Biomedical subjects

J V Lebesque

Publications and source records attributed to J V Lebesque.

At least 55 records · Page 3Linked to original sources

PubMed1996

Radiation pneumonitis imaged with indium-111-pentetreotide.

UNLABELLED: Early recognition of radiation pneumonitis enables adequate treatment with a reasonable chance to prevent late sequelae. The feasibility of 111In-pentetreotide in detecting this condition was explored in this study. METHODS: The degree of lung uptake of 111In-pentetreotide, evaluated both visually and quantitatively by irradiated-to-nonirradiated area ratios (INIA ratio) from planar images after 24 hr, was analyzed in relation to the radiation field and compared with ventilation/perfusion (V/Q) images and chest radiographs or CT in 11 patients who had received radiotherapy to the mediastinum or to the internal mammary nodes, 10 of whom were suspected of having clinical radiation pneumonitis. Additional SPECT studies were used to map lung uptake distribution. RESULTS: Indium-111-pentetreotide scans were positive in nine symptomatic patients examined 2-5 mo after radiotherapy; strongly or moderately positive in eight patients, one of whom was receiving steroid therapy without clinical response; and weakly positive in one patient with good steroid response. Indium-111-pentetreotide studies were negative in one asymptomatic patient examined 1 mo after radiotherapy and in one symptomatic patient, with subsequent diagnosis of aspecific viral pneumonitis, examined 4 mo after irradiation. Positive 111In-pentetreotide scans delineated areas of radiation pneumonitis that adequately correlated with areas of decreased ventilation/perfusion and x-ray abnormalities. INIA ratios varied from 1.01 to 2.16 and, in irradiated areas with visible uptake, the lowest value was 1.29. SPECT showed lung uptake in both superficial and deep lying areas in patients with mantle irradiation fields whereas distribution was limited to anterior areas in internal mammary lymph node chain irradiation. CONCLUSION: Indium-111-pentetreotide can detect radiation pneumonitis and may have a role in both the differential diagnosis of patients who have complaints after radiotherapy, and when supported by quantification in the monitoring of response to steroid therapy.

Feasibility Studies↗

PubMed1995

Quantification of organ motion during conformal radiotherapy of the prostate by three dimensional image registration.

PURPOSE: Knowledge about the mobility of organs relative to the bony anatomy is of great importance when preparing and verifying conformal radiotherapy. The conventional technique for measuring the motion of an organ is to locate landmarks on the organ and the bony anatomy and to compare the distance between these landmarks on subsequent computerized tomography (CT) scans. The first purpose of this study is to investigate the use of a three dimensional (3D) image registration method based on chamfer matching for measurement of the location and orientation of the whole organ relative to the bony anatomy. The second purpose is to quantify organ motion during conformal therapy of the prostate. METHODS AND MATERIALS: Four CT scans were made during the course of conformal treatment of 11 patients with prostate cancer. With the use of a 3D treatment planning system, the prostate and seminal vesicles were contoured interactively. In addition, bladder and rectum were contoured and the volume computed. Next, the bony anatomy of subsequent scans was segmented and matched automatically on the first scan. The femora and the pelvic bone were matched separately to quantify motion of the legs. Prostate (and seminal vesicle) contours from the subsequent scans were matched on the corresponding contours of the first scan, resulting in the 3D rotations and translations that describe the motion of the prostate and seminal vesicles relative to the pelvic bone. RESULTS: Bone matching of two scans with about 50 slices of 256 x 256 pixels takes about 2 min on a workstation and achieves subpixel registration accuracy. Matching of the organ contours takes about 30 s. The accuracy in determining the relative movement of the prostate is 0.5 to 0.9 mm for translations (depending on the axis) and 1 degree for rotations (standard deviations). Because all organ contours are used for matching, small differences in delineation of the prostate, missing slices, or differences in slice distance have only a limited influence on the accuracy. Rotations of the femora and the pelvic bone are quantified with about 0.4 degree accuracy. A strong correlation was found between rectal volume and anterior-posterior translation and rotation around the left-right axis of the prostate. Consequently, these parameters had the largest standard deviations of 2.7 mm and 4.0 degrees. Bladder filling had much less influence. Less significant correlations were found between various leg rotations and pelvic and prostate motion. Standard deviations of the rotation angles of the pelvic bone were less than 1 degree in all directions. CONCLUSIONS: Using 3D image registration, the motion of organs relative to bony anatomy has been quantified accurately. Uncertainties in contouring and visual interpretation of the scans have a much smaller influence on the measurement of organ displacement with our new method than with conventional methods. We have quantified correlations between rectal filling, leg motions, and prostate motion.

Femur↗

PubMed1995

Variation in volumes, dose-volume histograms, and estimated normal tissue complication probabilities of rectum and bladder during conformal radiotherapy of T3 prostate cancer.

PURPOSE: To determine the pattern of changes of rectum and bladder structures during conformal therapy of T3 prostate cancer and the impact of these changes on the accuracy of the dose-volume histograms (DVHs) and normal tissue complication probabilities (NTCPs) of these organs, based on the planning computed tomography (CT) scan only. METHODS AND MATERIALS: For 11 T3 prostate cancer patients treated with conformal therapy, three repeat CT scans were made in Weeks 2, 4, and 6 of the treatment. The bony anatomy was aligned with the planning CT scan, using three dimensional (3D) chamfer matching. The internal and external surfaces of rectum and bladder were contoured in each scan. Three volumes were calculated for each organ: solid organ (including filling), filling, and wall volume. DVHs and NTCPs were calculated for all structures. RESULTS: The solid organ and filling volumes varied considerably between patients and within a patient and they decreased with increasing treatment time. The largest patient variation was seen for patients with large initial filling volumes. The variations of rectum and bladder wall volumes during treatment were 9 and 17% (1 standard deviation (SD)), respectively, with no time trend. The changes of the high dose (> 80 and 90% of the prescribed dose) volumes of the rectum in response to rectum filling differences were proportional to the whole rectum volume changes. The variation of the high-dose rectum wall volume was relatively small (14%, 1 SD). As a result, the NTCPs of rectum and rectum wall were the same overall and the variation of the NTCPs during treatment was about 14% (1 SD) and not correlated with rectum filling. The variation of the high-dose bladder volumes (about 14%, 1 SD) was smaller than the variation of the whole bladder volumes (30%, 1 SD). The high-dose bladder wall volume decreased significantly due to wall distention as the bladder filling increased. As a result of this complex pattern, the variation of NTCPs of bladder (85%, 1 SD) and bladder wall (88%, 1 SD) during treatment was large and significantly correlated with bladder filling. CONCLUSIONS: The planning CT scan overestimates rectum and bladder filling during treatment. Furthermore, the variation of filling is so large that only the wall structures have relatively constant volumes during treatment. For the rectum wall, the DVHs and NTCPs, as estimated from the initial scan, are representative for the whole treatment, because no correlation was seen between these parameters and organ filling. For the bladder wall, however, such a correlation was present and consequently, the initial bladder wall DVHs and NTCPs can only be representative for the whole treatment, if the bladder filling can be kept reasonably constant during treatment.

Anthropometry↗

PubMed1995

Estimation of overall pulmonary function after irradiation using dose-effect relations for local functional injury.

PURPOSE: To predict the pulmonary function 3-4 months after irradiation for malignant lymphoma from the three-dimensional (3-D) dose distribution. METHODS: Dose-effect relations for the relative reduction of local perfusion (Q) and local ventilation (V), were calculated in 25 patients, using correlated SPECT (Single Photon Emission Computed Tomography) and CT data. By combining the 3-D dose distribution of an individual patient with the dose-effect relations averaged over all patients, the average reduction of local Q and V (i.e., the overall response parameters) in the whole lung was estimated for each patient. Correlation coefficients were calculated between these overall response parameters and the change in standard lung function tests. In addition, the relation between the overall response parameters and the incidence of radiation pneumonitis was determined. RESULTS: The overall response parameter for perfusion was correlated with the change in standard lung function tests, with correlation coefficients varying between 0.53 (p = 0.007) and 0.71 (p < 0.001) for the change of Vital Capacity and Forced Expiratory Volume at 1 s, respectively. For the overall response parameter for ventilation similar correlations were observed. Four out of the 25 patients developed radiation pneumonitis; in these four patients the overall response parameter for perfusion was on average somewhat higher (13.2 +/- 1.4% (1 standard error of the mean)) than in patients without radiation pneumonitis (10.5 +/- 1.0%), but this difference was not significant. A higher incidence of radiation pneumonitis was observed for larger values of the overall response parameter for perfusion; in patient groups with an overall response parameter for perfusion of 0-5%, 5-10%, 10-15%, and 15-20%, the incidence of radiation pneumonitis was 0 (0/1), 10 (1/10), 13 (1/8) and 33% (2/6), respectively. CONCLUSION: By combining the 3-D dose distribution with the average dose-effect relations for local perfusion or ventilation, an overall response parameter can be calculated prior to irradiation, which is predictive for the radiation-induced change in the overall pulmonary function, and possibly for the incidence of radiation pneumonitis, in this group of patients.

Adolescent↗

PubMed1995

Setup deviations in wedged pair irradiation of parotid gland and tonsillar tumors, measured with an electronic portal imaging device.

The first aim of this study was to quantify estimated translational setup deviations of patients treated with a wedged pair of oblique beams for parotid gland and tonsillar tumors, using portal imaging. The second aim was to design an off-line setup verification procedure, to improve the setup accuracy, if necessary. Thirty-one patients were treated with two conformal fields (anterior-oblique and posterior-oblique). The patients were immobilized with a head cast. For the last 10 patients, the rigidity of the cast was improved while, in addition, wax molds with metal markers were placed into the outer ear for image correlation. Portal images were acquired about weekly. Setup deviations were analyzed, using anatomical structures and, when available, metal markers for image matching. The consistency of the deviations was determined by the correlation between deviations in the cranio-caudal direction, as measured from both beams. When the deviations were consistent, the translational setup deviation during a treatment session could be described by a three-dimensional (3D) vector. A setup verification procedure was designed using a computer simulation. The statistics of the 3D setup deviations were used as input. The output consisted of the resulting setup accuracy and workload (i.e., the number of setup corrections and portal images). Using the anatomical structures for image correlation, the deviations in the cranio-caudal direction were not correlated, either for the old or the improved cast. However, by using the metal markers, the deviations were correlated and a 3D analysis could be performed. The standard deviations, averaged over the three directions, were equal to 1.8 and 1.4 mm for the distribution of systematic and random deviations, respectively. Application of a setup verification procedure, with 0.7 corrections on the average per patient, could potentially reduce the percentage of 3D systematic deviations larger than 4 mm from 30 to 2%. It can be concluded that it was not possible to obtain consistent translational setup deviations, due to rotations. To quantify 3D translational setup deviations, it was necessary to use additional metal markers, which were visible in the portal images of both beams. A further improvement of the setup accuracy is possible by using an off-line setup verification procedure.

Female↗

PubMed1995

Electronic portal imaging.

In our institute, we have developed an electronic portal imaging system based on a matrix of 256 x 256 ionisation chambers. By improvements to the electronics, the system produces images with the same quality as the original system but 3-10 times faster. Software for automatic image analysis has been applied to more than 10,000 images over the last two years. Using an off-line correction strategy, the systematic patient set-up error has been limited to 5 mm or less for 98% of the patients treated for prostate cancer.

Equipment Design↗

PubMed1994

Dose-effect relations for local functional and structural changes of the lung after irradiation for malignant lymphoma.

PURPOSE: To estimate the dose-effect relations for local functional (ventilation and perfusion) and structural (density) changes of the lung, 3-4 months after irradiation. METHODS: Twenty-five patients with malignant lymphoma were irradiated with a (modified) mantle field to an average dose of 38 Gy, given in 21 fractions. Single photon emission computed tomography (SPECT) ventilation (V) and perfusion (Q) scans, and CT scans were performed before and 3-4 months after radiation treatment. The three-dimensional dose distribution was calculated using the CT data. After correlation of SPECT and CT data sets, the average post-treatment value of V, Q and lung density per voxel was calculated relative to the pre-treatment value, per dose interval of 4 Gy. Subsequently, the dose-effect relations in each patient were normalized to the average value per voxel in the dose interval of 0-12 Gy. In addition, in each dose interval of 4 Gy the fraction of patients with changes larger than 20% was calculated for all three parameters. The dose-effect relations for perfusion and ventilation normalized to the low-dose regions, and the dose-incidence curves for the fraction of patients with changes larger than 20% were fitted for all three parameters, using a logistic model. RESULTS: Marked changes in the distribution of V and Q were found after irradiation. Prior to normalization to the low-dose regions, a change in V and Q was found in most patients in the dose interval of 0-12 Gy, varying from an increase of 37% to a decrease of 10%, which was followed by a decreasing trend at higher doses. The increase in the low-dose regions indicated a redistribution phenomenon, the magnitude of which was dependent of the irradiated volume. The logistic fit of the dose-effect relations for Q and V, normalized to the low-dose regions, resulted in values for D50 of 51 Gy and 54 Gy (given in 21 fractions on average), respectively, and for the steepness parameter k of 4.2 and 4.0, respectively. The logistic fit for the dose-incidence curves for Q, V and lung density resulted in values for D50 and k of 38 Gy, 37 Gy, 44 Gy and 10.3, 7.8 and 9.4, respectively. CONCLUSIONS: With the combined use of SPECT and CT scans, we have obtained dose-effect relations for local functional and structural damage in the lung, 3-4 months after irradiation.

Adolescent↗

PubMed1994

In vivo determination of the accuracy of field matching in breast cancer irradiation using an electronic portal imaging device.

The purpose of this study was to investigate the accuracy of field matching in patients treated by irradiation of the breast and adjacent lymph nodes. Field matching is performed by the radiographers during each session on a match line drawn on the patient's skin. Field edge positions were assessed in the cranial match plane of tangential breast fields and supraclavicular-axillary fields using an electronic portal imaging device and match line markers placed on the skin of the patients. The mean gap/overlap of the four fields for individual patients during each treatment session, derived from 374 marker projections, was +0.5 mm indicating that no systematic gap or overlap was observed. The uncertainty in the position of the four fields with respect to the match plane ranges from 3.1 to 5.1 mm (1 SD) for the individual patients. Gaps and overlaps between fields were also related to an absolute match line position, found by comparison of simulator and portal images, showing a small systematic uncertainty of 2.4 mm and a standard deviation of 3.3 mm. It can be concluded that the use of an electronic portal imaging device in combination with match line markers is a good method to quantify the accuracy of field matching in vivo. The results showed good stability and reproducibility in the field matching region for this treatment technique of breast cancer irradiation.

Breast Neoplasms↗

PubMed1994

The volume effect in radiation-related late small bowel complications: results of a clinical study of the EORTC Radiotherapy Cooperative Group in patients treated for rectal carcinoma.

PURPOSE: The purpose of this study was to quantify the correlation between irradiated small bowel volume and late occurring small bowel complications. METHODS: Small bowel volumes in the high-dose region were measured using orthogonal barium films for 203 patients treated for rectal carcinoma with pelvic postoperative radiotherapy to 50 Gy in an EORTC multicentric study. RESULTS: The 5-year estimate of late pelvic small bowel obstruction requiring surgery was 11%. No correlation between the irradiated small bowel volume and obstruction was detected. The actuarial 5-year estimate of chronic diarrhea varied from 31% in patients with irradiated small bowel volumes below 77 cm3 to 42% in patients with volumes over 328 cm3. This correlation was significant in the univariate and multivariate analysis (p = 0.025). The type of rectal surgery significantly influenced the incidence of chronic diarrhea and malabsorption, the actuarial 5-year estimate being 49% and 26% after low anterior resection and abdominoperineal resection, respectively (p = 0.04). CONCLUSIONS: This study demonstrated that there is a volume-effect in radiation-induced diarrhea at a dose of 50 Gy in 25 fractions. No volume-effect for small bowel obstruction was detected at this dose-level in pelvic postoperative radiotherapy. A review of the literature data on small bowel obstruction indicates that the volume effect at this dose level can only be demonstrated in patients who were treated with extended field radiotherapy (estimated small bowel volume 800 cm3) after intra-abdominal surgery.

Actuarial Analysis↗

PubMed1994

Transfer errors of planning CT to simulator: a possible source of setup inaccuracies?

The purpose of this study was to analyse whether the intended patient setup, based on a CT scan, was different from the setup at the simulator. Furthermore, we investigated how these possible transfer errors between the planned patient setup and the actual simulator setup affected the resulting overall treatment setup accuracy. Two groups, of 15 prostate patients each, were studied. For one group (group II), the simulation time was about twice as large as for the other (group I), since digitally reconstructed radiographs (DRRs) were used to get a good visual agreement between the intended and the simulator setup. For the purpose of this study DRRs were also calculated for the patients in group I, and for both groups DRRs were matched with the simulator images to obtain quantitative data of the transfer errors. The resulting overall treatment setup accuracy was determined by comparing the DRRs with portal images. For group I, the standard deviations (SD) of the differences between the DRRs and the simulator images ('transfer errors') were 1.5 mm and 4.5 mm in the lateral (x) and cranio-caudal (y) direction, respectively. For group II the SDs were smaller: 1.4 mm and 1.5 mm in the x- and y-direction, respectively. For both groups, the magnitude of the overall mean was less than 1.3 mm. For group I, the SDs of the resulting overall setup deviations during treatment were 1.6 mm and 4.1 mm in the x- and y-direction, respectively. For group II, these figures were 2.4 mm and 2.6 mm, respectively. For both groups, the magnitude of the overall mean was less than 1.0 mm.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗

PubMed1994

Quantification of patient to patient variation of skin erythema developing as a response to radiotherapy.

A method is described to determine accurately skin redness during a course of radiotherapy using reflectance spectroscopy utilizing information from across the visible spectrum according to the L*a*b* color coordinate system. The method was used to quantify the development of skin erythema during and after electron beam irradiation of the chest wall following mastectomy. A number of factors were identified which could influence the wide variation in response seen between patients. These were: intra- and inter-observer variation; intra- and inter-patient variation and variation in the actual dose delivered. Statistical analysis, including an analysis of variance of inter- and intra-patient variation, revealed that the major factor that accounts for the observed difference between patients is a true inter-patient variation, with a coefficient of variation, corrected for intra-patient variation, of 43%. Within the narrow dose range administered in this study, there was no demonstrable dose-effect relationship, raising questions about the role of cell death in the basal layer of the epidermis in the pathogenesis of radiation induced erythema.

Adult↗

PubMed1994

Quantifying local lung perfusion and ventilation using correlated SPECT and CT data.

UNLABELLED: A clinically applicable method for quantifying lung perfusion and ventilation on a subregional (local) scale from SPECT scans in order to estimate local lung function in patients with pre-existing pulmonary disease and to monitor local treatment effects was developed and evaluated. METHODS: SPECT 99mTc perfusion and 81mKr ventilation images were corrected for photon attenuation and scatter effect with a postreconstruction correction method incorporating a variable-effective linear-attenuation coefficient calculated from spatially-correlated CT data. A new algorithm was developed to quantify local ventilation from the SPECT data, which, in contrast with other algorithms, makes no assumptions on ventilation homogeneity over the lung. The quantification procedure was applied to clinical data from patients with a normal lung function and from patients suffering from radiation-induced pulmonary dysfunction. RESULTS: The calculated attenuation correction factors on the observed number of counts in the lung range from 2.0 to 3.0 and 2.3 to 3.5 for 81mKr and 99mTc, respectively, showing a systematic increase from the diaphragm to the lung apex. As a result of this correction, the values of local perfusion and ventilation differ 10%-15% from values calculated without attenuation correction. The calculated values of the local ventilation are 10%-50% lower than those found by quantification algorithms which assume homogeneous ventilation. CONCLUSIONS: The methods presented here are robust with respect to uncertainties in the input parameters and yield realistic values for perfusion and ventilation distribution in the lung with an intrinsic accuracy (largely determined by count statistics) of about 10%.

Algorithms↗

PubMed1993

Time trend of patient setup deviations during pelvic irradiation using electronic portal imaging.

An electronic portal imaging device (EPID) was used to detect patient setup displacement during the course of a 3-field pelvic irradiation of two groups of patients: 10 rectal and 10 prostate carcinomas. These patients were irradiated with conventional treatment techniques in routine clinical practice. A total of 469 portal images and 60 simulator films were used to determine the values of setup deviations in the X- Y- and Z-directions of a fixed coordinate system, corresponding to the medio-lateral, cranio-caudal and antero-posterior direction, respectively. The absolute displacement averaged over all setups and patients ranged between 0.4 mm and 1.4 mm with a standard deviation (S.D.) of 1.6-3.9 mm. The overall distribution along each direction could be separated into a distribution of random deviations (S.D.s ranging from 1.2 to 2.8 mm) around the mean deviation of each patient and a distribution of the means themselves: the distribution of systematic deviations (S.D.s ranging from 1.0 to 2.6 mm). Significant gradual displacement as a function of time was detected in 5 out of the 20 patients, 2 in the rectum and 3 in the prostate group. This "time trend" was found along each of the 3 directions specified. The magnitude of the time-dependent displacement throughout the course of treatment ranged between 4 and 11 mm. It can be concluded that for treatments requiring a high level of precision, portal images should be made and analyzed during the whole treatment course in order to detect and correct significant time trends.

Carcinoma↗

PubMed1993

A new method to determine dose-effect relations for local lung-function changes using correlated SPECT and CT data.

PURPOSE: To determine dose-effect relations for regional lung-function changes after radiotherapy. METHODS: Single Photon Emission Computed Tomography (SPECT) was performed to quantify regional ventilation and perfusion. CT scans were used to calculate the three-dimensional (3-D) dose distribution. Both SPECT and CT scans were performed prior to radiotherapy and 5 months after the start of the treatment. To obtain combined 3-D information on ventilation, perfusion and dose, the SPECT data were correlated with the corresponding CT data. The relative changes in ventilation and perfusion were calculated in each SPECT voxel (voxel size about 6 x 6 x 6 mm) and related to the dose in that voxel. The average relative changes were determined per dose interval of 4 Gy. This procedure was evaluated using the data from five patients treated for Hodgkin's disease with mantle field irradiation with a prescribed total dose of 40-42 Gy. RESULTS: Dose-effect relations for perfusion were observed in all patients, while in four of the five patients, a dose-effect relation was found for ventilation. The maximal uncertainty of the calculated radiation dose was 11%: a difference between the position of the patient during treatment and during CT scanning caused a maximal dose uncertainty of 6%, while the accuracy of the dose calculation algorithm itself was estimated to be within 5%. CONCLUSION: The results indicate that the combined use of SPECT and CT information is an effective method for determining dose-effect relations for regional lung function parameters in each individual patient.

Adolescent↗

PubMed1993

A verification procedure to improve patient set-up accuracy using portal images.

The purpose of this study was to establish which level of geometrical accuracy can be obtained during radiotherapy, using portal image analysis, with a minimum number of patient set-up measurements and corrections. A set-up verification and correction procedure using decision rules for improving the set-up of a patient during radiotherapy was investigated by means of a computer simulation. In this simulation study, set-up deviations were assumed to be the sum of random and systematic deviations and varying ratios of random and systematic deviations were studied. The distribution of random deviations (SD equal to sigma) was assumed to be equal for all patients of a specific treatment site. Set-up deviations are measured during the first N consecutive fractions after the start of the treatment or after a patient set-up correction. A set-up is corrected when the deviation averaged over these measurements is larger than an N-dependent action level. This action level is specified by alpha/square root of N, in which alpha is a variable initial action level parameter. After the start of the treatment or after each correction, Nmax measurements are made to decide on a possible (further) correction. By varying alpha and Nmax, the relation between the overall accuracy and the workload has been analyzed. It was possible to obtain a resulting overall accuracy level which is almost independent of the initial distribution of systematic deviations.(ABSTRACT TRUNCATED AT 250 WORDS)

Computer Simulation↗

PubMed1993

Pulmonary morbidity 10-18 years after irradiation for Hodgkin's disease.

Pulmonary function tests were performed in 78 patients who had been curatively treated for Hodgkin's disease with mantle field irradiation 10-18 years ago. Mean values of the total lung capacity (95.2%), vital capacity (VC) (95.9%), forced expiratory volume in 1 s (FEV1) (90.6%), and carbon monoxide diffusing capacity per unit alveolar volume (82.7%) showed significant deviations from the predicted normal values, standardised for age, sex, race and height. In a multiple regression analysis the normalised total dose of irradiation, the field of irradiation, and the interval since irradiation had independent negative effects on the test results. Patients reported more coughing, wheezing and dyspnoea on exertion in comparison with hospital-visitors. Their smoking habits and reported pulmonary disease were not different. It is concluded that small, but significant impairment of pulmonary function exists after a follow-up of 14 (2) years [mean (S.D.)]. The clinical impact of these findings seems, however, minimal. Further avoidance of pulmonary toxicity requires a careful quantitative study of the effects of the radiation dose and irradiated volume.

Adult↗

PubMed1993

Radiotherapy of tonsillar and base of the tongue carcinoma. Prediction of local control.

119 patients with squamous cell carcinoma of the tonsillar region (68) and the base of the tongue (51), who received external radiotherapy with curative intent between 1966 and 1984, are analysed with respect to overall treatment results, local tumour control and prognostic factors. Radiation doses were equivalent to 60-70 Gy in 6-7 weeks, with a mean fraction dose of 2.4 Gy on the cobalt 60 equipment and 2 Gy on the linear accelerator. Significant differences were found between both oropharyngeal subsites. Three-year overall survival was 57% in tonsillar carcinoma and 38% in base of the tongue (P = 0.006); disease-specific survival was 70% and 47%, respectively (P = 0.005); and local control rates were 82% and 61% (P = 0.02). Late damage to normal tissues, like persistent dysphagia and osteomyelitis, were seen in 11% of patients. Patients with large tumours in the tongue based developed significantly more complications (P = 0.04). T-stage and tumour subsite predicted local control independently before start of the treatment (P = 0.02 in both cases). A significant nonlinear correlation between Normalised Total Dose (using an alpha/beta ratio of 15 Gy) and local control rate was found (P = 0.006), the middle range having the worst prognosis. The size of radiation field and overall treatment time did not correlate with local control in either site. Response at the end of radiotherapy and 6 weeks later have additional prognostic value for local control, irrespective of the initial stage or subsite (P = 0.004 and < 0.001, respectively).

Adult↗

PubMed1993

The management of radiation-associated oesophageal carcinoma: a report of 16 cases.

16 patients, presenting with squamous cell carcinoma in previously irradiated sections of the oesophagus, are described. Oesophagectomy could be performed in 2 patients, resulting in long-term disease-free survival (38 and 60 months after diagnosis). 14 patients were treated with palliative radiotherapy (external beam or intraluminal), oesophageal stenting, bougienage or chemotherapy. Although most patients previously received curative dosages of mediastinal irradiation, additional full courses of high-dose radiotherapy could be given on five occasions; no major complications were encountered and adequate palliation for up to 10 months was achieved. Similar results were observed after oesophageal stenting and/or bougienage. Relief of dysphagia following intraluminal radiotherapy or chemotherapy was only minimal (2 months or less). Median survival in the palliative treatment group was 6.5 months (range 2-27 months), which is in keeping with results observed in non-radiation-associated oesophageal carcinoma. We concluded that, in selected cases, both surgery and radiotherapy offer good prospects for patients with radiation-associated oesophageal cancer.

Adult↗