Manufacturing technology
3D shields – the perfect solution? The use of 3D printing enables clinicians to design a shield that perfectly matches a patient’s individual anatomy. These shields are quicker to create and involve no discomfort for the patient.
In developing 3D-printed shields, James Byrne, assistant professor of radiation oncology at the University of Iowa, and his colleagues spent some time testing different high atomic number (Z) materials to determine which would be most effective at attenuating the radiation dose. Lead proved particularly successful.
Boluses improve radiotherapy treatments by protecting healthy tissue and helping target malignant cells.
boundary of the tumour quite closely.” This makes it possible to “spare several centimetres of healthy tissue at the deep aspect of the tumour, in some situations where you couldn’t before”.
A revolutionary treatment A 2021 review of research on 3D-printed boluses described the technology as “revolutionary in superficial tumour radiotherapy.” It can “reduce the air gap, improve the accuracy and uniformity of dose, better protect normal tissues, and has clear advantages in cost and time efficiencies”. It acknowledged, however, that there was “not yet a consensus about the material choice, and frequency of application”.
Another option for minimising radiation dose to healthy tissues is to create protective shields (or masks). These are typically used for head or neck cancers and are designed to protect the oral cavity, tongue, gums and temporal region. It can, however, be challenging to create shields that conform to the patient’s particular anatomy – if, for example, a patient is missing some teeth. The traditional solution of casting several moulds is expensive, labour-intensive and uncomfortable for the patient.
“They will fit patients, they will optimise radiation dose distributions to patients, and it will provide a much more personalised approach.”
James Robar
Oral stents are also frequently used to keep the mouth open during radiotherapy to move the healthy tissue out of the way of radiation. A hydrogel rectal spacer, placed between the prostate and the rectum, is sometimes used to protect healthy tissue during radiotherapy to treat prostate cancer.
66
The team then used CT scans to create the 3D-printed shields and tested them on rodents to see how effective they were at shielding the oral and prostate tissue during radiation to the oral cavity. The results were impressive: all seven of the control rodents developed gross ulcerations on the tongue, while none of the rodents protected by the shield did. This experiment was followed by tests on pigs to see if the technique was scalable rather than to assess effectiveness.
They then carried out dosimetric modelling to assess how effectively the devices could protect healthy tissue. The modelling revealed that irradiation of oral mucosa in human patients could be reduced by 30% in those undergoing head and neck cancer radiotherapy and by 15% in patients with prostate cancer – without affecting the radiation dose to the tumour. The rectal radioprotectant device was more cost effective than a hydrogel rectal spacer. The technology is some way off being commercially available, but Byrne believes that the sums add up: “I think even though there may be a bigger upfront cost to having this device in place, if we’re able to reduce that degree of toxicity, then it’s going to significantly reduce the cost of the backend, or the care of some of these conditions afterwards.”
The potential of 3D printing in radiotherapy has not yet been exhausted. Robar sees possible uses for the technology in brachytherapy, in which radiation is delivered by a source placed inside the body, either via a catheter or an applicator, to treat a localised cancer. It is commonly used to treat gynaecological cancers, such as cancer of the cervix or endometrium. Standard gynaecological applicators, says Robar, are often “rudimentary”, and he believes that it will be possible to use 3D printing in combination with biocompatible materials to customise each applicator to the individual patient’s body. “They will fit patients, they will optimise radiation dose distributions to patients and it will provide a much more personalised approach,” he says. ●
Medical Device Developments /
www.nsmedicaldevices.com
Adaptiiv
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148 |
Page 149 |
Page 150 |
Page 151 |
Page 152 |
Page 153 |
Page 154 |
Page 155 |
Page 156 |
Page 157 |
Page 158 |
Page 159 |
Page 160 |
Page 161 |
Page 162 |
Page 163 |
Page 164 |
Page 165 |
Page 166 |
Page 167 |
Page 168 |
Page 169 |
Page 170
