The Soviet Union: Gorbachev, perestroika and socialism
The Russian revolution of 1917 was originally conceived as part of a transition to socialism on a global scale. The failure of that strategy led to a far‐reaching debate about the means by which a relatively backward Soviet Russia could advance by itself to a communist future. The Gorbachev years saw the issue addressed in terms of the construction of a ‘humane, democratic socialism’, seen as part of a global process; individual scholars and publicists advanced still further towards a socialism that would embody a multi‐party system and a variety of forms of ownership. Increasingly, however, still more radical commentators identified the origin of Soviet difficulties as Leninism itself. There was, in fact, little popular support for a return to capitalism; but the experience of Soviet rule showed that the authorities in that country needed the political experience of the West as much as they needed its capital investment.
Ideology and Soviet Politics
There has been general agreement that the official ideology of Marxism-Leninism plays a central role in Soviet politics. To at least some Western scholars, the importance of the official ideology is such that we are justified in regarding the Soviet political system as an ‘ideology’ or even ‘utopia in power’, with the official ideology functioning as a kind of blueprint which determines, or at least prescribes, the course of that society’s development.1 To the Soviet authorities themselves, there is equally no doubt that (in the words of the current Constitution) the October Revolution has given rise to a ‘new type of state’, a ‘basic instrument for defending the gains of the revolution and for building socialism and communism’, which in turn is part of a world-wide transition from capitalism to socialism.2 Yet, at least in Western scholarly circles, the nature of the ideology itself has tended to be taken as a ‘given’ in discussions of this kind.
A quality control model that uses PTV-rectal distances to predict the lowest achievable rectum dose, improves IMRT planning for patients with prostate cancer.
BACKGROUND AND PURPOSE
To predict the lowest achievable rectum D35 for quality assurance of IMRT plans of prostate cancer patients.


MATERIALS AND METHODS
For each of 24 patients from a database of 47 previously treated patients, the anatomy was compared to the anatomies of the other 46 to predict the minimal achievable rectum D35. The 24 patients were then replanned to obtain maximally reduced rectum D35. Next, the newly derived plans were added to the database to replace the original clinical plans, and new predictions of the lowest achievable rectum D35 were made.


RESULTS
After replanning, the rectum D35 reduced by 9.3 Gy±6.1 (average±1 SD; p<0.001) compared to the original plan. The first predictions of the rectum D35 were 4.8 Gy±4.2 (average±1 SD; p<0.001) too high when evaluated with the new plans. After updating the database, the replanned and newly predicted rectum D35 agreed within 0.1 Gy±2.8 (average±1 SD; p=0.89). The doses to the bladder, anus and femoral heads did not increase compared to the original plans.


CONCLUSIONS
For individual prostate patients, the lowest achievable rectum D35 in IMRT planning can be accurately predicted from dose distributions of previously treated patients by quantitative comparison of patient anatomies. These predictions can be used to quantitatively assess the quality of IMRT plans.