Improving dose homogeneity in routine head and neck radiotherapy with custom 3-D compensation.

BACKGROUND AND PURPOSE: Anatomic contour irregularity and tissue inhomogeneity can lead to significant radiation dose variation across the complex treatment volumes found in the head and neck (H&N) region. This dose inhomogeneity can routinely create focal hot or cold spots of 10-20% despite beam shaping with blocks or beam modification with wedges. Since 1992, we have implemented the routine use of 3-D custom tissue compensators fabricated directly from CT scan contour data obtained in the treatment position in order to improve dose uniformity in patients with tumors of the H&N. MATERIALS AND METHODS: Between July 1992 and January 1997, 160 patients receiving comprehensive H&N radiotherapy had 3-D custom compensators fabricated for their treatment course. Detailed dosimetric records have been analyzed for 30 cases. Dose uniformity across the treatment volume and clinically relevant maximum doses to selected anatomic sub-sites were examined with custom-compensated, uncompensated and optimally-wedged plans. RESULTS: The use of 3-D custom compensators resulted in an average reduction of dose variance across the treatment volume from 19+/-4% for the uncompensated plans to 5+/-2% with the use of 3-D compensators. Optimally-wedged plans were variable, but on average a 10+/-3% dose variance was noted. For comprehensive H&N treatment which encompassed the larynx within the primary field design, the peak doses delivered were reduced by 5-15% with 3-D custom compensation as compared to optimal wedging. CONCLUSIONS: The use of 3-D custom tissue compensation can improve dose homogeneity within the treatment volume for H&N cancer patients. Maximum doses to clinically important structures which often receive greater than 105-110% of the prescribed dose are routinely reduced with the use of 3-D custom compensators. Improved dose uniformity across the treatment volume can reduce normal tissue complication profiles and potentially allow for delivery of higher total doses in an attempt to enhance locoregional tumor control.

Adjuvant radiation versus observation: a cost analysis of alternate management schemes in early-stage testicular seminoma.

PURPOSE: This study was designed to compare costs of adjuvant radiation versus observation in the management of early-stage testicular seminoma after inguinal orchiectomy. MATERIALS AND METHODS: A line-by-line inspection of the charges generated during a course of adjuvant pelvic and paraaortic radiotherapy and of three cycles of bleomycin, etoposide, and platinum salvage chemotherapy was performed for five patients who received irradiation and five patients who received salvage chemotherapy. The average charge for either treatment was then calculated. Only those charges directly associated with the diagnosis of seminoma were included in the analysis. Follow-up charges were also generated from the patients' billing records. The optimum follow-up regimen for either management option was derived from a synthesis of the international literature. A 5% rate of failure was assumed if adjuvant irradiation was administered, and a 15% rate of failure was assumed if observation was the option chosen. Charges were truncated at 5 years. RESULTS: The total charge generated over 5 years based on following a policy of observation is $27,223 per patient versus $19,557 if the option of adjuvant irradiation in chosen. Using University of Wisconsin institutional reimbursement rates, the estimated costs were $20,487 and $14,722 for the option of observation and adjuvant radiation, respectively. The cost equivalence point between the two options occurs at 2.5 years, when the initial cost of adjuvant radiotherapy is matched by the cost generated during the period of observation. The maximum cost difference is achieved by 5 years. CONCLUSION: Following a policy of observation postorchiectomy for early-stage testicular seminoma generates 39% more medical costs per patient over a 5-year follow-up period than does following the standard policy of adjuvant irradiation to the pelvic and paraaortic regions, with no reported difference in outcome.