Cost- and time-sparing simplified conformal therapy for prostate cancer: is it feasible?

A Method of Predicting Workload and Staffing Level for Radiotherapy Treatment Planning as Plan Complexity Changes

When assessing the impact on workload from an expanding number of new patients and increasing treatment complexity, radiotherapy clinics find that oversimplified workload parameters, such as number of patients or number of fields, are not suitable for managing and predicting workload and organisational dimension. Although the basic treatment equivalent concept is available for predicting linear accelerator utilisation, no corresponding parameter has been available for radiotherapy treatment planning. In this study, we derive a simple workload indicator for treatment planning. The dose plan unit (DPU) takes the complexity of the treatment plan into account. Categorising plans according to complexity in their production, and measuring corresponding time for completing the plans in these categories, leads to the following baseline values for workload prediction: 1 DPU (non-computed tomography [CT]), 3 DPU (CT-contour) and 6 DPU (full-CT). The measured average productivity of 0.65 DPU per hour (1 standard deviation, SD = 0.08 DPU), or alternatively 1 DPU = 92 min, for a dosimetrist in this clinic indicates that 79.0 DPU can be produced by each dosimetrist per month within normal working hours. The predictive power of the DPU is shown in terms of using it to quantify the impact on workload in treatment planning of changing treatment protocols for a particular anatomic treatment site.

Analysis of intraprostatic failures in patients treated with hormonal therapy and radiotherapy: implications for conformal therapy planning

PURPOSE

Conformal therapy of prostate cancer is based on high-dose irradiation to the entire prostate gland. The aim of this study was to analyze the pattern of intraprostatic recurrence in patients undergoing external beam radiotherapy (EBRT) at a dose of 65-70 Gy to evaluate whether conventional radiotherapy doses are adequate to control microscopic disease outside the primary tumor and therefore whether high-dose irradiation can be exclusively focused on the macroscopic disease.

METHODS AND MATERIALS

The clinical and radiologic reports of 118 patients with prostate cancer undergoing EBRT (64.8-70.2 Gy) combined with hormonal therapy were evaluated. In all patients, before and after therapy, the size and site of the primary neoplasm within the prostate were assessed by clinical examination and imaging studies.

RESULTS

With a median follow-up of 45 months (range 14-119), the 5-year actuarial local control rate was 83.9%. Twelve patients had an intraprostatic recurrence, with the appearance of a new nodule (in 5 patients with a complete response after therapy) or increased nodular size compared with the minimal size (in the 7 other patients). In all patients, on the basis of a semiquantitative evaluation of the site of recurrence, this was shown to originate within the initial tumor volume.

CONCLUSION

The results of this analysis seem to confirm some histologic findings observed in patients undergoing prostatectomy for local recurrence after radiotherapy that suggest that local recurrence usually originates in the primary tumor rather than in focal prostatic intraepithelial neoplasia. This observation might justify the application of conformal therapy procedures aimed at identifying the gross tumor volume, in the phase of boost, exclusively with the primary tumor.