Victor Hernandez

Acoustic analysis after radiotherapy in T1 vocal cord carcinoma: a new approach to the analysis of voice quality

PURPOSE The study of acoustic voice parameters (fundamental frequency, jitter, shimmer, and harmonics-to-noise ratio) in extended vowel production, oral reading of a standard paragraph, spontaneous speech and a song in irradiated patients for Tis-T1 vocal cord carcinoma. METHODS AND MATERIALS Eighteen male patients irradiated for Tis-T1 vocal cord carcinoma and a control group of 31 nonirradiated subjects of the same age were included in a study of acoustic voice analysis. The control group had been rigorously selected for voice quality and the irradiated group had previous history of smoking in two-thirds of the cases and a vocal cord biopsy. Radiotherapy patients were treated with a 6MV Linac receiving a total dose of 66 Gy, 2 Gy/day, with median treatment areas of 28 cm(2). Acoustic voice analysis was performed 1 year after radiotherapy, the voice of patients in extended vowel production, oral reading of a standard paragraph, spontaneous speech, and in a song was tape registered and analyzed by a Kay Elemetrics Computerized Speech Lab (model CSL# 4300). Fundamental frequency, jitter, shimmer, and harmonics-to-noise ratio were obtained in each case. Mann Whitney analysis was used for statistical tests. RESULTS The irradiated group presented higher values of fundamental frequency, jitter, shimmer, and harmonics-to-noise ratio. Mann-Whitney analysis showed significant differences for fundamental frequency and jitter in vowel production, oral reading, spontaneous speech, and song. Shimmer only showed differences in vowel production and harmonics-to-noise ratio in oral reading and song. CONCLUSIONS In our study only fundamental frequency and jitter showed significant increased values to the control group in all the acoustic situations. Sustained vowel production showed the worst values of the acoustic parameters in comparison with the other acoustic situations. This study seems to suggest that more work should be done in this field.

Prophylaxis with a cream containing urea reduces the incidence and severity of radio-induced dermatitis

IntroductionRadio-induced dermatitis is one of the most frequent side effects of radiotherapy. Among the commercially available products for the care of irradiated skin is a hydrating lotion containing 3% urea, polidocanol and hyaluronic acid. Its effectiveness for preventing the appearance of radiodermatitis or reducing its severity has been studied on a number of occasions.ObjectiveTo evaluate the effectiveness of “intensive use” of the lotion containing 3% urea, polidocanol and hyaluronic acid for preventing the appearance of acute radiodermatitis and controlling its severity.Material and methodsProspective observational study in 98 patients with breast cancer with a 10-week follow-up period. Skin toxicity (RTOG/EORTC scale) was evaluated weekly. To study the effectiveness we compared incidence and grade of toxicity with a sample of 174 breast cancer patients (control sample) treated in our centre during 2006 who used skin-support measures at the start of the radiotherapy or the occurrence of radiodermatitis.ResultsThe proportion of patients who did not develop radiodermatitis was significantly higher in the intensive use group (27.6% vs. 15.5%; p<0.05; OR: 2.07). Compared with the same lotion in standard conditions, the intensive use group showed lower incidence of radiodermatitis (p<0.01), lower grade of toxicity (p<0.001) and lower proportion of radiodermatitis grade 2 or higher (p<0.01). Conclusions Intensive use of the lotion doubles the likelihood that breast cancer patients will not develop radiodermatitis during radiotherapy. Furthermore, compared with standard use, intensive use is more effective in reducing the incidence of skin toxicity and skin toxicity grade 2 or higher.

Multicentre validation of IMRT pre-treatment verification: comparison of in-house and external audit.

BACKGROUND AND PURPOSE We performed a multicentre intercomparison of IMRT optimisation and dose planning and IMRT pre-treatment verification methods and results. The aims were to check consistency between dose plans and to validate whether in-house pre-treatment verification results agreed with those of an external audit. MATERIALS AND METHODS Participating centres used two mock cases (prostate and head and neck) for the intercomparison and audit. Compliance to dosimetric goals and total number of MU per plan were collected. A simple quality index to compare the different plans was proposed. We compared gamma index pass rates using the centres equipment and methodology to those of an external audit. RESULTS While for the prostate case, all centres fulfilled the dosimetric goals and plan quality was homogeneous, that was not the case for the head and neck case. The number of MU did not correlate with the plan quality index. Pre-treatment verifications results of the external audit did not agree with those of the in-house measurements for two centres: being within tolerance for in-house measurements and unacceptable for the audit or the other way round. CONCLUSIONS Although all plans fulfilled dosimetric constraints, plan quality is highly dependent on the planner expertise. External audits are an excellent tool to detect errors in IMRT implementation and cannot be replaced by intercomparison using results obtained by centres.

Clinical applications of geometrical field matching in radiotherapy based on a new analytical solution.

A new analytical formalism has been published recently that provides all the parameters necessary for geometrical field matching in radiotherapy. The present work applies the general expressions for craniospinal irradiation, breast irradiation with a supraclavicular half-field, and breast irradiation with a supraclavicular full-field. We also explore the formalism as a tool to analyze and compare different techniques. Field matching is achieved by imposing both parallelism and coincidence between the side planes of adjacent fields. The rotation angles and either the field aperture for a certain isocenter position or the isocenter coordinates for a given field aperture are supplied. All of the already known exact solutions are reproduced. New expressions for the field aperture and for the isocenter coordinates, which were not previously available, are also computed. If tangential fields at a fixed source-to-skin distance are used together with a supraclavicular full-field, different apertures for each tangential field are required to achieve a correct match. If an isocentric technique for the tangential fields or a supraclavicular half-field is used, this complication is avoided. The breast technique with the supraclavicular half-field is recommended, because it presents several advantages with respect to the supraclavicular full-field. This formalism provides a useful tool in cases where matching of adjacent fields is necessary.

Multi-centre audit of VMAT planning and pre-treatment verification

BACKGROUND AND PURPOSE We performed a multi-centre intercomparison of VMAT dose planning and pre-treatment verification. The aims were to analyse the dose plans in terms of dosimetric quality and deliverability, and to validate whether in-house pre-treatment verification results agreed with those of an external audit. MATERIALS AND METHODS The nine participating centres encompassed different machines, equipment, and methodologies. Two mock cases (prostate and head and neck) were planned using one and two arcs. A plan quality index was defined to compare the plans and different complexity indices were calculated to check their deliverability. We compared gamma index pass rates using the centres equipment and methodology to those of an external audit (global 3D gamma, absolute dose differences, 10% of maximum dose threshold). Log-file analysis was performed to look for delivery errors. RESULTS All centres fulfilled the dosimetric goals but plan quality and delivery complexity were heterogeneous and uncorrelated, depending on the manufacturer and the planners methodology. Pre-treatment verifications results were within tolerance in all cases for gamma 3%-3mm evaluation. Nevertheless, differences between the external audit and in-house measurements arose due to different equipment or methodology, especially for 2%-2mm criteria with differences up to 20%. No correlation was found between complexity indices and verification results amongst centres. CONCLUSIONS All plans fulfilled dosimetric constraints, but plan quality and complexity did not correlate and were strongly dependent on the planner and the vendor. In-house measurements cannot completely replace external audits for credentialing.

Do breast cups improve breast cancer dosimetry? A comparative study for patients with large or pendulous breasts

Abstract Purpose. Treating patients with large or pendulous breasts is challenging. Although brassiere cups are currently in use, no study has yet been carried out to assess their dosimetric impact. The aim of the present study was to evaluate the possible dosimetric advantages of the use of breast cups on patients with large or pendulous breasts. Materials and methods. Two CT studies were carried out on 12 breast cancer patients with large or pendulous breasts, with one study involving the use of breast cups. Radiation plans were developed in accordance with each of the CT studies. The following were compared: planning target volume (PTV), volume irradiated by the 95% isodose, conformity index, homogeneity index, mean lung dose, and mean heart dose was also compared for left breast treatment. The plan involving the use of cups was found to be the best option, leading to all patients being treated with cups. The resulting acute toxicity and cosmesis were also recorded. Both scenarios involved the use of film dosimetry to evaluate the skin doses. Results. The use of breast cups resulted in a significant reduction of the PTV volume (from 1640 cm3 to 1283 cm3), of the irradiated volume (from 2154 cm3 to 1477 cm3) and of the conformity index (from 1383 to 1213). Despite slight improvements in the homogeneity index (from 0.12 to 0.10), statistical significance was not attained. The use of breast cups also led to significant dose reductions in V20 for lung (from 13.7% to 1.7%) and V5 for heart (from 9.8% to 2.7%). No differences in acute toxicity or cosmesis were observed compared to patients treated without cups. Conclusions. Our results show that the use of brassiere cups during breast radiation therapy leads to improvements in the main dosimetric factors analyzed. Furthermore, modifications to standard irradiation protocols are not required. In summary, we consider the technique of using breast cups with radiation therapy highly appropriate when treating breast cancer patients with large or pendulous breasts.

Novel methodologies for dosimetry audits: Adapting to advanced radiotherapy techniques

With new radiotherapy techniques, treatment delivery is becoming more complex and accordingly, these treatment techniques require dosimetry audits to test advanced aspects of the delivery to ensure best practice and safe patient treatment. This review of novel methodologies for dosimetry audits for advanced radiotherapy techniques includes recent developments and future techniques to be applied in dosimetry audits. Phantom-based methods (i.e. phantom-detector combinations) including independent audit equipment and local measurement equipment as well as phantom-less methods (i.e. portal dosimetry, transmission detectors and log files) are presented and discussed. Methodologies for both conventional linear accelerator (linacs) and new types of delivery units, i.e. Tomotherapy, stereotactic devices and MR-linacs, are reviewed. Novel dosimetry audit techniques such as portal dosimetry or log file evaluation have the potential to allow parallel auditing (i.e. performing an audit at multiple institutions at the same time), automation of data analysis and evaluation of multiple steps of the radiotherapy treatment chain. These methods could also significantly reduce the time needed for audit and increase the information gained. However, to maximise the potential, further development and harmonisation of dosimetry audit techniques are required before these novel methodologies can be applied.

Comparison of complexity metrics for multi-institutional evaluations of treatment plans in radiotherapy

Highlights • Several complexity metrics were highly correlated and can be considered equivalent.• Other metrics produced different results, especially for plans from different TPSs.• Different TPSs prioritise modulation of different plan parameters.• The ranking of plan complexity can greatly depend on the metric used.• This must be carefully considered in multi-institutional plan comparisons.

Individualized 3D scanning and printing for non-melanoma skin cancer brachytherapy: a financial study for its integration into clinical workflow

Purpose Skin cancer is the most common tumor in the population. There are different therapeutic modalities. Brachytherapy is one of the techniques used, in which it is necessary to build customized moulds for some patients. Currently, these moulds are made by hand using rudimentary techniques. We present a new procedure based on 3D printing and the analysis of the clinical workflow. Material and methods Moulds can be made either by hand or by automated 3D printing. For making moulds by hand, a patient’s alginate negative is created and, from that, the gypsum cast and customized moulds are made by hand from the patient’s negative template. The new process is based on 3D printing. The first step is to take a 3D scan of the surface of the patient and then, 3D modelling software is used to obtain an accurate anatomical reconstruction of the treatment area. We present the clinical workflow using 3D scanning and printing technology, comparing its costs with the usual custom handmade mould protocol. Results The time spent for the new process is 6.25 hours, in contrast to the time spent for the conventional process, which is 9.5 hours. We found a 34% reduction in time required to create a mould for brachytherapy treatment. The labor cost of the conventional process is 211.5 vs. 152.5 hours, so the reduction is 59 hours. There is also a 49.5% reduction in the financial costs, mostly due to lack of need of a computed tomography (CT) scan of the gypsum and the mould. 3D scanning and printing offers financial benefits and reduces the clinical workload. Conclusions As the present project demonstrates, through the application of 3D printing technologies, the costs and time spent during the process in the clinical workload in brachytherapy treatment are reduced. Overall, 3D printing is a promising technique for brachytherapy that might be well received in the community.

An optimized posterior axillary boost technique in radiation therapy to supraclavicular and axillary lymph nodes: a comparative study.

To assess the advantages of an optimized posterior axillary (AX) boost technique for the irradiation of supraclavicular (SC) and AX lymph nodes. Five techniques for the treatment of SC and levels I, II, and III AX lymph nodes were evaluated for 10 patients selected at random: a direct anterior field (AP); an anterior to posterior parallel pair (AP-PA); an anterior field with a posterior axillary boost (PAB); an anterior field with an anterior axillary boost (AAB); and an optimized PAB technique (OptPAB). The target coverage, hot spots, irradiated volume, and dose to organs at risk were evaluated and a statistical analysis comparison was performed. The AP technique delivered insufficient dose to the deeper AX nodes. The AP-PA technique produced larger irradiated volumes and higher mean lung doses than the other techniques. The PAB and AAB techniques originated excessive hot spots in most of the cases. The OptPAB technique produced moderate hot spots while maintaining a similar planning target volume (PTV) coverage, irradiated volume, and dose to organs at risk. This optimized technique combines the advantages of the PAB and AP-PA techniques, with moderate hot spots, sufficient target coverage, and adequate sparing of normal tissues. The presented technique is simple, fast, and easy to implement in routine clinical practice and is superior to the techniques historically used for the treatment of SC and AX lymph nodes.