Irradiation of pacemakers and cardio-defibrillators in patients submitted to radiotherapy: a clinical experience.

AIMS AND BACKGROUND: A prospective analysis was carried out on a group of irradiated patients with pacemakers or implantable cardioverter-defibrillators to identify any relationship between the various types of devices and physical and dosimetric parameters. Cardiac toxicity of the treatment was also investigated. METHODS AND STUDY DESIGN: Forty-five irradiated patients, implanted with pacemakers or implantable cardioverter-defibrillators, were prospectively investigated from 1999 to 2007. An analysis of radiation damage to pacemakers, depending on the geometric and dosimetric characteristics of the radiation beams, was carried out. The electric and magnetic fields of linear accelerators (LINACs) were measured to evaluate any interference. The calculation of dose received by pacemakers was evaluated by dose-volume histograms. RESULTS: No dysfunction was observed in any pacemaker, nor were the substitution times negatively affected. We did not find problems with the devices due to the interaction with the electromagnetic fields. Dose-volume histograms calculated for patients treated in regions close to devices (head & neck, thorax) showed an average maximum dose equal to 2.5 Gy for the head & neck area and equal to 1.8 Gy for the thoracic area. Acute (3 cases) and late (2 cases) cardiac events were observed only in 5 patients who underwent chemoradiation treatment, but no dysfunction was observed in any pacemaker. CONCLUSIONS: Our study confirms the safety of radiotherapy for patients implanted with pacemakers or implantable cardioverter-defibrillators but suggests that chemoradiation represents a probable risk factor for cardiac toxicity. Furthermore, all cardiac events were observed in patients treated in the head and'neck or left thoracic areas. A standardized protocol is advisable in order to improve patient control during the radiotherapy treatment. It is mandatory to calculate the dose received at the pacemaker/heart, even in the case of palliative treatment.

Quality assurance of a record-and-verify system.

AIMS AND BACKGROUND: With the introduction of more complex three-dimensional conformal radiotherapy and intensity-modulated radiotherapy techniques in clinical practice, the use of record-and-verify systems is recommended to improve the accuracy of radiotherapy treatments. The aim of the present study was to evaluate, for a commercial record-and-verify system, the efficiency, integration with the treatment planning system, and impact of manual checking of data. The most frequent errors or misses were also evaluated. MATERIALS AND METHODS: The development of internal protocols to systematically implement new technologies has been identified as a priority in the departmental quality assurance process. Data electronically fed into the record-and-verify system were compared with those manually recorded in the clinical paper chart over a period of almost 6 years (October 2000 to December 2006). A total of 7768 treated patients was reviewed. The check was performed by using a homemade data base in which the errors are stratified as follows: 1) general section, 2) geometric and dosimetric section, and 3) delivered dose section. RESULTS: On a total of 7768 checked patients, one or more mismatches between treatment planning system data and record-and-verify system data or paper chart data were observed for 452 patients (5.8% of total number of inspected patients). The percentage of discrepancies out of the total was: 2.2% in the general section, 3.3% in the dosimetric and geometric section, and 4.2% in the delivered-dose section. CONCLUSIONS: Although record-and-verify systems assume a crucial role in the accuracy and reproducibility of radiation treatment, their inability to eradicate all the errors requires vigilance on the part of the radiation therapy and physics team.

Radiotherapy after partial laryngectomy: an analysis of 36 cases and a proposal to optimize radiotherapy.

AIMS AND BACKGROUND: Laryngeal cancer treatment options include radical surgery, "organ preservation surgery", radiotherapy and chemotherapy. There is no proven evidence of a significant increase in late toxicity with adjuvant radiotherapy after conservative surgery. The aim of this retrospective study was to evaluate the toxicity, local-regional control and overall survival of adjuvant radiotherapy after conservative surgery. METHODS: A total of 36 patients was treated with radiotherapy after partial laryngectomy at the Radiotherapy Department of the Institute for Cancer Treatment and Research (IRCC) of Candiolo and of the Mauriziano Hospital in Turin, between 1994 and 2007. The postoperative treatment doses ranged from 45 to 70.2 Gy with conventional fractionation. The Kaplan-Meier method was applied for statistical analysis. The RTOG-EORTC scale was used to evaluate late and acute toxicity. RESULTS: Overall 5- and 10-year survival was 93% and 47%, respectively. Local control was 93.5% at 5 and was unchanged at 10 years. Grade 2 acute cutaneous and mucous toxicity was 41% and 62%, and grade 3, 6.9% and 3.5%, respectively. Only one patient required percutaneous endoscopic gastrostomy due to severe dysphagia and one patient required temporary tracheostomy for severe acute laryngeal edema (grade 3). Two patients experienced late toxicity greater than grade 3. The median dose to the residual larynx was 59.5 Gy (range, 45-70.2), and the median dose to the neck was 50.4 Gy (range, 39.6 -55.8). CONCLUSIONS: The results of our study showed a dose-dependent increase in the late toxicity trend at doses over and above 60 Gy, which is higher than the cutoff dose reported in the literature. There was no indication from our data that adjuvant postoperative radiotherapy means additional toxicity. The use of highly conformal techniques can further reduce toxicity of the radiotherapy.

Emptying the rectum before treatment delivery limits the variations of rectal dose - volume parameters during 3DCRT of prostate cancer.

PURPOSE: To investigate the impact of rectum motion on dose - volume histograms of the rectum including filling and of the wall (DVH and DWH, respectively), during 3D-conformal radiotherapy (3DCRT) for localized prostate cancer. MATERIALS AND METHODS: Ten patients received a planning CT scan (CT(0)) and 11-14 CT during 3DCRT for prostate cancer (total CT scans=126). CT images were 3D matched using bony anatomy. A single observer drew the external contours of rectum and rectum wall and the CTV (prostate + seminal vesicles) on CT(0). Patients were asked to empty their rectum before every CT, as generally performed at the Institute for Cancer Research and Treatment (IRCC) before treatment delivery. Bladder was kept full by drinking 500 cm(3) of water 60 min before the scan, according to our protocol. A 4-field box 3DCRT technique was planned and dose statistics/dose - volume histograms of the rectum were calculated for each contour referred to CT(0),CT(1),...,CT(n) for each patient. Average DVHs during treatment were calculated along with their standard deviation (SD(rand)) and compared to the planned DVH. The analyses on the patient population included the assessment of systematic deviation (average difference and SD, named SD(sys)) as well as the average SD(rand) value expressing the random component of organ motion. Rectum shifts were also assessed by anterior and lateral BEV projections. RESULTS: As to the rectum, 8/10 patients showed a "better" average DVH than DVH on CT(0). Wilcoxon test showed a statistically significant reduction when correlating the difference Delta between the average DVH during therapy and planning DVH at CT(0): for instance V(70)Delta = -3.6% and p = 0.022, V(50)Delta = -5.5% and p = 0.022, D(med)Delta = -3.2 Gy and p = 0.007. Average values of DVH systematic difference (average difference between planning scan and treatment), standard deviations (SD(sys)) and average standard deviations of the random fluctuation (SD(random)) were -4.0%, 4.7% and 6.6%, respectively. Whilst the fluctuation results were slightly smaller for DWH. Volume analysis showed a slight systematic variation of the rectal volume between planning and treatment BEV. The average rectal volume during therapy was larger than at the planning CT in 8/10 patients. The systematic shifts of the rectal wall between the planning phase and the treatment were rather small, both below and above the flexure. The larger random fluctuation of the rectum shape was found to be in the cranial half (1 SD=4.4 mm). CONCLUSIONS: The practice of carefully emptying the rectum during simulation and therapy for prostate cancer, which is a safe and simple procedure, reduces the impact of organ motion on dose - volume parameters of the rectum.

Are quality indicators for radiotherapy useful in the evaluation of service efficacy in a new based radiotherapy institution?

AIMS AND BACKGROUND: A number of documents assess the need for quality assurance in radiotherapy, which must be constantly monitored and possibly improved. In this regard, a system that confirms the quality of a department has been suggested and quality indicators have been used to improve the quality of the service. The National Health Service (Istituto Superiore di Sanità) approved a National Research Project to increase the quality of radiotherapy. The aim of the present study was to analyze the practical feasibility and efficacy of the quality indicators elaborated by the National Health Service study group in a radiotherapy unit. PATIENTS AND METHODS: The voluntary accredited program was carried out by the Radiotherapy Department of IRCC in Candiolo from June to August 2002. We analyzed 8 of the 13 indicators according to the National Health Service Project. For this purpose, 133 consecutive patients treated in our Unit were analyzed, and the results are reported according to the appropriate indicator (number of staff related to patients treated, waiting list, case history accuracy, multidisciplinary approach, number of treatment plans performed by CT, number of fields per fraction, number of portal imaging performed per overall treatment, and patient satisfaction). RESULTS: The number of professional staff related to the number of patients treated was easy to calculate and it could be the basis for further evaluation. The overall waiting time was 55.4 days, and it changed for different radiotherapy goals. We obtained 80% conformity in case-history accuracy. The number of multidisciplinary consultations performed ranged between 50% and 100%. The number of CT plans was about 1.6 +/- 0.9 plans per patient. The mean number of fields performed per day and per patient is 3.5 +/- 1.7 and was in agreement with the fact that more than 50% of treatments in our Center were performed with conformal radiotherapy. An average of 16.7 +/- 10.0 portal imaging per case was performed. The percentage of patient satisfaction with the staff obtained a very high compliance. CONCLUSIONS: The self evaluation promoted by the National Health Service Project allows the monitoring of the activities of the service in order to asses critical factors and it can be the starting point to improve the quality of the service and to compare national and international quality assurance results.

Is one Gy always one Gy? The integration between conventional radiotherapy and special techniques.

The new radiotherapy techniques as HDR and LDR brachytherapy, stereotactic radiotherapy, 3D-CRT, and IMRT require an accurate knowledge of the biological characteristics of the tumor with correct definition of target volumes. As demonstrated by the two reported cases, the formulae equivalent to 2 Gy in the special techniques are useful for the increase in the total dose to GTV while sparing the organs at risk.

Laparotomy wound recurrence of endometrial carcinoma.

OBJECTIVES: Most endometrial cancer relapses are either pelvic or distant metastases. Recurrences in the laparotomy scar are extremely rare, as to our knowledge this is only the sixth reported case and the first treated with brachytherapy. We also present a review of the literature with an emphasis on radiation therapy treatment. CASE: A 64-year-old woman underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy for IIIA endometrial adenocarcinoma, followed by systemic chemotherapy and pelvic external-beam radiotherapy. Three years later, a recurrence in the laparotomy scar was resected and additional chemotherapy was administered. A solitary mass in the abdominal wound was then found 4 years after that and was reirradiated by combining external-beam radiation therapy and interstitial brachytherapy after complete resection. Histology of the abdominal wall implants was very similar to that of the primary tumour. CONCLUSIONS: Laparotomy wound recurrence (LWR) for endometrial cancer usually appears as a solitary mass that grows slowly without concomitant failure sites a few years after hysterectomy. In these six patients there is no common histology pattern that could suggest predictive factors for LWR. Common postoperative irradiation does not deliver sufficient a dose to the anterior abdominal wall to prevent this kind of failure.

Clinical application and dosimetric calibration procedure of the superficial and orthovoltage therapy unit Therapax DXT300.

AIMS AND BACKGROUND: The aim of this study was to configure a new superficial and orthovoltage therapy unit for clinical use and discuss the clinical indications for this kind of energy. There is renewed interest in radiotherapy using photon beams in the range from 40 to 300 kVp, in particular for the treatment of non-neoplastic diseases and superficial lesions. This is due to the fact that the latest units are of good quality, relatively cheap and reliable in comparison with alternative equipment. It is therefore necessary to document the steps involved in the clinical application of this therapeutic equipment. METHODS: The calibration procedure for a new superficial/orthovoltage therapy unit, Therapax DXT300 (Pantak, USA), installed at the Radiotherapy Department of the Mauriziano Hospital in Turin, was carried out by measurement of beam quality (half-value layer, HVL), percentage depth dose (PDD), profiles, internal dosimetry system, dose rate calibration and output factors. The Therapax DXT300 can be programmed to stop treatment either by time or dose, like a linear accelerator. It is equipped with one adjustable collimator (2 x 2 divided by 20 x 20 cm2) for orthovoltage therapy (focus skin distance, FSD = 50 cm) and six fixed applicators for superficial and orthovoltage therapy (FSD = 30 and 50 cm, respectively). Up to eight combinations of generating potential, tube current and added beam filter can be set. RESULTS: In the range of accelerating potentials from 40 to 300 kVp the Therapax provides beams with HVL ranging from 1.48 mm Al to 3.68 mm Cu. As regards the PDD curves, a slight difference between PDD values has been observed with potentials ranging from 200 to 300 kVp. The beam symmetry and flatness are almost the same in Y and X plane directions for accelerating potentials of less than 200 kVp. At higher kVp values these parameters are significantly worse in the anode-cathode axis direction, because the useful X-ray beam is extracted perpendicular to the anode-cathode axis direction: as the energy increases, the bremsstrahlung becomes more forward directed, resulting in a higher dose rate on the anode side. CONCLUSION: The present paper suggests a methodological approach for the clinical application of an orthovoltage/superficial therapy unit and discusses its current indications. It is necessary to maintain the performance of the equipment within predefined limits in order to meet the requirements of an efficient quality assurance program. This unit is particularly useful in the treatment of superficial lesions and non-neoplastic diseases and in palliative care (eg for bone metastases).