There is now an increased awareness of the importance of maintaining accuracy and avoiding mistakes in radiotherapy treatment. A necessary part of the planning procedure involves checking the accuracy of a treatment plan by another qualified person. The aim of this check is to help ensure that the plan meets the requirements of the clinician and that the absorbed dose will be given as prescribed in using the specified treatment unit set-up. The latter can be easily checked by calculating the percentage dose per monitor unit at the point intersected by the central axes of all the beams; however this can be a time-consuming and tedious process if done without the aid of a computer. A simple facility has been implemented at the Royal Marsden Hospital using a computerized spreadsheet to perform calculations of percentage dose per monitor unit, D, as well as other fundamental quantities, which otherwise would require the use of a pocket calculator, percentage depth dose charts and other tables.
