Clinical implementation of brass mesh bolus for chest wall postmastectomy radiotherapy and film dosimetry for surface dose estimates

Objective: This study presents the dosimetric data taken with radiochromic EBT3 film with brass mesh bolus using solid water and semi-breast phantoms, and its clinical implementation to analyze the surface dose estimates to the chest wall in postmastectomy radiotherapy (PMRT) patients. Materials and Methods: Water-equivalent thickness of brass bolus was estimated with solid water phantom under 6 megavoltage photon beam. Following measurements with film were taken with no bolus, 1, 2, and 3 layers of brass bolus: (a) surface doses on solid water phantom with normal incidence and on curved surface of a locally fabricated cylindrical semi-breast phantom for tangential field irradiation, (b) depth doses (in solid phantom), and (c) surface dose measurements around the scar area in six patients undergoing PMRT with prescribed dose of 50 Gy in 25 fractions. Results: Water-equivalent thickness (per layer) of brass bolus 2.09 ± 0.13 mm was calculated. Surface dose measured by film under the bolus with solid water phantom increased from 25.2% ±0.9% without bolus to 62.5% ± 3.1%, 80.1% ± 1.5%, and 104.4% ± 1.7% with 1, 2, and 3 layers of bolus, respectively. Corresponding observations with semi-breast phantom were 32.6% ± 5.3% without bolus to 96.7% ± 9.1%, 107.3% ± 9.0%, and 110.2% ± 8.7%, respectively. A film measurement shows that the dose at depths of 3, 5, and 10 cm is nearly same with or without brass bolus and the percentage difference is <1.5% at these depths. Mean surface doses from 6 patients treated with brass bolus ranged from 79.5% to 84.9%. The bolus application was discontinued between 18th and 23rd fractions on the development of Grade 2 skin toxicity for different patients. The total skin dose to chest wall for a patient was 3699 cGy from overall treatment with and without bolus. Conclusions: Brass mesh bolus does not significantly change dose at depths, and the surface dose is increased. This may be used as a substitute for tissue-equivalent bolus to improve surface conformity in PMRT

Research advances in radiotherapy after mastectomy combined with phase I breast reconstruction for invasive breast cancer / 中华放射肿瘤学杂志

The increasing need for ideal body shape makes more and more patients choose to receive different types of breast reconstruction surgery after mastectomy. Right now, it is a key problem for the multidisciplinary treatment to find an optimal sequence of comprehensive treatment from which those patients can receive the maximum benefits and a good balance between ideal body shape and satisfactory antitumor outcomes. This paper reviews the latest research advances in the effect of postoperative radiotherapy on breast shape after breast reconstruction, the sequential relationship between the replacement of the temporary tissue expander with the permanent breast prosthesis and postoperative radiotherapy, breast construction surgery, and radiotherapy techniques. To provide a basis for clinical practice, this paper proposes a flow chart for decision?making in reconstruction surgery and adjuvant treatment based on the current literature and clinical data.

Postmastectomy Radiotherapy and Chemotherapy in Patients with Breast Cancer / 대한방사선종양학회지

PURPOSE: To evaluate the treatment outcomes after postmastectomy radiotherapy (PMRT) and chemotherapy in patients with breast cancer. MATERIALS AND METHODS: The PMRT were retrospectively analyzed in 83 patients with stage II-III female breast cancer treated between 1989 and 1995. The median age was 46 years (range, 23-77); Seventy- seven patients had modified radical mastectomies, 5 radical mastectomies and 1 simple mastectomy. Three patients (4%) had pathologically negative axillae, and the remaining 80 (96%) had positive axillae. Eleven, 23, 44 and 5 patients had pathological stages IIA, IIB, IIIA, and IIIB, retrospectively. Eighty (96%) patients were treated with hockey-stick fields. The median dose of PMRT was 50.4 Gy, in 1.8 Gy fractions. Adjuvant systemic chemotherapy was given to 74 patients (89%). CMF-based or doxorubicin-containing regimens were given to 54 patients (65%). The median follow-up time was 82 months (range, 8-171) after the mastectomy. RESULTS: The 5 and 10-year overall survival rates for all patients were 65 and 49%, respectively. The univariate and multivariate analyses of the factors affecting the overall survival revealed the stage to be the most significant prognostic factor (p=0.002), followed by the combination of chemotherapy. Thirteen patients (16%) developed a LRF, at an interval of 4-84 months after radiotherapy, with a median of 20 months. The only significant prognostic factor affecting LRF was the combination of chemotherapy, in both the univariate and multivariate analyses. With respect to the sequence of chemoradiation, the sequence had no statistical significance (p=0.90). According to the time interval from mastectomy to the onset of radiotherapy, the LRFR of the patients group treated by RT within or after 6 month postmastectomy 6 months were 14 vs. 27%, respectively (p=0.24). One third of the patients (26/83) developed distant metastasis, in 2-92 months, after radiotherapy, with a median of 21 months. The most commonly involved site was bone in 13 cases. The pathological staging was the only significant prognostic factor in both the univariate and multivariate analyses that affected distant failure. Radiological findingof radiation pneumonitis on a simple chest x-ray was shown in 20% (17/83), with a time interval ranging from 2 to 7 months post-radiotherapy, with a median of 3 months. The stable lung fibrosis settled in 11 patients (65%). CONCLUSIONS: It was concluded through this analysis that the combination of PMRT with in chemotherapy resulted in better overall survival and local control than PMRT alone in patients needing PMRT.

The Benefit of Individualized Custom Bolus in the Postmastectomy Radiation Therapy:Numerical Analysis with 3-D Treatment Planning / 대한방사선종양학회지

PURPOSE: To reduce the irradiation dose to the lungs and heart in the case of chest wall irradiation using an oppositional electron beam, we used an individualized custom bolus, which was precisely designed to compensate for the differences in chest wall thickness. The benefits were evaluated by comparing the normal tissue complication probabilities (NTCPs) and dose statistics both with and without boluses. MATERIALS AND METHODS: Boluses were made, and their effects evaluated in ten patients treated using the reverse hockey-stick technique. The electron beam energy was determined so as to administer 80% of the irradiation prescription dose to the deepest lung-chest wall border, which was usually located at the internal mammary lymph node chain. An individualized custom bolus was prepared to compensate for a chest wall thinner than the prescription depth by meticulously measuring the chest wall thickness at 1 cm2 intervals on the planning CT images. A second planning CT was obtained overlying the individualized custom bolus for each patient's chest wall. 3-D treatment planning was performed using ADAC-Pinnacle3 for all patients with and without bolus. NTCPs based on "the Lyman-Kutcher" model were analyzed and the mean, maximum, minimum doses, V50 and V95 for the heart and lungs were computed. RESULTS: The average NTCPs in the ipsilateral lung showed a statistically significant reduction (p<0.01), from 80.2+/-3.43% to 47.7+/-4.61%, with the use of the individualized custom boluses. The mean lung irradiation dose to the ipsilateral lung was also significantly reduced by about 430 cGy, from 2757 cGy to 2,327 cGy (p<0.01). The V50 and V95 in the ipsilateral lung markedly decreased from the averages of 54.5 and 17.4% to 45.3 and 11.0%, respectively. The V50 and V95 in the heart also decreased from the averages of 16.8 and 6.1% to 9.8% and 2.2%, respectively. The NTCP in the contralateral lung and the heart were 0%, even for the cases with no bolus because of the small effective mean radiation volume values of 4.4 and 7.1%, respectively. CONCLUSION: The use of an individualized custom bolus in the radiotherapy of postmastectomy chest wall reduced the NTCP of the ipsilateral lung by about 24.5 to 40.5%, which can improve the complication free cure probability of breast cancer patients.