Development and clinical implementation of a new template for MRI-based intracavitary/interstitial gynecologic brachytherapy for locally advanced cervical cancer: from CT-based MUPIT to the MRI compatible Template Benidorm. Ten years of experience.

PURPOSE: To study outcome and toxicity in 59 patients with locally advanced cervix carcinoma treated with computed tomography (CT)-based Martinez universal perineal interstitial template (MUPIT) and the new magnetic resonance imaging (MRI)-compatible template Benidorm (TB). MATERIAL AND METHODS: From December 2005 to October 2015, we retrospectively analyzed 34 patients treated with MUPIT and 25 treated with the TB. Six 4 Gy fractions were prescribed to the clinical target volume (CTV) combined with external beam radiotherapy (EBRT). The organs at risk (OARs) and the CTV were delineated by CT scan in the MUPIT implants and by MRI in the TB implants. Dosimetry was CT-based for MUPIT and exclusively MRI-based for TB. Dose values were biologically normalized to equivalent doses in 2 Gy fractions (EQD2). RESULTS: Median CTV volumes were 163.5 cm3 for CT-based MUPIT (range 81.8-329.4 cm3) and 91.9 cm3 for MRI-based TB (range 26.2-161 cm3). Median D90 CTV (EBRT + BT) was 75.8 Gy for CT-based MUPIT (range 69-82 Gy) and 78.6 Gy for MRI-based TB (range 62.5-84.2 Gy). Median D2cm3 for the rectum was 75.3 Gy for CT-based MUPIT (range 69.8-132.1 Gy) and 69.9 Gy for MRI-based TB (range 58.3-83.7 Gy). Median D2cm3 for the bladder was 79.8 Gy for CT-based MUPIT (range 71.2-121.1 Gy) and 77.1 Gy for MRI-based TB (range 60.5-90.8 Gy). Local control (LC) was 88%. Overall survival (OS), disease free survival (DFS), and LC were not statistically significant in either group. Patients treated with CT-based MUPIT had a significantly higher percentage of rectal bleeding G3 (p = 0.040) than those treated with MRI-based TB, 13% vs. 2%. CONCLUSIONS: Template Benidorm treatment using MRI-based dosimetry provides advantages of MRI volume definition, and allows definition of smaller volumes that result in statistically significant decreased rectal toxicity compared to that seen with CT-based MUPIT treatment.

A new template for MRI-based intracavitary/interstitial gynecologic brachytherapy: design and clinical implementation.

PURPOSE: To describe the potential clinical use of a new brachytherapy applicator for gynecological tumors, with special attention to locally advanced cervical carcinoma. This device allows the combination of intracavitary radiotherapy and MRI-compatible transperineal interstitial needles. The design of this template addresses the disadvantages of currently commercially available templates: the inability of the intracavitary component to reach deep into the cervix (MUPIT), and the MRI-incompatibility of these templates (MUPIT and Syed), which necessitates use of CT imaging for the dosimetry. MATERIAL AND METHODS: The newly developed Benidorm Template applicator allows titanium needles in a template with straight and angled holes to provide different angles of divergence to be used with currently existing MRI-compatible intrauterine tubes. It can provide total coverage of the craniocaudal and lateral extension of the tumor (intrautherus, parametrial, and paravaginal). This method is mainly indicated in advanced cervical carcinoma with bulky parametrial invasion (medial or distal), with bulky primary disease that responds poorly to external beam radiotherapy extensive paravaginal involvement (tumor thickness greater than 0.5 cm) extending to the middle or lower third of the vagina, or for disease that has invaded the bladder or rectum (stage IVA). RESULTS: Between April 2013 until December 2014, we treated 15 patients with locally advanced cervical carcinoma employing the Benidorm Template. The median dose at D90 for the CTV was 79.8 Gy (71.5-89.9 Gy), at D2cc for the bladder it was 77.6 Gy (69.8-90.8 Gy), and at D2cc for the rectum it was 71.9 Gy (58.3-83.7 Gy). Values expressed in EQD2, assuming α/ß of 10 for CTV and 3 for OAR. CONCLUSIONS: This new applicator allows the use of MRI-based dosimetry, thus providing the advantages of MRI volume definition. As such, it facilitates determination of complete intracavitary and interstitial CTV coverage and the sparing of normal tissues.

Depth determination of skin cancers treated with superficial brachytherapy: ultrasound vs. histopathology.

PURPOSE: The purpose of this study is to compare high frequency ultrasonography (HFUS) and histpathologic assessment done by punch biopsy in order to determine depth of basal cell carcinoma (BCC), in both superficial and nodular BCCs prior to brachytherapy treatment. MATERIAL AND METHODS: This study includes 20 patients with 10 superficial and 10 nodular BCCs. First, punch biopsy was done to confirm the diagnosis and to measure tumour depth (Breslow rate). Subsequently, HFUS was done to measure tumour depth to search for correlation of these two techniques. RESULTS: Neither clear tendency nor significance of the punch biopsy vs. HFUS depth determination is observed. Depth value differences with both modalities resulted patient dependent and then consequence of its uncertainty. Conceptually, HFUS should determine the macroscopic lesion (gross tumour volume - GTV), while punch biopsy is able to detect the microscopic extension (clinical target volume - CTV). Uncertainties of HFUS are difficult to address, while punch biopsy is done just on a small lesion section, not necessarily the deepest one. CONCLUSIONS: According to the results, HFUS is less accurate at very shallow depths. Nodular cases present higher depth determination differences than superficial ones. In our clinical practice, we decided to prescribe at 3 mm depth when HFUS measurements give depth lesion values smaller than this value.