Society of Radiological Technologists Sri Lanka
SOCIETY OF RADIOLOGICAL TECHNOLOGISTS _ SRI LANKA. Founded 1975
Affiliated to International Society of Radiographers and Radiological Technologists
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Lecture Notes from Mrs. Beverly Snaith, Lead Consultant Radiographer, UK

The lecture notes at the Radiographers Workshop held on 18th August 2013 is given below in  PDf. Click to view and down load.
…... I so enjoyed my time in Sri Lanka, particularly meeting all the radiographers who were so enthusiastic.
I am so pleased that the sessions stimulated some debate amongst the radiographers and that this provides opportunity for reflection and planning for the future of the profession in Sri Lanka.  ……….

 Regards
       Bev

    Bev Snaith
    Lead Consultant Radiographer
    Mid Yorkshire Hospitals NHS Trust

Introduction
Note 1
Note 2
Note 3

The Development of Mammography Service in Central Province of Sri Lanka.

Weerakoon BS1. , Hewavithana PB2

Department of Radiography, Faculty of Allied Health Sciences,University of Peradeniya.1Department of Medicine, Faculty of Medicine, University of Peradeniya2.

ABSTRACT

Breast carcinoma is a leading cause of death in women in all over the world.Mammography is the primary effective detection technique to reduce breast cancer mortality.The objectives of the study were to describe how the mammography service was established and evolved in Central province,the quality of the service and the experiences of the mammographers who were providing the service.Method: A cross-sectional descriptive study using a self administered structured questionnaire.The results were comparatively discussed with the existing literature& Mammography Quality Standard Act. Results andConclusion: The mammography service in Central province is still in primitive stage. Poor developments can see in the fields of technology, education of the mammographers and screening programs. More Click here

Technological Advances in Radiotherapy for the Treatment of
Localized Prostate Cancer - A Systematic Review 

Jayatissa R.M.G.C.S.B. (B.Sc.) 
Department of Radiography/Radiotherapy, Faculty of Allied Health Sciences, University of Peradeniya, 
Sri Lanka CLICK HERE

[PATIENTSAFETYLS3] Bloodstream infection study results released Dr Sandy Yule (Mr) OBE, DSc, JP CEO, ISRRT

Bloodstream infections (BSI) related to central catheter lines are known to occur routinely in patients admitted to intensive care units all over the world and are associated with high mortality and morbidity rates, extended ICU stays and increased health-care costs. Recent studies have shown that certain multifaceted interventions aimed at increasing compliance with known evidence-based measures can significantly reduce BSI.

BACTERIEMIA ZERO, a collaborative effort between WHO, the Spanish Ministry of Health, Social Policy and Equity and the Spanish Society of Intensive and Critical Care Medicine and Coronary Units (SEMICYUC), is a project aimed at decreasing or eliminating bloodstream infection related to central catheter lines in around 200 intensive care units throughout Spain. The project is a replication of the successful work that the team from Johns Hopkins led by Professor Pronovost carried out in hospitals in the State of Michigan, USA. Consisting of a patient safety culture change bundle and the adoption of a number of technical practices, BACTERIEMIA ZERO led to a 50% reduction in the rates of infection. This demonstration study showed that interventions such as this one can be effective in different health-care systems despite varying levels of organizational structure and safety culture.

The full results of the study will be presented on 27 October 2011 in Madrid, during an event being hosted by the Spanish Ministry of Health, Social Policy and Equity in which WHO Envoy for Patient Safety Sir Liam Donaldson will represent WHO Patient Safety.

For more information, please visit
http://www.who.int/patientsafety/implementation/bsi/en/index.html

Principle of Multislice Detect

Click here to view

Iodinatod contrast media, Their adverse ractions and Remedies

An article compiled by V.G Wimalasena from an international journal Clickhere to view 

Radiation Protection
View more presentations from Santam Chakraborty
 Guide line for Exposure Factors selection in Film-Screen Radiography

Effect of kV, MA & Time

KVP => Energy of x-rays => higher penetrability, it moves through tissue.
The energy determines the QUALITY of x-ray produced.
1. increase in KVP => electrons gain high energy
2. higher the energy of electrons => greater quality of x-rays
3. greater quality = greater penetrability

KVP => QUANTITY => increased kVp = more x-rays produced.
MA = tube current = number of electrons and quantity of x-rays produced.
MA does not affect quality of x-rays produced.

KVP => quality & quantity
MA => quantity
Time => quantity

Purpose of using Grids
1.) Increases contrast
2.) Reduces density
3.) Must use more MAS with a grid.

The choice to use a grid depends on:
1.) KVP used
2.) thickness of part
Parts 10 cm or larger with a KVP higher than 60 produce enough scatter to necessitate the use of a grid.

Air Gap Technique:
This is like a grid. Less scatter on film but less detail also. You can increase SID to help with detail. The greater the gap the less scatter reaches film.
10 inch air gap = 15:1 grid (small body part 10cm)

Need proper balance of density and contrast
Density = overall blackness
Primary controlling factor for density is MAS

To make a visible change in density:
Requires a minimum 30% change in MAS or double
KVP affects density - alters amount and penetrating ability of x-ray beam, so, increasing penetration of x-ray   beam results in more radiation – results into more density on x-ray.

^ KVP = ^ quantity of radiation ^ density

Effect of Changes in KVp is not equal throughout the ranges of KV (low med. & high)
A greater change is required at a higher KVp (greater than 90) compared with a lower      KVP (less than 70)
KVP affects density and other aspects - so, KVP is not primary factor for changes in density.
example:  50 kVp increase by 10 kVp very dark> greater change
                  90 kVp increase 10 kVp slightly darker> smaller change
To maintain density with KVp use the 15% rule:
change KVP by 15% and you will have the same effect on density as doubling MAS
example: 82KVP  change to 94 (15%) is same as 10MAS  change to 20 (double)

Patient thickness
In general, for every 4cm of thickness of patient, you need to adjust MAS by a
factor of 2
example:         thin pt. 18 cm          use 40 MAS
                          thicker pt. 22 cm use 80 MAS to maintain density
(40 X 2 = 80 for the additional 4cm of thickness)


KVP (penetrating power) is the controlling factor for contrast.
High KV => more densities (tones)but fewer differences => low contrast
Low KV => fewer densities (tones) but greater differences => high contrast


KV also affects amount of scatter
High KV => increase in scatter - only adds unwanted density (fog) on film. So,
increasing fog always decreases contrast.
Low KV => decreases scatter - reduces fog, so, increases contrast.

Influencing Factors of Contrast
The most influencing factor for contrast is controlling the amount of scatter.
     less scatter (fog) => increases contrast

1.) Grids - absorption of scatter that exits patient
2.) Collimation - wider field => more scatter => less contrast
                               smaller field => reduces scatter => greater contrast

3.) Air Gap - distance between patient and film - this reduces the amount of scatter getting   to film.
                       So, when amount of scatter is reduced => higher contrast

4.) Body Part - composition, thickness, compactness.

These differences make the range of densities (contrast)
Tissues with higher atomic number absorb more radiation e.g- bone, contrast medium
Tissues with lower atomic number absorb less radiation – e.g -air

Wide range of tissue composition => high contrast
similar types of tissue => low contrast
Thicker tissue => more scatter => less contrast


USING A HIGHER KV FOR A THICKER PART ONLY ADDS TO THE INCREASE IN SCATTER.
This degrades the quality of film. This creates fog which decreases the contrast.
Skinny person -> good contrast
Heavy person -> fog, one density, not a lot of contrast on film

Exposure Modifications:
Pediatric chest = use fast exposure times to stop motion.
Minimum KVP to Penetrate Chest in Children
Premature 50 KV
Infant 55 KV
Child 60 KV

Pediatric patients skull - younger than 6 years old - use 15% less KVP
Adapting exposure factors for children based on exposure factors for adults, excluding chest and skull exams

Age /Exposure factor adaptation
0-5 years ;-25% of MAS that is indicated for adults
6-12 years;-  50% of MAS that is indicated for adults
Casts
Casts can be made of fiberglass or plaster. Fiberglass generally requires no change in exposure factors. Plaster require an increase in exposure, this depends on whether the cast is still wet or whether it is dry.

Dry cast - increase of 2 times the MAS
Wet cast - increase of 3 times the MAS

Pathology: If changes are needed to compensate for diseases it is (generally) best to adjust the KVP because this affects the penetrating ability. (minimun of 15% rule)

Additive conditions - may need to add KVP
    Abdomen - aortic aneurysm, ascites, cirrhosis, hypertrophy of some organs     (splenomegaly)
   Chest - atelectasis, congestive heart failure, malignancy, pleural effusion, pneumonia
   Skeleton - hydrocephalus, metastases, osteochondeoma, Paget's disease (late stage)
   Etc. - abscess, edema, sclerosis

Destructive conditions - may need to decrease KVP
    Abdomen - bowel obstruction, free air
    Chest - emphysema, pneumothorax
     Skeleton - gout, metastases, multiple myeloma, Paget's disease (early stage) osteoporosis
     Etc. - atrophy, emaciation, malnutrition

Soft Tissue:
Objects in soft tissue: if less density is required - MAS should be decreased
Important to know whether contrast should be increased or decreased
     e.g. airway for soft tissue neck - contrast should be increased
            Foreign body - decrease contrast to visualize both bone and soft tissue
Soft tissues that require a decrease in density should use a decreased MAS
Soft tissues that require a higher or lower contrast should use a change in KVP

Quality of x-ray image depends on both the visibility and the sharpness of the recorded detail.
Variables and their effect on the photographic properties of the x-ray image:

Radiographic variables                    Density           Contrast
                                                           
Increase MAS                                   increase          no change
Decrease MAS                                  decrease         no change
increase KVP                                     increase          decrease
decrease KVP                                    decrease         increase
increase SID                                       decrease        no change
decrease SID                                     increase          no change
increase OID                                     decrease         increase
decrease OID                                    increase          decrease
increase Grid ratio                             decrease         increase
decrease grid ratio                             increase          decrease
increase film-screen speed                  increase          no change
decrease film-screen speed               decrease         no change
increase collimation                          decrease         increase
decrease collimation                         increase          decrease
increase focal spot size                     no change       no change
decrease focal spot size                    no change       no change
increase central ray angle                  decrease         no change

Using 100 mA(small focal spot) station for extremity has better detail than
Using the same mAs and same kV with higher ma station

Scatter radiation is detrimental to the quality of film and adds unwanted density to the film without adding any patient information.
Scatter decreases contrast and using grids increase the contrast.
Beam restricting devices and grids are used to limit scatter radiation.

Two major factors that affect the amount of scatter radiation - KVP and the volume of tissue irradiated (opening collimation and larger patient).
1.) Using higher KVP produce more scatter as compared with a lower KVP.
2.) Larger field size and the thicker the patient the greater amount of scatter produced from the patient.
You should use appropriate KVP and limit x-ray beam to limit scatter.

Beam restriction serves two purposes - this increases contrast also
1.) limits patients exposure
2.) reduces scatter

Because collimation decreases x-ray field, less scatter is produced within the
patient, so, less scatter and contrast increases.

Exposure factors may need to be changed when increasing collimation. (less density) So, as collimation increases (smaller area), density decreases, as collimation decreases (larger area), density increases.
When collimating a lot you must increase exposure to compensate for loss of density. The KVP should not be increased because it results in decreased contrast. To change density only, MAS should be changed.
It is recommended with a lot of collimation requires an increase in as much as 30% to 50% of the MAS to compensate for the loss of density.
Increasing Factor:             Effect
Collimation -              Patient dose decreases
                                     scatter decreases
                                    contrast increases
                                    density decreases
Field Size -                 Patient dose increases
                                    scatter increases
                                    contrast decreases
                                    density increases

Purpose of using grids:
1.) increases contrast
2.) reduces density
3.) must use more MAS with a grid

The choice to use a grid depends on:
1.) KVP used
2.) thickness of part

Grids -
Improve contrast, using a grid requires additional MAS resulting in a higher patient dose.
Grids are typically used only when the patient part is 10 cm (adult knee size)or greater and when using more than 60 KVP.

Air gap technique:
This is like using a grid. Less scatter on film but also less detail. You can increase SID to help with the detail. The greater the gap the less scatter.
Using an increases OID is necessary for the air gap tech. However, this decreases quality. To decrease unsharpness and increase detail, you must increase SID.
Accurate measurement of part thickness is critical to the effective use of exposure technique charts.

Two types of technique charts:
      1.) Variable KVP/fixed MAS
      2.) Fixed KVP/variable MAS

1.) Variable KVP/fixed MAS: (Best with small extremities)
KVP increases as part size increases.
Baseline KVP is increased by 2 for every 1cm increase in part thickness, and MAS stays the same.
Accurate measurement of part thickness is critical to use this type of chart.
In general changing the KVP for variations in part thickness is ineffective throughout the entire range of x-rays. This kind of chart is most effective with small extremities such as hands and feet. At low KVP levels, small changes in KVP may be more effective than changing the MAS. Contrast will vary and these
types of charts tend to be less accurate for part size extremes. Adequate penetration of the part is not assured, and the x-ray produced with the use of this type f chart tend to have higher contrast.

2.) Fixed KVP/variable MAS
This uses an Optimal KVP which is the KVP value that is high enough to ensure penetration of the part but not too high to diminish x-ray contrast. Then the MAS is varied to the part thickness.

In general, for every 4-5 cm change in part thickness, the MAS should be adjusted by a factor of 2. (double MAS)

Accurate measurement of part thickness is important but less critical compared with variable KVP. An advantage of using this chart is that patient groups can be formed around 4-5 cm changes. You can use patient thickness groups. It is easier
to use, more consistency on films, standardization of contrast.


General rule for increase in density
(15% increase in KVp = doubling MAS)
To make a visible change in density it requires at least 30% change in MAS .
Changes in KV differ at high and low levels. greater change is needed with 90 KV compared to 50 KV

90 KV and increase 10 KVP => slightly darker
50 KV and increase 10 KVP => very dark
To maintain density with KVP use 15% rule

so 15% rule KVP = doubling MAS maintains density
KVP 82 change to 94 (15%) is same as MAS 10 change to 20 (double)

For each additional 4cm thickness you need to double MAS to maintain density.

15% rule =

          60 = 69 ,

          62 =71.3,

          65 = 74.75,

          68 = 78.2,

          70 = 80.5,

          72 = 82.8,

          75 = 86.25

_End_




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