Write short note on film speed.
Answer. Film speed refers to the amount of radiation required to produce a radiograph of standard density.

• Film speed is indicated over the label side of intra-oral film packet and also on the outside of film box or container.

Film speed in radiography

• Factors determining the film speed are:
  • Size of silver halide crystals
  • Thickness of emulsion
  • Presence of special radiosensitive dyes.
• Film speed should determine that how much radiation and the exposure time are necessary to produce an image on the film.

Factors affecting X-ray film speed

• For example, a fast film needs less radiation exposure because film responds more quickly; response of fast film is quick because silver halide crystals in the emulsions are larger. Larger are the crystals, faster is the film speed.
• For identifying the speed of film an Alphabetical classification system is used. X-ray films are given speed ratings which range from A speed i.e. slowest to F speed i.e. fastest. Only D and F speed films are used for intraoral radiography. E-speed films are discontinued by Kodak.
• American Dental Association and American Academy of Oral and Maxillofacial Radiology currently recommend the use of F-speed film.

D-speed vs F-speed film

• F-speed film need 60% of exposure time of D-speed film and has comparable image contrast and resolution.
• Use of F-speed film leads to less radiation exposure for the patient.
• F-speed film is faster as compared to D-speed due to the larger crystals and increased amount of silver bromide inside the emulsion.

Radiographic film classification

• Recently used F-speed films not only reduce the radiation dose to the patient but also provide stable contrast characteristics under various processing conditions.
• Ekta speed films (E – speed films) are the only E-speed films which are used in clinics, as they allow good radiographic visualization with minimum radiation exposure.

The post Film Speed appeared first on BDS Notes.

Write short note on IOPA.
Answer. Full form of IOPA is intra oral periapical X-ray.

Size of IOPA Films

• Size 0: (22 × 33 mm): Used in children for both periapical and bitewing films, used for small mouths.
• Size 1: (24 × 40 mm): Used for the adult anterior periapical.

IOPA full form in dentistry

• Size 2: (31 × 41 mm): Used for the adult posterior periapicals and can also be used for occlusal films in children.
• Size 3: (57 × 76 mm): Used for occlusal films (mainly in adults).

Contents of ioPa Film Packet

• One corner of IOPA film has a small raised dot which is used for orientation film. Indentation dot is present on film cover and film.
• As film is placed in mouth of the patient, side of the film with raised dot is positioned facing X-ray tube and towards the occlusion.

Intraoral periapical X-ray technique

• IOPA film packets consist of one or two sheets of film. Film is encased in the protective black paper wrapper and then in plastic wrapping which is resistant to moisture.
• Outer wrapping indicates location of raised dot and identifies which side of film should be directed towards X-ray tube.
• Between the wrapper, the is a thin lead foil backing that is embossed in the pattern. Foil is positioned in film packet behind the film away from tube.

Structures seen in IOPA

• Tooth
• Periapical structures
• Lamina dura
• Alveolar bone surrounding the tooth
• Inferior dental canal
• Maxillary antrum outline in relation to upper molars
• Outline of nasal cavity

Indications of IOPA

• Detection of apical infection/inflammation
• For assessing the periodontal status
• After trauma to assess the teeth and alveolar bone
• Assessment of presence and position of unerupted tooth

IOPA indications in dentistry

• Assessment of root morphology before extraction
• During endodontic therapy
• For preoperative assessment and postoperative appraisal of periapical surgery
• For detailed evaluation of apical cysts and other lesions within alveolar bone.
• For assessment of position and prognosis of implants.

The post IOPA Techniques appeared first on BDS Notes.

Write a short note on X-ray film.
Answer. An X-ray film serves as a recording medium or image receptor. A latent image is recorded in the X-ray film when it is exposed to information-carrying X-ray photons.

Storage of an X-ray Film

• X-ray film gets adversely affected by heat, humidity, and radiation.
• So following points are considered for storing the X-ray films:

X-ray film fog prevention

• X-ray film must be kept in a cool and dry place to prevent film fog.
• The optimum temperature to store X-ray film ranges from 50 to 700 F.
• The optimum humidity level to store X-ray film ranges from 30 to 50%.

X-ray film in radiology

• X-ray film should be stored in areas that are shielded from the source of radiation.
• Lead-lined or radiation-resistant storage boxes are used to prevent film fog.
• X-ray films must be used before expiry date.
• The oldest film in the stock must be used before using any new film.

The post X-Ray Film appeared first on BDS Notes.

Write short note on differential diagnosis for radiolucent lesion in maxillary anterior region.
Answer.

Radiolucent Lesion in Maxillary Anterior Region

• Periapical granuloma
• Radicular cyst
• Periapical scar
• Periapical abscess
• Surgical defect
• Osteomyelitis
• Acute apical perodontitis
• Traumatic bone cyst
• Dentigerous cyst
• Giant cell granuloma

The post Radiolucent Lesions appeared first on BDS Notes.

Write short note on cephalogram.
Answer. Cephalogram is an extraoral radiography of skull.

• This view is used to evaluate facial growth and development trauma, disease and developmental anomalies.
• This projection demonstrate the bones of face, skull as well as the sof tissue projection of the face.
• In oral surgery and prosthesis, it is used to establish pretreatment and post-treatment records.

Film Position

Cassette is placed perpendicular to the flor with the long axis of the cassette placed vertically.

Position of Patient

• Left side of the patient’s head is positioned against the cassette.
• Mid-sagittal plane is perpendicular to the flor and parallel to the film.
• Patient’s head is stabilized with the help of the ear rods, nasion positioner and the orbital rod.
• Patient is asked to keep the teeth in occlusion.

Central Ray

• Central ray is directed perpendicular to the cassette through the portion.
• The distance between the X-ray source and the mid-coronal plane of the patient is 60 inches.

Exposure Parameter

kVp: 84.

mA: 13.

Seconds: 1.6.

The post Cephalogram appeared first on BDS Notes.

Write short note on radiographic features of periapical granuloma.
Answer. Following are the radiographic features of periapical granuloma:

• Periapical area is radiolucent with loss of lamina dura.
• Radiolucency is of variable size at the apex of tooth, diameter is usually less than 1.5 cm.
• Lesion may or may not have well defied border, which can or cannot be hyperostotic.
• Presence of loss of lamina dura and periapical bone known as “periapical rarefying osteitis”.
• Involved tooth can show a deep restoration, extensive caries, fracture or a narrow pulp canal with non-vital pulp.

The post Radiographic Features Of Periapical Granuloma appeared first on BDS Notes.

Write short note on technique and indication for PA Water’s view.
Answer.

PA Water’s View

Structure shown

This projection is used to demonstrate the maxillary sinus. It also shows frontal and ethmoidal sinus. The orbit, frontozygomatic suture, nasal cavity, coronoid process of the mandible and the zygomatic arch are also seen.

Film Placement

• Cassette is placed perpendicular to the flor in a cassette holding device.
• Long axis of the zygomatic arch is also seen.

Position of Patient

Position of patient should be such that the mid-sagittal plane should be vertical and perpendicular to the plane of film.

• Patient’s head is extended so that only the chin touches the cassette.
• Cassette is centered around the acanthion.
• The canthomeatal line should be at 37° to the plane of the fim external auditory meatus to the mental protuberance should be perpendicular to the fim.
• Water specified that the tip of the nose should be 0.5 to 1.5 mm away from the cassette.
• Patient’s head is extended as far as comfortable, to make lower border of mandible as parallel to cassette as possible. Only chin touches the cassette. Canthomeatal line should be approximately parallel to plane of the film.

Central Ray

Perpendicular and to the mid point of the fim.

Exposure Parameter

kVp: 65.

mA: 10.

Seconds: 2.3.

Indication

For demonstrating maxillary sinus, frontal and ethmoidal sinus.

The post PA Water’s View appeared first on BDS Notes.

Define radiation. Explain with the help of diagram the construction of X-ray tube and production of X-rays.
or
Discuss in detail about production of X-ray. draw a well-labeled circuit diagram of X-ray tube.
or
Draw a labeled diagram for X-ray tube and discuss production of X-rays.
Answer. Radiation is defined as the emission and propagation of energy through space or a substances in form of waves or particles.

Construction of X-ray tube

• X-ray tube: It is the main X-ray generating system. It consists of three parts i.e. lead glass housing, negative cathode and positive anode.
  • Lead glass housing is a glass vacuum tube which prevents X-rays in escaping all the directions.
  • Negative cathode consists of filament and focusing cup. Filament is basically a coiled wire of tungsten and produces electron on heating. Focusing cup is a holder formed by molybdenum and it houses the filament. Focusing cup focus electrons in a narrow beam and direct beam across the tube towards tungsten target of anode. Cathode supply the electrons which are necessary in generation of X-rays.
  • Positive anode converts electrons into X-ray photons. Anodes are of two types, i.e. stationary and rotating anode.
• Circuits: In X-ray machine, two types of circuits are used, i.e. filament circuit or high voltage circuit.
  • Filament circuit is of low voltage, i.e. 3 to 5 volts. It regulates flow of electric current to filament of X-ray tube.
  • High voltage circuit uses 65,000 to 1,00,000 volts which provide high voltage required to accelerate electrons for generation of X-rays in X-ray tube
• Transformers: It either increases or decrease voltage in an electrical circuit. Transformers are of three types i.e.
  • Step-down transformer: It decreases the voltage from incoming 110 to 220 line voltage to 3 to 4 volt as required for the filament circuit.
  • Step-up transformer: It increases the voltage from incoming 110 to 220 line voltage to 65,000 to 1,00,000 volts as required by high voltage circuit.
  • Auto transformer: It serves as a voltage compensator, which correct minor fluctuation in current.
• Timer: It completes the circuit with high voltage transformer and controls the time for which high voltage is applied to the tube.
• Tube rating: It is the maximum safe interval the tube is energized at given range of voltage (kVp) and the tube current (mA) values.
• Duty cycle: It refers to how frequently successive exposures can be made.

The post Components Of X-Ray Tube appeared first on BDS Notes.

Write short note on collimator.
Answer. Radiation beam emitted by X-ray tube is shaped using special diaphragm known as collimator. Collimation is the method by which one can control size and shape of the X-ray beam.

• Collimator decreases the risk of radiation, minimizes scattered radiation and decreases the fog with sharp image and better contrast.
• Collimators used in intra-oral machines are fixed while in extra-oral machines collimators used are adjustable.

Types of Collimators

Following are the type of collimators:

Diaphragm collimator

• It consists of a thick plate of radiopaque material with opening in it.
• Collimator should lie over the port in X-ray head by which X-ray beam emerges.
• Aperture should be of different size and shape depending on requirement.

Tubular collimator

• It is a tube which is manufactured by radiopaque material.
• Combination of diaphragm type and tubular type is used.
• The combination helps in reducing the penumbra at periphery of image.
• Longer the tube small is penumbra.

Rectangular collimator

• They limit the size and they are larger than size of an X-ray film.
• It can be incorporated in a film-holding device.

Slit collimator

It is used in OPG machines.

In CT machines, collimators are of two types i.e:

• Source collimator: It lies in front of X-ray tube and reduces the beam of radiation to form maximum required fan beam and determines the emitted dose.
• Detector collimator: It is positioned directly in front of detector and is used to shield detector against scattered radiation and prevents the artifacts.

The post Collimator appeared first on BDS Notes.

Write short note on osteoradionecrosis.
Answer. Osteoradionecrosis is a radiation-induced pathologic process characterized by the chronic and painful infection and necrosis is accompanied by the late sequestration and sometimes permanent deformity.
This is one of the most serious complications of radiation to head and neck seen frequently today because of better treatment modalities and prevention.

Factors Leading to osteoradionecrosis

• Irradiation of an area of previous surgery before adequate healing had taken place.
• Irradiation of lesion in close proximity to bone.
• Prolong oral hygiene and continued use of irritants.
• Poor patient’s corporation in managing irradiated tissues.
• Surgery in irradiated area.
• Failure to prevent trauma to irradiated bony areas.

Pathogenesis

Osteoradionecrosis Clinical Features

• Mandible is more commonly affected as compared to maxilla due to low vascularity. Mostly the posterior region of mandible is affected.
• Presence of trismus, pyrexia and halitosis.
• There is also presence of intermittent swelling with drainage of pus extraorally.
• Pain is severe which continue from weeks to months.
• Persistently draining sinuses are present.
• Bone exposure is the hallmark of osteoradionecrosis.
• As the bone become necrotic due to lack of supply of blood sequestrum is formed.
• Pathological fracture of bone is a common feature.

Osteoradionecrosis Treatment

• Debridement of necrotic tissue should be done along with removal of sequestrum.
• Administration of intravenous antibiotic and hyperbaric oxygen therapy are essential.
• Maintenance of oral hygiene is necessary.

The post Osteoradionecrosis appeared first on BDS Notes.