BackgroundThis study evaluates the dose distribution of reversed planned tangential beam intensity modulated radiotherapy (IMRT) compared to standard wedged tangential beam three-dimensionally planned conformal radiotherapy (3D-CRT) of the chest wall in unselected postmastectomy breast cancer patientsMethodsFor 20 unselected subsequent postmastectomy breast cancer patients tangential beam IMRT and tangential beam 3D-CRT plans were generated for the radiotherapy of the chest wall. The prescribed dose was 50 Gy in 25 fractions. Dose-volume histograms were evaluated for the PTV and organs at risk. Parameters of the dose distribution were compared using the Wilcoxon matched pairs test.ResultsTangential beam IMRT statistically significantly reduced the ipsilateral mean lung dose by an average of 21% (1129 cGy versus 1437 cGy). In all patients treated on the left side, the heart volume encompassed by the 70% isodose line (V70%; 35 Gy) was reduced by an average of 43% (5.7% versus 10.6%), and the mean heart dose by an average of 20% (704 cGy versus 877 cGy). The PTV showed a significantly better conformity index with IMRT; the homogeneity index was not significantly different.ConclusionsTangential beam IMRT significantly reduced the dose-volume of the ipsilateral lung and heart in unselected postmastectomy breast cancer patients.

PurposeThe purpose of the study was to evaluate the patient set-up error of different anatomical sites, to estimate the effect of different frequencies of online verifications on the patient set-up accuracy, and to calculate margins to accommodate for the patient set-up error (ICRU set-up margin, SM).Methods and materialsAlignment data of 148 patients treated with inversed planned intensity modulated radiotherapy (IMRT) or three-dimensional conformal radiotherapy (3D-CRT) of the head and neck (n = 31), chest (n = 72), abdomen (n = 15), and pelvis (n = 30) were evaluated. The patient set-up accuracy was assessed using orthogonal megavoltage electronic portal images of 2328 fractions of 173 planning target volumes (PTV). In 25 patients, two PTVs were analyzed where the PTVs were located in different anatomical sites and treated in two different radiotherapy courses. The patient set-up error and the corresponding SM were retrospectively determined assuming no online verification, online verification once a week and online verification every other day.ResultsThe SM could be effectively reduced with increasing frequency of online verifications. However, a significant frequency of relevant set-up errors remained even after online verification every other day. For example, residual set-up errors larger than 5 mm were observed on average in 18% to 27% of all fractions of patients treated in the chest, abdomen and pelvis, and in 10% of fractions of patients treated in the head and neck after online verification every other day.ConclusionIn patients where high set-up accuracy is desired, daily online verification is highly recommended.

PurposeThe purpose of this study was to compare the surface dose of 7-field IMRT (7 F-IMRT), tangential beam IMRT (TB-IMRT), and tangential beam 3D-CRT (3D-CRT) of breast cancer patients receiving adjuvant radiotherapy by means of in vivo GafChromic film dosimetry.Material and methodsBreast cancer patients receiving adjuvant radiotherapy of the whole breast or the chest wall were eligible for the study. Study patients were treated with a treatment plan using two different radiotherapy techniques (first patient series, 3D-CRT followed by TB-IMRT; second patient series, TB-IMRT followed by 7 F-IMRT). The surface dose was evaluated on three consecutive treatment fractions per radiotherapy technique using in vivo GafChromic film dosimetry. The paired t-test was used to assess the difference of in vivo GafChromic film readings or calculated plan parameters of the compared pairs of radiation techniques for statistical significance.ResultsForty-five unselected breast cancer patients were analysed in this study. 7 F-IMRT significantly reduced the surface dose compared to TB-IMRT. Differences were greatest in the central and lateral breast or chest wall region and amounted to a dose reduction of -11.8% to -18.8%. No significant difference of the surface dose was observed between TB-IMRT and 3D-CRT. A corresponding observation was obtained for the calculated skin dose derived from dose-volume histograms.ConclusionsIn adjuvant breast cancer radiotherapy, 7 F-IMRT offers a significantly reduced surface dose compared to TB-IMRT or 3D-CRT.

BackgroundThe goal of this study was to assess a possible dosimetric advantage of intensity modulated radiotherapy (IMRT) of upper abdominal malignancies compared to three-dimensional conformal radiotherapy (3DCRT), and to assess the impact of IMRT on acute toxicity.MethodsThirty-one unselected consecutive patients with upper abdominal malignancies were treated with definitive (n =16) or postoperative (n =15) IMRT. Twenty-one patients (67.7%) received concomitant chemotherapy. 3DCRT plans were generated for comparison, and analysis of variance (ANOVA) for repeated measurements was used to test for significant difference of dosimetric parameters. Acute toxicity was assessed weekly using the Common Terminology Criteria for Adverse Events (CTCAE) grading scale.ResultsIMRT plans showed a small but statistically significant improvement of the conformity index compared to 3DCRT plans (difference (95% confidence interval), -0.06 (−0.109 to-0.005); p = 0.03). The homogeneity index was not significantly improved (p = 0.10). A significantly reduced high dose volume on cost of a significantly increased low dose volume was observed for the kidneys. The acute toxicity appeared to be less than commonly reported for corresponding patients treated with 3DCRT. No patient developed grade 3 or 4 non-hematological acute toxicity, and the most common grade 2 toxicity was vomiting (9.7%).ConclusionsIMRT offers the potential of a clinically relevant dosimetric advantage compared to 3DCRT in terms of a reduced acute toxicity. Further optimization of the radiotherapy technique and more clinical trials are required before IMRT is routinely used for upper abdominal malignancies.

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