167: Measurement of Tumour Hypoxia in Patients with Locally Advanced Non-Small Cell Lung Cancer (NSCLC) Using Positron Emission Tomography (PET) with 18F-Fluoroazomycin Arabinoside (18F-FAZA)
Bibliographic record
Abstract
Purpose: Consider a 2x2x1.5 cm basal cell cancer invading right medial canthus periocular embryonic fusion plane.Usual techniques fail: an irregular PTV 4x4x2.5 cm deep, a concave surface, a deep tumour, and adjacent ocular structures.Oculoplastics/Mohs risk enucleation.Electrons with an internal eye shield require bolus and limit energy to 9 MeV.High energy conformal RT risks medial retinal damage.Systemic agents may palliate but do not cure.We describe low energy electron RT (e-) with an orthovoltage (ortho) bump."Bump" modulates energy by replacing some e-dose with ortho to increase surface dose and optimize dose distribution.Bump applies to any anatomic location to a depth of 2-3 cm.Bump can use e-with a tungsten eye shield and ortho for maximal eye-sparing.With orbit invaded, morbidity follows.Radiotherapy may be the best eyepreserving option.Methods and Materials: Central-axis dose calculation using measured % depth dose were compared with central and offcentral axis dose calcs using kVDoseCalc, a dose engine validated in kV cone-beam and ortho therapy; and Monte Carlo for e-offaxis dose calc.We compare conformal RT, arcs, and bump, for periocular cancer cases.We compared central axis data for a 4x4 cm field with: 1) 9 MeV alone; 2) 9 MeV with 0.7 cm custom wax; 3) 9 MeV, 80% of dose, 100 kV DXR bump, SSD 10 cm, 20% of dose; 4) 9 MeV, 80% of dose, 200 kV DXR bump, SSD 50 cm, 20% of dose.Patients treated at our institution in 10 or 20 treatments received 8 or 16 electron treatments (prescribed to account for REB of electrons) and 2 or 4 photons treatments, for a total dose of 45 Gy in 10 fractions, or 50 Gy in 20 fractions.Results: For the case above tables based on measured dose give: Surface dose ( 1) 86%; (2) 90%; (3) 100%; (4) 94% Dmax (100%) (1) 2.0 cm; (2) 1.3 cm; (3) 2.0 cm; (4) 2.0 cm Dose @ 2.7 cm (1) 89%; (2) 58%; (3) 87%; ( 4) 91% Surface and depth refer to skin surface.Dose is normalized: Dmax = 100%.REB and geometry are not included.Comparing dynamic conformal ARCs, VMAT, electrons +/-bolus or tantalum mesh, and bump show the benefits of 9 MeV with 100-200 kV bump.Dose drop off is swift at ~40%/cm beyond D90%.Dose spares eye.Low SSD, low kV bump results in best homogeneity and surface dose; high kV bump gives best dose at depth.Patients can be scanned with a 3D printer wax replica eye shield to reduce artifact and enable accurate dose calculation.Actual patient results are illustrated with isodose distributions; for three clinical cases, the dose above 80% to retina was 2.5 cc for conformal treatment, 1.0 cc for dynamic conformal arc and < 0.5 cc for bumps, demonstrating excellent shielding for the bump technique.Conclusions: Energy modulation with ortho and electrons can result in improved dose distribution.Benefits include: increased treatment depth, improved dose homogeneity, no bolus, increased shield effectiveness, and reduced penumbra; important when treating near the eye.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".