)
Image viewing conditions (calibrated to fit purpose)
Cleanliness (extremely important-to avoid artifacts)
What radiographers can do in optimization

35. Improper collimation can cause an incorrect exposure indicator value: Fuji CR
S = 183, L = 1.9
S = 578, L=1.8

36. As seen by radiologist
Actual radiation field

37. Incorrect collimation can cause inappropriate image processing: Agfa CR
Automatic processing
Manual reprocessing
Radiation Protection in Digital Radiology L06 Avoiding Artefacts in Computed Radiography

38. Gonadal shielding has drawbacks
Ovary locations vary
Shield may obscure clinical features
Shield may interfere with automatic image processing
Processed
Unprocessed

39. What radiographers can do in optimization
Image quality and dose
Diagnostic information content in digital radiology is generally higher than in conventional radiology if equivalent dose parameters are used
The wider dynamic range of the digital detectors and the capabilities of post processing allow to obtain more information from the radiographic images
What radiographers can do in optimization

40. What radiographers can do in optimization
Exposure level
Some digital systems provide the user with a so called “exposure level” index which expresses the dose level received at the digital detector and orientates the operator about the goodness of the radiographic technique used
The relation between dose and exposure level is usually logarithmic: doubling the dose to the detector, will increase the “exposure level” to a factor of 0.3 = log(2).
What radiographers can do in optimization

41. Difficulty to audit the number of images per procedure
Deleting useless images before sending them to the PACS is also very easy in digital fluoroscopy
This makes difficult any auditing of the dose imparted to the patient
The same applies to projection radiography to audit the retakes.
What radiographers can do in optimization

42. What radiographers can do in optimization
Actions that can influence image quality and patient doses in digital radiology (2)
Eliminate post-processing problems, digitizer problems, local hard disk, fault in electrical power supply, network problems during image archiving etc.
Avoid loss of images in the network or in the PACS due to bad identification or others
Reduce artifacts due to incorrect digital post-processing (creation of false lesions or pathologies)
What radiographers can do in optimization

43. Diagnostic reference levels
In digital radiology, the evaluation of patient doses should be performed more frequently than in conventional radiology:
Easy improvement of image quality
Unknown use of high dose technique
Re-assessment of local reference levels when new digital techniques are introduced is recommended to demonstrate the optimization of the systems and to establish a baseline value useful for future patient dose assessment

44. Conventional Reason for Repeated Exam
Artefacts
Mispositioning
Over-collimation
Patient motion
Double exposure
Inadequate inspiration
Overexposed - too dark
Underexposed - too light
Marker missing or wrong
Wrong exam
Wrong patient
Film lost in processor
Radiation Protection in Digital Radiology L03 Optimisation in CR and DR

45. CR/DR Reason for Repeated Exam
Overexposed - high exposure index
Underexposed - low exposure index
Marker missing or wrong
Wrong exam
Wrong patient
Lost image
corrupt data, cannot transfer
deleted by operator (waste bin)
Artefacts
Mispositioning
Over-collimation
Patient motion
Double exposure
Inadequate inspiration
Radiation Protection in Digital Radiology L03 Optimisation in CR and DR

46. Remember digital imaging can lead to many artefacts
PSP Plates
Scratches in the plate.
Abdomen of a 3rd trimester pregnant woman. 2 18

47. CR Imaging plates do not last forever
Imaging plate artefact
Agfa plate defect
Same defect,
different orientation
Artefact remedy: The Imaging plate (IP) must be replaced when cracks occur in clinically useful areas

48. Imaging plate artefact
PSP Plates
Artifact due to humidity 2 18

49. Imaging plate artefact
Phosphor plate misused. Impossible to clean.

50. Dust on collection optics causes line in slow-scan dimension (Fuji CR)
Dirt on the light guide in the CR reader. The light guide collects light emitted from the imaging plate when it is scanned by the laser.
Artefact remedy: the light guide of the photomultiplier tube was cleaned by service personnel.
Radiation Protection in Digital Radiology L06 Avoiding Artefacts in Computed Radiography

51. Plate reader artefact Digitiser Processing 2 18
Radiation Protection in Digital Radiology L06 Avoiding Artefacts in Computed Radiography 2 18

52. Part No...., Module No....Lesson No
Module title
Summary
Digital radiology requires some specific training to benefit of the advantages of this new technique.
Image quality and diagnostic information are closely related with patient dose.
The transmission, archiving an retrieving of images can also influence the workflow and patient doses
Quality assurance programs are specially important in digital radiology due to risk of increasing patient doses
Let’s summarize the main subjects we did cover in this session. (List the main subjects covered and stress again the important features of the session)
IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

53. THANK YOU!