Knowledge Hub · Saxsons PET L-Bench
HVL ~ 4.1 mm; TVL ~ 13.5 mm; the operator-face lead-glass window is the dominant dose path. NCRP 49 / 147 sets the shielding-design framework; AAPM Report 88 sets the radiopharmacy-QA expectations; AERB Safety Code carries the licensing parameter. This page is the physics behind the tier choice and the OR-side trade-offs the L-bench resolves.
Why this matters
Lead attenuation at 511 keV
At 511 keV — the F-18 / Ga-68 / Cu-64 annihilation photopeak — the half-value layer (HVL) in pure lead is roughly 4.1 mm and the tenth-value layer (TVL) is roughly 13.5 mm. A 50 mm lead wall delivers ~ 12 HVL of attenuation (~ 99.97 % of the primary photon flux removed); a 60 mm wall delivers ~ 14.6 HVL. Below 50 mm the wall stops gating exposure for a typical PET dispense activity; above 60 mm the marginal exposure reduction is small while the structural mass becomes a hot-lab loading problem.
Lead-glass viewing-window physics
A shielded bench is only as good as its weakest point — and the weakest point is the lead-glass viewing window the operator looks through. The Saxsons PET L-Bench ships in standard and premium lead-glass tiers; the premium tier upgrades viewing-window attenuation for high-throughput dispensing benches where the operator-face dose path is the dominant control. The right answer is to spec the highest-tier lead-glass the workflow allows, then size the rest of the wall to match the cumulative shift activity. Full per-tier specifications are shared on request under NDA.
Source: NCRP Report 147 — Structural Shielding Design for Medical X-Ray Imaging Facilities.
AERB framework for PET hot-labs
AERB Safety Code for Nuclear Medicine Facility requires that the cumulative occupational dose at the operator position remain inside the ICRP 103 framework (20 mSv/year average, 50 mSv in any single year). For PET radiopharmacies dispensing 25–40 FDG unit doses per shift, the bench-shielding parameter is the dominant control on operator whole-body dose. The shielding spec is part of the AERB licence renewal documentation — the per-batch lead-thickness certificate from the manufacturer is what the regulator audits.
Source: AERB Safety Code for Nuclear Medicine Facility; ICRP Publication 103 occupational dose framework.
L-shape geometry
The L-shape carries the lead mass on the vertical back wall — the surface that intercepts the operator-facing scatter path. The horizontal worktop is the dispensing surface; it does not need the full lead thickness because the operator is not standing on it. The L geometry decouples the structural-load problem (vertical mass on the floor) from the workspace-ergonomics problem (the dispensing surface stays at bench height). Pairs naturally with a base-lead variant when the bench sits over a basement / occupied floor below.
Source: AAPM Report 88 — Quality Assurance for Radiopharmacy; clinical hot-lab fit-out design references.
MS vs SS 304 outer finish
Mild-steel (MS) painted finish is cost-optimised, decontaminable for the standard hot-lab cleaning cycle (epoxy paint resists alkaline wipe-down for the expected service life). SS 304 stainless-steel outer is the right choice when the hot-lab cleaning-validation schedule includes daily wet wipe-down — stainless steel withstands repeated wet cleaning without coating degradation, and gives the clean-room / GMP-grade surface the auditor wants. Same lead-shielding mass inside either outer; the choice is on the surface, not on the protection.
Pairs with the Saxsons workflow
The L-bench sits between the Saxsons Dose Calibrator and the Saxsons Lead-Lined Fume Hood — the radiopharmacist works at the L-bench surface, reaches forward through the lead-glass window into the dispense well, then transfers the shielded syringe to the dose-calibrator on one side and to the patient-dose tray on the other. The Saxsons own-brand product chain (Dose Cabinet, Fume Hood, L-Bench, Syringe Shields, Vial Shields, Sharps Container, Waste Bins) gives one supplier, one quality system, one warranty for the full hot-lab perimeter.
Source: Saxsons Healthcare hot-lab fit-out reference catalogue (own-brand product family).
AERB, NCRP, AAPM and NIST anchoring the PET dispensing-bench design choice in India.
Indian regulatory framework for nuclear-medicine facility licensing — hot-lab shielding, dose-monitoring, dispensing-equipment expectations.
NCRP framework for shielding-design calculations including HVL / TVL methodology applicable to nuclear-medicine hot-lab walls.
Foundational NCRP shielding-design reference; energy-dependent HVL / TVL values for lead at the 100 keV – 1 MeV range.
AAPM framework for radiopharmacy QC including shielded-dispensing-equipment expectations and operator-protection workflow.
Authoritative reference for photon attenuation coefficients in lead and lead-glass at PET / SPECT / I-131 energies.
Current ICRP framework defining the 20 mSv/year average and 50 mSv in any single year occupational dose limits.
IAEA framework covering hospital-radiopharmacy hot-lab design, operator protection and dispensing-bench specification.