The experience of our radiation nurses has been that is a real difference between regular IMRT and tomo IMRT in the extent of side effects they have to deal with - backed up by the experience of our RO who did a six month's comparison between tomo vs. conventional IMRT when the tomo machine first arrived, and after six months, put all his head/neck cancer patients on tomo. Studies have shown that tomo can allow a much sharper margin between target and non-target tissues and can reduce the radiation dose to nontarget areas by as much as 50% with a slight increase (probably not clinically significant, however) of dose to the target areas.

However I must caveat this that a lot also depends on the individual radiation plan, as the radiation field for tomo can be made as large as that for regular IMRT and any RO is going to design a plan so that all areas which could harbor cancer are going to get a full radiation dose. Thus patients with unknown primary or bulky disease may well not experience any difference in side effects w/ tomo vs. conventional IMRT. In fact, at Hopkins many of these patients were put on the regular IMRT machines as they would not benefit from tomo and access to the single tomo machine was limited, as it had to be shared with prostate and some brain cancer patients (who also benefit greatly from the precise targeting and regular repositioning tomo provides.)

The major side effect differences (to which my husband can attest) were far less damage to the outer oral cavity and tongue -- he had a very sharp line of demarkation between his ororpharynx which was getting the full dose and his tongue, inside cheeks, gums etc. which were getting a much reduced dose -- no mucositis in the outer mouth, no sores or ulcers etc. Although he did experience loss of taste to an extent he retained some taste throughout, esp. on the outer tongue, and regained it quite quickly, within a couple of months. He also had relatively little damage to his parotids considering, and retains almost normal saliva production in the left one (his left neck got a prophylactic dose of rads, his primary being on the right) and good saliva production in the right which (according to the RO and also, the radiation physicist ) would have been 100% fried with conventional IMRT. This has continued to improve and in a check-up yesterday his MO remarked how much mouth moisture he has. Also, our RO said tomo allowed him to avoid radiating Barry's inner ears, which (since he already had high-end hearing loss) was a special issue. The RO presented some of his data re salivary function: with conventional IMRT, he could spare ~50% and with tomo ~65% or better.

Unfortunately, since then the tomo machine at Hopkins has been having a lot of mechanical issues and many HNC patients have been put onto the conventional IMRT to avoid delay in treatment -- we spoke to our RO nurse yesterday and she said they were now dealing with more dry mouth issues and other side effects again.

Our RO told us that there are several new radiation machines coming on line which also provide more precise targeting (similar to the HiArt tomo device) and which will also allow conforming radiation (that is, changing the radiation field as the tumor shrinks during treatment) which is sort of the "next big thing" in RT, so it will be interesting to see how these may reduce unwanted side effects.

Gail