RAD 354 Chapt. 16 Image QUALITY “Finite” Radiographic quality Noise Resolution Spatial resolution Contrast resoultion

Film/Screen Factors Speed of the “system” Characteristic Curve Digital vs Film/screen Optical Density Factors directly and indirectly effecting density Log Relative Exposure sensitivity of the human eye

Contrast Image contrast Subject contrast How to compensate for subject contrast Film/screen contrast Image receptor/film screen contrast Film/receptor processing

Geometric factors Magnification Distortion Focal spot blur Direct vs distortion Mag factor vs mag ratio Distortion Focal spot blur Sid – Oid relationships Heel effect

RAD 354 Chapt. 17 Image Artifacts Usually TECHNOLOGIST dependant Patient Preparation Clothes left on (zippers, jewelry, dentures) Positioning errors (patient, tube, bucky, receptor) Wrong screen-film combination Upside down film casstte/receptor

Processing Artifacts Roller marks Cascading (curtain effect/run down) Guide shoe lines Pi lines Dirty rollers Chemical fog “Wet-pressure sensation” varied amount of pressure on the rollers = uneven film “splotches”

Handling Artifacts Light/Radiation Fog Kink marks Sensitivity prior and after exposure Kink marks Static (Tree, smudge are the most common) Hypo retention (test is mandatory for mammo)

RAD 354 Chapt. 18 Quality Control Quality Assurance is a JCAHO required 10 step PEOPLE process Quality Control is an imaging intrumentation and equipment process

QC- 3 Step Process Acceptance testing Routine performance monitoring Maintenance

Radiography QC Filtration – annually Collimation – semiannually (+/-2% of the SID) F.S. size Annually (+/-50%) Frequently MISSED parameter! kVp calibration – annually (+/-10%) Exp. Timer Accuracy – annually (based on ms used – more leeway with longer exposures) Linearity – annually (+/-10%) of same mAs with differing mA/times – but SAME mAs Exp. Reproducibility – Same cont./Dens., etc when exposures are repeated

Focal Spot Check Tools/Frequency Annually Pin hole camera (somewhat hard to use) Star Pattern (down to .3 mm sizes) Slit camera – easiest to use/preferred method

Other RAD QC Filtration Collimation (PBL) kVp/Timer Exposure Linearity (same mAs with varied mA and times) Intensifying screens Protective apparel Film illuminators Computer station monitors

Fluoro QC Exposure rate Spot film exposures Automatic Exposure System (ABS – AEC)

Tomo QC Tube travel/Arc Fulcrum level Pt. Expossure

Processor QC See table 18-8 (p. 313) for QC for RAD Processor items/intervals Processor Maintenance Scheduled maintenance Preventative maintenance Non-scheduled maintenance

Processor Monitoring Temperatures Replenishment Sensitometry/Densitometry