Digital radiographs & photos 

CMOS  complementary metal oxide semiconductors


Hidden decay in  10-25% of children

Prof Adrian Lussi Bern    EAPD Strasbourg May 2012

 
 

A new age of imaging adapted in the Nikon D3 for digital photography is beyond expectation and a similar application for digital radiography (x-rays) by Suni Ray with MacPractice software. CMOS sensors require the least amount of radiation to produce the highest resolution quality of 22 lines per millimeter. This is the highest resolution currently available.

In Slievemoredental they are connected to our iMac using powered hub USB ports to increase their sensitivity and accuracy at tiny amounts of exposure to ionizing radiation.

iMac has grey scale equivalent to the best digital radiograph monitors available which further enhance the picture radiograph quality.

Digital dental radiographs using this equipment are perfectly safe and remarkably accurate.

The radiation dose per radiograph is  very low indeed(see below for details).


Background radiation is the normal exposure to ionizing radiation such as when walking in the open air or  by the ingestion of certain foods such as Brazil nuts, Jars of mussels,eating bananas , drinking water , airport back scatter airport scanner  or flying in aircraft - the higher you fly the greater the exposure!

It is all very small indeed and nothing to be concerned about.

Background radiation can vary - for instance a two week holiday in Cornwall gives a radiation dose equivalent to three months in Dublin.


SOME USEFUL FACTS:  http://en.wikipedia.org/wiki/Ionizing_radiationreference

In Ireland a year of background radiation = 1mSv(milliSieverts) or 1000uSv(microSieverts)

This is equal to 2.7uSv per day in Dublin     Cornwall x6 times =16.2uSv per day.

On average people living in the UK receive 2700 microseverts of ionizing radiation from all sources in a year  primarily from natural & medical sources.

Source Health Protection Agency formerly NRPB National radiological protection board

www.hpa.org.uk


In northern Iran (Ramsar) a year of background radiation = 260mSv or 260000 uSv     712uSv /day  x 263 times background radiation in Dublin.

This background radiation would be the equivalent of having 650,000 dental radiographs a year  or 1780 radiographs per day and there is no evidence of harmful effects in local population in Iran.


I hour of aircraft flying at 36000 ft gives you a background radiation of 6usv - 8 usv.





This is rectangular collimation where there is

a rectangle of lead on the head of the X-Ray machine

so the beam of x rays matches the shape of the sensor


The reduces the radiation dose by 50%


It also improves the quality of the image as there is

no possible scatter.





How are the calculations made ?

Reference :Napier ID 1999 Reference doses for dental radiography BDJ 186(8):392-6

Two bite wing radiographs or peri apical dental radiographs taken without rectangular collimation using E Speed film = 4.0uSv  therefore One film = 2.0uSv (two micro severts)

Possible reductions in dosage

Phosphor plate system x 0.25 - 0.75 

Digital  imaging system  x 0.5             =  50% reduction

Rectangular collimation x 0.5             =  50% reduction

F speed Film    x 0.5                           =   50% reduction

DC Constant potential 65-70Kv x 0.8 =  20% reduction

Powered USB port for digital 



Dental Digital CMOS technology(effective dose reduction 50%) peri apical radiograph with rectangular collimation (effective dose reduction further 50%) and using a DC direct current (effective dose reduction of 20%) long cone 65-70Kv X-Ray machine can be as low as 0.4uSv   = 4 minutes of flying time  =  4 bananas  = 20  minutes of Dublin background radiation = 3 minutes of background radiation in Cornwall = 7 seconds in Ramsar


Medical Procedure Comparison

To put a comparative perspective relative to a medical procedure using image intensifier for lets say a Coronary (heart) procedure (interventional radiography) the average dose is 15.1milliseverts = 15,100microseverts which is equivalent to 37,750 peri apical dental radiographs using the most modern equipment.

Barium Enema 7.2mSv =7200usv = 18000 dental peri apical radiographs

CT scan of chest 8msv =8000usv   = 20000 dental peri apical radiographs

CT scan of head  2msv= 2000usv   = 5000  dental peri apical radiographs

Dental CT scan  per jaw   0.5msv= 500usv  = 1000 dental peri apical radiographs



Banana equivalent dose   see http://en.wikipedia.org/wiki/Banana_equivalent_dose

A banana a day for a year gives a radiation dose of 36uSv   = 90 dental radiographs at this practice using the most modern technique.



Long Cone X-Ray machines with tiny focal points of emission produce the best source of parallel beam of radiation for the most accurate radiograph images.

Dental Practices account for the tiny amount of 0.4% of medical ionizing radiation.

This figure will be reduced to 0.08% of medical ionizing radiation when all practices are digital with CMOS  equivalent technology use DC constant potential 70Kv X Ray machines and rectangular collimation .




Direct Current X Ray units produce better images at reduced power.

Rectangular Collimation reduces radiation dose by 50%.

Holders specifically designed for sensors and rectangular collimation ensure 100% accuracy of positioning maintaining parallel position and ensure reproducibility of image under the same standard conditions for a true comparative view on follow-up evaluation.

These holders are not only cleaned in our washer/disinfector but are also bagged and autoclaved for maximum safety.




The benefits of such technology is applied to the full at Slievemore dental where reported instant high quality images can be instantly e mailed to a patient for greater clarity and transparency of treatments planned and treatments completed.

The image quality , like photos on the iMac equals the best monitor image quality available.


We do not use dental panoramic tomography where all the teeth radiographed. The resolution is relatively very poor and their usefulness  is very limited [oral surgery & overall periodontal assessment & Orthodontic assessment]. There is extensive research on a sample of over a million  that proved their usefulness to be 1-3%. That is 97- 99% useless.[Eric Whaites Head of department of Dental Radiological Imaging London Guy’s King’s & Thomas’ Hospitals.]

Dympna Daly (Paedodontist) said about panoramic x-rays “they are a bit like a school photograph , they tell you how many are there but no real detail of any of them”.


Lead aprons or non lead  radiation resistant aprons -

The official status in Ireland   June 2011  Radiolgical Protection Institute of Ireland

There is no justification for their routine use in dental radiography

There is no requirement to use lead apron for pregnant patients

The use of aprons for dental radiography has been shown to actually increase the radiation dose by containing internal scatter and are not used at Slievemore dental.

Their use have been “positively discouraged in the UK since 1994 

see ”http://www.youtube.com/watch?v=pTshgOkRJr0&feature=related


In the UK aprons have been”positively discouraged” for dental radiography since 1994

NRPB  Selection Criteria 1998

Normal selection criteria for dental radiography DO NOT need to be influenced by the possibility of a female patient being at ANY stage of a pregnancy.

Documents of National Radiological Protection Body UK 1998.


The FAA has a recommended limit of 1 mSv (1000 uSv) equivalent to 2500 dental peri apical radiographs at this practice total for a pregnancy, and no more than 0.5 mSv (500 uSv ) equivalent to 1250 dental peri apical radiographs per month.[20] Information originally based on Fundamentals of Aerospace Medicine published in 2008.                        http://en.wikipedia.org/wiki/Ionizing_radiation