PT CARE Unit 1 lecture 8/18/25

X-ray tube: produces X rays; housed in a lead-lined glass/tube; powered by electricity; X rays are a form of energy that must be generated by the machine.
Collimator: controls and shapes the beam (rectangles or squares); uses a light to visualize the beam path since X rays are invisible.
Radiographic table: patient support; typically height-adjustable; four-way floating to move in multiple directions; radiolucent to avoid blocking X rays.
Bucky: the image receptor assembly (upright bucky for chest, table bucky); can be built-in or use detachable digital plates; modern plates are wireless to computer.
Tube supports: ceiling-mounted (common in hospitals) or floor-mounted (older/office setups); overhead crane allows movement across room.
Generator: provides the high voltage electricity to produce X rays.
Control console: interface to set exposure parameters; newer systems may use voice activation or touch controls; includes audible/visual cues when beam is on.
Image receptor options: historical film, now digital plates; typical plate size is 14'' \times 17'' (35 cm x 43 cm) and can be placed portrait or landscape.
Alignment concept: radiation field must align with image receptor; improper alignment wastes dose and degrades image.
Terminology readiness: expect to learn terms for positions, movements, and safety.

X-ray production requires electricity; X rays exit the tube, pass through the collimator, then reach the patient and finally the image receptor.
Collimation confines the beam to the anatomy of interest to minimize patient exposure.
The image receptor captures transmitted X rays to form the image; beam should not extend beyond the receptor.

Field shapes: rectangles or squares; rounded shapes are not supported by typical collimators.
Field size indicators show dimensions in the machine readout; distance indicators show the patient-to-receptor setup in cm.
Automatic collimation (PBL) vs manual collimation; PBL automatically adjusts field size to fit the plate size.
Field size practice: field should be appropriate for the part (e.g., chest vs finger) and ideally not larger than the image receptor.
Typical full-size field: 14'' \times 17'' (or 35\,\text{cm} \times 43\,\text{cm}); fields can be reduced for smaller anatomy.

Upright bucky for chest X-rays; table bucky under the patient for table exams.
Digital plates: wireless transfer to computer; older systems required wired connections.
Radiolucent table materials (carbon-graphite fiber) allow X rays to pass with minimal attenuation.
Radiopaque materials (e.g., metal markers) show up white on images.
Alignment: ensure tube, patient, and image receptor are in proper alignment for accurate imaging.

Tables are usually four-way floating to ease positioning; most are motorized or foot-pedal controlled.
Trendelenburg: head lower than feet; Fowler: head higher than feet.
Table safety: lock wheels, use side rails, avoid leaving a patient unattended on the table.
Transfer safety: use slide boards when moving patients; ensure patient hands are visible to prevent injury.
Radiolucent skin and soft tissues appear relatively faint on X-ray; bones and metals are more radiopaque (white).

Longitudinal (along the table’s long axis) movement; Transverse/Lateral (short axis) movement.
Vertical movement: raise/lower the tube height.
Angulation: cephalad (toward head) or caudal (toward feet); some exams use transverse angulation.
Detent: magnetic lock that latches positions; some systems require a click to lock.
All movement and positioning should maintain alignment among tube, patient, and receptor.

SID: distance from the X-ray source to the image receptor; affects magnification and exposure.
Chest radiographs commonly at 72'' (approx. 180\,\text{cm}); extremities at 40'' (approx. 100\,\text{cm}).
Vertical positioning defines how the tube is placed relative to the patient.

Exposure consists of Quantity (mass) and Quality (penetration).
MA (milliamperes) controls the amount of X rays produced; time controls how long exposure lasts.
MAS (MA × time) gives the total radiation dose delivered.
KV (kilovoltage) controls beam quality and penetrating power.
Formula relation: MAS = MA × time; higher KV increases penetration, not necessarily dose.
Anatomic programming and AEC (automatic exposure control) help estimate the needed exposure and stop when images are adequate.
Not all exams use AEC; some require manual setting of MAS and KV based on body part and patient size.

AEC uses detectors to terminate exposure when sufficient signal is reached.
Anatomical programming provides starting MAS and KV values; adjustments may be needed for size, projection, or pathology.
You must still position the patient accurately; poor positioning can’t be fully corrected by exposure settings.

Portables/mobile units used when the patient cannot be moved; battery-powered with charging.
Wireless or wired image receptors; images can be viewed on a screen at the bedside or on a central system.
Fluoroscopy: live X-ray (dynamic imaging) with an image intensifier and C-arm or U-arm; used in interventional radiology and some diagnostic procedures.
C-arm: portable fluoroscopic system that can move around the patient; essential in OR for procedures like cholangiograms, pacemaker placements, and orthopedic work.

Interventional radiography uses live imaging to guide procedures (angioplasties, stents, vessel work).
Safety: avoid banging the tube or collimator into patient; keep alignment; prevent excessive tube rotation due to high voltage cables.
Always secure the patient with rails, locks, and proper transfer techniques; never leave a patient unattended on the table.
Kill switchs and emergency controls exist for safety; be familiar with their location and purpose.

Imaging is a combination of physics, technique, and patient care.
You are problem-solving: choose appropriate MAS and KV, ensure proper SID and alignment, and use AEC/technique as needed.
Real-world workflow includes moving equipment, positioning patients, and coordinating with teams; safe, precise, and efficient practice is essential.

Longitudinal: movement along the table’s long axis; Transverse/Lateral: along the short axis.
Cephalad: toward head; Caudal: toward feet.
Trendelenburg: head lower than feet; Fowler: head higher than feet.
SID: Source-to-Image Distance; typical chest: 72''\ (180\,\text{cm}); extremities: 40''\ (100\,\text{cm}).
MAS: \text{MAS} = \text{MA} \times t; KV: kilovoltage; MA: milliamperes.
Field size: rectangle/square; maximum approx. 17''\times17'' or 14''\times17''; typical default 10''\times10''.
Image receptor: film vs digital plate; bucky alignment with tube is essential for proper exposure.