Per Diem, PRN, Travel, Local Contract: What the Terms Mean

Imaging staffing comes with its own vocabulary, and the same shift can be described in very different terms depending on who is posting it. This glossary collects the words radiologic technologists meet most often and defines each one in a single, quotable paragraph, so you can find a meaning quickly and know exactly what a listing is offering.

Per diem

Per diem, Latin for “by the day,” refers to imaging work scheduled one shift at a time, as needed, with no long-term commitment. A per diem technologist accepts individual shifts and is paid by the hour for the hours worked, rather than earning a fixed salary.

PRN

PRN, from the Latin pro re nata (“as the situation demands”), is used interchangeably with per diem. It describes as-needed shift work rather than a fixed schedule, and it is the label many facilities use on their shift listings. If you are weighing the two words themselves, per diem vs. PRN settles the difference directly.

Float pool

A float pool is a group of technologists a facility or health system keeps available to move, or “float,” between departments and units wherever coverage is short on a given shift. A technologist in a float pool is not tied to one fixed area and may cover different modalities or locations from day to day, which rewards broad competency and flexibility.

Travel assignment

A travel assignment is a fixed-length contract, often around 13 weeks, at a facility away from where you live. Travel roles usually combine a taxable hourly rate with stipends for housing and meals, and they suit technologists willing to relocate temporarily for higher total pay.

Local contract

A local contract is a fixed-length assignment, similar to travel work, at a facility within commuting distance of home. Because there are no travel stipends, the pay is usually a single hourly rate, and the technologist keeps their own living arrangements.

Block scheduling

Block scheduling is an arrangement in which a technologist commits to a defined group, or block, of shifts in advance rather than picking up single shifts one at a time. A block might be several consecutive days or a recurring weekly pattern. It gives the facility predictable coverage and gives the technologist a known schedule, sitting between open per diem work and a fixed-length contract.

Guaranteed hours

Guaranteed hours are a contractual promise that a technologist will be paid for an agreed number of hours in a pay period even when the facility has less work available than expected. If shifts are cancelled or cut short, the guarantee means the technologist is still paid up to that amount. Guarantees are common on travel and local contracts and are less typical of open per diem shifts.

On-call and call pay

On-call work requires a technologist to remain available to come in on short notice during a defined period, even when not actively working a shift. Call pay is the standby rate paid for that availability, and it is usually lower than the active shift rate. If the technologist is called in, the hours worked normally convert to the regular or a premium rate. Such coverage is common for after-hours and weekend imaging.

Shift differential

A shift differential is extra pay added to the base hourly rate for working less desirable hours, such as nights, weekends, or holidays. It is expressed as an added amount or percentage on top of the standard rate and compensates for the inconvenience of the schedule. Differentials vary by facility and by the specific hours worked.

Cancellation policy

A cancellation policy sets out what happens when a scheduled shift is called off, usually by the facility, before it is worked. It defines how much notice is required and whether the technologist is paid anything when a shift is cancelled inside that window. Clear terms matter most for per diem and contract work, where a late cancellation can otherwise mean lost income.

W-2 versus 1099

W-2 and 1099 describe how you are paid and taxed. A W-2 worker is an employee with taxes withheld automatically; a 1099 worker is an independent contractor who receives the full payment and sets aside taxes independently. Per diem work can fall under either, so it is worth confirming which applies before you accept a shift.

Credentialing

Credentialing is the process of verifying a technologist's licenses, certifications, and qualifications before they work. It confirms that credentials such as ARRT certification and state licensure (which varies by state, as our state-by-state licensing reference lays out) are current and valid, and it is normally completed once, up front, rather than repeated for every shift.

Compliance and onboarding

Compliance and onboarding cover the documents and steps a technologist completes before starting at a facility, including background checks, health screenings, immunization records, and site-specific orientation. It overlaps with credentialing but is broader, reaching past license verification to the requirements a particular site imposes. Finishing it in advance is what lets a technologist begin a shift without delay.

Modality

A modality is a type of medical imaging, such as X-ray, CT, MRI, mammography, nuclear medicine, fluoroscopy, or interventional radiology. Shifts are posted by modality, and the pay often varies from one modality to another based on skill requirements and demand.

Bill rate versus pay rate

The pay rate is what the technologist earns per hour; the bill rate is what the facility pays the staffing provider. The difference covers the provider's costs and margin. On a direct marketplace, the gap between the two is typically narrower than in traditional agency staffing.

Rate transparency

Rate transparency means the pay for a shift or assignment is stated clearly and up front, so a technologist can see what they will earn before accepting the work. It contrasts with arrangements where the rate is vague, negotiated case by case, or hidden inside the gap between bill rate and pay rate. Transparent rates let technologists compare opportunities on equal terms.