Part No...., Module No....Lesson No Module title IAEA Regional Training Course on Radiation Protection of patients for Radiographers, Accra, Ghana, 11-15 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.) Duration: (Add presentation time or duration of the session – hrs) 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

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

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

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

Optimization in Conventional Radiography What radiographers can do in optimization

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

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

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

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

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

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

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

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 (30 - 60%) Room temperature < 20° Film storage conditions 15.1: Optimization of protection in radiography: technical aspects

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

Viewing box color and brightness 5 7 8 1 6 2 3 4 9 BLUE COLOR WHITE COLOR WRONG CONFIGURATIONS (cd/m2) What radiographers can do in optimization

Example of poor viewing box What radiographers can do in optimization

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

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 (140-200) cm Abdominal x-ray examinations: FFD= 115 (100-150) cm What radiographers can do in optimization

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

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

………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

…. 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

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

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

Optimization in Digital imaging What can radiographers do in optimization

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

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

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

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

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

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

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

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

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

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

As seen by radiologist Actual radiation field

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

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

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

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

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

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

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

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

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

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

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

Imaging plate artefact PSP Plates Artifact due to humidity 2 18

Imaging plate artefact Phosphor plate misused. Impossible to clean.

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

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

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

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