Networking in Shared Care – First Steps towards a Shared Electronic Patient Record for Cancer Patients

Objectives: This paper aims at identifying the data protection and security requirements for a cross-institutional EPR. Three possible models and the first steps towards a cross-institutional EPR for the Thoraxklinik Heidelberg and the Department of Clinical Radiology of the University Medical Center of Heidelberg shall be discussed.

Methods: A comprehensive analysis of literature and legal documents supplied information for determining the data protection and security requirements. By means of information system analysis, the technical preconditions in both institutions as well as three possible models towards a cross-institutional EPR were identified.

Results: According to the German penal code it is only allowed to reveal patient information to external physicians in cases of so-called “treatment connection”. An extension of the written consent, signed by the patient, verifying the patient agreement that his/her patient data will be stored in a cross-institutional EPR is needed. Among the three models that we identified, the model that constitutes of a virtual EPR with distributed data capture in both institutions was favored. By means of SecuRemote™ software a secure connection between the Thoraxklinik Heidelberg and the Department of Clinical Radiology was established, allowing the physicians to view the complete cross-institutional health information of a jointly treated patient during the weekly consultation on radiotherapy.

Conclusions: Many requirements listed in this paper are requirements for electronic patient records in general. Besides these general requirements there are specific requirements for a cross-institutional EPR. The legal situation in Germany complicates the development and implementation of a cross-institutional EPR. However, we think that the efforts are reasonable, because a cross-institutional EPR will be able to improve the communication between health institutions, medical disciplines and persons involved in shared care processes. It provides them with more complete health information about the jointly treated patients. A cross-institutional EPR is, therefore, expected to improve the quality of patient care.

Networking in shared care--first steps towards a shared electronic patient record for cancer patients

OBJECTIVES

This paper aims at identifying the data protection and security requirements for a cross-institutional EPR. Three possible models and the first steps towards a cross-institutional EPR for the Thoraxklinik Heidelberg and the Department of Clinical Radiology of the University Medical Center of Heidelberg shall be discussed.

METHODS

A comprehensive analysis of literature and legal documents supplied information for determining the data protection and security requirements. By means of information system analysis, the technical preconditions in both institutions as well as three possible models towards a cross-institutional EPR were identified.

RESULTS

According to the German penal code it is only allowed to reveal patient information to external physicians in cases of so-called "treatment connection". An extension of the written consent, signed by the patient, verifying the patient agreement that his/her patient data will be stored in a cross-institutional EPR is needed. Among the three models that we identified, the model that constitutes of a virtual EPR with distributed data capture in both institutions was favored. By means of SecuRemote software a secure connection between the Thoraxklinik Heidelberg and the Department of Clinical Radiology was established, allowing the physicians to view the complete cross-institutional health information of a jointly treated patient during the weekly consultation on radiotherapy.

CONCLUSIONS

Many requirements listed in this paper are requirements for electronic patient records in general. Besides these general requirements there are specific requirements for a cross-institutional EPR. The legal situation in Germany complicates the development and implementation of a cross-institutional EPR. However, we think that the efforts are reasonable, because a cross-institutional EPR will be able to improve the communication between health institutions, medical disciplines and persons involved in shared care processes. It provides them with more complete health information about the jointly treated patients. A cross-institutional EPR is, therefore, expected to improve the quality of patient care.

Irradiation for inhibition of endothelial cell growth in vitro

The clinical effect of ionising radiation on ocular neovascularisations is controversial, not only because of the variety of treatment modalities. The aim of our study was to investigate an experimental model which allows to evaluate radiation parameters and to study the mechanism of the inhibitory effect on neoangiogenesis. In vitro experiments were performed using human umbilical vein endothelial cells and human corneal keratocytes. The cells were irradiated with different doses of photon beam radiation and counted daily after treatment. Cell cultures confirmed the efficiency of irradiation in inhibiting proliferation of vascular endothelial cells. Radiosensitivity was shown to be higher in vascular endothelial cells than in corneal stromal keratocytes. This might be helpful in investigating therapy parameters for treating ocular neovascularisations, as well as underlying mechanisms.

[Effect if 3D compared with 2D radiotherapy planning within a conventional treatment schedule of advanced lung cancer]

BACKGROUND

The effect of 3D radiotherapy planning (3D RTP) in comparison to 2D radiotherapy planning (2D RTP) was evaluated in a usually practiced treatment schedule (starting by v./d. opposing portals, continued with computer-planned portals) for non-small-cell lung cancer.

PATIENTS AND METHODS

In 20 patients with locally advanced non-small-cell lung cancer the computer-planned part of the treatment schedule was calculated 2- and 3-dimensionally. Target volume were the primary tumor, the involved and the electively irradiated mediastinal lymph nodes. The results of the 2D RTP were recalculated 3-dimensionally and the mean doses to target volume and organs at risk were defined. Further the normal tissue complications were calculated.

RESULTS

Under the prerequisite of 44 Gy maximally allowed to the spinal cord and a dose to the reference point of 50 Gy a small, but significant advantage with 2.1 Gy to the target (p = 0.004) and a reduction of 3.6 Gy to the heart (p = 0.05) was achievable for 3D RTP. The dose to the lungs did not differ significantly (19.7 Gy for 2D RTP, 20.3 Gy for 3D RTP). The dose to the heart was not estimated critical by NTCP (normal tissue complication probability). The NTCP for the ipsilateral lung was 16.1 and 18.7% for 2D RTP and 3D RTP, respectively. Regarding the simulator-planned ap/pa fields at the start of the radiotherapy the advantage of 3D RTP was further reduced but remained significant. Favorable with respect to the mean lung dose and the NTCP (18.7% NTCP ipsilateral lung for early onset of 3D planned radiotherapy vs 31.7% for late onset of 3D planned radiotherapy) but not significantly measurable is the early start of the treatment by computerized RTP.

CONCLUSION

The main advantage of 3D RTP in treatment of advanced lung cancer is the better coverage of the target volume. A reduction of the mean lung dose cannot be expected. A dose escalation by 3D RTP to target volumes as described here seems not to be possible because of unchanged high lung exposure.

Radiation pneumonitis as a function of mean lung dose: an analysis of pooled data of 540 patients

PURPOSE

To determine the relation between the incidence of radiation pneumonitis and the three-dimensional dose distribution in the lung.

METHODS AND MATERIALS

In five institutions, the incidence of radiation pneumonitis was evaluated in 540 patients. The patients were divided into two groups: a Lung group, consisting of 399 patients with lung cancer and 1 esophagus cancer patient and a Lymph./Breast group with 78 patients treated for malignant lymphoma, 59 for breast cancer, and 3 for other tumor types. The dose per fraction varied between 1.0 and 2.7 Gy and the prescribed total dose between 20 and 92 Gy. Three-dimensional dose calculations were performed with tissue density inhomogeneity correction. The physical dose distribution was converted into the biologically equivalent dose distribution given in fractions of 2 Gy, the normalized total dose (NTD) distribution, by using the linear quadratic model with an alpha/beta ratio of 2.5 and 3.0 Gy. Dose-volume histograms (DVHs) were calculated considering both lungs as one organ and from these DVHs the mean (biological) lung dose, NTDmean, was obtained. Radiation pneumonitis was scored as a complication when the pneumonitis grade was grade 2 (steroids needed for medical treatment) or higher. For statistical analysis the conventional normal tissue complication probability (NTCP) model of Lyman (with n=1) was applied along with an institutional-dependent offset parameter to account for systematic differences in scoring patients at different institutions.

RESULTS

The mean lung dose, NTDmean, ranged from 0 to 34 Gy and 73 of the 540 patients experienced pneumonitis, grade 2 or higher. In all centers, an increasing pneumonitis rate was observed with increasing NTDmean. The data were fitted to the Lyman model with NTD50=31.8 Gy and m=0.43, assuming that for all patients the same parameter values could be used. However, in the low dose range at an NTDmean between 4 and 16 Gy, the observed pneumonitis incidence in the Lung group (10%) was significantly (p=0.02) higher than in the Lymph./Breast group (1.4%). Moreover, between the Lung groups of different institutions, also significant (p=0.04) differences were present: for centers 2, 3, and 4, the pneumonitis incidence was about 13%, whereas for center 5 only 3%. Explicitly accounting for these differences by adding center-dependent offset values for the Lung group, improved the data fit significantly (p < 10(-5)) with NTD50=30.5+/-1.4 Gy and m=0.30+/-0.02 (+/-1 SE) for all patients, and an offset of 0-11% for the Lung group, depending on the center.

CONCLUSIONS

The mean lung dose, NTDmean, is relatively easy to calculate, and is a useful predictor of the risk of radiation pneumonitis. The observed dose-effect relation between the NTDmean and the incidence of radiation pneumonitis, based on a large clinical data set, might be of value in dose-escalating studies for lung cancer. The validity of the obtained dose-effect relation will have to be tested in future studies, regarding the influence of confounding factors and dose distributions different from the ones in this study.

Combined error of patient positioning variability and prostate motion uncertainty in 3D conformal radiotherapy of localized prostate cancer

PURPOSE

To measure the patient positioning and prostate motion variability and to estimate its influence on the calculated 3D dose distribution in 3D conformal radiotherapy of patients with localized prostate carcinoma.

METHODS AND MATERIALS

Patient positioning variability was determined retrospectively by comparing 54 orthogonal simulator films with 125 corresponding portal films from 27 patients. Prostate motion variability was determined by 107 computed tomography (CT) examinations with a CT simulator in 28 patients during radiotherapy.

RESULTS

In each observed direction, the patient positioning variability and prostate motion showed a normal distribution. This observation enabled the calculation of a combined error of both components. The standard deviation (1 SD) of the patient positioning error in three directions ranged from 3.1 to 5.4 mm; the prostate motion variability was significantly greater in the anterior-posterior direction (1 SD = 2.8 mm) than in the mediolateral direction (1 SD = 1.4 mm). The 1 SD of the estimated combined error was in the anterior-posterior direction 6.1 mm and in mediolateral direction 3.6 mm.

CONCLUSION

The range of patient positioning variability and prostate motion were statistically predictable under the patient setup conditions used. Dose-volume histograms demonstrating the influence of the combined error of both components on the calculated dose distribution are presented.

The impact of 3-D radiotherapy planning after a pneumonectomy compared to a conventional treatment set-up

Three-dimensional radiotherapy planning (3-D RTP) is becoming more available in clinical practice, although so far there is little data showing its clinical advantage. The goal of this study was to compare 3-D RTP and dose delivery with conventional treatment planning in pneumonected lung cancer patients, receiving postoperative irradiation. Adjuvant radiotherapy in 20 pneumonected patients was planned with a 3-D system and patients were irradiated according to this plan. The resulting dose distribution was compared with the combination of a simulator and 2-D planned treatment to the same target volume. Dose volume histograms of the target, the lung and the heart of both treatment plans were analysed. A biophysical model was added to estimate the differences in the biological effect. 3-D RTP significantly reduced the mean dose to the lung in 14/20 patients and to the heart in 20/20 patients. The mean dose delivered to the target was equal in both planning methods. The early clinical results do not differ from published results in postoperatively treated lung cancer patients.

Estimation of pneumonitis risk in three-dimensional treatment planning using dose-volume histogram analysis

PURPOSE

Investigations to study correlations between the estimations of biophysical models in three dimensional (3D) treatment planning and clinical observations are scarce. The development of clinically symptomatic pneumonitis in the radiotherapy of thoracic malignomas was chosen to test the predictive power of Lyman's normal tissue complication probability (NTCP) model for the assessment of side effects for nonuniform irradiation.

METHODS AND MATERIALS

In a retrospective analysis individual computed-tomography-based 3D dose distributions of a random sample of 46/20 patients with lung/esophageal cancer were reconstructed. All patients received tumor doses between 50 and 60 Gy in a conventional treatment schedule. Biological isoeffective dose-volume histograms (DVHs) were used for the calculation of complication probabilities after applying Lyman's and Kutcher's DVH-reduction algorithm. Lung dose statistics were performed for single lung (involved ipsilateral and contralateral) and for the lung as a paired organ.

RESULTS

In the lung cancer group, about 20% of the patients (9 out of 46) developed pneumonitis 3-12 (median 7.5) weeks after completion of radiotherapy. For the majority of these lung cancer patients, the involved ipsilateral lung received a much higher dose than the contralateral lung, and the pneumonitis patients had on average a higher lung exposure with a doubling of the predicted complication risk (38% vs. 20%). The lower lung exposure for the esophagus patients resulted in a mean lung dose of 13.2 Gy (lung cancer: 20.5 Gy) averaged over all patients in correlation with an almost zero complication risk and only one observed case of pneumonitis (1 out of 20). To compare the pneumonitis risk estimations with observed complication rates, the patients were ranked into bins of mean ipsilateral lung dose. Particularly, in the bins with the highest patient numbers, a good correlation was achieved. Agreement was not reached for the lung functioning as a paired organ.

CONCLUSIONS

Realistic assessments for the prediction of radiation-induced pneumonitis seem to be possible. In this respect, the implementation of DVH-analysis in 3D planning could be a helpful tool for the evaluation of treatment plans.

Influence of the positioning error on 3D conformal dose distributions during fractionated radiotherapy

The influence of patient immobilization error on 3D planned conformal radiation therapy in tumors of the thorax and pelvis was studied. The mean positioning error in 43 patients with carcinomas of the thorax and pelvis undergoing 3D conformal radiotherapy (laser supported alignment, no immobilization device) was measured. A total of 194 portal films were superposed with the corresponding simulator radiographs according to anatomic landmarks and using a subtrascope. x-, y- and z-axis deviation was determined within a coordinate system. Using specialized software including Fourier transformation the mean positioning error was employed to recalculate the dose distributions of all cases under the influence of random (Gaussian) immobilization uncertainty. The mean two-dimensional positioning error using the data from all patients was 5.5 (+/- 3.7) mm. The distribution was Gaussian. Dose volume histograms (DVHs) of each patient with and without consideration of positioning uncertainty were compared on the base of tumor control probability estimations (TCP) using published DVH reduction and TCP algorithms. Inclusion of the positioning error resulted in a mean decrease in TCP (given as the difference between the TCP assuming no positioning error and the TCP modified by the positioning error) of 2% in a series of esophagus carcinomas and of 5% in the prostate carcinomas when looking at gross tumor volume (GTV), only. Planning target volume (PTV) exhibited a relative decrease in TCP of 5% and 11%, respectively.

Conservative treatment of breast cancer: modified irradiation technique for women with large breasts

Seven patients with large, pendulous breasts received external beam irradiation to the whole breast (50 Gy in 25 fractions plus boost) after lumpectomy. A special breast holding mask was shaped for each patient. Three-dimensional treatment plans and dose-volume histograms of the same patient with and without a mask were compared. Day-to-day variance was checked. This technique provides improvements in dose homogeneity, reproducibility, and sparing of normal tissues. Cosmetic outcome at present is good.

[The improved determination of the dose rate in irregular photon fields]

A revised formula for calculation of dose per time or monitor unit ("dose rate") of irregular megavoltage photon beams is proposed. The formula considers additionally the shading by secondary shieldings of the plane source describing the scattered radiation in the head. Therefore, in addition to the primary output factor C(ac) as function of the equivalent square ac x ac of the collimator field size a secondary output factor S(as) is introduced denoted as function of the equivalent square as x as of the irregular field. S is determined using a satellite diaphragm formed of shielding blocks in combination with a totally opened collimator. In this definition, S includes both the effects of radiation scattered in tissue (phantom scatter factor PSF) and of missing photons from the plane source by the blocks (satellite diaphragm factor SAT). In the usual formula to calculate the "dose rate" (output) at reference point in depth t, PSF is replaced by S: D = D0 x C(ac) x [PSF(as)/PSF(ac)] x T x R(as,t). There T is representing the block tray factor and R(as,t) the tissue phantom ratio or relative depth dose, depending on the irradiation technique used. Thus the modified formula is given by D = D0 x C(ac) x [S(as)/S(ac)] x T x R(as,t). Measurements show that the revised formula provides an additional precision of up to 2% in the calculation of dose, depending on the type of accelerator respectively on the size of the plane source of scattered radiation.

[Comparison of dosimetric properties of 15-MV-photons and 14-MeV-neutrons in external stereotaxic convergence therapy]

Dosimetric properties for stereotaxic convergent beam therapy techniques with small field sizes have been investigated as well as for the linear accelerator Mevatron 77 as for the neutron generator KARIN. Additionally we also measured the dose distribution of single plane rotational therapy. As an indication of quality we calculated the V50 ratio as V50 = (F50-F90)/F90 and the corresponding V20 values. For the single plane irradiation there is a considerable difference in dose distribution in favour of photons. V50 (axial) amounts to 1.77 for photons and to 2.7 for neutrons. For the convergential non coplaner arc-therapy using nine plans there is nearly no difference in the high dose region including the 50%-isodose. V50 (axial): 1.16 and 1.6 respectively; (frontal) 1.36 and 1.35 respectively. Regarding to physical dose distributions our results indicate, that 14-MeV neutrons are suitable for high dosed stereotactic single irradiations.