About – Oncology Toolkit

Oncology Toolkit

These tools are designed to support clinical workflow in radiation oncology and general medical practice, providing quick access to diagnostic codes and calculation utilities used in day-to-day charting and patient management.

Tools

ICD-10 Code Search — Fast full-text lookup of ICD-10 diagnostic codes with specialized filtering for oncology and radiation therapy indications, including an IMRT-focused subset.
PSA Doubling Time Calculator — Calculates PSA doubling time from serial PSA measurements by log-linear regression, with a 95% confidence interval, log-scale goodness of fit (R²), and PSA velocity. Accepts flexible date and value input formats, plots an interactive growth curve with a confidence band and a shaded projection region, toggles between linear and log y-axes, and allows date-point querying directly on the graph. See how the doubling time is calculated below.
BED / EQD2 Calculator — Computes Biologically Effective Dose and Equivalent Dose in 2 Gy fractions for a given prescription across configurable α/β tissue values (Tumor, Late, Prostate/Spine). An alternative fractionation section converts the same BED to isoeffective total doses for 1, 3, 5, and any arbitrary number of fractions. Based on a spreadsheet by Dr. Mike Wahl.
Composite Dose Calculator — Estimates the remaining tolerable dose to a previously irradiated structure. Takes structure tolerance dose/fractions/αβ, a prior dose with optional time discount factor, and a planned fraction count to compute the remaining safe dose and dose per fraction. Based on a spreadsheet by Dr. Mike Wahl.
Dose Constraint Reference — Searchable database of normal tissue dose constraints from QUANTEC and HyTEC guidelines. Filter by organ, endpoint, fractionation scheme, or data source. Includes constraint values, complication rates, and literature citations.
Reirradiation Dose Calculator — Estimates remaining organ-at-risk dose tolerance for reirradiation cases using UMich ReRT guidelines. Accepts prior plan fractionation, α/β, and time since prior RT. OARs are selected from a checklist of 24 serial and parallel structures; each displays the prior physical dose converted to EQD2, tissue recovery factor (TRF) columns for all documented time intervals with the active bucket highlighted, and a results table showing remaining EQD2 and isoeffective physical doses for 1, 3, 5, and a custom number of fractions — all updating in real time.

How the PSA doubling time is calculated

Each measurement is converted to a point in time (days from the first value). The calculator fits an exponential model PSA = A · e^B·t by unweighted least-squares linear regression of ln(PSA) on time — the standard clinical PSA-doubling-time method. Each measurement is weighted equally in log space, which is the appropriate error model for PSA, where variation is multiplicative (roughly proportional to the value). The doubling time is ln(2) / B. A negative slope means PSA is falling, and the result is reported as a halving time.

The reported figures around the doubling time mean:

95% confidence interval — derived from the uncertainty in the fitted slope. It needs at least three measurements. When the slope’s interval includes zero (no statistically clear trend), the doubling-time interval is unbounded and is reported as “not estimable” rather than a misleadingly tidy range.
R² (log fit) — goodness of fit on the log scale: how closely the measurements follow a single exponential. It is a measure of fit quality, not a guarantee that the extrapolation is correct.
PSA velocity — computed separately as the slope of a simple linear regression of raw PSA on time (ng/mL per year). This is a different model from the exponential doubling-time fit and is provided for reference.

The shaded confidence band around the curve is a confidence interval for the underlying trend, not a prediction interval — it describes uncertainty in the fitted curve, not the range where an individual future PSA measurement is expected to fall. The shaded region to the right of your last measurement is extrapolation.

Measurements with a PSA of zero (or below the assay detection limit) cannot be placed on a log scale and are excluded from the fit; the calculator notes when this happens. The tool applies no cohort-eligibility rules (minimum interval between values, treatment-free interval, assay-change or PSA-bounce handling) that some clinical protocols specify. It is intended for education and quick estimation, not as a validated risk classifier.

Created by Nick Boehling, MD — Radiation Oncologist, Bend, OR — View on GitHub

Feedback

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Privacy

Oncology Toolkit collects no personal information, no protected health information (PHI), and no patient data. Calculator inputs are processed entirely in your browser and are never transmitted to a server.

The site uses two analytics services to understand aggregate traffic patterns:

Google Analytics 4 — sets _ga and _ga_* cookies to count unique visitors and measure page views. IP addresses are truncated by Google before storage. Ad personalization features (Google Signals) are disabled.
Cloudflare Web Analytics — cookieless; collects anonymous page-load and performance metrics only.

The site also uses browser local storage (not cookies) to remember your theme preference, recent calculator inputs, and cached ICD-10 data for offline use. This data stays on your device and is never sent anywhere. You can clear it at any time through your browser settings.

To opt out of Google Analytics, use a browser extension such as the Google Analytics Opt-out Add-on or enable your browser’s tracking-protection / Do Not Track features.