OzRadOnc - new forum threads

Effective Field Size

Fri, 15 Jan 2016 15:00:25 +0000

A collimated field size is 10 x 10cm. 30% of the field is blocked. The effective field size is approximately how many cm?

Seriously hv no idea how to do this
Any tips?

Patient treatment with photon beam

Fri, 15 Jan 2016 01:23:58 +0000

1. The problem statement, all variables and given/known data
Doing some past papers but I got stuck to this question! Any medical physicists can give me a hand please?

A patient is treated with a 6MVphoton beam, 12.5 x 12.5cm at 110cm (Source to Axis Distance: SAD) to a 9cm depth. The machine is calibrated to deliver 1.0cGy per MU at 100cm for a 10 x 10cm field. The number of monitor units required to deliver 150cGy at the isocentre is?

Given the information below:
Tissue Maximum Ratio (TMR) for 6Mv Photons

Depth (cm)	10 x 10cm	12 x12cm	14 x 14cm
1.5	1.0000	1.0000	1.0000
9.0	0.810	0.818	0.824

A. 183
B. 210
C. 247
D. 221

2. Relevant equations
MU = DOSE / ( OUTPUT FACTOR X SAD FACTOR)
SAD FACTOR = (SAD/ SAD + D)2

3. The attempt at a solution
Tried using the equations to solve but still not getting the correct answer which is supposed to be 221.
I got 183 but without using the SAD factor.

Patient treatment with photon beam

Fri, 15 Jan 2016 01:18:49 +0000

1. The problem statement, all variables and given/known data
Doing some past papers but I got stuck to this question! Any medical physicists can give me a hand please?

A patient is treated with a 6MVphoton beam, 12.5 x 12.5cm at 110cm (Source to Axis Distance: SAD) to a 9cm depth. The machine is calibrated to deliver 1.0cGy per MU at 100cm for a 10 x 10cm field. The number of monitor units required to deliver 150cGy at the isocentre is?

Given the information below:
Tissue Maximum Ratio (TMR) for 6Mv Photons
Depth (cm) — 10 x 10cm -- 12 x12cm —14 x 14cm
1.5 ---— 1.0000 -- 1.0000 ---1.000
9.0 --- 0.810 -- 0.818 -- 0.824

A. 183
B. 210
C. 247
D. 221

2. Relevant equations
MU = DOSE / ( OUTPUT FACTOR X SAD FACTOR)
SAD FACTOR = (SAD/ SAD + D)2

3. The attempt at a solution
Tried using the equations to solve but still not getting the correct answer which is supposed to be 221.
I got 183 but without using the SAD factor.

Energy of the secondary electrons in soft tissue from MV beams

Sun, 19 Jul 2015 22:56:26 +0000

Hello, I am writing from London but trained at the PeterMac. I am trying to work out what happens in tumour when hit by 4 - 6 MV beam in the presence of gold nanoparticles. Hence my interest in section 8.3.2 (webpage above) where it appears that the average secondary electron liberated by 6 MV photon has 1- 2 MeV. Could anyone please give me the references where all this data (energy of secondary electrons page 8.3.2 ONLY) comes from, as I need to quote it for possible PhD presentation. Many thanks for your hep and any input.

Normalisation

Wed, 21 May 2014 15:35:06 +0000

Can anyone explain to me, in simple terms, what is meant by normalisation in radiotherapy planning?Is the norm point the same thing as the ICRU ref point?

Missing equation

Mon, 07 Apr 2014 18:45:23 +0000

At the end of the topic 8.6 - Photon Beam Calculations the formula of scatter air ratio is missing. Could anyone fix this problem?

Ongoing Work

Fri, 21 Feb 2014 02:22:35 +0000

Hello everyone.

The site will continue to be updated over time.

If you have any comments, suggestions, or want to contribute please let me know.

There are still large areas that are incomplete, particularly in the medical expert / phase 2 / clinical oncology sections.

Short term training in Radiation Oncology

Wed, 29 May 2013 08:04:02 +0000

Hi,
I am a qualified Radiation Oncologist from India with 10 years of post graduate experience in the field. I need some information on Short term training in Radiation Oncology for international medical graduates.
It will be really nice if some body can provide me some information and help for the same.
Thanks

Nesting of cancer pathology

Fri, 12 Apr 2013 01:26:34 +0000

When I open up the "Pathology" tab of the "Diagnosis" section of Patient Manager, the first category is "Cell Histology".

There are three drop-down boxes:

Cell Category
Cell Type
Cell Grade

Cell Category gives a drop down list of cell pathology categories (e.g. adenocarcinoma, squamous cell carcinoma) that are pertinent to the ICD-O site selected. When selected, this influences the options in the "Cell Type" drop down box. I'm concerned that for some tumour types (e.g. testicular tumours) the "Cell Category" box is not very helpful (it gives Seminoma, Embryonal Carcinoma, Teratoma, Malignant Teratoma), grouping Yolk Sac Tumour under Embryonal Tumours and not including choriocarcinoma at all.

Is there any way to edit this options as the administrator or is it 'hard wired' into the software?

Inverse square law and percentage depth dose

Sat, 23 Feb 2013 01:06:07 +0000

Hi fairly new to this so bear with me….im currently in my second year of a UK therapeutic radiotherapy degree and am kinda stuck with a physics essay. I have to talk about the factors that affect depth dose distribution within the body, and just cannot get my head around how as distance from the source increases,the beam becomes more penetrative as the influence of the square law reduces??

If anybody on here can explain this to me in really simple terms, id be seriously grateful!!

Training programme

Mon, 08 Oct 2012 23:26:39 +0000

Hi, I ws wondering if anyone had any useful tips for getting in the radiation oncology training programme? Any advice would be greatly appreciated!

in-vivo dosimetry with diodes

Fri, 06 Jan 2012 10:49:44 +0000

Hi! I am new here and didn't know where to post this.
First of all - thanks to the organiser! - Good project for trainees!

In the section '11.10.9 - In Vivo Dosimetry' I read this: 'Diodes are also relatively small and have the benefit of an instantaneous readout. Their disadvantage is the need to connect them to a power supply during dose delivery.'

This is not quite correct: diodes do not require exteral power/voltage. They are connected to an electrometer which enables to take diode readings.

Benign (non-neoplastic) Disease treated with Radiotherapy

Tue, 06 Dec 2011 22:51:25 +0000

Ankylosing Spondylitis
Plantar Fasciitis
Hypersalivation
Heterotopic Ossification
Keloid
Hidradenitis suppurativa
Graves Ophthalmopathy
Macular Degeneration
Arterio-venous Malformation

Neoplastic benign conditions include:

Pituitary Adenoma
Warts
Langerhans Cell/Histiocytosis X
Giant cell tumours

algorithms

Wed, 24 Aug 2011 07:17:56 +0000

Dear sir,
can you explain the dose calculation algorithm in external plan radiotherapy and how we can calculate anisotropy function in brachy therapy..

Mobile phone apps

Thu, 21 Jul 2011 01:59:23 +0000

I've seen a few different apps for Rad Onc calculations, each one a bit different but serves its purpose nicely when the PC is not nearby. I got one on the Droid market called B.E.D. Calculator that works just fine for doing some quick dose comparisons. What apps have you found useful, or what kind of app would you like to see created that you think you would actually use?

Back online

Mon, 09 May 2011 09:56:50 +0000

Hey, I don't know if anyone still comes here (wouldn't blame you) but the site is again active and can be joined. The forums are also up for discussing questions or bringing errors to attention!

I won't be posting any more assignment answers however.

Radiocurability

Sat, 15 Jan 2011 05:37:04 +0000

Hi,

Great website.. Has come in very handy.. I was wondering where you got your definitions for radiocurability and radioresponsiveness?

Thanks

Pathology study proforma

Wed, 01 Dec 2010 10:35:16 +0000

Organ
History of the disease
- what happened in the past?
Incidence
- Risk groups
  - genetic syndromes
  - endemic groups
- Characteristic presentations
- Associated pathologies)
Prevalence
Prognosis
Risk Factors
- Behaviours
- Substances
  - Natural
  - Social
  - Therapeutic
  - Industrial
- Infections
- Infestations
- Trauma
- Congenital conditions
Pathogenesis
Diagnosis
Histopathology
- Cellular Classification
  - types
  - variants
- Risk features
- Prognsotic features
- Cell markers
Staging
- prognostic factors
Natural History
- detection
- Screening
- Presentation
- Patterns of spread
- Management
- Influence of pathology on Treatment options
- Metastatic patterns
- Methods of death
Imaging
- characteristic patterns
- sample images

abscopal effect

Sun, 14 Nov 2010 10:04:06 +0000

hi there. excellent website. thanks so much for publishing it.

i was wondering where you got your info for the abscopal effect? it's not indexed in any of the books i've read, and the distant bystander effect is the closest thing i can find, but that doesn't sound the same as the abscopal effect.

thanks

Surface dose for photon beams

Wed, 06 Oct 2010 23:12:02 +0000

Hi - quick question…
What is the surface dose for your 18MV photon beam?

Physics tutorial links not working

Fri, 24 Sep 2010 07:00:11 +0000

Well done on creating this site!
The physics tutorials are excellent! However, some of the links for the tutorials are not working properly, eg tutorials 12 and 13. Cheers