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OBJECTIVE@#To identify the problems in clinical radiotherapy planning for cervical cancer through quantitative evaluation of the radiotherapy plans to improve the quality of the plans and the radiotherapy process.@*METHODS@#We selected the clinically approved and administered radiotherapy plans for 227 cervical cancer patients undergoing external radiotherapy at Sun Yat-sen University Cancer Center from May, 2019 to January, 2022. These plans were transferred from the treatment planning system to the Plan IQTM workstation. The plan quality metrics were determined based on the guidelines of ICRU83 report, the GEC-ESTRO Working Group, and the clinical requirements of our center and were approved by a senior clinician. The problems in the radiotherapy plans were summarized and documented, and those with low scores were re-planned and the differences were analyzed.@*RESULTS@#We identified several problems in the 277 plans by quantitative evaluation. Inappropriate target volume selection (with scores < 60) in terms of GTV, PGTV (CI) and PGTV (V66 Gy) was found in 10.6%, 65.2%, and 1% of the plans, respectively; and the PGTV (CI), GTV, and PCTV (D98%, HI) had a score of 0 in 0.4%, 10.1%, 0.4%, 0.4% of the plans, respectively. The problems in the organs at risk (OARs) involved mainly the intestines (the rectum, small intestine, and colon), found in 20.7% of the plans, and in occasional cases, the rectum, small intestine, colon, kidney, and the femoral head had a score of 0. Senior planners showed significantly better performance than junior planners in PGTV (V60 Gy, D98%), PCTV (CI), and CTV (D98%) (P≤0.046) especially in terms of spinal cord and small intestine protection (P≤0.034). The bowel (the rectum, small intestine and colon) dose was significantly lower in the prone plans than supine plans (P < 0.05), and targets coverage all met clinical requirements. Twenty radiotherapy plans with low scores were selected for re-planning. The re-planned plans had significantly higher GTV (Dmin) and PTV (V45 Gy, D98%) (P < 0.05) with significantly reduced doses of the small intestines (V40 Gy vs V30 Gy), the colon (V40 Gy vs V30 Gy), and the bladder (D35%) (P < 0.05).@*CONCLUSION@#Quantitative evaluation of the radiotherapy plans can not only improve the quality of radiotherapy plan, but also facilitate risk management of the radiotherapy process.
Subject(s)
Humans , Female , Uterine Cervical Neoplasms/radiotherapy , Rectum , Colon , Kidney , Organs at RiskABSTRACT
Background: Radiotherapy in head-and-neck cancer (HNC) is a challenging task, and the anatomical alterations occurring during the course of intensity-modulated radiotherapy (IMRT) can be compensated by adaptive radiotherapy (ART) which utilizes repeat computed tomography (CT) scans during the treatment course for replanning. In this study, the clinical and dosimetric benefits of ART were compared with the conventional IMRT. Materials and Methods: Sixty patients with locally advanced HNC were randomized into two arms to receive IMRT up to a curative dose of 70 Gy with concurrent weekly chemotherapy and were prospectively analyzed between March 2018 and March 2019. Repeat CT scan was acquired after the 3rd week of radiation. Patients in the study arm underwent replanning, whereas those in the control arm continued with the first IMRT plan. Assessment was done weekly till the end of treatment and at 1, 3, and 6 months post IMRT for disease response and toxicities. Tumor volume reduction rate (TVRR) and dose reduction to organs at risk were also recorded. Results: Complete response was observed in 90% and 96.7% patients in the control and study arms, respectively, at the end of 6 months. Insignificant differences were found between the two arms in terms of toxicities. Xerostomia was statistically significantly higher in the control arm at 6 months (P = 0.01). TVRR was found to be 31.85%. Dose to spinal cord, ipsilateral, and contralateral parotid reduced by 4.3%, 6%, and 2.2%, respectively, with ART. Conclusion: Mid-treatment adaptive replanning can help in better target coverage and minimize toxicities in HNC patients
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Introduction: In head and neck cancer the location, size, shape of disease, and normal anatomy change in 6-7 weeks radiotherapy. As a result, steep dose gradients move across target and critical structures resulting in underdose to target and overdose to critical structures. Aim: comparison of target coverage in initial IMRT plan and replan and to quantify dose changes to normal structures in two plans. Methods and Material: 30 patients with locally advanced head and neck cancer patients planned for curative radiotherapy were selected and treated with 3DCRT plan. For dosimetric comparison IMRT plan was created for pre-treatment and repeat CT, which was done after 40Gy. Statistical analysis used: Statistical methods (student’s paired t-test) were applied. Results: Both PTV coverage (V95 from 96.29±1.12 to 97.33±0.80) and dose (D95 from 66.64±0.87 to 67.57±0.74) increased in replanned CT. Both max and mean doses to the brainstem and spinal cord along with mean dose to parotid glands increased in replanned CT. Conclusions: Replanning is necessary during mid-treatment to accommodate anatomical and dosimetric changes during curative radiotherapy.
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Intensity-modulated radiotherapy(IMRT)is the first-line treatment for nasopharyngeal carcinoma currently. Previous studies have shown that regression of primary tumor and metastatic lymph nodes or a decrease in body weight causes the contour of normal organs and head-and-neck to shrink during the course of radiotherapy, which may lead to underdose in primary tumor and overdose in organs at risk (OARs)and then adversely affect treatment outcomes. Replanning during the course of radiotherapy can maintain the dose to target volume and reduce the exposure of OARs, which improves outcomes in some patients. For replanning during the course of IMRT, however, the advantages have not been widely recognized and there is still a long way to go before widely accepted timing and frequency of replanning are set up. Further studies are needed to figure out how to identify patients appropriate for plan modification.
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Adaptive re-planning contributes to improve the dosimetric uncertainties induced by anatomical changes during intensity-modulated radiation therapy (IMRT) for head and neck cancer patients and can enhance the local control rate and quality of life of patients.Previous research has demonstrated that presence of relatively large lymph nodes before treatment and significant loss of body weight during treatment are pivotal predictive factors of re-planning during IMRT.At 4 weeks after IMRT,the volume of the target and peripheral organ at risk (OAR) tends to steadily decrease.One to two cycles of adaptive re-planning are recommended at 3 or 4 weeks after IMRT.
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Objective To investigate the anatomical changes and dose distribution deviations of locally advanced nasopharyngeal carcinoma ( NPC ) patients during intensity-modulated radiation therapy ( IMRT) . Methods Weekly cone beam CT ( CBCT) was applied to investigate the anatomical changes of enrolled 18 patients with locally advanced NPC. Dosimetric deviations were investigated with new IMRT plans after 20 fractions. Results The volumes of gross tumor volume ( GTVnx ) and GTVnd were decreased by 3. 15% and 5. 67% weekly, and decreased by a total of 22. 03% and 39. 68%, respectiely. The volumes of left and right parotids were decreased by 4. 93% and 5. 26% weekly, and decreased by a total of 29. 60% and 31. 56%, respectively. The volumes of GTVnd and parotids showed significant retraction in the first four weeks of radiation, then the retraction slowed down. The D95 of PGTVnd in Plan 2 decreased by 2. 20% (t=2. 382, P <0. 05) compared that in the initial Plan 1, while there was no significant difference on the D95 of PGTVnx , PTV1 and PTV2 . The Dmean , D50 and V30 of the left and right parotids in Plan 2 increased by 7. 34%, 12. 68%, 10. 90% (t = -3. 376, -3. 738, -3. 679,P<0. 05), and 6. 13%, 11. 17%, 9. 72% (t= -2. 550, -2. 446, -2. 673, P<0. 05), respectively, compared with Plan 1. The Dmean of larynx increased by 8. 69% in Plan 2 compared with Plan 1 ( t = -3. 099, P <0. 05). The D95 of PGTVnd in Plan(1+2) increased by 1. 37% (t= -3. 555, P<0. 05) compared with Plan 2. The Dmean, D50 and V30 of the left and right parotids in Plan(1+2) were decreased by 2. 90%, 2. 73%, 4. 62% (t=3. 089, 2. 718,2. 705, P < 0. 05), and decreased by 3. 49%, 3. 44%, 3. 80%(t=2. 781, 2. 958,4. 275, P<0. 05), respectively, compared with Plan 1. The Dmean of larynx decreased by 3. 29% (t=2. 747, P<0. 05) in Plan(1+2) compared with Plan 1. Conclusions The volumes of GTV and parotids of locally advanced NPC patients showed significant shrinks during IMRT. Replanning is necessary during the middle of IMRT to improve the target coverage and to spare the organ at risks ( OARs) .
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Intensity-modulated radiotherapy (IMRT) is gradually replacing conventional radiation therapy and has become the mainstream radical treatment for patients with nasopharyngeal carcinoma (NPC). IMRT can conform and increase radiation doses to tu-mor-associated regions as well as decrease exposure doses and volumes on normal organs and tissues to avoid damage on critical or-gans. Aside from system and setup errors, other factors, such as the gradual reduction of the primary NPC lesion and the decrease in vol-ume of involved neck lymph nodes as well as body weight loss and changes in the head and neck shape during IMRT, may cause devia-tions in the radiation doses and volume delivered to the NPC targets and the organs at risk. These factors may affect the accuracy of IMRT. Several researchers have attempted to correct such deviations during IMRT for NPC patients by using adaptive radiotherapy (ART). The results indicate that ART is feasible to a certain degree and can correct the deviations, including decrease in tumor volume, body weight loss, and changes in head and neck shape of NPC patients.
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Objective To study the dynamic changes of anatomy and the dosimeter distribution those changes influenced. Methods Initially simplified intensity modulated radiation therapy (sIMRT)were performed to twenty-nine patients with phase Ⅲ - Ⅳa esophageal carcinoma from January 2007 to March 2009. The target volumes and involving organs were contoured on the primary spiral CT pictures.After sIMRT planning being finished, secondary CT scan was acquired to rectify the treatment center. For eleven patients at every other week and eighteen patients at the fourth week, spiral CT images were acquired according to the same treatment center, and thereafter fused with the first CT images. Firstly, the law of change and the best time of replanning were searched:the changed gross tumor volume (GTV), gross node volume (GTVnd), plan target volume (PTV) and normal organs (lung, spinal cord, heart and outline) on the fusion interface were modified by a single physician, the changes for each structure throughout treatment were measured by system software. Secondly, dose distributions were computed and evaluated for replanning CT using the same beams arrangement as the initial plan. Cumulative dose was estimated using weighted average and compared with the original plan. Results For eleven patients, The law of change:the volume of outlines and GTV gradually decreased, and the change come to peak in the fourth week. The conformal index for PTV gradually decreased, whereas the heterogeneous index gradually increased. For twenty-nine patients on the fourth week, the dose of GTV were more than 60 Gy. The dose of PTV-D95 and CTV-D99 decreased ( t = 1.49, P = 0. 147 and t = 2. 07, P = 0. 048 respectively). The dose of CTV-D99 in two patients deceased to 54 Gy or less. The cord-Dmax and lung V30 increased significantly ( t = - 2. 42, P = 0. 022 and t = -2. 26,P =0. 032). Conclusions During the course of sIMRT for esophageal cancer, the volume of GTV decreased and the change come to peak in the fourth week. It is the best time for evaluating the change of dose of target volume using CT-CT fusion. For some patients, revise of the treatment plan is needed to ensure adequate target volume dosage and safety of normal tissues.
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Objective To study the dynamic change of anatomy and dosimetry distribution and its influence during intensity modulated radiation therapy(IMRT) for nasopharyngeal carcinoma(NPC). Methods From June 2006 to August 2007,12 patients with stage Ⅲ-Ⅳ NPC receiving initial IMRT concurrently combined with chemotherapy were included in the study. The target volumes and,involving organs were contoured on the first set of spiral CT images. When IMRT planning was finished,a second CT scans was acquired to rectify the treatment center. Weekly spiral CT images acquired during the treatment period according to the same treatment center were fused with the first CT images. In order to determine the best time of replanning, modified plan target volume( PTV1 ) and normal organs( parotids and outline) were contoured on the fusion interface by a single physician. Changes of each structure throughout treatment period were measured by a system software. Then the dose distributions were computed and evaluated for replanning CT using the same beams arrangement in the original plan. Cumulative dose was estimated compared with the original plan. Results The volume of outlines and parotids decreased gradually, and the change came to peak in the fifth week. So the fifth and first week CT scans were selected as research objectives. No significant changes in maximal and mean dose was observed in the brainstem, spinal cord or mandible. Despite volume changes,D99 and D95 of the PTV1 did not change siguificantly(P＞0.05). D95 of the bilateral parotids increased significantly ( PL = 0.03,PR = 0.01 ). Conclusions During IMRT for NPC, the volume of PTV1, the outlines and parotids decrease,and the change come to peak in the fifth week. Comparing to the first treatment plan, the dose parameters of the parotids increase significantly in the second plan based on the fifth week CT,but those of the brainstem,cord,mandible and PTV1 change slightly.
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Se reconoce que para la gestión de algunos servicios de salud, entre ellos los Laboratorios Clínicos, se aplican al mismo tiempo, criterios que provienen de las ciencias duras, como los que se observan en la planificación operativa y científica, y otros que son propios de las ciencias sociales, como los utilizados para la gestión del personal o para la económico-administrativa. Esto supone la existencia de mecanismos explícitos, como por ejemplo los planteados por Shewart-Deming (planificar, hacer, controlar, corregir) y de otros implícitos, como aquellos que le confieren a la gestión el carácter sistémico y que pueden explicarse a partir de la Teoría General de Sistemas (TGS). Tanto el planteo de Shewart-Deming como el sistémico, son complementarios y en ellos se basan varias de las normas internacionales y nacionales que refieren a sistemas de calidad y a la gestión de sistemas integrados. El mismo tipo de gestión por procesos está presente en ambos modelos, donde los elementos se incluyen en una entrada y en una salida que resulta como consecuencia de procesos de transformación. El valor del resultado/servicio está dado por las interfases entre procesos y por mecanismos de retroalimentación que tornan más "flexible" el sistema Laboratorio, en algunos casos para corregir desvíos, en otros para mejorar y madurar en la gestión, y en otros muy escasos para innovar y crecer. Estos criterios, modelizados o no, vinculan al Laboratorio, como un sistema abierto, con la atención de sus múltiples intereses, internos y externos, y permiten la planificación estratégica y la replanificación, como core de la gestión. En este caso, se presenta un ejemplo de las interfases generadas entre los sistemas de calidad, ambiental, de seguridad y salud ocupacional y se discute cómo influyen los mecanismos sistémicos en la gestión de sistemas integrados (SIG) aplicados al Laboratorio Clínico.
It is recognized that in order to manage some health services in which Clinical Laboratories are included, some criteria derived from the hard sciences are at the same time applied, as observed in the scientific and operative planning and other criteria from the social sciences, like the ones used for staff or economic-administrative management. When the quality of these services is managed, the so called organized complexity that supposes the existence of explicit mechanisms, in work activities like the ones posed by Shewart-Deming, and other implicit ones, like those that confer a systemic character to management, comes up. The same type of management by processes is present in both models, where the resources are included in an entry or input and where the exit or output is the consequence of the work done through transformation processes. The service or result value is set by the interface among processes and by the feedback generated, this understood as the control plus communication that allow, among other things, to balance the system, to later correct it, in some cases to improve it, and in other few cases to innovate it. Both approaches are complementary and some national and international regulations that refer to quality systems and integrated system managements (SIG) are based on them. These criteria, modeled or not, link the Laboratory as an open system considering its many internal and external interests, and enable a strategic planning and replanning as the core of the management. In this case, an example of the interfaces generated among the quality, environment, and occupational safety and health systems is shown. The way the recognition of the systemic mechanism influences the management of integrated systems (SIG) applied to the Clinical Laboratory is discussed.