# TDF Calculator

> Radiotherapy tool for calculating normal tissue tolerance dose using TDF factors. (iPhone/iPad app by Hiroyuki KATOH.)

- Source: https://appshunter.io/ios/app/tdf-calculator/id900087159 (this page in markdown: same URL + `.md`)
- Developer: [Hiroyuki KATOH](https://appshunter.io/developer/898546586)
- Category: Medical, Education
- Price: Free
- Rating: 5.00/5 from 1 App Store ratings · 3 written reviews indexed
- Age rating: 17+
- Requires: iOS 8.0 · 14 MB
- Languages: American English
- Released: 2014-07-30
- Data updated: 2026-07-19
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/tdf-calculator/id900087159/reviews.md

## What is TDF Calculator?

- In practice of radiotherapy, it is very important to check the normal tissue tolerance dose.
- TDF factor defined by Orton et al. is one of the tool to estimate the normal tissue tolerance dose for radiotherapy, but one of the problem is too complex and too many parameters to calculate.
- We considered that it is wonderful to calculate it with iPhone, iPod and iPad that we carry always.
- That’s why we designed new App “TDF Calculator”.
- Considering use in practice, primary concept of design is easy to use and quick to get the results.
- Please try TDF Calculator!

We have released “EQD Calculator” that is capable to calculate the BED and EQD with LQ-model.
Please, try also “EQD Calculator”.
See “View More by This Developer” appeared above.

#Strong points
- This App is designed for the professionals working in the field of Radiation Oncology.
- Although there are a lot of numbers on the screen, this App is designed to look like a table calculation, therefore you can understand easily the indication of each values.
- You can organize this App with URL scheme (jp.37.TDFcalculator://)
 in other Apps such as launchers.

#Main features
- This App calculates TDF factors that is defined by Orton et al. and is one of the tool to estimate the normal tissue tolerance dose for radiotherapy.
- Although we are usually using the BED defined by LQ-model for comparing the treatments recently, we thinks that the TDF factor is also useful tool, using it appropriately.
- TDF factors are given 100 as a full tolerance for each tissues, so you can find the numbers as difference among the each tissues effected by fractionation. Therefore, this - App maybe also good educational tool about radiotherapy.
- This App can calculate 2 type of TDF which are published in 1973 and 1986 by Orton et al.
- This App can also calculate TDF factors together in three different conditions stated by three items (fraction dose, number of fractions and frequency per week), and the summation of them automatically.
- Setting either a total dose or a fraction dose, related fraction dose or total dose is calculated respectively, depending on the fractionation times.
- The formulas and parameters in this App are cited mainly from the two literatures published in 1973 and 1988.
- TDF factors have some limitations such as unsuitable for irradiation with under 4 fractions, therefore you should check carefully the reference literatures before using this App.
- This App (from ver.1.2.0) is just designed for iPhone and iPad with iOS8.

#References
1. Orton CG, Ellis F: A simplification in the use of the NSD concept in practical radiotherapy. Br J Radiol 1973;46:529-537.
2. Orton CG: Bioeffect dosimetry in radiation therapy. Radiation Dosimetry: Physical and Biological Aspects (Orton CG ed.) Plenum Press, New York, 1986.
3. Orton CG, Cohen L: A unified approach to dose-effect relationships in radiotherapy. I: Modified TDF and linear quadratic equations. Int J Radiat Oncol Biol Phys 1988;14:549-556.

#Disclaimer
Please check carefully End User License Agreement (EULA) before using the App.
Additionally, you may not use this App unless you agree to terms included below.
You agree to assume full and sole responsibility for any use of this App.
We are not responsible for any damages or injury, including but not limited to special or consequential damages, that result from your use of (or inability to use) this App, including any damages or injury caused by any failure of performance, error, omission, interruption, defect, delay in operation, computer virus, or other computer malfunction.

## Key features

- Calculates TDF factors for normal tissue tolerance dose
- Supports two TDF factor versions (1973 and 1986)
- Calculates TDF factors for three different conditions simultaneously
- Automatically sums TDF factors
- Calculates related total or fraction dose
- Organizable with URL scheme

## Recent user reviews (3 of 3)

All indexed reviews: https://appshunter.io/ios/app/tdf-calculator/id900087159/reviews.md

### 1/5 — Not working

*2024-04-30, version 2.3.0*

App is repeatedly crashing
Tried 10 times to open it, finally uninstalled it

### 4/5 — Not working with IOS17.1

*2023-11-11, version 2.3.0*

Not working with IOS17.1

### 5/5 — Excellent app..

*2015-03-31, version 2.3.0*

Very useful for Radiation Oncologist..

## Frequently asked questions about TDF Calculator

### What is TDF Calculator used for?

TDF Calculator is used to estimate the normal tissue tolerance dose in radiotherapy by calculating TDF factors. It helps radiation oncology professionals understand the impact of fractionation on different tissues.

### Is TDF Calculator free to use?

Yes, TDF Calculator is available for free. It does not require any payment to download or use its features.

### What devices does TDF Calculator support?

TDF Calculator is designed for iPhone, iPad, and iPod devices running iOS 8 or later. It is optimized for these Apple platforms.

### How often is TDF Calculator updated?

The latest version, 2.3.0, was released on March 27, 2015. While updates may not be frequent, the app provides core functionality for its intended users.

### Can TDF Calculator be integrated with other apps?

Yes, TDF Calculator can be organized and launched from other applications using its URL scheme (jp.37.TDFcalculator://). This allows for integration into custom workflows.

### What are the limitations of TDF Calculator?

TDF Calculator has limitations, such as being unsuitable for irradiation with under 4 fractions. Users should consult reference literature before using the app to ensure appropriate application.

### Does TDF Calculator have ads?

No, TDF Calculator is ad-free. Users can utilize its features without any advertisements interrupting their workflow.

### What is the age rating for TDF Calculator?

TDF Calculator has an age rating of 17+. This indicates that its content and complexity are intended for adult users, particularly professionals in the medical field.

## Version history (last 5 releases)

### 2.3.0 — 2015-03-27

This app has been updated by Apple to display the Apple Watch app icon.

- “Contact Me” was prepared at the Information of the App.
- The issue with third-party custom keyboard fixed.

### 2.2.3 — 2015-01-30

- Slightly modification of internal cords.

### 2.1.1 — 2015-01-06

- Slightly modification of the keyboard.

### 2.1.0 — 2014-12-29

- Design of the keyboard was modified.
- Setting a total dose became capable.
- Other minor problems were fixed.

### 1.1.0 — 2014-12-19

- The App became compatible with iPad (became Universal App).
- URL scheme (jp.37.TDFcalculator://) became capable to use.
- The development language of the App changed from Objective-C to
 Swift.
- From this version, the design of the App is just for iOS8, hence
 iOS7 or before was already incompatible.

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## More apps by Hiroyuki KATOH

- [EQD Calculator](https://appshunter.io/ios/app/eqd-calculator/id898546583)
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All apps by Hiroyuki KATOH: https://appshunter.io/developer/898546586

## Related topics

[tdf calculator](https://appshunter.io/ios/topics/tdf-calculator)

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-07-19.*