Bone Scan (Tc-99m MDP)

Whole-body scintigraphy using technetium-99m methylene diphosphonate (or HDP) — sensitive for osseous metastatic disease, stress fractures, osteomyelitis, Paget's disease, and avascular necrosis. Remains the workhorse bone imaging study despite growing NaF PET / CT use in high-volume oncology centers.

Clinical pathway

IV injection of 20–30 mCi Tc-99m MDP.
Three-hour uptake period — patient encouraged to hydrate and void before imaging.
Whole-body planar imaging — anterior + posterior, 10–15 min scan time.
SPECT or SPECT / CT of area of interest — spine, pelvis, skull as indicated.
Reporting — photopenic and hypermetabolic foci, superscan pattern in diffuse metastatic disease.

Typical systems

SPECT / CT resolves scintigraphic foci against anatomy — standard of care for indeterminate planar findings.

Room + procedure characteristics

Total visit: ~4 hours (injection + uptake + scan).
Dose: ~6 mSv effective dose per study.
Team: nuclear medicine tech + nuclear radiologist.

Equipment considerations that bite

CT side of SPECT / CT — diagnostic-quality CT (Symbia Intevo) versus attenuation-correction-only low-dose CT (Infinia Hawkeye) is a different clinical tool. Bone-scan workups that need crisp osseous CT need the diagnostic CT side.
Detector head sensitivity — uniformity, intrinsic resolution, and energy resolution drift over years. Daily flood QC and weekly extrinsic uniformity catch it; missed QC degrades the whole-body image first.
Whole-body imaging speed — collimator selection (LEHR vs LEAP vs LEUHR) and table speed control planar acquisition time. Older systems on slower table drives don't move the bottleneck on routine scans.
Radiopharmacy access — Tc-99m generator availability and Mo-99 supply is the upstream constraint. A camera with no isotope is an idle camera; this hits sites without on-site radiopharmacy hardest.
Hot lab + dose calibrator — daily QC, NRC license posture, RSO documentation. Inspection-ready records matter as much as camera condition.

Operational reality

Volume is steady but slowly eroding in cancer-intensive centers as NaF PET / CT and FDG PET / CT pick up indications. Community sites still rely on bone scan as the cost-effective default.
Throughput is uptake-room limited, not camera-limited. A second uptake chair adds more capacity than a faster camera.
Refurb economics — older Anger-camera SPECT systems with current-software workstations are the dominant entry-tier configuration. Software / workstation refresh is often the highest-yield refurb upgrade.