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Prostate Cancer Diary: Day 115 — Therac 25 and a thankfully minor glitch in my radiotherapy


[Note to readers: I am not posting prostate cancer (PCa) diary entries every day. To be honest, I can't keep up. The hormone therapy (ADT) that I started three and a half months ago has slowed me down, as has the radiotherapy (RT) which I started on the first of July. I've been warned that the effects of RT build toward the end of the sessions and even beyond, before tapering off. Thankfully my last session is July 28. Hoping to pick up the pace mid-August. In the meantime, I will post what I can, when I can.]

July 24. 2026

This morning, I was off to a flying start at the Arden Cancer Centre. Arrived early for my 9:15 appointment thanks to light traffic. Was called in at 9:13. Bladder scan was positive and I was ushered into theatre right away. The team was in good mood, joking with M, one of the TRs I haven't met before. Apparently, she had "saved the day" the day before when a late start due to routine system checks backed up appointments pretty badly. (News that made me even more grateful that they had squeezed me in early yesterday.)

I hopped up on the scanning table, pulled my pants down, and they quickly placed the modesty wrapper in place. Then it was just a few minutes before the targeting scan was happening. Whir, whir, as the massive VersaHD head unit rotated, imaging my innards in great detail, then:

Click! The machine froze and started going beep, beep, beep...

Naturally, my first thought was: Therac-25! Quickly followed by: "Don't worry, the photon beam is not on, there's no radiation happening, this is just the targeting run." Also: "Surely they can hear this beeping."

Turns out, they could hear the beeping, and they spent several minutes trying various measures to clear the error that was causing it before coming into the room. They assured me it was nothing to worry and an engineer was on his way. They also started checking the equipment to find a way to silence the beeps. Eventually, the beeps stopped and the engineer arrived. 

The decision was made to proceed with my session on a different, identical VersaHD machine, and the bed was lowered. I pulled up my pants and was helped down. As I was putting on my shoes to walk to the other machine, I said something like:

1980s radiotherapy machine, the Therac-25
(Original source: untraceable)

"At least it's not a Therac-25." 

To which several of the team responded, "What's that?"

But to my delight, the engineer launched into a very good summary of the Therac-25 incident.

This was a series of six massive radiation overexposure accidents involving a computer-controlled radiation therapy machine called the Therac-25, between 1985 and 1987, driven by race conditions, poor software design, and removed hardware safety interlocks. These software faults caused patients to receive up to 250 times the intended radiation dose, resulting in severe burns and multiple deaths. (Wikipedia).

Fortunately, when the details of these horrific incidents came to light, the entire medical technology world took notice, and the Therac-25 was subjected to intense scrutiny. A range of problems was identified:

  • a race condition in the software that allowed the high-power beam to fire without the beam-spreader plate in place, 
  • an overconfidence in software safety that led engineers to remove hardware interlocks present in earlier models, 
  • poor error reporting that displayed cryptic codes like "Malfunction 54" instead of clear warnings, 
  • and a culture at the manufacturer, AECL, that was slow to investigate and acknowledge the reports of injury.

The fallout reshaped how the industry thinks about safety-critical software. Nancy Leveson and Clarence Turner's 1993 investigation became a foundational case study, still taught in software engineering and systems safety courses today. It clarified the dangers of relying too heavily on software alone to enforce safety without independent hardware checks.

More concretely, the incidents contributed to tighter US FDA oversight of software in medical devices, spurring the development of formal standards such as IEC 62304 for medical device software lifecycle processes and IEC 60601 for electrical safety. 

The Therac-25 failures also pushed the field toward practices like formal hazard analysis, independent redundant safety mechanisms, and rigorous change-control procedures for software updates, recognizing that a single software fix, applied without full re-verification, can introduce new failure modes just as dangerous as the ones it was meant to fix.

And that is why I was not too alarmed by today's glitch in the VersaHD that has been photon-beaming me. Although the hardware and software employed in prostate cancer radiotherapy today are orders of magnitude more complex than those of 40 years ago, I am confident they are far safer as well.

Prostate Cancer Diary Day Two (of too many?)


Yesterday's trip to Sainsbury's did not yield a suitable physical diary in which to record my "prostate cancer journey." But I did enjoy a couple of eggs on toast and a decaf flat white. I did not make a decision about which prostate cancer treatment path to pursue.

Sunday 29 March, 2026

Unknown Illustrator, Public domain, via Wikimedia Commons: Digital rectal exam (DRE); drawing shows a side view of the male reproductive and urinary anatomy, including the prostate, rectum, and bladder; also shows a gloved and lubricated finger inserted into the rectum to feel the prostate.  https://commons.wikimedia.org/wiki/File:Digital_rectal_exam.jpg
Prostate identified in digital rectal exam (DRE)

I always take a little time on Sunday mornings to reflect. It's a lingering echo from growing up in a churchgoing family. A regular topic of that reflection is gratitude. I am truly grateful for how fortunate I have been in life, and how to have had a life full of many wonderul experiences and people, a life that has lasted over seven decades so far. 

All of which helps when you have to face the fact that there are cancer cells growing deep inside your body. Cells that could reach your spine and other organs and eventually kill you. Cells that are not going to go away without some fairly serious trauma. In the case of prostate cancer like mine that trauma is either:

A. Surgical removal or all or part of the prostate - an organ about which many of us humans remain relatively ignorant for most of our lives. (See diagram for location, relative size, etc.)

OR

B. A two-pronged attack through hormone manipulation and radiotherapy. The latter uses high-energy electromagnetic radiation to "zap" (target and damage) body tissue, specifically and hopefully, the cancer cells in the prostate.

The odds that either A or B will put the cancer into remission (no longer active) are about the same. Unfortunately, both A and B can have some serious side effects like incontinence, loss of erection and/or ejaculation, and more. I will delve into these in a future post.


Prostate Cancer Diary Day One (of how many?)


The most recent NHS figures show a huge rise in prostate cancer cases, jumping from just under 52,000 in 2021 to more than 64,000 in 2022.
UK Prostate Cancer statistics from NHS via Prostate Cancer UK



















Prostate cancer, often referred to by doctors as PCa, appears to be on the rise in the UK and the US. Ten years ago my brother found out he had it. That prompted me to get tested and in 2021 doctors detected "a tiny amount of cancer" in my prostate. Unfortunately, by 2025 that amount had increased to the point where treatment was needed. By March of 2026, the medical system was ready to offer me that  treatment. 

[Note: This blog post was supposed to be the start of a diary documenting the process of deciding which treatment to have, and then my experience of that treatment. Unfortunately, I have not be able to find the time and/or energy to write many diary entries beyond this one. But I have left it here in the hopes of filling in the gaps later.]

Saturday 28 March, 2026

When I woke up today I found I was thinking about prostate cancer treatment; not just my prostate cancer treatment, about which I must make a decision in the next few days, but prostate cancer in general. More specifically, my mind was going over the timing of that treatment and, as I put on my dressing gown and headed for the stairs, the term lackadaisical came to mind.

According to Vocabulary.com: "Even though lackadaisical sounds like it has something to do with a shortage of daisies, it means lacking in spirit or liveliness, showing little enthusiasm, effort, or determination. And that's the vibe I've been getting throughout my "prostate cancer journey." That journey started slow and low key in 2021, which was fine, but in the past 12 months it has heated up. The medical response has not been as urgent as I would have liked.

However, when I got downstairs, thoughts of cancer treatment were suddenly replaced by remembrance of something I didn't do yesterday: reconfigure the WiFi so that printer works properly. I remembered this because I need to print out the latest correspondence from the urologist if I am going to make the case for greater urgency. 

The reason why I didn't fix the printer yesterday, when I realized there was a problem, will help illuminate my current situation. The problem occured while my partner, CC, was using the Internet, and I didn't want to bother her. This would not have been a big deal six or seven years ago, but these days CC suffers from chronic fatigue and is cognitively impaired due to two brain haemorrhages and an insidious genetic condition. All of which makes tackling domestic IT issues a lot more complicated than it used to be.

On the plus side, CC sleeps until nine in the morning most days, so stuff like reconfiguring the WiFi is best done at the start of the day. However, by the time I made my cereal and coffee and sat down to catch up on email and news this morning, I could already hear CC getting up to go to the bathroom. 

When that happens I listen for her to walk back to her room because, if she is not planning to go back to sleep, she will typically call downstairs to ask for a beverage. Today she requested a ginger ale, not the usual tea or hot chocolate. So I took her a glass of GA and decided to do the WiFi tomorrow.

Which was fine because today I need to write down the big idea I had when I woke up this morning: Write a diary! My thoughts about the many days that have passed between the various stages of my prostate cancer diagnosis and treatment. The idea? 

Microscopic view of prostate cancer, specifcally histopathologic changes indicative of adenocarcinoma of the prostate. By Dr. Edwin P. Ewing, Jr. of the US CDC ergo public domain. Cropped and rotated by Stephen Cobb
Prostate cancer (PCa)
under a microscope
Yes, I know writing a diary is not an original idea. Indeed, it would be natural to expect that a human in their eighth decade, one who has been writing stuff for seven of those decades, an educated chap who for many years earned a living from his writing, would be no stranger to keeping a diary. Yet somehow I've managed to get this far without keeping track of my thoughts any actions on a daily basis. 

Of course, like many writers, the thought "must write a diary" was not immediately followed by the act of putting pen to paper. No, my first impulse was to tell myself I needed to buy a diary to write in. Pretty sure I've seen A5-size diaries at Sainsbury's. So maybe the next step on this journey is drive there, grab a diary and an early lunch, and ponder my prostate cancer treatment options.

Given the stage I am at, technically known as Grade Group 3, Gleason 7 (4+3), organ-confined, the basic choice is between surgery to remove the prostate, or a combination of radiotherapy and hormone therapy to kill off the cancerous cells and the testosterone on which they feed.


On the edge of my home town: drone's eye view of Coventry's west side


Using drones to make movies and take pictures can be a lot of fun. It offers new ways in which to see our world, ways previously limited to birds and flying insects. I took up drone photography as a hobby last December (2025). I recorded this footage in January and added a bit of sound and text.


This clip gives a 360-degree view from about 30 meters above where we live, on the west side of the city of Coventry, in England. The neighbourhood we live in is known as Mount Nod because that is what it was called long before there were houses here. You can see it near the middle of this map from 1895.


Think before you park illegally


Here's a quick reminder that some parking rules are made for very valid reasons. Can you see the harm caused by this driver? Scroll down for a closer look.

Photo of a white BMW parked on the grass verge adjacent to a double-yellow line, they parked over the telecomm access points for our building. This prevented a long awaited fibre optic install

The driver of this vehicle not only parked on the grass verge adjacent to a double-yellow line, they parked over the telecomm access points for our building. This prevented a long awaited fibre optic install for a 40-employee charity that could provide even my care for the people of Coventry and Warwickshire if it had the full fibre business broadband access promised by BT back in March.


Here's just one of the access points this person blocked.


They managed to block three in a row!

And this was not an isolated incident.
(Pure coincidence that both violators were driving BMW?)


Guess which car has an expired MOT?


Talk about mixed emotions


I am writing this in the waiting room of the nuclear medicine facility at UHCW (University Hospitals Coventry and Warwickshire). I am about to have a bone scan to see if the cancer in my prostate has spread beyond said organ. This procedure requires me to be out of the house for about six hours. Not normally a problem, but…

…two weeks ago, Chey’s slow cognitive decline accelerated and it has not yet rebounded. This means that, for the first time ever, I felt the need to have a professional carer present in our home while I was absent from it.

On the plus side, living in Coventry means that we have access to affordable, professional, compassionate care. And one of those professional compassionate carers is currently at the house in case Chey needs anything while I am gone.

Arranging this care is partly a dry run for when I have to go in for prostate cancer treatment which could, probably will, limit my abilities to look after Chey myself for a couple of weeks.

So that’s the first pair of mixed emotions. I’d rather not have prostate cancer and I’d rather Chey had her full cognitive and physical abilities restored, but in the absence of those things we are fortunate to have access to care and support that we need. (A big shout out to Carers Trust Heart of England for it’s excellent work supporting carers.)

Another set of mixed emotions involves our dearly departed Lola, a lovely feline companion for the last five years. Sadly, she became ill three months ago and it turned out to be inoperable stomach cancer, so we had to say goodbye. That was also two weeks ago. 

Photo of an English tabby cat rubbing faces with and old white English man named Stephen
Lola

Thankfully, Lola left us with many wonderful memories and thousands of cat pics! However, at the risk of sounding overly dispassionate and pragmatic, her departure has also eased the care burden on me, enabling me to focus more on Chey, while also supporting my mum (who it must be said, is healthier than both of us and looking forward to her 97th birthday next month).

So there’s #Hope that Chey will improve and my prostate cancer can be treated without a gap in care for Chey. And there’s #Gratitude that we are in a position to access the treatment and care we need. We both have books still to write and places yet so go.  

Yes, as cruel months go, February, 2026 has been quite the contender (wry literary reference for anyone who’s had to read T. S. Eliot). But at least we’ve witnessed the first arrest of an heir to the throne in over 350 years!

As time permits I will be writing up notes on Chey’s health and mine. In the meantime, offerings to the weather gods would be appreciated. Seeing a lot more sun and a lot less rain would help, preferably before April. 

P.S. I already made a website to share Chey's underlying health issues, it's called She's No Okay, Yet.