Women who require breast reductions are assessed on a sometimes unreliable and ad-hoc basis, leading doctors claim.
About 15,000 breast reduction operations are considered each year
Whether the woman is accepted for the operation, and how much breast tissue is removed, is determined by the surgeon's personal assessment.
But a survey of consultants by the British Association of Plastic Surgeons found a 30% variation when asking them to judge breast volume on a mannequin.
Cosmetic surgeons say using a 3D body scanner gives more reliable results.
Around 15,000 women a year are considered for a breast reduction or an operation to correct asymmetry.
Common guidelines are used to decide who qualifies for the operation, such as a requirement for at least 500g of tissue to be removed from each breast.
Volume is thought to be key because large breasts can be linked to spinal problems, back pain and disability.
But women are assessed using physical examination and observation.
Some plastic surgeons say this does not take into account factors such as the patient's relative trunk size - whether she is big or small-framed - and body mass index (BMI) - used to assess if people are a healthy weight.
Mark Henley, a consultant plastic surgeon at Nottingham City Hospital, told the BBC News website: "There is an inequality of healthcare provision for patients with large breasts.
"They are currently assessed 'by eye', by surgeons who may or may not recommend them for the operation based on a flawed assessment.
"This is very subjective and prone to error."
Within normal range'
The 3D scanner - used in the fashion industry to determine body shapes and sizes for clothing manufacturers, has been adopted by the 13 PCTs in Nottinghamshire and Southern Derbyshire.
Mr Henley, a council member of both the British Association of Plastic Surgeons (BAPS) and the British Association of Aesthetic Plastic Surgeons (BAAPS), said: "Using the scanner enables us to evaluate the volume of the breast and whether it is in proportion with the woman's torso.
"We are aiming to give women a figure which is within the normal range for her size.
"It is about providing equity of availability by standardising assessments."
In comparison to the wide variation seen when doctors assessed breast volume, the scanner - which has been used to assess around 900 women - shows consistent results.
Before the scanning was introduced, all GP-referred patients received outpatient appointments with a plastic surgeon. Some would later be refused surgery, and nearly half placed on waiting lists.
Since its introduction, there has been an 80% reduction in the numbers referred by GPs, so patients who do need to see a surgeon face a shorter wait.
Richard Richards, Director of Public Health for Newark and Sherwood PCT said: "This programme has resulted in more dignified and acceptable assessments that are easily understood by patients.
"There are significant cost reductions owing to the elimination of inappropriate referrals and resources can now be targeted to the patients that are most in need.
"This innovative technology should be present in hospitals nationwide."