Stereotactic radiotherapy is an ever more common technique, regardless of the location treated. However, spinal stereotactic radiotherapy requires a particular technicality in order to ensure its ...proper realization. There is now a large literature defining the type of imaging to be used, the dose to be delivered and the delineation of target volumes. This technique can achieve a significant local control and an interesting analgesic efficiency. However, its place in relation to conventional radiotherapy remains limited because it requires MRI imaging and a significantly longer patient management during the treatment fraction. In this context, it is currently mainly restricted to oligometastatic patients or for re-irradiations.
Radiotherapy of bone metastases Thureau, S.; Supiot, S.; Jouglar, E. ...
Cancer radiothérapie,
February-April 2022, 2022 Feb-Apr, 2022-02-00, 20220201, Letnik:
26, Številka:
1-2
Journal Article
Recenzirano
We present the update of the recommendations of the French society of oncological radiotherapy on bone metastases. This is a common treatment in the management of patients with cancer. It is a ...relatively simple treatment with proven efficacy in reducing pain or managing spinal cord compression. More complex treatments by stereotaxis can be proposed for oligometastatic patients or in case of reirradiation. In this context, increased vigilance should be given to the risks to the spinal cord.
Nous présentons la mise à jour des recommandations de la Société française de radiothérapie oncologique sur les indications et les modalités techniques de réalisation de la radiothérapie des métastases osseuses. Elle représente un traitement fréquent dans la prise en charge des patients suivis pour un cancer. Il s’agit d’un traitement relativement simple avec une efficacité prouvée pour la diminution des douleurs ou la prise en charge des compressions médullaires. Des traitements plus complexes en conditions stéréotaxiques peuvent être proposés chez les patients atteints de cancer oligométastatique ou en cas de réirradiation. Dans ce cadre, une vigilance accrue devra être accordée quant aux risques médullaires.
Due to high dose gradients, stereotactic body radiation therapy requires high precision in the location of the tumour. Uncertainties in the positioning can introduce serious damage on organs at risk ...and consequently can reduce tumour local control. A better tumour location can be achieved by controlling its position with an efficient inter and intrafraction imaging procedure. The various imaging techniques available on treatment systems are presented and performances are discussed. Finally, propositions are given in terms of imaging system according to the location treated by stereotactic body radiation therapy.
Image-guided radiotherapy takes place at every step of the treatment in lung cancer, from treatment planning, with fusion imaging, to daily in-room repositioning. Managing tumoral and surrounding ...thoracic structures motion has been allowed since the routine use of 4D computed tomography (4DCT). The integration of respiratory motion has been made with "passive" techniques based on reconstruction images from 4DCT planning, or "active" techniques adapted to the patient's breathing. Daily repositioning is based on regular images, weekly or daily, low (kV) or high (MV) energy. MRI and functional imaging also play an important part in lung cancer radiation and open the way for adaptative radiotherapy.
The technique of acoustic generation by microwave excitation in structures is applied here to study the in-plane vibration of full or hollowed elliptic plates. The absorption of pulsed microwave ...irradiations by a material causes a sudden rise of its temperature and the generation of an acoustic wave by thermoelastic effect. A semi-analytic theoretical model is developed to predict the in-plane displacement fields in elliptic thin plates submitted to a uniform temperature rise. It is assumed that the isotropic and viscoelastic plate constitutive material is submitted to a thermoelastic excitation under a plane stress state. The wave equations that govern the Helmholtz displacement potentials are resolved in an elliptic cylindrical system of coordinates by means of infinite angular and radial Mathieu functions series. The displacement field is finally obtained by taking into account the zero stress conditions on the boundaries of the plates. The comparison between the theoretical and the experimental responses of full and hollowed elliptic plates shows a good agreement that permits the validation of the developed model.
The dosimetric impact of VMAT in lung cancer compared with 3DCRT is well known and confirmed by several publications. The aim of this study is to quantify these results more accurately in our local ...clinical context, based on thirty-six patients treated with 3DCRT between 2015 and 2017.
For each patient treated with 3DCRT for non-small cell pulmonary tumors with a prescription dose of 2 Gy/daily to 66 Gy, a second VMAT treatment plan was calculated with the Eclipse 13.6 treatment planning system (AAA 13.6.23, Varian®).
Volumetric modulated arc therapy plans were created using either two complete arcs or two partial arcs, depending on the location of the irradiated volume.
The Paddick conformity index and a homogeneity index (D98% -D2%/ Dmoy) were used to compare the doses delivered at the target volume (PTV). Concerning the organs at risk we compared the values of the usual dosimetric parameters used to validate a plan treatment. The volumes of the 5, 10 and 15 Gy isodose lines were compared to investigate the low doses delivered to the body by the two irradiation plans.
The Paddick conformity index for the PTV is 52% greater for VMAT (0.87) than the 3DCRT (0.57) (p < 0.001). The homogeneity of dose is better by 39% in VMAT than in 3DCRT, the homogeneity index being respectively 0.07 and 0.11 (p < 0.001).
For the spinal cord PRV, the average maximum dose is 45.6 Gy in 3DCRT against 19.3 Gy in VMAT (p < 0.001). Heart volume receiving at least 35 Gy (V35) decreased from 15.6% in 3DCRT to 8.28% in VMAT (p < 0.001). Esophageal V50 is also higher in 3DCRT than in VMAT, increasing from 14.03 to 25.45% (p = 0.002).
The mean lung dose is 17.9 Gy in 3DCRT versus 15.5 Gy in VMAT, a decrease of 13% (p = 0.041); the V30 value is 23.6% in 3DCRT and 18.8% in VMAT, an improvement of 20% (p = 0.001). Nevertheless, there is no significant decrease in the V20 value, from 29% in 3DCRT to 24.84% in VMAT (p = 0.105).
With regard to the low doses, it is found that the volumes receiving 5, 10 and 15 Gy, are not significantly different between the two irradiation techniques when the VMAT dosimetry is performed with partial arcs (p> 0.09). On the other hand, the volume receiving 5 Gy is significantly higher by 50% (p = 0.024) in VMAT compared to the 3DCRT for full arcs set up.
The conformity and homogeneity indices at the target volume are improved in VMAT compared to the 3DCRT. The doses received by the organs at risk are significantly reduced, in particular the maximum dose to the spinal cord PRV and the V35 value for the heart, excepting the V20 value in lung which is not significantly smaller although it is an essential parameter in a lung plan evaluation. All these benefits are possible without increasing low doses when using a two partial arcs planning strategy.
La radiothérapie stéréotaxique est une technique de plus en plus usuelle quel que soit la localisation traitée. La radiothérapie stéréotaxique rachidienne nécessite toutefois une technicité ...particulière afin de s’assurer de sa bonne réalisation. Il existe une littérature maintenant importante permettant de définir le type d’imagerie à utiliser, la dose à délivrer et la méthode de délinéation des volumes cible et des organes à risque. Cette technique permet un très bon taux de contrôle local et une efficacité antalgique intéressante. Cependant, sa place vis-à-vis de la radiothérapie classique reste limitée car elle nécessite notamment la réalisation d’une IRM de planification et une prise en charge du patient, lors des séances de traitement, significativement plus longue. Dans ce contexte, elle est actuellement essentiellement réservée aux patients atteints de cancer oligométastatique ou aux ré-irradiations.
Stereotactic radiotherapy is an ever more common technique, regardless of the location treated. However, spinal stereotactic radiotherapy requires a particular technicality in order to ensure its proper realization. There is now a large literature defining the type of imaging to be used, the dose to be delivered and the delineation of target volumes. This technique can achieve a significant local control and an interesting analgesic efficiency. However, its place in relation to conventional radiotherapy remains limited because it requires MRI imaging and a significantly longer patient management during the treatment fraction. In this context, it is currently mainly restricted to oligometastatic patients or for re-irradiations.
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