Comparison

TDF Calc vs Spine Physics

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

TDF Calc

This app calculates the biologically effective dose (BED) for radiation therapy fractionation regimens. It allows for comparisons of different treatment schedules and helps determine dose per fraction based on desired treatment duration.

Highlights
  • Linear-quadratic (LQ) method implementation
  • Biologically effective dose (BED) calculation
  • External beam radiation therapy (EBRT) fractionation
  • Low dose rate (LDR) brachytherapy
  • Permanent implant brachytherapy
  • Dose per fraction calculation
Features
Read full description

TDFCalc is an application which implements the linear-quadratic (LQ) method for comparing the biologically effective dose (BED) of external beam radiation therapy (EBRT) fractionation regimens as well as low dose rate (LDR) and permanent implant brachytherapy treatments. It calculates BED for a given alpha/beta ratio as a function of the dose per fraction and number of fractions for EBRT, and initial dose rate for brachytherapy. For a predetermined BED, the app solves the quadratic equation to calculate dose per fraction as a function of the number of fractions desired. This enables quick comparison of modified fractionation regimens (e.g. hypofractionation or compensating for missing treatment fractions) vs a conventional and/or originally intended regimen.

About

Spine Physics

This app visualizes how obesity affects the body, using a teeter-totter analogy for the spine to explain the importance of maintaining a healthy abdominal girth. It serves as an educational tool for patients, drawing on a surgeon's perspective.

Highlights
  • Obesity impact visualization
  • Spine teeter-totter analogy
  • Abdominal girth importance
  • Surgeon's educational tool
  • General health information
Features
Read full description

Spine Physics visualizes the effects of obesity on the body. The analogy of the spine to a teeter totter shows the importance of keeping the abdominal girth small and light. As a surgeon, I draw this all the time for my patients to educate them. ***Disclaimer*** No advice: This app (“App)” provides only information, is not medical or treatment advice and may not be treated as such by the user. As such, this App may not be relied upon for the purposes of medical diagnosis or as a recommendation for medical care or treatment. The information on this App is not a substitute for professional medical advice, diagnosis or treatment. All content, including text, graphics, images and information, contained on or available through this App is for general information purposes only Professional Medical Advice and Assistance: You are strongly encouraged to confirm any information obtained from or through this App with your physician or another professional healthcare provider and to review all information regarding any medical condition or treatment with your physician or other a professional healthcare provider. No Reliance: YOU MUST NEVER RELY ON ANY INFORMATION OBTAINED USING THIS APP FOR ANY DIAGNOSIS OR RECOMMENDATION FOR MEDICAL TREATMENT. YOU MUST NEVER RELY ON THE INFORMATION RECEIVED FROM THIS APP AS ALTERNATIVE TO MEDICAL ADVICE FROM YOUR PHYSICIAN OR OTHER PROFESSIONAL HEALTHCARE PROVIDER. YOU MUST NEVER DISREGARD PROFESSIONAL MEDICAL ADVICE OR DELAY SEEKING MEDICAL TREATMENT AS RESULT OF ANY INFORMATION YOU HAVE SEEN ON OR ACCESSED THROUGH THIS APP. IF YOU HAVE ANY SPECIFIC QUESTIONS ABOUT ANY MEDICAL MATTER YOU SHOULD CONSULT YOUR PHYSICIAN OR OTHER PROFESSIONAL HEALTHCARE PROVIDER. IF YOU THINK YOU MAY BE SUFFERING FROM ANY MEDICAL CONDITION YOU SHOULD SEEK IMMEDIATE MEDICAL ATTENTION. No Warranty: The information provided by this App is provided “as is” without any representations or warranties, express or implied. This App makes no representations or warranties in relation to the medical or other information in this App.

Screenshots

TDF Calc4 screens
Spine Physics3 screens

Verdict

The call

The clearest difference is update cadence: Spine Physics at every 2 days against TDF Calc's every 67 months. TDF Calc's advantage is iOS requirement (13.2 vs 15.0). On price, rating, ratings volume and ads there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

On the App Store both sit at effectively the same score — 5.0 for TDF Calc against 5.0 for Spine Physics. Both are backed by a comparable volume of ratings — 1 and 1 respectively.

UpkeepUpdate frequency

TDF Calc ships an update every 67 months, Spine Physics every 2 days. The most recent releases landed on June 5, 2026 and September 10, 2026 respectively.

Scorecard2 real differences · 8 level
TDF Calc versus Spine Physics: the parameters behind the verdict, then further details
ParameterTDF CalcSpine Physics
PriceFreeFree
Rating5.0 (1 ratings)5.0 (1 ratings)
Positive reviews100.0% of reviews—
Number of ratings11
Update frequencyEvery 67 monthsEvery 2 days — better
AdsNoNo
In-app purchasesNoNo
MonetizationFreeFree
DevicesiPhone, iPodiPhone, iPod
Requires iOS13.2 — better15.0
Further details — not scored
Size2 MB10 MB
Age rating4+12+
DeveloperEye PhysicsJonathan Nakhla

Customer experience

TDF Calc

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews1 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

Spine Physics

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

None

TDF Calc

No in-app purchases

None

Spine Physics

No in-app purchases

Questions

Is TDF Calc free?
TDF Calc is free to download, with no in-app purchases.
Is Spine Physics free?
Spine Physics is free to download, with no in-app purchases.
Which has better reviews, TDF Calc or Spine Physics?
TDF Calc and Spine Physics are both rated 5.0 out of 5 on the App Store, from 1 and 1 ratings respectively.
Do TDF Calc or Spine Physics have ads?
Neither TDF Calc nor Spine Physics shows ads.
Which is updated more often, TDF Calc or Spine Physics?
TDF Calc ships an update every 67 months, and Spine Physics every 2 days. Most recently, TDF Calc was updated on June 5, 2026 and Spine Physics on September 10, 2026.

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