C-arm and operation theater radiography

C-arm and operation theater radiography

Where operative procedure requires imaging control, the radiographer plays an important part in the form of the orthopaedic theater team. Fluoroscopy imaging is required during the Trauma Orthopaedic Procedure. But radiographer is also required during some Non-Trauma corrective orthopaedic procedure. However in both instances the radiographer is required to work primarily in an operation theater environment using a mobile C-Arm image intensifier

Non-Trauma corrective orthopaedic surgery

Nowadays, a large number of Non-Trauma corrective orthopaedic procedures are performed. In which there are a large number of joint replacements such as severe osteoarthritis (OA) of Hip joint is treated with prosthetic total hip joint replacement, which does not require imaging control (C-Arm) at all. Still, more complex pediatric operative procedures (e.g. osteotomies for joint alignment) require imaging control.

Trauma Orthopaedic Surgery

Most of the radiographer's work during the Orthopaedic Procedure focuses on the aid of the following Trauma Orthopaedic surgery - Successful reduction of fracture.  Implantation and removal of internal or external fixing devices.

K-wire insertion

K-wire insertion is mostly done for corrective simple fracture extrimity surgery of extrimity such as simple fracture of fingers, hands, wrists, elbow and feet. Imaging controls are required in these procedures. Before processing, it is ensured that the C-Arm is rotating up to 180 °. To reduce magnification and improve image quality, keep the affected area as close to the detector as possible.

Open Reduction and Internal Fixations

Open Reduction and Internal Fixations  are mostly done in situations where the fracture cannot be satisfactorily conducted by any other means. The mid shaft forearm fracture can be stabilized with compression plate and screws. In this situation, to reduce magnification and improve image quality, keep the affected area as close to the detector as possible.

This imaging control is mostly required at the beginning and end of the procedure. During the operation the surgeon can directly view the fracture site and the fixation device.

During the process, collimation should be used in the area of ​​interest, which reduces scatter radiaiton and improves image quality.

Intramedullary Nailing 

During intermittent imaging control is required during the entire procedure. This not only tells the surgeon what is the path of the nail in the medulla in the long bone but also helps in proximal and distal locking in the cortex by the nail screw.

Interventional Procedure

Imaging control is also required during this time. There are many procedures where the radiographer has to assist during the procedure like-

Retrograde pyelography

It is also called ascending pyelography. In this, organic iodinated contrast agents are mechanically filled with renal calyces and pelvis and seen with the help of C-Arm. For this, with the help of cystoscopy, a catheter is attached to locate the affected kidney. For this, a mobile C-Arm image intensifier / solid state detector and radiolucent theater table which are suitable for cystoscopy are used. The patient is made supine. The C-Arm is set for PA projection

Percutaneous Nephrolithotomy (PCNL) 

This is an interventional procedure in which the renal stone is removed with the help of a direct nephrotomy tract. For this, a mobile C-Arm image intensifier / solid state detector and radiolucent theater table which are suitable for cystoscopy are used. In this, large renal stone is damaged by electrohydraulic lithotripsy or ultrasound shock waves.

pelvis and hip all positions

pelvis and hip all positions

Pelvic with both hip -
Pelvis antero-posterior both hip is a common projection used for first evaluation of pelvis bone and hip joint. The positioning of the pelvis and both hip is the same, only the centering point of the x-ray beam is different. Comparative study of both hip joints can be done in AP image and fracture in pubic ramus is also covered.

Position -
pelvis ap with both hip position The patient puts the supine on the bucky table and keeps the median Sagittal Plane coincident of the perpendicular and midline of the cassette.  

Both anterior superior iliac spine are placed at the same distance from the table so that there is no rotation in the patient

 At this time the coronal plane is parallel to the image receptor, for this we have non-opaque pad under the buttock. For this, CR cassette (35 X 43) of sufficient length is used so that the entire bony pelvis is included in the radiyograph.

The limbs are slightly abducted and rotated internally so that the neck of the femer image is parallel to the receptor.

Direction and Location of X-ray beam Collimated vertical x ray beam centers between the anterior superior iliac spine and the line joining the upper border of the symphysis pubis. The top edge of the image receptor is placed 5cm above the upper border of the iliac crest so that the entire bony pelvis is included in the radiograph due to the divergent beam.

Image characteristics

Both hip chant should appear in both hip image and upper third femora image. In Pelvis view both iliac crest, proximal femora as well as lesser trochanter image should be visible correctly. To prove that there is no rotation in the image, the dimensions of both bones should be same and both obturator foramina should be of the same shape. Shenton's line should be visible correctly. It is the curve between the inferior aspect of the femoral neck and the inferior margin of the superior pubic remi. Any type of disruption in this curve indicates femoral neck fracture.

Hip joints frog leg projection

This projection is done for comparison of both hip joint with basic antero-posterior projection. This is done in children for osterochondritis of capital epiphysis (Perthe's disease) and slipped upper femoral epiphysis (SUFE). This position is called the frog position. According to departmental protocol, gonad protection device is used.

position
frog lateral radiograph for hip joint The patient puts the supine on the bucky table and keeps the median Sagittal Plane coincident of the perpendicular and midline of the cassette. Both anterior superior iliac spine are placed at the same distance from the table so that there is no rotation in

the patient. Flex both hips and knees of the patient and rotate both limbs to lateral 60 °. In this case, both the knees are separated from each other and the planter surface of both feet comes in contact with each other. For this, CR cassette (35 X 43) of sufficient length is used so that the entire bony pelvis is included in the radiyograph. Center the image receptor at the level of the femoral pulse.

Collimated vertical x ray beam centers between the line of the femoral pulse.

Hip joint ap view

Position -
The patient puts the supine on the bucky table and puts the median Sagittal Plane perpendicular to the cassette.

Both anterior superior iliac spine are placed at the same distance from the table so that there is no rotation in the patient.

At this time the coronal plane is parallel to the image receptor, for this we have non-opaque pad under the buttock. The hip joint is detected by palpate the femoral pulse and placing it in the center of the image receptor. The limbs are slightly abducted and rotated internally so that the neck of the femer image is parallel to the receptor.

The collimated vertical x ray beam centers vertically on the femoral pulse 2.5cm away from the line joining the anterior superior iliac spine and the upper border of the symphysis pubis. The primary beam collimates on the examination area and uses gonad protection.

The image should include the proximal 1/3 part of the femer and when X-ray arthroplasty is performed to check the positioning and integrity, the prosthesis and femer should be visible in full length in the radiograph.

chest x ray

CHEST X RAY

*         CHEST X RAY POSTERIOR ANTERIOR (PA VIEW) INTRODUCTION - In the chest x-ray, radio graphs of the organ located in the thoracic part of the body are taken. The thoracic cavity contains some of the main organs of its body, such as the heart, lungs, trachea, esophagus, aorta, etc. To protect all of this, thoracic cages are removed, in which anteriorly sternum, posteriorly vertebral column and lateral ribs are located.

·         THE CASES IN WHICH WE DO -Fever,chest pain,ribs broken,Heart Failure,lung cancer etc  

·         PREPARATION - If there is any surgical implanted device of the patient like pacemaker or heart valve, then the doctor should be told first. In this case, the doctor may consider any other alternative of chest x-ray such as CT Scan or Sonography etc. Before X-ray, the patient is asked to remove the clothes above his waist and wear a hospital gown.

·         CENTERING POINT - at the level of the 7th thoracic vertebrae,near the inferior angle of scapulae

·        COLLIMATION  - superiorly 5 cm above the shoulder joint to allow proper watching of upper airways

·         CASSETTE ORIENTATION - landscape or portrait  (depend upon patients)

·        CASSETTE SIZE - 35*43

·        EXPOSURE -  kv- 101-109 and mas - 4-5

·         CENTRAL RAY- perpendicular to cassette

·        FFD- 180 cm

·        grid - yes

·        RESPIRATION- suspended inspiration

FILM CONSTRUCTION

FILM CONSTRUCTION

This film basically has two parts -- the base and the emulsion Fig. 9.1). Most films have the emulsion coated on both side and therefore are called double-emulsion film. Between the emulsion and the base is a thin coating of material called the adhesive layer to ensure uniform adhesion of the emulsion to the base . The emulsion is enclosed by a protective covering of gelatin, called the super coating. This protects the emulsion from scratching, pressure, and contamination during use and processing and allows for relatively rough manipulation of X-ray film before exposure. The thickness  of the 5. sheet of radiographic film ranges form 200-300 um (about10.25 mm).

The double coating film helps in getting better density and contrast and also to reduce the exposure required. This also helps to avoid curling of the film.

The Base - The base is the foundation for radio graphic film and it provides a rigid structure into which the emulsion can be coated. It is flexible and unbreakable and allows easy handling of films. The base of radio graphic film maintains its size and shape during use and processing so that it does not contribute to image distortion. This property of the base is known as dimensional stability. The base is inert so that sensitometric property of the emulsion is not affected. The base is of uniform lucency for viewing the radio graphs clearly. During manufacture, dye is added to the base to slightly tint the film blue. Compared with untinted film, this coloring results in less eye strain and fatigue for the  radiologist.

Two types of bases are available-cellulose triacetate and polyester. Polyester is more resistant to wrapping with age and stronger than cellulose triacetate. Its dimensional stability is superior. Polyester bases are thinner than triacetate bases (approx. 160 um compared with 180 um respectively) but are just as strong. The polyester base is similar in composition to the polyester fibres in clothing

The Emulsion - The emulsion is the heart of the X-ray film. It is the material 2 which X-ray or light photons from screen interact and transfer information. The emulsion consists of a homogenous mixture of gelatin and silver halide crystals. Besides above, also contains various additives like chemical sensitizers, wetting agents antifoggants, hardeners, etc. which impart the required qualities to the film. Emulsion should be clear so at it transmits light and is sufficiently porous for the processing chemicals to penetrate to the crystals of silver halide during processing. its principal function is to provide mechanical support for the silver halide crystals by holding them uniformly dispersed.

HYSTERESIS LOOP

HYSTERESIS LOOP

The variation of flux density with magnetic field intensity is not linear. A graph plotted between B and Has shown in the Figure 2.13. is called B-H curve. From this graph, it is clear that the curve rises rapidly at first indicating big change in the value of B for a corresponding small change in H. The slope of this curve gradually decreases indicating a small change in 3 for increasingly larger values of H. A stage is reached when the slope of the curve becomes constant and this condition is known as saturation..

If we take ferromagnetic material in completely demagnetized state and make it to undergo through a cycle of magnetization in which H is increased from zero to a maximum, then decreases to zero, then reversed and again taken to-H max and finally brought back to zero. The variation of B with respect to H can be represented by a closed hysteresis loop shown in the figure.

A study of hysteresis loop of different magnetic materials helps us to know their magnetic properties. For example, the area of the hysteresis loop for soft iron is smaller than for  steel. Hence energy lost per cycle is correspondingly less. So soft iron is preferred steel for cores of dynamos, transformers, etc. which are subjected to a large number of  cycles so that the loss of energy may be minimum

ELECTROMAGNETIC RADIATION

ELECTROMAGNETIC RADIATION

Electromagnetic Radiation - An electric charge is surrounded by an electric field. If the charge moves, a magnetic field is produced. When the charge undergoes an acceleration or deceleration, the magnetic and the electric fields of the charge will vary. The combined variation of the electric and magnetic fields results in loss of energy. The charge radiates this energy in a form known as electromagnetic radiation. The electromagnetic radiation moves in the form of sinusoidal waves .

"The electromagnetic wave possess wavelength (a), frequency (v) and velocity (c). The distance between two consecutive positive peaks is known as wavelength. The number of cycles of the wave which pass a fixed point per second is known as the frequency of the wave. The velocity of the wave is the distance traveled per second by the wave. The relation between wavelength, frequency and velocity of the electromagnetic wave can be expressed as c - v. All electromagnetic waves, travel at the same velocity in a given medium. In vacuum the velocity is about 2.998 * 108 meter per second.

Moving Coil Galvanometer

Electrical Instruments Electrical instruments are of fundamental importance in the field of measurements. They are almost based on the magnetic effects associated with current. Some of the common electrical instruments are () moving coil galvanometer (ii) ammeter (iii) voltmeter, and (iv) the multimeter.

 Moving Coil Galvanometer

 Moving Coil Galvanometer - A galvanometer is a device used for indicating the flow of current in a circuit. There are two types of galvanometers namely (1) moving magnet, and (ii) moving coil type. The most commonly used galvanometer is the moving coil type.

The moving coil galvanometer was first devised by Lord Kelvin and later modified by D'Arsonval. The principle on which the galvanometer works is that when a conductor carrying current is placed in a magnetic field, experiences a mechanical force given by Fleming's left hand rule.

It consists of a rectangular coil of fine copper wire suspended by a thin phosphor bronze e P) Between the poles pieces of a horse-shoe magnet. P carries a small concave mirror (M) to measure small deflections of the coil with a lamp and scale arrangement (Fig. 2.18). The phosphor bronze wired provides the controlling couple for the moving coil. The current enters and leaves the coil via suitable terminals connected to P and the fine spring Q. The pole pieces of the horse shoe magnets are curved inside and a soft iron piece is placed inside the coil without touching it. This makes the lines of magnetic force to be concentric towards the center of the space between the poles and hence render radial magnetic field. When current (l) is passed through the coil, the coil gets deflected through an angle (0)

The relation between 1 and is given by 1 = Ge where G=C/nBA, which is known as galvanometer constant.

C - Is the torsional couple per unit twist

n - Is the number of turns in the coil

B - is the magnetic induction

A - is the area of the coil

from this it is clear that the defection of the coil is directly proportional to the current passing through the coil. The scale is calibrated and it can give directly the magnitude of current

Shunt Sometimes the galvanometer is connected in a circuit in which large current is flowing. If the whole current is allowed to pass through the galvanometer, it will spoil the coil. To avoid this, a' low resistance is connected in parallel with the galvanometer so as to bypass a major part of the total current through this resistance. As a result, only a very small fraction of total current passes through the galvanometer. This parallel low resistance is called a shunt