Too much radiation?

Q Our daughter has scoliosis in the lumbar region, to an extent which puts her on the borderline for surgery. She has had a lot of x-rays, not all of which were necessary in our view. The consultant assured us that the amount of radiation would be equivalent to (and no worse than) "for a passenger on a transatlantic flight". Can this be correct? Our daughter wants children, and we are worried about the x-ray exposure

A You are quite right that the radiation for lumbar spine x- rays is significant. A chest x-ray is a relatively insignificant amount of radiation; equivalent to three days of background radiation and half as much as flying to Spain. The excess risk of developing cancer from a chest x-ray is about the same as smoking one cigarette. But x-rays of the pelvis and lumbar spine are equivalent to about six months of background radiation. Having said that, even repeated lumbar spine x- rays cause an excess cancer risk of less than 1%. If your daughter is careful to avoid all x-rays that are not strictly necessary for the rest of her life, she will minimise her risk. And if she eschews the risk factors for cancer such as smoking, she could end up at less risk than most of the population.

Foot sore

Q Over the past few months I have found that if I walk for any length of time I get a burning (sort of ripping) sensation in the balls of my feet. This is very painful and has inhibited my being able to drive. I'm 50 years of age and used to jog regularly (I finished a marathon some years ago) although I'm much less active nowadays (due to sloth rather than sickness). I'd welcome your advice.

A This is such a common complaint but no less painful for that! The pulpy part of your foot has become inflamed from taking your weight over the years on unforgiving, hard surfaces. This has the grand name of plantar fasciitis.The trick is to put padding between yourself and the ground. Bouncy trainers with thick rubber soles, cushioned insoles, avoiding walking barefoot or on thin-soled shoes and walking or jogging on grass or treadmills rather than tarmac are the key to a pain-free life. Losing excess weight obviously helps. Podiatrists can fashion wonderful, but expensive, custom-made insoles for your shoes but expect to pay up to £200. Doctors can inject the painful spot or prescribe anti-inflammatory drugs but in my experience, the padded trainers work better.

My sweat smells

Q I am a young woman of 21 years and suffer from a rather upsetting problem. I tend to perspire ordinary amounts but recently I've noticed that my smell has changed. I was never able to detect an odour of sweat before but now I am unable to counteract it with a deodorant. I've even tried so-called problem perspiration deodorants but to no avail. I only have this problem when I'm out at college or when I'm nervous.

A Body odour is caused by sweat, stale clothes and chemicals. You may be sweating more because you're anxious, have an overactive thyroid, are taking hormones such as the pill, have put on lots of weight or are exerting yourself or getting stuck in hot and poorly ventilated places. You may be sweating the same amount as previously but are wearing synthetic clothes that retain sweat. Or perhaps you're not able to wear a clean top every day and they are becoming a little stale smelling. I'd suggest cotton underwear and tops change daily, shaving underarms, and the antiperspirant Driclor that contains aluminium chloride that reduces sweat. You may want to stop the pill or change to Dianette which may reduce sweating and have a check- up, including blood pressure and a blood test for thyroid function. Ask a friend for independent verification - some people believe they smell bad but don't, others think they smell lovely and smell to high heaven.

• These answers are intended to be as accurate and full as possible, but should never be used as a substitute for visiting a doctor and seeking medical help. If you have a question for Dr Robinson, email :drann@dircon.co.uk or write to her c/o The Health Editor, The Guardian, 119 Farringdon Road, London EC1R 3ER. She regrets that she cannot enter into personal correspondence.