UpThera Radiation Exposure Simulator
Place the staff, change the technique and the shielding, and turn the beam on to see where scatter goes and what each person receives.
Training estimates from a simplified model of published data. Not measurements, not anyone’s dose record, and never an authorization to stay in a location for any length of time.
Free demo, visit 1 of 5. Each visit lasts 30 minutes. Register free or log in to keep using it and save scenarios.
Typed text is read by the simulator in your browser and sent nowhere. Speaking uses your browser’s speech service, so the audio leaves this device. Describe the set-up only, never patient names or details.
Drag a person to move them, or click the floor to move Surgeon. Drag the room to turn the view.
KAP and CAK are patient indicators; operator values are personnel dose. Never interchangeable. Training estimates.
- Table skirtCuts legs −99+%
- Ceiling shieldCuts whole body −31%lens −99+%
- Mobile barrierLittle effect on Surgeon where they stand
Patient entrance air-kerma rate, as measured or displayed.
Operator scatter follows KAP roughly: the same KAP gives similar scatter whatever the field size, while a larger field at the same skin rate raises both. For reference, NCRP Report No. 168 suggests patient follow-up from 5 Gy Ka,r or 500 Gy·cm² KAP.
Everyone in the room
Personnel dose estimates over 5.00 min of beam-on time, each at their own position and with their own protection.
| Person | From isocentre | Whole body | Lens | Extremity | Under apron |
|---|---|---|---|---|---|
| 0.67 m | 4.91 µSv (0.491 mrem) | 143 nSv (0.0143 mrem) | 628 µSv (62.8 mrem) | 9.78 µSv (0.978 mrem) | |
| 2.04 m | 538 nSv (0.0538 mrem) | 2.80 µSv (0.280 mrem) | 12.7 µSv (1.27 mrem) | 682 nSv (0.0682 mrem) |
Surgeon: personnel dose estimates
Per minute of beam-on time, and over 5.00 min.
| Quantity | Per minute | Over 5.00 min |
|---|---|---|
| Whole body: effective dose equivalent, NCRP 122 two-dosimeter methodCompared with whole-body limits | 982 nSv (0.0982 mrem) | 4.91 µSv (0.491 mrem) |
| Lens dose equivalent, Hp(3)Compared with the lens limit | 28.6 nSv (0.00286 mrem) | 143 nSv (0.0143 mrem) |
| Extremity, Hp(0.07): the hands receive the mostCompared with the extremity limit | 126 µSv (12.6 mrem) | 628 µSv (62.8 mrem) |
| Embryo/fetus, estimated from the waist dosimeter under the apronCompared with the declared-pregnancy limit | 1.96 µSv (0.196 mrem) | 9.78 µSv (0.978 mrem) |
| Personal dose equivalent Hp(10), collar, outside the apronWhat a collar badge would read | 146 nSv (0.0146 mrem) | 729 nSv (0.0729 mrem) |
| Thyroid, Hp(10) | 4.37 nSv (0.000437 mrem) | 21.9 nSv (0.00219 mrem) |
Air kerma at each point on the body
- Eyes: 59.5 nGy/min, 0.90 m, behind the ceiling shield
- Collar (outside the apron): 121 nGy/min, 0.77 m, behind the ceiling shield
- Chest: 9.83 µGy/min, 0.67 m, behind the ceiling shield
- Waist (under the apron): 27.2 µGy/min, 0.61 m
- Lower legs (below the apron): 115 nGy/min, 0.91 m, behind the table skirt
- Hands (at the table): 96.6 µGy/min, 0.30 m
Patient
Patient dose indicators, kept apart from personnel dose: they are different quantities and never interchangeable.
- Entrance air-kerma rate
- 10.0 mGy/min
- Entrance air kerma over 5.00 min
- 50.0 mGy
- KAP over 5.00 min
- 20.0 Gy·cm²
- 4.00 Gy·cm²/min
- CAK (Ka,r) over 5.00 min
- 59.3 mGy
- 11.9 mGy/min
- Basis
- Measured entrance air-kerma rate, as entered
CAK at the reference point, 15 cm from the isocentre toward the tube. Incident air kerma, without backscatter: neither is the patient’s skin dose. For reference, NCRP Report No. 168 suggests patient follow-up from 5 Gy Ka,r or 500 Gy·cm².
Peak skin dose (training estimate)
57.2 mGy
over 5.00 min · 11.4 mGy per beam-on minute
100% is one fixed projection. Changing the C-arm angle or moving the table spreads the dose over more skin; lower this to match.
10.0 mGy/min entrance air kerma × 5.00 min × table and pad transmission 0.80 × backscatter factor 1.35 × tissue-to-air ratio 1.06 × same skin in the field 1.00
From this scenario’s assumptions, not the patient’s skin dose. One projection on a flat skin surface; table transmission only with the tube under the table. 3 of its coefficients not yet verified by a physicist.
Ways the model shows Surgeon’s exposure could come down
The same model, run again with one change at a time. Training estimates, not advice for a real procedure: talk to your RSO.
- Standing half a metre further from the table: the model estimates 86% less extremity dose.
- Standing half a metre further from the table: the model estimates 55% less effective dose.
- Collimating the field to 15 cm: the model estimates 55% less extremity dose.
- Collimating the field to 15 cm: the model estimates 51% less effective dose.
- Collimating the field to 15 cm: the model estimates 46% less lens dose.
- Keeping hands away from the table while the beam is on: the model estimates 28% less extremity dose.
TIME TO DOSE THRESHOLD · Surgeon
This is a mathematical training comparison, NOT an authorization to remain in that location for that duration.
Florida Department of Health, Bureau of Radiation Control. Part III, Standards for Protection Against Radiation, applies to Florida licensees and registrants, including X-ray registrants (64E-5.301(2)).
Regulatory limit · Fla. Admin. Code R. 64E-5.304(1) · per year · version: Amended 12-26-13 · citation not yet reviewed by a physicist or RSO. The more limiting of TEDE 0.05 Sv or 0.5 Sv to any organ other than the lens.
For the same period as the threshold (per year), including doses from other employment. A training value: enter 0 for a fresh example. It is never assumed to be zero.
In this model, dose accrues only while the beam is on: scatter stops when the beam does. Beam-on is 7% of the time in the room.
- CURRENT DISTANCE
- 0.67 m
- Chest to the beam’s isocentre
- CURRENT ESTIMATED DOSE RATE
- 982 nSv (0.0982 mrem)/min
- Whole body: effective dose equivalent, NCRP 122 two-dosimeter method · 58.9 µSv (5.89 mrem)/h of beam-on
- SELECTED DOSE THRESHOLD
- 50.0 mSv (5,000 mrem)
- per year · Fla. Admin. Code R. 64E-5.304(1)
- PRIOR ACCUMULATED DOSE
- Not entered
- Needed for the calculation
- REMAINING DOSE THRESHOLD
- —
- FACILITY ALARA INVESTIGATION LEVEL
- 1.25 mSv (125 mrem) / 3.75 mSv (375 mrem)
- Level I / II, per calendar quarter · example levels
- ESTIMATED TIME TO SELECTED DOSE THRESHOLD
- Enter the dose already received during the period to calculate.
- MODEL ASSUMPTIONS AND VALIDITY
Scatter from the irradiated patient volume (54 elements), with attenuation in a water-equivalent patient, Klein–Nishina angular distribution, and shields by line of sight with energy- and angle-dependent transmission; pinned to NCRP 147’s 0.1% at 1 m. Approximate educational estimates. Not modelled: tube leakage, scatter from the table, walls, floor and ceiling (so shields look more effective than in practice), buildup in detail, direct beam exposure. Dose only while the beam is on.
32 coefficients behind this estimate not yet verified by a medical physicist.
Training alerts · Surgeon · this scenario (5 min beam-on)
- Whole body (effective)Below configured investigation level0% of Level I (1.25 mSv (125 mrem))
- Lens of the eyeBelow configured investigation level0% of Level I (3.75 mSv (375 mrem))
- ExtremityBelow configured investigation level5% of Level I (12.5 mSv (1,250 mrem))
Model requires physicist review: 32 unverified coefficients.
Compared with your facility’s Level I and II (example levels until your facility sets its own). The dose already received is included only when the facility level is the selected threshold, so the periods match.
Example levels in the pattern of published ALARA programs (e.g., University of Maryland, Baltimore, Radiation Safety Procedure 1.6). Not your facility’s levels.
About ALARA and investigation levels
ALARA means keeping exposure as low as reasonably achievable, not just below the limit. An investigation level is a facility’s own trigger, well below the regulatory limit: reaching it prompts the RSO to review how the dose was received and whether it could reasonably be reduced. It is not a limit, and being below it is not a finding that an exposure was safe. Talk to your RSO about any scenario that reaches a level, and about how the dose could be reduced: time, distance, shielding, and technique.
Enter the dose already received to draw the accumulated dose against beam-on time.
Scenarios and reports
Register free or log in to save scenarios and compare them.
People in the room
The room’s shields hang beside this person.
Beam and technique
A thicker patient scatters from more tissue, and lets less scatter out the far side. The entrance rate is set separately.
Air gap from the patient to the receptor: 29 cm. Mobile C-arms must keep at least 30 cm between the focal spot and the skin (21 CFR 1020.32(g)).
Off: the entrance rate is as entered, whatever the geometry.
From your unit’s physics survey, or the reference air-kerma rate it displays. A survey in R/min (exposure) converts at 8.76 mGy air kerma per R. The survey’s maximum rate is the most the unit can deliver, not a typical case.
Surgeon: position
Chest 0.67 m from the beam’s isocentre.
Surgeon: protection, and the room’s shields
Beside the primary operator, facing the beam: it follows them. Use the sliders, or drag it in the room.
Shield transmission changes with kVp and with the angle scatter crosses the shield; rays through the gaps around a shield are not attenuated. Limitation: scatter from the walls, floor, ceiling and people isn’t modelled, so a well-placed shield looks close to perfect here. Measured reductions in practice are smaller, typically several-fold.
Beam-on time
Coefficients and their sources
Reference values from the published literature. Each stays marked unverified until a medical physicist checks it against its source and approves it, or replaces it with a measured value.
| Coefficient | Value | Status | Source |
|---|---|---|---|
| Backscatter factor at the skin, 80 kVp, about 20 × 20 cm | 1.35 factor | Not verified | Typical published backscatter factors for diagnostic beams of 70–100 kVp and fields of 10–25 cm: about 1.3 to 1.45 (Petoussi-Henss et al., Phys Med Biol 1998; Jones & Pasciak, J Appl Clin Med Phys 2011, Part I). Depends on kVp, filtration and field size. |
| Skin dose per unit air kerma (mass energy-absorption ratio, tissue to air) | 1.06 Gy per Gy | Not verified | Ratio of mass energy-absorption coefficients, soft tissue to air, about 1.05 to 1.07 across diagnostic beam qualities (IAEA Technical Reports Series No. 457, 2007; Jones & Pasciak, J Appl Clin Med Phys 2011). |
| Table and pad transmission, tube under the table | 0.8 fraction transmitted | Not verified | Typical published transmission of carbon-fibre tables with a pad, about 0.7 to 0.85 at 70–100 kVp (Jones & Pasciak, J Appl Clin Med Phys 2011; AAPM Report No. 190). Replace with a measurement for your table and pad. |
| Scatter fraction at 1 m, 90°, per 400 cm² field | 0.001 ratio to entrance air kerma | Not verified | NCRP Report No. 147 (2004), scatter fraction for a 400 cm² field at 1 m; the widely taught “one-thousandth at one metre” rule, also given as “about 0.1% of incident exposure at 1 m for a 23-cm field” (Schueler, AAPM 2003 continuing education course, Personnel Protection During Fluoroscopic Procedures). |
| Primary beam reaching the exit surface of a 22 cm patient | 0.01 fraction of entrance air kerma | Not verified | Commonly cited order of magnitude for an average adult abdomen at 70–90 kVp: about 1% of the entrance air kerma exits the patient (e.g., Bushberg et al., The Essential Physics of Medical Imaging). Approximate. |
| Attenuation of scatter leaving the patient, relative to the primary beam | 0.5 factor on μ | Not verified | Approximation for broad-beam conditions: multiply scattered photons build up, so scatter escapes thick tissue more readily than a narrow-beam coefficient predicts. No single published value; to be set against measured isokerma data. |
| Effective energy of the beam, as a fraction of kVp | 0.4 keV per kVp | Not verified | Rule of thumb for filtered diagnostic beams: effective energy roughly one-third to one-half of the peak kVp. Approximate. |
| Water mass attenuation coefficient, 30 keV | 0.3756 cm²/g | Not verified | NIST XCOM / Hubbell & Seltzer, NISTIR 5632, water (liquid), total with coherent scattering. |
| Water mass attenuation coefficient, 40 keV | 0.2683 cm²/g | Not verified | NIST XCOM / Hubbell & Seltzer, NISTIR 5632, water (liquid). |
| Water mass attenuation coefficient, 50 keV | 0.2269 cm²/g | Not verified | NIST XCOM / Hubbell & Seltzer, NISTIR 5632, water (liquid). |
| Water mass attenuation coefficient, 60 keV | 0.2059 cm²/g | Not verified | NIST XCOM / Hubbell & Seltzer, NISTIR 5632, water (liquid). |
| Water mass attenuation coefficient, 80 keV | 0.1837 cm²/g | Not verified | NIST XCOM / Hubbell & Seltzer, NISTIR 5632, water (liquid). |
| Water mass attenuation coefficient, 100 keV | 0.1707 cm²/g | Not verified | NIST XCOM / Hubbell & Seltzer, NISTIR 5632, water (liquid). |
| Lead mass attenuation coefficient, 30 keV | 30.32 cm²/g | Not verified | NIST XCOM / Hubbell & Seltzer, NISTIR 5632, lead. |
| Lead mass attenuation coefficient, 40 keV | 14.36 cm²/g | Not verified | NIST XCOM / Hubbell & Seltzer, NISTIR 5632, lead. |
| Lead mass attenuation coefficient, 50 keV | 8.041 cm²/g | Not verified | NIST XCOM / Hubbell & Seltzer, NISTIR 5632, lead. |
| Lead mass attenuation coefficient, 60 keV | 5.021 cm²/g | Not verified | NIST XCOM / Hubbell & Seltzer, NISTIR 5632, lead. |
| Lead mass attenuation coefficient, 80 keV | 2.419 cm²/g | Not verified | NIST XCOM / Hubbell & Seltzer, NISTIR 5632, lead (below the 88 keV K-edge). |
| Scatter fraction at 60 kVp, relative to 80 kVp | 0.8 × the 80 kVp value | Not verified | Trend of scatter fraction with tube potential in NCRP Report No. 147, Appendix C. |
| Scatter fraction at 100 kVp, relative to 80 kVp | 1.2 × the 80 kVp value | Not verified | Trend of scatter fraction with tube potential in NCRP Report No. 147, Appendix C. |
| Scatter fraction at 120 kVp, relative to 80 kVp | 1.35 × the 80 kVp value | Not verified | Trend of scatter fraction with tube potential in NCRP Report No. 147, Appendix C. |
| Tube output at 80 kVp, 1 m from the focal spot | 50 µGy per mAs | Not verified | Typical diagnostic tube output with standard filtration. Replace with the measured value from your unit’s physics (REPE) report. |
| Transmission, 0.25 mm Pb-equivalent apron | 0.1 fraction transmitted | Not verified | Typical published transmission of lead-equivalent garments for scattered radiation at 70–100 kVp (e.g., NCRP Report No. 168; Christodoulou et al., Med Phys 2003). |
| Transmission, 0.35 mm Pb-equivalent apron | 0.06 fraction transmitted | Not verified | Typical published transmission of lead-equivalent garments for scattered radiation at 70–100 kVp (e.g., NCRP Report No. 168). |
| Transmission, 0.5 mm Pb-equivalent apron | 0.03 fraction transmitted | Not verified | Typical published transmission of lead-equivalent garments for scattered radiation at 70–100 kVp (e.g., NCRP Report No. 168). |
| Transmission, 0.5 mm Pb-equivalent thyroid collar | 0.03 fraction transmitted | Not verified | As for a 0.5 mm Pb-equivalent apron (NCRP Report No. 168). |
| Lens dose reduction, 0.75 mm Pb-equivalent glasses | 0.4 fraction remaining | Not verified | Clinical reduction factors for protective eyewear (ICRP Publication 139, 2018; Magee et al., J Radiol Prot 2014): a factor of about 2–3, far less than the lead alone, because scatter reaches the eye from the side and below. |
| Transmission, 0.5 mm Pb-equivalent ceiling-suspended shield | 0.03 fraction transmitted | Not verified | Lead-equivalent acrylic at 70–100 kVp scatter (NCRP Report No. 168). |
| Transmission, 0.5 mm Pb-equivalent table skirt | 0.03 fraction transmitted | Not verified | Lead-equivalent drape at 70–100 kVp scatter (NCRP Report No. 168). |
| Hp(10) per unit air kerma, scattered fluoroscopy spectrum | 1.2 Sv per Gy | Not verified | ICRP Publication 74 (1996) conversion coefficients, weighted for a scattered 70–100 kVp spectrum. |
| Hp(3) per unit air kerma, scattered fluoroscopy spectrum | 1.2 Sv per Gy | Not verified | ICRP Publication 74 (1996) and ISO 4037-3 data, scattered 70–100 kVp spectrum. |
| Hp(0.07) per unit air kerma, scattered fluoroscopy spectrum | 1.3 Sv per Gy | Not verified | ICRP Publication 74 (1996), scattered 70–100 kVp spectrum. |
| H*(10) per unit air kerma, scattered fluoroscopy spectrum | 1.3 Sv per Gy | Not verified | ICRP Publication 74 (1996) ambient dose equivalent conversion coefficients, approximate value for a scattered 70–100 kVp spectrum (mean energy around 30–50 keV). Approximate: replace with the physicist’s value. |
| Effective dose estimate: weight on the under-apron (waist) dosimeter | 0.5 weight | Not verified | NCRP Report No. 122 (1995), two-dosimeter method: E = 0.5 H(waist, under apron) + 0.025 H(collar, over apron). |
| Effective dose estimate: weight on the collar (over-apron) dosimeter | 0.025 weight | Not verified | NCRP Report No. 122 (1995), two-dosimeter method. |
3D models
The finished simulator uses licensed, medically accurate models. Until each is supplied, the room shows an interim model of the right size and position. The calculations never depend on which model is drawn.
- Gowned clinician (blue gown, face shield)Supplied model in use
public/models/simulator/staff-gowned-clinician.glbStatic, not rigged: the arms stay at the sides, so “hands at the table” moves the hand dose point, not the model’s hands. Lead apron, collar and glasses are drawn over the model when worn.
- Nurse (pink scrubs)Supplied model in use
public/models/simulator/staff-nurse.glbStatic, not rigged: the arms stay at the sides, so “hands at the table” moves the hand dose point, not the model’s hands. Lead apron, collar and glasses are drawn over the model when worn.
- Mobile C-armChecking…
public/models/simulator/mobile-c-arm.glb- A recognisable mobile C-arm with cart, X-ray tube housing, collimator and flat-panel or image-intensifier detector, about 1.9 m tall.
- Origin at the isocentre. The C must contain nodes named "arm" (rotated about the patient’s long axis), "tube" and "detector", with the tube below the isocentre at rest.
- Source-to-image distance about 1.0 m, focal spot about 0.6 m from the isocentre, so the drawing matches the physics.
- Radiolucent procedure tableChecking…
public/models/simulator/procedure-table.glb- A carbon-fibre procedure table about 2.1 m long and 0.54 m wide, top at 0.9 m. Origin on the floor below the centre of the top.
- Patient (supine)Checking…
public/models/simulator/patient-supine.glb- An anatomically proportionate adult lying supine, head toward +X, draped, about 1.75 m long and 0.22 m thick. Origin at the centre of the back, at table height.